1) Synoptic history

The tropical wave that eventually developed into Cindy moved westward across the coast of Africa on 24 June. The wave moved quickly westward for the next three days with little convection. By 28 June, deep convection developed along the northern portion of the wave axis just east of the Lesser Antilles. While the southern portion of the wave broke away and continued westward, the active northern portion moved west-northwestward across the northern Caribbean Sea. On 3 July, thunderstorm activity became more concentrated over the northwestern Caribbean Sea. Surface observations showed the development of a broad low pressure area, and reports from an AFRC aircraft indicated a tropical depression formed at 1800 UTC that day about 70 n mi east of Chetumal, Mexico (Fig. 1).

The depression moved slowly west-northwestward along the southern periphery of a deep-layer subtropical ridge, with the center crossing the east coast of the Yucatan peninsula about 55 n mi north-northeast of Chetumal early on 4 July. The cyclone then turned northwestward and reached the north coast of the Yucatan just east of Merida, Mexico at around 1500 UTC 4 July. A midlevel trough over the central United States dropped southward into the southern plains and the northwestern Gulf of Mexico, causing the depression to accelerate. Although the cyclone was in an environment of moderate southerly shear, it became a tropical storm over the central Gulf of Mexico at 0600 UTC 5 July. Cindy turned northward with some decrease in forward speed. Decreasing shear resulted in steady strengthening, and Cindy became a hurricane at 0000 UTC 6 July about 40 n mi south-southwest of Grand Isle, Louisiana. It maintained hurricane status until it made landfall just southwest of Grand Isle 3 h later.

Cindy turned northeastward and weakened to a tropical storm over extreme southeastern Louisiana. It again made landfall at 0900 UTC 6 July near Ansley, Mississippi, then continued northeastward and weakened to a tropical depression by 1800 UTC that day over southwestern Alabama. Cindy then moved across central Alabama to northern Georgia, where it merged with a frontal system and became an extratropical low. The low moved northeastward along the eastern slopes of the Appalachian Mountains and emerged off the mid-Atlantic coast of United States on 8 July. Over the Gulf Stream, the low turned northeastward and then northward, strengthening to just below gale force near Cape Cod, Massachusetts, on 9 July. It moved inland along the southwestern coast of Maine later that day, then it weakened and moved northeastward across northern Maine and New Brunswick, Canada, on 10 July. The system dissipated over the Gulf of St. Lawrence on 11 July.

2) Meteorological statistics

An automated station operated by Louisiana State University at South Timbalier Block 52 (40.4-m elevation) reported sustained winds of 67 kt at 0100 UTC 6 July, along with a peak gust of 75 kt (Table 4). The moveable semisubmersible oil rig Deepwater Horizon (call sign V7HC9; likely 45–90-m elevation) located 37 n mi east of the center reported a southeast wind of 60 kt at 1700 UTC 5 July. In addition, fixed oil platform South Timbalier (ST-308; 45-m elevation) reported a northwesterly wind gust of 87 kt at around 1800 UTC 5 July. Tropical-storm-force winds were reported at New Orleans Lakefront Airport from 0400 to 0930 UTC 6 July, and tropical storm conditions were reported at other stations along the northern Gulf Coast.

Real-time SFMR data obtained from the NOAA WP-3D aircraft on 5 July at 1821 UTC showed 63–66-kt winds about 13 n mi east of the center. However, poststorm analysis and recalibration by the NOAA/Hurricane Research Division (HRD) indicates the maximum SFMR observed winds were actually 59 kt at that time.

Cindy was operationally assessed to be a tropical storm with 60-kt winds at its Louisiana landfall on 6 July. No aircraft data were available in the last few hours before landfall. However, poststorm analysis of Doppler velocity data from the NWS Slidell, Louisiana, Weather Surveillance Radar-1988 Doppler (WSR-88D) radar indicated Cindy was briefly a 65-kt hurricane. The data showed a narrow but relatively long swath of spotty velocities of at least 71 kt east of the center between 8 500–11 500 ft. These winds were first detected at 2330 UTC 5 July at a distance of about 120 n mi south of the radar site and continued to just inland of the southeastern Louisiana coast a few hours later. The velocities imply, when applying the 90% adjustment factor used for 700-mb aircraft winds, a region of surface wind speeds exceeding 64 kt from 0000 UTC to at least 0220 UTC 6 July.

Cindy generated a storm surge of 4–6 ft above normal tide levels along the coasts of southeastern Louisiana and Mississippi, including Lake Borgne and the south shore of Lake Pontchartrain. Storm surge values of 3–4 ft were reported along the Alabama coast, while a storm surge of 2–3 ft occurred as far west as southwestern Louisiana and as far east as the western Florida panhandle.

Rainfall totals were generally 100–150 mm across southeastern Louisiana, southern Mississippi, and southern Alabama, with a maximum total of 241.3 mm at St. Bernard, Louisiana. Heavy rains triggered flooding across portions of Louisiana, Mississippi, Alabama, and Georgia. Significant rainfall amounts also occurred during the extratropical stage from the Carolinas northward to the mid-Atlantic states. Localized flooding occurred in Virginia, where more than 5 in. of rain fell across a large portion of the Appalachian Mountain region.

In the United States, a total of 33 tornadoes occurred from 5 to 7 July: 8 in North Carolina, 7 each in Alabama and Virginia, 6 in Georgia, 2 in Mississippi, and 1 each in Louisiana, South Carolina, and Maryland. The bulk of the tornadoes formed well after landfall on 6–7 July, which is not uncommon. While the vast majority of the tornadoes were small and short-lived F0s or F1s, a damaging F2 tornado occurred near Hampton, Georgia, on 6 July.

3) Casualty and damage statistics

Cindy directly caused one fatality. An 18-yr-old male was swept to his death in a flooded drainage ditch in Peachtree City, Georgia, on 6 July. An F0 tornado caused one injury in Elmore, Alabama, on 6 July.

In the New Orleans metropolitan area and much of southeastern Louisiana, wind damage occurred to trees, other foliage, and power lines. An estimated 278 000 customers lost electrical power during the event. Storm surge flooding and overwash caused some beach erosion at Grand Isle. The tornadoes caused considerable damage to roofs, mobile homes, and commercial and industrial buildings, with the Hampton tornado causing more than $40 million in damage at the Atlanta Motor Speedway. The PCS estimates the insured property losses in the United States at $160 million. Therefore, total damages in the United States are estimated to be $320 million.

1) Synoptic history

Dennis formed from a tropical wave that moved westward from the coast of Africa on 29 June. A broad low pressure area with two embedded swirls of low clouds formed on 2 July. Convection increased near both low-level centers on 3 July. The western system moved through the southern Windward Islands on 4 July and lost organization over the southeastern Caribbean. The eastern system continued to develop, becoming a tropical depression over the southern Windward Islands near 1800 UTC 4 July (Fig. 1).

The depression initially moved westward over the eastern Caribbean, then it turned west-northwestward on 5 July as it became a tropical storm. Dennis reached hurricane strength early on 7 July south of Hispaniola. It then rapidly intensified into a category 4 hurricane with winds of 120 kt before landfall near Punta del Ingles in southeastern Cuba near 0245 UTC 8 July. During this intensification, the central pressure fell 31 mb in 24 h.

Dennis weakened to a category 3 hurricane over southeastern Cuba. Once offshore in the Gulf of Guacanayabo, the hurricane moved west-northwestward parallel to the south coast of Cuba and again intensified to category 4 strength. Maximum sustained winds reached a peak of 130 kt at 1200 UTC 8 July, then decreased to 120 kt before Dennis made landfall near Punta Mangles Altos, Cuba, near 1845 UTC that day (Fig. 4). Dennis then traversed a long section of western Cuba before emerging into the Gulf of Mexico just east of Havana around 0900 UTC 9 July. Dennis weakened significantly over Cuba, with the maximum sustained winds decreasing to 75 kt by the time the center left the island.

Dennis slowly intensified for the next 6–12 h over the Gulf of Mexico, then began rapid intensification near 1800 UTC 9 July, accompanied by a turn toward the north-northwest. The central pressure fell 37 mb in 24 h, including 20 mb in 6 h and 11 mb in 1 h 35 min. Maximum sustained winds reached a third peak of 125 kt near 1200 UTC 10 July. Thereafter, weakening occurred, likely due to mid-/upper-level dry air from the western Gulf of Mexico entraining into the hurricane. The maximum sustained winds decreased to 105 kt and the central pressure rose to 946 mb before Dennis made landfall on Santa Rosa Island, Florida, between Navarre Beach and Gulf Breeze, at about 1930 UTC 10 July.

Dennis continued north-northwestward after landfall, with the center moving across the western Florida panhandle into southwestern Alabama before it weakened into a tropical storm. It became a depression as it moved into east-central Mississippi on 11 July. The cyclone turned northward later that day and northeastward on 12 July as it moved into the Ohio Valley. On 13 July, Dennis weakened to a low pressure area that meandered over the Ohio Valley through 15 July. The remnants of Dennis accelerated northeastward on 16 July and were absorbed into a larger low over northwestern Ontario on 18 July.

2) Meteorological statistics

The 53rd WRS made 43 center penetrations or “fixes” on Dennis, with NOAA aircraft contributing an additional 10 fixes. The maximum flight-level winds observed at 700 mb were 150 kt at 1325 UTC 8 July. Eyewall dropwindsondes reported 116-kt surface winds at 1515 UTC 10 July and 114 kt at 1705 UTC 8 July. The minimum aircraft-reported central pressure was 930 mb at 1143 UTC 10 July, with a 937-mb pressure measured at 1517 UTC 8 July. The last aircraft-reported pressure near landfall in Florida was 946 mb at 1930 UTC 10 July.

Dennis brought hurricane conditions to portions of southeastern Cuba, and to a swath through central and western Cuba (Table 5). Cabo Cruz reported 116-kt sustained winds with a gust to 129 kt at 0200 UTC 8 July, with a minimum pressure of 956 mb at 0240 UTC just before the eye passed over the station. The anemometer was destroyed, and it is possible stronger winds occurred. Unión de Reyes reported sustained winds of 96 kt with a gust to 107 kt at 2350 UTC 8 July, and there were numerous other reports of sustained hurricane-force winds.

Dennis also brought hurricane conditions to portions of the western Florida panhandle and southwestern Alabama. An instrumented tower run by the Florida Coastal Monitoring Program (FCMP) at Navarre (5-m elevation) measured 1-min average winds of 86 kt and a gust to 105 kt at 1921 UTC 10 July. This tower was a few nautical miles east of the radius of maximum winds. Another FCMP tower at the Pensacola Airport (10-m elevation) measured 1-min average winds of 71 kt with a gust to 83 kt just west of the eye at 1946 UTC. A Florida Automated Weather Network station at Jay reported sustained winds of 62 kt at 1845 UTC.

While hurricane-force winds associated with Dennis covered only a small area near the eye, it had a large cyclonic envelope with tropical-storm-force winds extending well east of the center over Florida. The Coastal Marine Automated Network Station (C-MAN) at Sombrero Key, Florida (48.5-m elevation), reported 2-min average winds of 64 kt with a gust of 76 kt at 0800 UTC 9 July. A National Ocean Service (NOS) station at Panama City Beach, Florida (6.1-m elevation), reported 6-min average winds of 51 kt with a gust to 63 kt at 1800 UTC 10 July. Tropical storm conditions also occurred over the metropolitan areas of southeastern Florida, elsewhere along the Florida west coast and the Florida Big Bend region, over portions of southwestern Alabama, and across Jamaica. Wind gusts to tropical storm force occurred as far inland as eastern Mississippi and as far west as southeastern Louisiana.

The FCMP tower at the Pensacola Airport measured a pressure of 956.3 mb at 1943 UTC 10 July, while the FCMP tower in Navarre measured a pressure of 965.2 mb at 1909 UTC that day. A storm chaser in Pace, Florida, unofficially measured a pressure of 945 mb at 1910 UTC 10 July as the eye passed over.

Dennis produced a storm surge of 6–7 ft above normal tide levels on Santa Rosa Island near where the center made landfall. This surge washed over Santa Rosa Island near and west of Navarre Beach. A storm surge of 6–9 ft above normal tide levels occurred in Apalachee Bay, Florida (roughly 150 n mi east of the landfall area), which inundated parts of the town of St. Marks and other nearby areas. This surge was higher than known wind reports would support, and roughly 3.5 ft higher than the surge forecast from the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. This surge was likely triggered by an oceanic trapped shelf wave that propagated northward along the Florida west coast. Modeling by the Center for Ocean–Atmospheric Prediction Studies at The Florida State University suggest this remotely generated sea level rise added 3–4 ft to the surge in and around Apalachee Bay (Morey et al. 2006). A storm surge of 4–6 ft occurred elsewhere along the Florida panhandle. Storm surges of 3–5 ft above normal tide levels occurred elsewhere along the Florida west coast, in the Florida Keys, and along the coast of Alabama. Storm tides of 2–4 ft above normal were reported along the coasts of Mississippi and southeastern Louisiana. Storm surge data from Cuba are not available.

Dennis produced widespread heavy rainfall over Cuba. Topes de Collantes reported a 24-h total of 702.8 mm, while Las Piedra reported a 24-h total of 384.3 mm. Storm totals for both places were likely higher. Rainfall of 150–300 mm was reported from other Cuban stations. Very heavy rains also occurred in Jamaica, where Mavis Bank reported a storm total of 623.3 mm and Shirley Castle reported a total of 591.1 mm. In the United States, Dennis produced widespread heavy rainfall along the track from the western Florida panhandle to the Ohio Valley, and east of the track in Georgia and the remainder of Florida. A station 8 n mi northwest of Camden, Alabama, reported a storm-total rainfall of 325.1 mm, while Monticello, Florida, reported 176.5 mm.

Dennis caused nine tornadoes in Florida and one in Georgia. All were rated F0 except for an F1 near Bradenton, Florida. Additionally, numerous strong squalls occurred in the outer bands of Dennis over southern Florida. These squalls produced a gust of 73 kt at the Fowey Rocks C-MAN station and a gust of 63 kt at Chekika in southern Miami-Dade County.

3) Casualty and damage statistics

Reports from the Meteorological Service of Jamaica and the media indicate that Dennis was directly responsible for 42 deaths—22 in Haiti, 16 in Cuba, 3 in the United States, and 1 in Jamaica. The fatalities in the United States included a drowning on a sunken boat in the Florida Keys, a drowning in rough surf at Dania Beach, Florida, and a man crushed by a falling tree near Atlanta, Georgia. Dennis was also indirectly responsible for 12 deaths in Florida—2 from electrocution, 2 from carbon monoxide poisoning, 4 from automobile accidents, 2 accidental falls during cleanup, and 2 cases of natural causes exacerbated by storm stress.

The PCS estimates the insured property damage in the United States at $1.115 billion. Therefore, the total U.S. damage estimate for Dennis is $2.23 billion. The Meteorological Service of Jamaica estimates the damage from Dennis at $1.9 billion Jamaican (approximately $31.7 million U.S.).

1) Synoptic history

Emily developed from a tropical wave that moved across the west coast of Africa on 6 July. The wave was associated with a large area of cyclonic vorticity and disturbed weather while it crossed the eastern tropical Atlantic. Shower activity became more concentrated on 10 July, and by 0000 UTC 11 July the system had become a tropical depression about 1075 n mi east of the southern Windward Islands (Fig. 1).

The depression moved westward to the south of a narrow ridge. Initial development was slow because of modest easterly shear and a relatively dry environment. Although the circulation remained broad and somewhat ill defined, the system became a tropical storm at 0000 UTC 12 July about 800 n mi east of the southern Windward Islands. Emily accelerated westward on 12 July due to a low-level easterly surge. This surge enhanced the dry environment and produced some westerly shear that appeared to prevent further convective organization. On 13 July, however, with the core convection still disorganized, the central pressure hovering near 1003 mb, and flight-level winds showing little change, visual estimates of the sea state suggested increasing surface winds. Aircraft center fixes at 2331 UTC 13 July and 0112 UTC 14 July suggested that the center of circulation reformed northeast of its previous position within the convection. It is estimated that Emily became a hurricane at about this time when centered about 85 n mi east-southeast of Grenada. The convective pattern became much more symmetric and organized over the next several hours, and Emily’s maximum winds increased to near 75 kt by the time the center passed over Grenada near 0700 UTC 14 July.

Emily entered the Caribbean Sea and turned west-northwestward, maintaining this heading for the next week as midlevel high pressure built westward to the north of the hurricane. It continued to strengthen, with its peak winds reaching 115 kt (category 4) and its minimum pressure falling to 952 mb early on 15 July. Near 1200 UTC an AFRC aircraft reported concentric eyewalls of 8 and 25 n mi diameter, and by 1800 UTC Emily had weakened to category 2 strength. A second strengthening phase began almost immediately, however, and continued on 16 July while Emily passed about 90 n mi south of Jamaica. Emily became a category 5 hurricane, with winds of 140 kt and a minimum pressure of 929 mb, at 0000 UTC 17 July about 100 n mi southwest of Jamaica (Fig. 5).

Emily began to slowly weaken on 17 July in the western Caribbean Sea, this time in the absence of concentric eyewalls but also without any obvious external synoptic forcing. It was still a category 4 hurricane, with winds of 115 kt, when the eyewall passed over Cozumel and when the center made landfall on the Yucatan peninsula near Tulum at 0630 UTC 18 July. Emily quickly cut across the Yucatan, emerging into the Gulf of Mexico near 1200 UTC that day while just maintaining hurricane strength.

Once over water, Emily began its third and final intensification phase as it continued west-northwestward. Because of the broad overall circulation, Emily strengthened slowly for the first 24 h or so over the Gulf, its winds increasing to 80 kt by 1200 UTC 19 July. Over the next 12 h, however, a sharp inner wind maximum developed, the minimum pressure fell 29 mb, and maximum winds increased to near 110 kt. Early on 20 July as Emily neared the coast, data from land-based radars and reconnaissance aircraft showed a well-defined concentric eyewall structure, with the strongest flight-level winds associated with the outer feature. Intensification stopped and Emily made landfall near San Fernando, Mexico at 1200 UTC 20 July as a category 3 hurricane with winds of near 110 kt. After landfall, Emily turned westward and weakened rapidly, dissipating on 21 July over the Sierra Madre Oriental of Mexico.

2) Meteorological statistics

Emily’s peak intensity is estimated to be 140 kt, based on 700-mb flight-level winds of 153 kt observed at 0324 UTC 17 July. Application of the standard 90% adjustment gives a surface estimate of 138 kt—just above the category 5 threshold. Two surface-adjusted flight-level observations of 136 kt during the preceding several hours also met the category 5 threshold. An eyewall dropwindsonde reported an instantaneous surface wind of 136 kt at 0536 UTC 17 July, although surface estimates inferred from layer averages of the dropwindsonde profile were near 115 kt. The lowest aircraft-reported central pressure reported was 929 mb, at 2341 UTC 16 July.

Emily’s intensity on 13–14 July was particularly difficult to assess. Flight-level winds near 1200 UTC 13 July implied an intensity near 45 kt, while visual sea-state observations by the AFRC aircrew suggested surface winds near 55 kt. Later, near 0100 UTC 14 July, an AFRC aircraft reported an 850-mb flight-level wind of 79 kt, which corresponds to 63 kt at the surface using typical adjustment factors. Concurrent with this latter observation was a dropwindsonde that suggested surface winds were near 80 kt. It is possible that during this intensification phase the surface winds were leading the winds aloft.

Emily passed directly over Grenada. Point Salines International Airport, just south of the path of the center, reported a peak gust of 58 kt (Table 6). The northeastern tip of Grenada, as well as the smaller islands of Carriacou and Petite Martinique to the northeast, bore the brunt of the hurricane, but no wind measurements from these areas are available.

Heavy rains from Emily affected Jamaica, with the heaviest accumulations occurring in St. Elizabeth Parish on the southwestern part of the island. Potsdam reported 391.9 mm of rainfall, with other reports in excess of 250 mm.

At 0509 UTC 18 July, as the eyewall passed over Cozumel, an AFRC aircraft a few nautical miles offshore measured a 700-mb flight-level wind of 124 kt. A flight-level wind of 141 kt was reported 2 h earlier. These are the basis for the 115-kt intensity for the Yucatan landfall. No wind observations are available from the landfall area. An unofficial report received via amateur radio estimated a 15-ft storm surge in San Miguel on Cozumel. Official rainfall totals on the Yucatan were generally close to 25 mm, although there was an unofficial report from Cozumel of 124.4 mm.

No surface data are available at the coast for Emily’s final landfall. An automated station at San Fernando, located about 30 n mi inland from the landfall location, reported a 10-min sustained wind of 55 kt, a gust to 84 kt, and a minimum pressure of 965 mb. There were several reports from northeastern Mexico of rainfall in excess of 250 mm, with 350.0 mm reported at Cerralvo. No estimates of storm surge at the final landfall were received.

In Texas, there were a few reports of sustained tropical-storm-force winds, with the highest sustained wind reported at Harlingen. Minor coastal flooding occurred in south Texas, with estimated storm tides in the 4–5-ft range. Moderate beach erosion was reported in Cameron County. Eleven tornadoes were reported in southeastern Texas.

3) Casualty and damage statistics

The Caribbean Disaster Emergency Response Agency reports that in Grenada damage was concentrated in the northern parishes of St. Patrick’s and St. Andrew’s, where many homes lost their roofs, and on the outlying islands of Petite Martinique and Carriacou, where the island’s only hospital suffered roof damage, forcing the evacuation of patients to another portion of the building. There were also scattered reports of flooding, and media reports mention the destruction of crops. There was some roof damage in St. Vincent, the Grenadines, and Tobago.

Playa del Carmen, Tulum, and the island of Cozumel were hardest hit during Emily’s first landfall in Mexico, although the reported damage was unexpectedly light, suggesting that Emily’s strongest winds were extremely limited in extent. The winds, however, were strong enough to snap concrete utility poles between Playa del Carmen and Cancun. Water was knee-deep in some streets. At Emily’s second landfall in northern Mexico, officials reported that 80%–90% of the homes in the fishing community of Laguna Madre were destroyed. Elsewhere near the landfall site, the storm drove 90 000 people from their homes, and thousands of buildings were reported destroyed.

In Texas, damage was minor; there were reports of tree damage in the Brownsville area and scattered minor roof damage on South Padre Island.

Six deaths were directly attributed to Emily. One fatality occurred in a Grenada mudslide. In southwestern Jamaica, four people in a car were driving through a flooded roadway when a surge of water pushed them over a cliff. One person assisting the motorists also perished. Amazingly, there were no deaths directly attributable to Emily’s two landfalls in Mexico, although a helicopter crash before the storm claimed two lives. Massive evacuations, which by some estimates involved nearly 100 000 people, mostly tourists, undoubtedly contributed to the lack of casualties.

1) Synoptic history

The complex genesis of Katrina involved the interaction of a tropical wave, the midtropospheric remnants of Tropical Depression 10, and an upper-tropospheric trough. This trough, located over the western Atlantic and the Bahamas, produced strong westerly shear across Tropical Depression 10, causing it to degenerate on 14 August approximately 825 n mi east of Barbados. The remnant low-level circulation weakened, becoming an open wave on 18 August and dissipating near Cuba on 21 August. Meanwhile, a midtropospheric circulation originating from the depression lagged behind and passed north of the Leeward Islands on 18–19 August. A tropical wave, which departed the west coast of Africa on 11 August, moved through the Leeward Islands and merged with the midtropospheric cyclone on 19 August. The merger produced a large area of showers and thunderstorms north of Puerto Rico. This activity moved slowly northwestward, passing north of Hispaniola and then consolidating just east of the Turks and Caicos on 22 August. Dvorak satellite classifications began at 1800 UTC that day. The upper-tropospheric trough weakened as it moved westward, and the shear relaxed enough to allow the formation of a tropical depression by 1800 UTC 23 August over the southeastern Bahamas about 175 n mi southeast of Nassau (Fig. 1).

The depression became better organized over the central Bahamas that evening, and convective banding increased early on 24 August. The cyclone became a tropical storm at 1200 UTC that day about 65 n mi east-southeast of Nassau. Initially, Katrina moved northwestward within a weakness in the lower-tropospheric subtropical ridge. However, as it developed an inner core and greater vertical depth, a strengthening mid- to upper-tropospheric ridge over the northern Gulf of Mexico and southern United States dominated the steering and turned Katrina westward on 25 August. An intense burst of deep convection developed over the center that afternoon, which led to Katrina becoming a hurricane near 2100 UTC 25 August.

The strengthening ridge steered the cyclone west-southwestward as it neared southern Florida. Katrina made its first landfall in the United States as a category 1 hurricane with 70-kt winds near the border of Miami-Dade County and Broward County around 2230 UTC 25 August. A well-defined eye became evident on the NWS Miami WSR-88D just prior to landfall. This feature became better defined during landfall and remained intact during its 6-h track across the peninsula. The convective pattern of Katrina over southern Florida was asymmetric because of northerly shear, which placed the strongest winds and heaviest rains south and east of the center in Miami-Dade County. Katrina briefly weakened to a tropical storm over mainland Monroe County, with the center emerging into the southeastern Gulf of Mexico at approximately 0500 UTC 26 August just north of Cape Sable. The cyclone regained hurricane strength an hour later.

A large upper-level anticyclone dominated the Gulf of Mexico, resulting in weak wind shear and increasingly efficient upper-level outflow. This allowed two periods of rapid intensification during 26–28 August. The first period saw maximum sustained winds increase from 65 to 95 kt in the 24-h period ending 0600 UTC 27 August. An eye appeared in infrared satellite imagery early on 27 August, and Katrina became a category 3 hurricane at 1200 UTC that day about 365 n mi southeast of the mouth of the Mississippi River. Intensification then temporarily stopped as the hurricane underwent an eyewall replacement cycle. Accompanying these developments was a significant expansion of the wind field. Based on the radii of tropical-storm-force winds, Katrina nearly doubled in size on 27 August, and by the end of that day those winds extended up to 140 n mi from the center. The mid- to upper-tropospheric ridge shifted eastward toward Florida, while a midlatitude trough amplified over the north-central United States. This evolving pattern resulted in a general westward motion on 27 August and a turn toward the northwest on 28 August when Katrina moved around the western periphery of the ridge. The new eyewall evolved into a sharply defined ring by 0000 UTC 28 August at the start of the second period of rapid intensification. Katrina strengthened from category 3 to category 5 in less than 12 h, reaching an intensity of 145 kt by 1200 UTC 28 August. It reached a peak intensity of 150 kt 6 h later (Fig. 6) while centered about 170 n mi southeast of the mouth of the Mississippi River. The wind field expanded further on 28 August, and by late that day tropical-storm-force winds extended out about 200 n mi from the center, while hurricane-force winds extended out about 90 n mi. This made Katrina exceptionally large as well as extremely intense.

Katrina turned northward toward the northern Gulf Coast early on 29 August and weakened. The hurricane made landfall at 1110 UTC that day near Buras, Louisiana, with estimated maximum sustained winds of 110 kt (category 3). Katrina continued northward and made its final landfall near the mouth of the Pearl River at the Louisiana–Mississippi border at 1445 UTC with an estimated intensity of 105 kt (category 3).

Katrina’s weakening during the last 18 h or so before the first Gulf Coast landfall was primarily due to the deterioration of the inner eyewall and the partial development of a new outer eyewall. Additional possible factors include entrainment of dry air over the western semicircle, gradually increasing wind shear, slightly lower SSTs, and (following the first Gulf landfall) interaction with land. Extensive investigation is required to assess their relative roles. Other major hurricanes approaching the northern Gulf Coast have weakened when one or more of these factors were present. Indeed, since 1980 all 11 hurricanes having a central pressure less than 973 mb 12 h before landfall in the northern Gulf of Mexico weakened during these last 12 h. (Conversely, in that time all 11 hurricanes having a central pressure higher than 973 mb 12 h before landfall in the northern Gulf of Mexico have strengthened.) It should be noted that Katrina remained very large as it weakened, as the extent of tropical-storm-force and hurricane-force winds changed little between late on 28 August and the final landfall.

Katrina continued to weaken over Mississippi, becoming a category 1 hurricane by 1800 UTC 29 August and a tropical storm 6 h later. It accelerated northeastward on 30 August between the ridge over the southeastern United States and the eastward-moving trough over the Great Lakes. Katrina became a tropical depression at 1200 UTC 30 August over the Tennessee Valley, with the depression becoming extratropical by 0000 UTC 31 August. The extratropical low was absorbed by a frontal zone later that day over the eastern Great Lakes.

2) Meteorological statistics

Selected surface observations from land stations and from coastal and fixed ocean data buoys are given in Table 7. Data from many Automated Surface Observing System (ASOS) sites, C-MAN stations, and buoys are incomplete because of power outages and other weather-induced failures.

Katrina was almost continuously monitored by aircraft from genesis until final landfall. The 53rd WRS flew 12 missions, which produced 46 center fixes. NOAA/AOC WP-3D aircraft flew three missions, producing 19 center fixes, real-time data from the SFMR, and airborne Doppler radar–derived wind analyses provided by the HRD. Additionally, the NOAA G-IV jet conducted six synoptic surveillance missions during 24–29 August. A 53rd WRS aircraft conducted one surveillance mission jointly with the G-IV on 25 August.

Radar velocity data from the Miami WSR-88D, along with 65-kt winds measured by the SFMR, indicated that Katrina became a hurricane at 2100 UTC 25 August. Subsequent radar velocity data were the basis for the Florida landfall intensity. The eye passed over the NWS Miami WFO/NHC, where a pressure of 983 mb was measured at 0105 UTC 26 August. The eastern eyewall then moved over the facility, with sustained winds of 60 kt and a gust to 76 kt measured near 0115 UTC. The strongest sustained wind measured in southeastern Florida was 63 kt on Virginia Key. Velocities from the Miami and Key West radars suggest that Katrina weakened to a tropical storm over mainland Monroe County. However, these data and Dvorak intensity estimates showed it regained hurricane strength upon reaching the Gulf of Mexico. The C-MAN station at Dry Tortugas, Florida (6-m elevation), reported hurricane-force winds for 2 h on 26 August, with 2-min average winds of 71 kt and a gust to 91 kt at 2000 UTC that day. The station reported a pressure of 974.4 mb at that time. The remainder of the Florida Keys experienced sustained tropical-storm-force winds with peak gusts of 60–70 kt on 26 August. Katrina also caused tropical storm conditions in portions of western Cuba on 27 August, with gusts as strong as 54 kt and some rainfall totals exceeding 200 mm.

During Katrina’s second period of rapid intensification, aircraft observations indicate the central pressure fell 32 mb in 12 h, to 909 mb by 1200 UTC 28 August. The central pressure fell to 902 mb about 6 h later. The strongest 700 mb flight-level wind was 166 kt near 1400 UTC that day, corresponding to about 150 kt at the surface using the standard 90% adjustment. Dropwindsonde surface wind estimates, derived from the mean wind over the lowest 150 m of the sounding, were 130–135 kt, but a few sondes directly measured 140–143-kt spot winds at the surface (10 m). No sondes were released where the flight-level winds were 166 kt, and it is thus unlikely the sondes measured the maximum surface wind. The SFMR, using a poststorm recalibration to correct a previous low bias at extremely high wind speeds, estimated surface winds as strong as 141 kt on the afternoon of 28 August, when maximum 700-mb flight-level winds were about 160 kt. These data indicate that, on average, the standard 90% adjustment was valid until late on 28 August.

By the time of the initial Louisiana landfall, Katrina’s central pressure had risen to 920 mb. Maximum 700-mb flight-level winds were 130–135 kt east of the eye around that time, which agreed well with NWS Slidell radar velocity data. Poststorm analysis of dropwindsondes, flight-level winds, and SFMR data suggest the flight-level to surface wind adjustment on 29 August was closer to 80% or perhaps even less. Further evidence of this change comes from airborne Doppler radar–derived wind speed cross sections obtained from the NOAA aircraft (Fig. 7). These data reveal an unusual, broad, and elevated wind maximum in the 2–4-km layer (centered near the 700-mb flight level), well above the more typical location of the maximum wind near the top of the boundary layer (∼500 m) seen on 28 August.

The estimated intensity of 110 kt at the Buras landfall is very low relative to other Atlantic hurricanes with comparable minimum central pressures. In fact, the central pressure of 920 mb is the lowest of record in the basin for that intensity, surpassing Hurricane Floyd (1999; Lawrence et al. 2001), which at one point had a central pressure of 930 mb with an intensity of 110 kt. Application of the Holland (1980) wind model using the central pressure of 920 mb, the concurrently observed outermost pressure of 1006 mb, and the B parameter set to 1 yields an intensity of 102 kt, so the estimated landfall intensity is within Holland’s analytical bounds. Katrina’s combination of relatively weak winds and low pressure resulted from a broadening of the pressure field on 29 August that decreased the pressure gradient, along with a general weakening of the convection that likely reduced momentum mixing of winds aloft down to the surface. The 920-mb pressure is the third lowest at U.S. landfall of record, behind only Hurricane Camille in 1969 (909 mb; Simpson et al. 1970) and the 1935 Labor Day hurricane that struck the Florida Keys (892 mb; McDonald 1935).

It should be noted that Katrina was likely at category 4 strength a couple of hours before the first Louisiana landfall. Because of a large radius of maximum winds, it is possible that sustained winds of category 4 strength briefly impacted the extreme southeastern tip of Louisiana before landfall.

The central pressure in Katrina rose to 928 mb before the final landfall near the Louisiana–Mississippi border at about 1445 UTC. However, aircraft data indicated only a slight decrease in the winds between the first and last Gulf Coast landfalls.

The strongest sustained wind measured from a fixed location at the surface on the morning of 29 August was 76 kt at 0820 UTC by the C-MAN station at Grand Isle (16-m elevation). The anemometer failed near 0900 UTC, about 2 h before closest approach of the eye. The Southwest Pass, Louisiana, C-MAN station (30-m elevation) measured a sustained wind of 71 kt at 0420 UTC, with the station failing because of storm surge about 4 h prior to the closest approach of the eye. The strongest reported wind gust, although unofficial, was 117 kt in Poplarville, Mississippi, at the Pearl River County Emergency Operations Center (EOC). A gust to 108 kt was reported in Pascagoula, Mississippi, at the Jackson County EOC, and a gust to 106 kt was reported by an amateur radio operator at Long Beach, Mississippi. The strongest gust from an official reporting station was 99 kt at the Grand Isle C-MAN station at 0838 UTC 29 August.

When the eye of Katrina passed about 20 n mi east of downtown New Orleans, winds of category 3 intensity were likely present only over water east of the eye. Wind speeds in New Orleans are speculative because of sparse observations and incomplete data records. A few instrumented towers placed in the metropolitan area by the FCMP and by Texas Tech University measured sustained winds in the range of 61–68 kt. The Mid-Lake Pontchartrain NWS site (16-m elevation), located along the Lake Pontchartrain Causeway about 8 n mi north of the south shore of the lake, measured a 1-min average wind of 68 kt. Even though these sites likely did not sample the maximum wind in the area, the Mid-Lake Pontchartrain site had open marine exposure, unlike most locations in the city of New Orleans. The NASA Michoud Facility (about 12-m elevation) measured a peak gust of 107 kt, and a nearby chemical facility (about 9-m elevation) measured a peak gust of 104 kt. Overall, it appears likely that most of the city experienced sustained surface winds of category 1 or category 2 strength.

Precise measurements of Katrina’s storm surge along the northern Gulf Coast were complicated by many factors, including the widespread failures of tide gauges and destruction of coastal buildings that could have provided still-water marks. Despite this, high water marks were located and analyzed along the Louisiana, Mississippi, and Alabama coasts under the direction of the Federal Emergency Management Agency (FEMA). These data indicate that the storm surge was about 24–28 ft along the Mississippi coast across a swath about 15–20 n mi wide, centered roughly on St. Louis Bay. The highest observed storm surge was 27.8 ft at Pass Christian, on the immediate Gulf Coast just east of St. Louis Bay. A storm surge of 17–22 ft occurred along the eastern Mississippi coast, roughly from Gulfport to Pascagoula. The surge appears to have penetrated at least 5 n mi inland in many portions of coastal Mississippi and up to 10 n mi inland along bays and rivers. It crossed Interstate 10 in many locations. A lesser, but still significant, storm surge of 10–15 ft occurred along the open coast in Mobile County, Alabama, including Dauphin Island. Surge heights of 8–12 ft were seen in Mobile Bay, particularly along the northern and western shores where flooding occurred several nautical miles inland. Katrina caused a storm surge of up to 10 ft along the coast of Baldwin County, Alabama.

A significant storm surge also occurred west of the path of the eye. The level of Lake Pontchartrain rose, and a 12–16-ft storm surge occurred along its northeastern shore in St. Tammany Parish, including communities from Slidell to Mandeville, Louisiana. A storm surge of 15–19 ft was documented in eastern New Orleans, St. Bernard Parish, and Plaquemines Parish, while a surge of 10–14 ft occurred in western New Orleans along the southern shores of Lake Pontchartrain. Farther west, surge heights reached 5–10 ft along the shores of western Lake Pontchartrain. The surge severely strained the levee system in the New Orleans area, with several levees and floodwalls being overtopped and/or breached. Overtopping occurred along large sections of the levees east of New Orleans, in Orleans Parish and St. Bernard Parish, while a breach occurred along the Industrial Canal east of downtown New Orleans. The Lake Pontchartrain surge caused breaches along the London Avenue Canal north of downtown New Orleans and the 17th Street Canal northwest of downtown. As a result, about 80% of the city of New Orleans flooded, with depths up to about 20 ft, within a day or so after landfall. Following setbacks caused by additional flooding associated with the passage of Hurricane Rita, the Army Corps of Engineers reported on 11 October 2005, 43 days after Katrina’s landfall, that all floodwaters had been removed from the city of New Orleans.

The massive water rise produced by Katrina, which was greater than would be expected for a “normal” category 3 hurricane, was due to two factors. The first was Katrina’s large size. The radius of maximum winds at the Gulf Coast landfall was about 25–30 n mi, and hurricane-force winds extended at least 75 n mi east of the center. By comparison, Camille, which made landfall in the same area along a similar path, was more intense but far more compact. Camille produced storm surge values comparable to Katrina’s along a narrower swath. Second, Katrina had already generated large northward-propagating swells, leading to substantial wave setup along the northern Gulf Coast. NOAA buoy 42040, located 64 n mi south of Dauphin Island, reported a significant wave height (defined as the average of the one-third highest waves) of 30 ft as early as 0000 UTC 29 August and measured a peak significant wave height of 55 ft at 1100 UTC that day. This matches the largest significant wave height ever measured by a NOAA/National Data Buoy Center buoy.

Katrina also produced storm surge in Florida. Surge heights ranged from up to about 6 ft along the coast of the western Florida panhandle to about 1–2 ft along most of the west-central coast of Florida. A 2–4-ft surge occurred along the extreme southwestern Florida coast. A storm surge of about 2 ft was reported at Key West as Katrina passed to the north on 26 August. Similar surge was reported along portions of the southeastern coast of Florida.

Rainfall distributions associated with Katrina across southern Florida were highly asymmetric about the storm track, with the greatest amounts occurring south of the center. Rainfall totals from Miami-Dade County include 414.8 mm at Perrine, 356.6 mm at Homestead Air Force Base, 311.2 mm at Florida City, and 282.7 mm at Cutler Ridge. Rainfall amounts north of the center over northern Miami-Dade County and Broward County were generally 50–100 mm. Rainfall amounts over interior and western portions of the southern Florida peninsula generally ranged from 25 to 75 mm.

Precipitation amounts during the landfall along the northern Gulf Coast were greatest along and just west of the track of the center. A large swath of 200–250-mm amounts fell across southeastern Louisiana and southwestern Mississippi, with an area of 250–300 mm over eastern Louisiana, including 295.4 mm at the Slidell, Louisiana, WFO. Katrina also produced rainfall amounts of 100–200 mm well inland over Mississippi and portions of the Tennessee Valley.

Katrina produced 43 reported tornadoes. One tornado was reported in the Florida Keys on the morning of 26 August. On 29–30 August, 20 tornadoes were reported in Georgia, 11 in Alabama, and 11 in Mississippi. The Georgia tornadoes were the most in that state for any single day in August.

3) Casualty and damage statistics

Katrina’s size and power, combined with the particular vulnerability of the northern Gulf Coast to storm surge, led to loss of life and property damage of immense proportions. The scope of human suffering inflicted by Hurricane Katrina in the United States has been greater than that of any hurricane to strike this country in several generations.

The total number of known fatalities, either directly or indirectly related to Katrina, is 1833, based on reports from state and local officials: 1577 in Louisiana, 238 in Mississippi, 14 in Florida, 2 in Georgia, and 2 in Alabama. The total number of fatalities directly related to the forces of Katrina is estimated to be about 1500, with about 1300 of these in Louisiana, about 200 in Mississippi, 6 in Florida, and 1 in Georgia. Especially for Louisiana and Mississippi, the number of direct fatalities is highly uncertain and the true number will probably never be known. Several hundred persons are still reported missing in association with Katrina.

Presumably, most fatalities in Louisiana were directly caused by the widespread storm-surge-induced flooding in the New Orleans area. However, several indirect fatalities in Louisiana have been confirmed or are suspected, and some deaths included in the total might not be related to Katrina at all. Persons of more than 60 yr of age constituted the majority of the Katrina-related fatalities in Louisiana. The vast majority of the fatalities in Mississippi probably were directly caused by the storm surge and waves in the three coastal counties. In Florida, three direct fatalities were caused by downed trees in Broward County, with three others due to drowning in Miami-Dade County. A tornado caused one death in Georgia, with a second in a car accident indirectly related to the storm. Alabama reported two indirect fatalities in a car accident during the storm. While inland freshwater floods have produced the majority of fatalities due to tropical cyclones during the past few decades, Katrina provides a grim reminder that storm surge still poses the greatest potential cause for large loss of life in hurricanes.

Where Katrina ranks among the deadliest hurricanes of record in the United States is somewhat uncertain. Katrina is surpassed by the Galveston, Texas, hurricane in 1900 that claimed at least 8000 lives, and by the 1928 Lake Okeechobee, Florida, hurricane with over 2500 fatalities. If the estimated number of directly caused fatalities is correct, then Katrina ranks as the third deadliest hurricane in the United States since 1900, and the deadliest in 77 yr. Two hurricanes in 1893 might each have been directly responsible for more fatalities in the United States than Katrina. One struck the southeastern Louisiana barrier island of Cheniere Caminanda and killed about 2000 people, while the other struck Georgia and South Carolina and claimed between 1000 and 2000 lives. Thus, Katrina ranks fourth or fifth on the list of the deadliest hurricanes of record in the United States.

The extent, magnitude, and impacts of the damage caused by Katrina are staggering beyond the scope of this paper. Thousands of homes and businesses throughout entire neighborhoods in the New Orleans metropolitan area were destroyed by flood. Wind damage also occurred in the New Orleans area, including downtown where windows in some high-rise buildings were blown out and the roof of the Louisiana Superdome was partially peeled away. The storm surge obliterated entire coastal communities along the Mississippi coast, with little more than the foundations of homes, businesses, government facilities, and historical buildings left in some areas. The surge over Dauphin Island destroyed or damaged dozens of beachfront homes and cut a new inlet through the island’s western end. The heavy rains in southern Florida flooded some neighborhoods, primarily in Miami-Dade County. Some structures from Florida and Georgia westward to Louisiana that avoided surge or freshwater floods were damaged by strong winds (Mississippi and Alabama) and tornadoes (Georgia, Mississippi, Alabama, Florida). Katrina left about three million people without electricity, some for several weeks.

The economic and environmental ramifications of Katrina were widespread and could be long-lasting, because of impacts on large population and tourism centers, the oil and gas industry, and transportation. The hurricane severely damaged or destroyed workplaces along the northern Gulf Coast, resulting in thousands of lost jobs and millions of dollars in lost tax revenues for the impacted communities and states. Many severely impacted areas along the northern Gulf Coast could take years to completely rebuild. Large numbers of evacuees have not returned home, producing a shortage of workers for businesses that have reopened. A significant percentage of U.S. oil refining capacity was disrupted due to flooded refineries, crippled pipelines, and rigs or platforms damaged, set adrift, or capsized. Several million gallons of oil spilled from damaged facilities in southeastern Louisiana. Key transportation arteries were disrupted or cut off by the hurricane. Traffic along the Mississippi River was below normal capacity for at least two weeks following the storm. Major highways into and through New Orleans were blocked by floods. Major bridges along the northern Gulf Coast were destroyed, including several in Mississippi and the Interstate 10 Twin Span Bridge connecting New Orleans and Slidell. Major beach erosion occurred along the tourism-dependent coasts of Mississippi and Alabama.

The PCS estimates that Katrina is responsible for $40.6 billion of insured losses in the United States. The total estimated damage cost of Katrina in the United States is thus about $81 billion. This figure makes Katrina the costliest hurricane in U.S. history. Even after adjusting for inflation, the estimated total damage of Katrina is roughly double that of Hurricane Andrew (1992; Blake et al. 2005).

Data provided by FEMA indicate that over 1.2 million people along the northern Gulf Coast from southeastern Louisiana to Alabama were under some type of evacuation order, but it is unclear how many people actually evacuated. Media reports indicate that many displaced residents moved either temporarily or permanently to other areas in the United States. It is also reported that many of these people may never return to their pre-Katrina homes or cities. Thousands of people remained displaced from their homes as of this writing.

1) Synoptic history

Ophelia formed from a nontropical weather system. A cold front moved off the eastern coast of the United States on 1 September. The front moved southeastward and became part of an elongated trough of low pressure extending from Tropical Depression Lee east of Bermuda to near the Florida peninsula. Two areas of low pressure formed in the trough on 4 September. The eastern low became Hurricane Nate. The western low, near the Bahamas, became Ophelia.

The pre-Ophelia low initially drifted southward. It began a northward drift on 5 September while the associated shower activity became better organized. Based on satellite, surface, and radar observations, it is estimated the low became a tropical depression near 0600 UTC 6 September between Andros and Grand Bahama Islands (Fig. 1). The depression continued generally northward, with the center crossing Grand Bahama about 1600 UTC 6 September. It then moved north-northwestward parallel to the east coast of Florida, reaching a position about 70 n mi east-northeast of Cape Canaveral on 7 September. The cyclone became a tropical storm early on 7 September, and gradual strengthening occurred during the next 24 h as Ophelia made a slow counterclockwise loop off the Florida east coast. Steering currents were weak at this time, as Ophelia remained embedded in a broad trough that extended from Hurricane Maria east of Bermuda through the developing Nate and Ophelia and across Florida.

Ophelia was briefly a hurricane late on 8 September. A similar short-lived hurricane phase occurred late on 9 September while Ophelia moved east-northeastward away from Florida. Ophelia became a hurricane for a third time on 10 September, this time reaching an intensity of 75 kt and maintaining hurricane status for 36 h. The cyclone made a slow clockwise loop on 11–12 September, and it is possible that weakening back to a tropical storm on 12 September was due to Ophelia passing over its wake of upwelled cooler waters. After completing the loop, the storm drifted northwestward on 13 September.

Ophelia moved slowly northward early on 14 September and became a hurricane for the fourth time. A gradual turn toward the north-northeast brought the northern portion of the 50 n mi wide eye over the coast of North Carolina near Cape Fear later that day, although the actual center of circulation stayed offshore. Ophelia moved generally east-northeastward parallel to the North Carolina coast for much of 14–15 September, with the northern eyewall passing over the coastal area from Wilmington to Morehead City. During this time, the hurricane again reached an intensity of 75 kt.

Ophelia turned eastward late on 15 September while its center was south of Cape Hatteras. A combination of increasing vertical shear and dry air intrusion caused weakening, and Ophelia became a tropical storm early on 16 September. As an upper-level trough and associated surface front approached from the west, the storm turned northeastward and accelerated late on 16 September. This motion brought the center about 60 n mi southeast of the Massachusetts coast on 17 September, then over eastern Nova Scotia and Newfoundland, Canada, on 18 September. Ophelia gradually lost organization during this period, and it became extratropical early on 18 September. As an extratropical low, Ophelia moved east-northeastward across the Atlantic on 19–20 September, then northeastward on 21–22 September. The cyclone dissipated over the North Sea on 23 September.

2) Meteorological statistics

AFRC and NOAA aircraft made 105 center fixes during Ophelia’s lifetime. The maximum flight-level winds observed during the storm were 91 kt from a NOAA aircraft at 700 mb at 2124 UTC 11 September. While this would support surface winds of 80 kt using the normal 90% adjustment, winds from the SFMR, dropsondes, and other flight levels suggest surface winds closer to 65 kt at that time. The peak intensity of 75 kt on 11 September is based on 85-kt winds at 700 mb at 0615 UTC, supported by a dropwindsonde wind of 80 kt at 13 m at 0434 UTC. The second peak intensity of 75 kt on 14–15 September is based on multiple occurrences of 80–85-kt winds at 700 mb and SFMR observations of 75–80-kt winds. A notable aircraft observation was a 74-kt wind at 925 mb on 16 September measured by the first ever successful Aerosonde robotic aircraft mission into the core of a tropical cyclone. The lowest aircraft-observed central pressure was 976 mb at 1218 UTC 10 September.

Ophelia brought hurricane conditions to portions of the North Carolina coast; selected surface observations from land stations and data buoys are given in Table 8. The Cape Lookout C-MAN station (9.8-m elevation) reported 2-min average winds of 65 kt at 2309 UTC 14 September with a gust to 80 kt. The Wrightsville Beach NOS station reported 6-min average winds of 59 kt at 1700 UTC 14 September with a gust of 69 kt. There was an unofficial report of a gust of 90 kt in Davis. Significant ship observations included a report of 64-kt winds from the Sanmar (call sign V2EX) at 0000 UTC 15 September, and a report of 62-kt winds from the Maersk New Orleans (call sign ELZY3) at 0600 UTC 14 September. Both observations were taken about 85 n mi east-northeast of the center.

Ophelia also brought tropical-storm-force winds to portions of the east-central coast of Florida and the northeastern coast of South Carolina. A NASA station at Cape Canaveral reported sustained winds of 34 kt at 1520 UTC 8 September with a gust of 52 kt. Myrtle Beach, South Carolina, reported a gust of 38 kt.

The lowest pressure observed by a coastal station or buoy was 980.7 mb at the Frying Pan Shoals, North Carolina, C-MAN station at 1300 UTC 14 September. The nearby NOAA buoy 41013 measured a 980.8-mb pressure 3 h earlier as the large eye drifted across both stations.

Ophelia caused storm surges of 4 to 6 ft above normal tide levels in the Pamlico Sound including the lower reaches of the Neuse, Pamlico, and Newport Rivers. Surges of 4 to 6 ft also occurred along the open coasts in Onslow and Cartaret counties. Storm surges of 3 to 4 ft above normal tide levels were common elsewhere along the affected areas of the North Carolina coast. Ophelia also caused tides of 1 to 2 ft above normal along the Florida coast.

Ophelia’s slow movement near the North Carolina coast helped produce locally heavy rains. The water treatment plant at Oak Island reported a storm-total rainfall of 444.5 mm, while the Remote Automated Weather Stations (RAWS) station at the Nature Conservancy reported 298.2 mm.

No tornadoes were reported with Ophelia.

3) Casualty and damage statistics

One death was directly associated with Ophelia—a drowning in high surf in Palm Beach County, Florida. One death was indirectly associated with Ophelia after it became extratropical due to a fall from a roof during rain in Nova Scotia.

The PCS estimates the insured property damage from Ophelia at $35 million. This yields a property damage estimate for the United States of $70 million.

1) Synoptic history

Rita originated from a complex interaction between a tropical wave and the remnants of a cold front. The tropical wave moved off the west coast of Africa on 7 September, and it produced little deep convection as it traversed the tropical Atlantic, except for one brief period on 13 September. Meanwhile, a cold front pushed southward over the central Atlantic during 11–12 September and became stationary a couple hundred nautical miles north of the Leeward Islands on 13 September. The southern portion of the front became a remnant surface trough on 14 September. This trough drifted westward on 15 September as strong high pressure built eastward over the western Atlantic. It passed north of Puerto Rico and the Virgin Islands the next day, producing a large but disorganized area of disturbed weather.

Accompanied by limited convection, the tropical wave moved westward across the Leeward Islands on 16 September and then merged with the surface trough north of Puerto Rico early on 17 September. Shower and thunderstorm activity became more concentrated later that day north of the Dominican Republic, and the area of disturbed weather was given its first satellite classifications at 1800 UTC. Gradually increasing organization was associated with slight relaxation of vertical shear, as a mid- to upper- tropospheric low previously over the western Atlantic shifted westward over Cuba and the northwestern Caribbean Sea. A tropical depression is estimated to have formed by 0000 UTC 18 September approximately 70 n mi east of Grand Turk in the Turks and Caicos (Fig. 1).

On 18–19 September, the cyclone moved toward the west-northwest over the Turks and Caicos and the southeastern Bahamas. Strong convection wrapped around the north side of the center, and the depression became a tropical storm by 1800 UTC 18 September about 25 n mi east-southeast of Mayaguana in the southeastern Bahamas. Moderate southerly vertical shear east of the mid- to upper-level low confined the upper-level outflow and deep convection to the north of the center. Thus, while the steering flow was generally toward the west, the low-level center steadily reformed to the north, resulting in a west-northwestward motion. The upper-level low weakened on 19 September and the shear over Rita relaxed. This allowed Rita to reach an intensity of 60 kt by 1800 UTC that day. The storm turned more westward early on 20 September along the southern periphery of a deep-layer ridge over the western Atlantic and Florida. Rita remained a tropical storm until it reached the Florida Straits. Once there, however, Rita strengthened to a hurricane by 1200 UTC 20 September about 100 n mi east-southeast of Key West. Rita became a category 2 hurricane by 1800 UTC that day, and its center passed about 40 n mi south of Key West about an hour later.

Rapid to explosive deepening ensued as Rita continued westward over the warm waters of the Loop Current in an environment of weak wind shear. Rita became a major hurricane early on 21 September, then reached an intensity of 145 kt by 1800 UTC that day (Fig. 9). Rita had strengthened from a tropical storm to a category 5 hurricane in less than 36 h. It remained at category 5 strength for about the next 18 h, reaching its estimated peak intensity of 155 kt around 0300 UTC 22 September while located about 270 n mi south-southeast of the mouth of the Mississippi River. During that time it also turned toward the west-northwest around the western extent of the mid- to upper-tropospheric ridge centered over the southeastern United States.

The inner eyewall deteriorated later on 22 September and Rita weakened to a category 4 hurricane by 1800 UTC that day. By early on 23 September a new, outer eyewall had consolidated and the hurricane had grown in size. However, Rita did not reintensify after the eyewall replacement cycle. Increasing southwesterly shear and slightly cooler waters caused steady weakening on 23 September. Rita rounded the western periphery of the ridge and turned northwestward that day. It weakened to a category 3 hurricane by 1800 UTC 23 September about 140 n mi southeast of Sabine Pass at the Texas–Louisiana border. Rita made landfall with an estimated intensity of 100 kt (category 3) at 0740 UTC 24 September in extreme southwestern Louisiana between Johnson’s Bayou and Sabine Pass.

The cyclone weakened after landfall, remaining a hurricane until only about 1200 UTC 24 September when it was centered about 35 n mi north of Beaumont, Texas. As a steadily weakening tropical storm, Rita proceeded northward, with its center moving near the Texas–Louisiana border for the rest of that day. Rita weakened to a tropical depression by 0600 UTC 25 September over southwestern Arkansas and then turned northeastward ahead of an approaching frontal system. The depression degenerated to a remnant low early on 26 September over southeastern Illinois. The low was absorbed into a frontal zone later that morning over the southern Great Lakes.

2) Meteorological statistics

Selected surface observations from Rita are included in Table 9. As was the case during Katrina, records from many ASOS sites, C-MAN and NOS stations, and buoys were incomplete because of weather-induced failures.

The 53rd WRS flew 16 operational missions into Rita, producing 63 center fixes. Seven missions flown by the NOAA WP-3D aircraft produced 15 center fixes, surface wind speed data from the SFMR with poststorm calibration conducted by the HRD, and airborne Doppler radar–derived wind analyses also provided by HRD. Additionally, the NOAA G-IV jet conducted eight synoptic surveillance missions around Rita during 19–23 September.

Radar and aircraft data indicate that Rita’s strongest winds stayed just south of the Florida Keys on 20 September, although sustained hurricane-force winds might have briefly impacted portions of the extreme Lower Keys. The Sand Key C-MAN station reported a 10-min average wind of 63 kt at 2110 UTC with an earlier peak gust to 80 kt. Higher winds may have occurred after the instrument was destroyed around 2200 UTC. The Key West International Airport measured a 2-min sustained wind of 54 kt with a gust to 66 kt at 2314 UTC. Most of the remainder of the keys experienced tropical storm conditions. Wind gusts of tropical-storm-force occurred over much of the Florida peninsula south of Lake Okeechobee on 20 September. Tropical storm conditions also occurred in western Cuba on 20–21 September while the center of Rita passed about 40 n mi from the north coast of the island.

Aircraft and satellite data on 21 September indicated that Rita intensified from 95 kt (category 2) to 145 kt (category 5) in just 18 h. The maximum 700-mb flight-level wind during that period was 161 kt at 1935 UTC, which corresponds to about 145 kt at the surface based on the average 90% adjustment. The SFMR estimated 146-kt winds at 1912 UTC 21 September and 144 kt at 1945 UTC. Two dropwindsondes directly measured surface winds of 142 and 149 kt shortly after 1930 UTC that day. A 700-mb flight-level wind of 165 kt was observed at 0538 UTC 22 September, corresponding to about 149 kt at the surface.

The central pressure in Rita fell a remarkable 70 mb in the 24-h period ending 0000 UTC 22 September, reaching an estimated 897 mb with an estimated intensity of 150 kt. This pressure is based upon an 899-mb dropwindsonde observation at 2309 UTC 21 September that had a surface wind of 32 kt. The next central pressure measurements were 898 mb at 0538 UTC 22 September and 899 mb (with a surface wind of 35 kt) at 0715 UTC. Because of the 6-h data gap, the actual lowest pressure and maximum winds are speculative. Since the pressure fell before 0000 UTC and rose after 0600 UTC, and since the aircraft-reported eye diameter contracted during that time, it is estimated that the minimum pressure was 895 mb around 0300 UTC 22 September. At the end of the rapid strengthening, Rita had become a large hurricane, with 34-kt winds extending up to 160 n mi from the center at the time of peak intensity.

The weakening of Rita during the last 48 h before landfall was associated with significant changes in its internal structure. The eyewall replacement cycle on 22–23 September resulted in a 30 n mi wide eye. One consequence of this was additional expansion of Rita’s wind field. By early on 23 September, tropical-storm-force winds extended up to about 180 n mi from the center, and hurricane-force winds extended up to about 75 n mi out. While the central pressure rose slowly, aircraft data indicate the maximum sustained winds decreased fairly quickly, especially in the first 24 h after peak intensity.

During Rita’s passage across the Gulf, it passed directly over NOAA buoy 42001, which reported 10-min average winds of 88 kt with a gust to 119 kt at 0030 UTC 23 September. The buoy also reported a minimum pressure of 925.7 mb at 2300 UTC 22 September.

Near the time of landfall, the strongest 700-mb flight-level winds were 111–115 kt northeast of the eye. WSR-88D velocity data from Lake Charles, Louisiana, showed winds near the top of the boundary layer (about 500 m in altitude) of about 120 kt. Also, a dropwindsonde at 0544 UTC provided an estimated 92-kt surface wind, derived from an average 80% adjustment of the 115-kt mean boundary layer wind speed. Based on these data, and the premise that the maximum surface wind at landfall was likely not sampled, the landfall intensity is set to 100 kt.

The central pressure at landfall measured by dropsondes was 937 mb. The landfall pressure and the 935-mb best-track pressure at 0600 UTC 24 September are the lowest of record in the Atlantic basin for an intensity of 100 kt. Application of the Holland wind model using the central pressure of 935 mb, the concurrently observed outermost pressure of 1009 mb, and the B parameter set to 1 yields an intensity of 94 kt. Similar to Katrina, Rita’s combination of relatively weak winds and such a low pressure resulted from an observed broadening of the pressure field during its last 48 h over the Gulf of Mexico that weakened the pressure gradient.

The C-MAN station at Sea Rim State Park, Texas (13-m elevation), reported 2-min average winds of 71 kt with a gust to 86 kt at 0700 UTC 24 September (Table 9). Sustained hurricane-force winds were also reported at the Southeast Texas Regional Airport in Beaumont, Texas (70 kt), and at the Calcasieu Pass, Louisiana, NOS station (67 kt), although the latter failed more than 2 h prior to landfall. Several instrumented towers in southeastern Texas also measured sustained hurricane-force winds, as strong as 82 kt, with peak 3-s gusts up to about 100 kt. Many areas in extreme southeastern Texas and extreme southwestern Louisiana experienced category 1 hurricane conditions, with a few areas experiencing category 2 conditions. Category 3 hurricane conditions were confined to a small area east of the eye along the coast of southwestern Louisiana. Rita produced tropical storm conditions over large portions of southern Louisiana (including cities such as Baton Rouge) and southeastern Texas (including the Houston and Galveston areas).

Rita produced a significant storm surge in vulnerable southwestern Louisiana. Because of the widespread destruction of structures and gauges, only a few high water marks have been collected and analyzed under the direction of FEMA. These data, along with unofficial visual estimates, suggest that the storm surge reached 15 ft in portions of the Cameron, Louisiana, area. Surge heights reached as high as 8 ft in communities along the shore of Calcasieu Lake such as Grand Lake. The surge propagated up the Calcasieu River, flooding portions of the Lake Charles area and reaching Interstate 10 (about 25 n mi inland). Flood waters in downtown Lake Charles were up to 6 ft deep. Farther east, most or all of Vermillion, Iberia, and St. Mary Parishes south of Highway 14 and U.S. 90 (several nautical miles inland) were inundated by the storm surge, visually estimated at 8–12 ft in some of these areas; a high water mark of nearly 12 ft was observed in western St. Mary Parish near the town of Louisa.

Rita also produced a storm surge of 4–7 ft in coastal areas of southeastern Louisiana, flooding some areas that had been impacted by the surge from Hurricane Katrina, including New Orleans, Slidell, and Mandeville. Some levees in southern Jefferson and southern Terrebonne Parishes were overtopped or breached, as were a few repaired levees in the New Orleans area. This surge prolonged the efforts to remove floodwaters from the New Orleans area.

West of the track of the center, incomplete gauge data suggest a storm surge of at least 5 ft occurred at Sabine Pass. Surviving gauges along Sabine Lake measured peak water levels of about 4–5 ft. Storm tides along much of the Texas coast were generally in the 3–5-ft range, and mostly occurred on 23 September. Some flooding occurred along the northern shores of Galveston Island and the Bolivar Peninsula as northerly winds pushed the waters of Galveston Bay southward. Tropical-storm-force winds also resulted in a surge of about 1.5 ft on Lake Livingston, located in southeastern Texas about 50 n mi north of Houston.

Rita also produced storm surge in the Florida Keys during the close pass of the center on 20 September. Visual estimates suggest the maximum storm surge in the keys was about 4–5 ft along the south-facing shores of Key West and the Lower Keys, and 3–4 ft along portions of the Atlantic shores of the Middle and Upper Keys. The surge flooded the runway at Key West International Airport, and streets up to four blocks inland in Key West were flooded to depths of about three feet.

Rita produced widespread heavy rains across portions of Mississippi, Louisiana, and extreme eastern Texas, with numerous storm totals of 125–225 mm and isolated totals of 250–400 mm. The maximum reported total was 406.4 mm at Bunkie, Louisiana. Flash floods occurred in several areas, including the Big Black River basin of west-central Mississippi, and several cities reported flooded streets. Storm-total rainfall in the Lower and Middle Florida Keys was generally 50–100 mm, with radar estimates of greater than 125 mm across portions of the Upper Keys. A few storm totals exceeding 75 mm were reported over the extreme southern Florida peninsula. Rita caused 75–150 mm of rain in portions of Arkansas.

Rita caused at least 90 tornadoes, mainly north and east of the center in portions of Alabama, Mississippi, Louisiana, and Arkansas. Fifty-six of the tornadoes occurred in central Mississippi, northeastern Louisiana, and southeastern Arkansas. Eleven tornadoes were reported in other portions of Arkansas, and 23 tornadoes were reported in Alabama.

3) Casualty and damage statistics

The approach of Rita provoked one the largest evacuations in U.S. history. Media reports indicate that the number of evacuees in Texas could have exceeded two million. Additional evacuations involving smaller numbers took place in Louisiana.

Rita directly caused seven fatalities. One person drowned near Lake Charles, Louisiana; two people died in Hardin, Texas, when a tree was blown down onto their home; one person died when a tree fell on her home in Point Blank, Texas; another person was killed by a falling tree in Angelina County, Texas; one person was killed in a tornado near Isola, Mississippi; and one person drowned in a rip current at Miramar Beach in the Florida panhandle on 24 September. At least 55 indirect fatalities have been reported in Texas. A bus accident south of Dallas during the evacuation killed more than 20 persons, mostly elderly evacuees from a nursing home. Six fatalities occurred in Beaumont due to carbon monoxide poisoning. Other persons died during the evacuation due to heat exhaustion.

Rita’s storm surge devastated communities in coastal areas of southwestern Louisiana, including Holly Beach, Cameron, Creole, and Grand Cheniere in Cameron Parish. Almost every structure in these areas was destroyed, and some were completely swept away. Farther inland, numerous homes in Grand Lake were damaged or destroyed. Many portions of the Lake Charles area suffered substantial flood damage, including downtown and some surrounding residential communities. In Vermillion Parish, most structures in the town of Pecan Island were destroyed, and dozens of other homes and businesses were flooded and damaged. Storm-surge damage to homes and businesses in low-lying areas occurred along the entire coast of Louisiana, although the impact in the New Orleans area was not nearly as widespread as during Hurricane Katrina. In Jefferson County, Texas, adjacent to Sabine Lake, the storm surge flooded several homes, and some mobile homes floated away from their original locations. The surge on Lake Livingston caused some damage to the Lake Livingston Dam. Rita also caused surge damage to homes and businesses in portions of the Florida Keys.

Rita’s winds, tornadoes, and freshwater floods also damaged homes and businesses in portions of Louisiana, eastern Texas, Mississippi, Alabama, Arkansas, and the Florida Keys. Rita caused wide swaths of downed trees and power lines, leaving well over one million customers in these areas without electrical service. The hurricane disrupted oil and gas production and refining in the northwestern Gulf of Mexico region (largely due to evacuations), but the impacts were not as severe as those due to Katrina. The most recent available estimate by the PCS of the insured property damage in the United States caused by Rita is $5.63 billion. This produces an estimate for total damage of about $11.3 billion.

1) Synoptic history

A tropical wave that moved across the coast of Africa on 17 September was the likely precursor to Stan. This wave showed little distinction as it moved over the eastern and central tropical Atlantic. The associated cloudiness and showers increased as the wave neared 50°W longitude on 22 September, but north-northeasterly shear created an environment unfavorable for tropical cyclone formation. The wave moved into the eastern Caribbean Sea on 25 September, while shear over the system diminished. By 27 September, associated deep convection became more consolidated over the central Caribbean Sea. Over the next several days, organization of the system waxed and waned as it moved into the western Caribbean Sea. Development began in earnest on 1 October when the system neared the eastern coast of the Yucatan peninsula. Based on the extent and organization of deep convection as well as surface observations, it is estimated that a tropical depression formed around 1200 UTC 1 October centered about 115 n mi southeast of Cozumel (Fig. 1).

Lower- to midtropospheric ridging north and northeast of the tropical cyclone resulted in a west-northwestward steering current, and an upper-tropospheric anticyclone developed over the area. The depression strengthened into a tropical storm shortly before its center made landfall on the east coast of the Yucatan peninsula, just south of Tulum, around 1000 UTC 2 October. The center of Stan crossed the peninsula in about 18 h while the system weakened back to a depression. It quickly regained tropical storm strength, however, after it moved back over water. Deep-layer high pressure over the western Gulf of Mexico forced the system to turn toward the west-southwest and southwest over the Bay of Campeche. This turn may also have been due to the interaction with a broad, deep-layer cyclonic circulation that covered eastern Mexico and most of Central America. As Stan approached the southern Gulf Coast of Mexico, it became a hurricane around 0600 UTC 4 October. It made its second landfall as a category 1 hurricane around 1200 UTC about 80 n mi east-southeast of Veracruz. Once inland, the cyclone weakened rapidly, and it dissipated over the mountainous terrain of the Mexican state of Oaxaca just after 0600 UTC 5 October.

2) Meteorological statistics

An AFRC mission just prior to landfall on 4 October measured a peak 700-mb flight-level wind of 79 kt around 1000 UTC. A little earlier, a dropwindsonde from this mission yielded surface wind estimates of 69–72 kt. These data are the primary bases for setting the peak (and landfall) intensity of Stan at 70 kt.

Three ships reported tropical storm winds during Stan. The Veendam (call sign C6NL6) reported 40-kt winds at 0600 UTC 5 October, the Edyth L (call sign ZCAM4) reported 37-kt winds at 1200 UTC 2 October, and the Albert (call sign DGTX) reported 35-kt winds at 0000 UTC 5 October.

Stan produced widespread heavy rains over portions of southeastern Mexico. There are numerous reports of storm totals of 100–200 mm, with scattered amounts of 200–300 mm. The maximum reported total was 306.8 mm at El Novillero, with 305.1 mm reported at Cuetzalan.

3) Casualty and damage statistics

It is impossible to determine how many people were killed by Stan. According to the government of Mexico, there were 80 deaths in the Mexican states of Veracruz, Oaxaca, and Chiapas. The actual surface circulation of the tropical cyclone seems to have been confined to Mexico. However, the tropical cyclone appeared to be embedded within the western portion of a broader-scale low-level cyclonic circulation. This larger system produced extensive very heavy rains over portions of extreme eastern Mexico and Central America that resulted in disastrous floods. Estimates of the total number of lives lost, including the 80 direct deaths, in Mexico and Central America are mostly in the range of 1000–2000, with some even higher. Guatemala was particularly hard hit; over 1000 persons may have perished in that country.

1) Synoptic history

Wilma had a complex origin. During the second week of October, an unusually large, monsoon-like lower-tropospheric circulation and a broad area of disturbed weather developed over much of the Caribbean Sea. This system appeared to have been enhanced by an extensive area of diffluent flow south and southwest of an upper-level cyclone over the southwestern Atlantic. The easternmost portion of this low pressure area moved northeastward and merged with an extratropical cyclone. However, a more concentrated area of disturbed weather and surface low pressure formed near Jamaica by 14 October, possibly aided by a couple of tropical waves traversing the Caribbean during this time. By 1800 UTC 15 October, the surface circulation became well defined, with sufficiently organized deep convection, to mark the formation of a tropical depression about 190 n mi east-southeast of Grand Cayman (Fig. 1).

A weak and ill-defined steering flow prevailed for the first couple of days, with a 500-mb high covering the Gulf of Mexico and another midtropospheric anticyclone located well east-northeast of the tropical cyclone. The depression moved slowly and erratically westward to west-southwestward for a day or so and then drifted south-southwestward to southward for a day or two. There was only slow strengthening during this period, and the system is estimated to have become a tropical storm at 0600 UTC 17 October. On 18 October Wilma turned toward the west-northwest and strengthened into a hurricane. Later that day, a remarkable, explosive strengthening episode began. During the 24 h ending at 0600 UTC 19 October, Wilma intensified from a 60-kt tropical storm to a 150-kt category 5 hurricane, representing an unprecedented intensification for an Atlantic tropical cyclone. Wilma reached its estimated peak sustained wind speed of 160 kt at around 1200 UTC 19 October (Fig. 10). During the strengthening episode, AFRC aircraft observations indicated that the eye of the hurricane contracted to a diameter of 2 n mi; this is the smallest eye known to NHC staff. The estimated minimum central pressure at the time of peak intensity is 882 mb, which is a new record low value for a hurricane in the Atlantic basin. As discussed below, the actual minimum pressure may have been lower.

Wilma maintained category 5 status until 20 October, when its winds decreased to 130 kt (category 4), and the tiny eye was replaced by one about 40 n mi across. The hurricane would retain an eye of about 40 to 60 n mi in diameter for most of the remainder of its lifetime. By 21 October, as midlevel ridging northeast of Wilma increased somewhat and a series of short-wave troughs in the westerlies began to erode the high over the Gulf of Mexico, the hurricane turned toward the northwest and north-northwest, taking aim at the Yucatan peninsula of Mexico. Wilma’s maximum winds remained near 130 kt when its center made landfall on the island of Cozumel around 2145 UTC 21 October, and it was still category 4 when it crossed the coast of the Yucatan peninsula about 6 h later. On 22 October, the midtropospheric high pressure area north of Wilma dissipated, and the hurricane moved slowly northward, crossing the extreme northeastern Yucatan peninsula. Wilma emerged into the southern Gulf of Mexico around 0000 UTC 23 October, with maximum winds of near 85 kt. Although Wilma’s intensity had been reduced because of its passage over land, it was still a large and powerful hurricane.

A vigorous midtropospheric trough, moving eastward from the central United States, provided a southwesterly steering current that accelerated Wilma northeastward toward southern Florida. As the upper-level flow over the hurricane increased, so too did the vertical shear, and by early on 24 October the environmental 850–200-mb shear (averaged over an annulus about 100 to 400 n mi from the center) was roughly 25 kt. Despite the strong shear in its surroundings, Wilma strengthened to 110 kt as it approached Florida. Maximum sustained winds were estimated to be near 105 kt (category 3) at landfall in southwestern Florida near Cape Romano around 1030 UTC 24 October. Accelerating further, the hurricane crossed the southern Florida peninsula in 4.5 h, with the center emerging into the Atlantic just southeast of Jupiter around 1500 UTC. Maximum winds decreased to near 95 kt (category 2) during the crossing of Florida. A vigorous cold front associated with the midtropospheric trough swept across the area west of Wilma, yet the cooler and drier air behind the front could not fully penetrate the inner core of the hurricane to weaken it. Upon reaching the Atlantic, the hurricane reintensified one last time, and its winds again reached 110 kt around 0000 UTC 25 October. Thereafter, Wilma weakened because of an unfavorable atmospheric environment while racing northeastward at 40–50 kt. It became extratropical around 0000 UTC 26 October while centered about 200 n mi southeast of Halifax, Nova Scotia. This extratropical low was absorbed by another extratropical cyclone located over eastern Nova Scotia around 0000 UTC 27 October.

2) Meteorological statistics

Near the time of peak intensity, the AFRC aircraft measured a 700-mb flight-level wind of 168 kt wind in the southeastern eyewall at 0610 UTC 19 October. Using the standard 90% adjustment yields a surface wind of 151 kt. Since the central pressure was still falling when the aircraft last passed through the eye at 0801 UTC, it is likely that the winds also increased from then until 1200 UTC. Therefore the peak intensity of Wilma is estimated to be 160 kt at 1200 UTC that day. When Wilma was over the southeastern Gulf of Mexico, the AFRC measured a 700-mb wind of 135 kt at 0646 UTC 24 October, apparently associated with a short-lived mesocyclone in the southeastern eyewall. Because of tilting of the eyewall convection by strong southwesterly shear, the ratio of surface to flight-level winds was probably less than normal. Therefore, the adjustment for 700-mb flight-level winds is reduced from the normal 90%–80%, resulting in an estimated intensity of 110 kt at 0600 UTC 24 October. Later aircraft and radar data in the southeastern eyewall showed that the winds had diminished somewhat, so the intensity of Wilma at landfall in southwestern Florida was assessed at 105 kt.

Wilma deepened at an incredible rate during 18–19 October. Over the period from 1954 to 0801 UTC, the aircraft-measured central pressure fell from 970 to 882 mb (7.3 mb h⁻¹), and over the period from 2310 to 0433 UTC, the aircraft-measured central pressure fell from 954 to 901 mb (9.9 mb h⁻¹). The largest 6-, 12-, and 24-h drops in best-track central pressure for Wilma, 54 mb from 0000 to 0600 UTC 19 October, 83 mb from 1800 UTC 18 October to 0600 UTC 19 October, and 97 mb from 1200 UTC 18 October to 1200 UTC 19 October, respectively, are by far the largest in the available records for these periods going back to 1851. The previous record 6-h deepening was 38 mb in Hurricane Beulah, September 1967 (Sugg and Pelissier 1968), the previous record 12-h deepening was 48 mb in Hurricane Allen, August 1980 (Lawrence and Pelissier 1981), and the previous record 24-h deepening was 72 mb in Hurricane Gilbert, September 1988 (Lawrence and Gross 1989).

The minimum central pressure measured by dropsondes was 884 mb at 0801 UTC 19 October. Surface winds from these dropsondes were measured to be 23 kt, so the dropsondes probably did not capture the lowest pressure in Wilma’s eye. Therefore the pressure at that time was estimated at a slightly lower 882 mb. Given that the pressure was still falling, it is possible that the pressure then dropped a little below 882 mb.

Selected surface observations from land stations and data buoys are given in Table 11. During Wilma’s landfalls in Mexico, Cancun observed a 10-min average wind of 87 kt with a gust to 113 kt, but it is not certain if these were the maximum values at that station. Islas Mujeres, near Cancun, experienced hurricane-force winds in gusts for nearly a 24-h period on 21–22 October.

The highest sustained wind measured at an official surface observing site in Florida was a 15-min average speed of 80 kt from a South Florida Water Management District (SFWMD) observation site in Lake Okeechobee. It should be noted that another SFWMD platform located only about 5 n mi to the north recorded a 15-min wind speed of 79 kt at the same time. It is reasonable to assume that these measurements correspond to a peak 1-min average wind speed of at least 90 kt. Several ASOS sites in Miami-Dade and Broward Counties stopped reporting data at their highest noted sustained wind speeds, such as Opa-Locka Airport at 74 kt and Pompano Beach Airport at 72 kt. Stronger winds likely occurred at these sites. Data from the NWS Miami radar indicated a peak velocity of 138 kt at an elevation of about 1500 m over western Broward County. A comparison of Doppler velocities with collocated, official 2- and 1-min surface wind measurements in Miami-Dade and Broward Counties suggests that the ratios of surface to 1500-m sustained wind velocities over southeastern Florida in Wilma were likely in the range of 0.65–0.70. This results in a maximum surface wind speed estimate of 90–95 kt.

Based on the surface and radar data, most of the southeastern Florida peninsula experienced at least category 1 hurricane conditions, and that some parts of northern Miami-Dade County, Broward, and Palm Beach Counties likely had category 2 hurricane conditions, including wind gusts to near 100 kt, at the standard 10-m height above ground.

A storm surge of 4–8 ft was reported from coastal Collier County. It is likely, however, that higher storm surges occurred over uninhabited areas of southwestern Florida south of where Wilma made landfall. Storm surges of 4–5 ft were observed over much of the lower and middle Florida Keys, locally to near 7 ft. However, a storm surge of near 9 ft was estimated visually in the Marathon area. Storm surges were generally in the 4–5-ft range over the upper keys. These resulted in flooding over substantial portions of the keys. Relatively minor storm surge flooding occurred on the Biscayne Bay shoreline of Dade County. Storm surges of 12 ft or more were measured along the southwestern coast of Grand Bahama Island.

Wilma produced torrential rainfall as it moved slowly over portions of the eastern Yucatan peninsula. According to the Meteorological Service of Mexico, a 24-h rainfall total of 1576.1 mm occurred at Islas Mujeres. Because the hurricane moved quickly across the Florida peninsula, however, the rain amounts there were on average not very large. Storm totals ranged generally from 75–175 mm, with a maximum reported total of 336.8 mm at the Kennedy Space Center. Some locations in southeast Florida had totals of not more than 25–50 mm.

Wilma produced 10 tornadoes over the Florida peninsula on 23–24 October: one each in Collier, Hardee, Highlands, Indian River, Okeechobee, and Polk Counties, and four in Brevard County.

3) Casualty and damage statistics

Twenty-three deaths have been directly attributed to Wilma: 12 in Haiti, 1 in Jamaica, 4 in Mexico, 5 in Florida, and 1 in the Bahamas on Grand Bahama Island.

Very severe damage was reported in portions of the northeastern Yucatan peninsula, which dealt a major blow to the tourist industry in that area. Major flooding from storm surge and/or wave action occurred in portions of western Cuba. In southern Florida, damage was unusually widespread, including numerous downed trees, substantial crop losses, downed power lines and poles, broken windows, extensive roof damage, and destruction of mobile homes. Wilma caused the largest disruption to electrical service ever experienced in Florida. Media reports indicate up to 98% of south Florida lost electrical service, and Florida Power and Light reported outages in 42 Florida counties. The total insured damage compiled by the PCS is $10.3 billion. The total property damage in the United States is thus estimated at $20.6 billion, making Wilma the third costliest hurricane in United States history, behind only Katrina and Andrew. Significant damage also occurred in the southwestern coastal area of Grand Bahama Island, with widespread destruction of roofs and vehicles along with toppling of poles and trees.

1) Synoptic history

Analysis of geostationary satellite imagery indicates Beta formed from the same tropical wave that produced Tropical Storm Alpha. After Alpha formed, the wave continued westward, and by 25 October deep convection consolidated somewhat over the extreme southwestern Caribbean Sea. On 26 October, curved banding features developed, and the system gained sufficient organization by 1800 UTC that day to designate the formation of a tropical depression, centered about 90 n mi north of the northern central coast of Panama (Fig. 1).

Initially the motion was northwestward, but in response to a midtropospheric short-wave trough over the southern Gulf of Mexico and a midtropospheric ridge well to the east-northeast, the system gradually turned toward the north. Within an environment of weak vertical wind shear and SSTs of at least 29°C, the cyclone strengthened into a tropical storm around 0600 UTC 27 October. Only slow strengthening occurred over the ensuing 36 h or so, probably due to disruption of the system by weak to moderate northeasterly shear. Beta intensified into a hurricane shortly after 0000 UTC 29 October near Isla de Providencia. As the Gulf of Mexico short-wave trough lifted northeastward and a midtropospheric high built to the north and northwest of the hurricane, Beta turned toward the west and west-southwest and continued to strengthen. The strengthening rate increased around 0000 UTC 30 October, and Beta reached an estimated peak intensity of 100 kt (category 3) about 6 h later (Fig. 11), the seventh and last major hurricane of the season. Moving southwestward, the center of the hurricane made landfall near La Barra del Rio Grande on the central coast of Nicaragua around 1200 UTC 30 October. Shortly before landfall, warming of the central cloud tops suggested weakening, and the landfall intensity is estimated to have been 90 kt (category 2). Beta turned back toward the west and dissipated over west-central Nicaragua by 0600 UTC 31 October.

2) Meteorological statistics

The highest 700-mb flight-level winds measured by AFRC aircraft were 77 kt at 2003 UTC 29 October. However, just after the aircraft left the area, microwave imagery showed that the eye contracted, and Dvorak estimates indicate that Beta strengthened rather rapidly from 0000 to 0600 UTC 30 October.

Aircraft flight-level wind data and satellite images indicate that Beta was a small tropical cyclone; the radius of tropical-storm-force winds was generally 50 n mi or less. Despite the small size, two ships reported tropical-storm-force winds from Beta. The Edyth L (call sign ZCAM4) reported 50-kt winds at 0900 UTC 28 October, while the Dioli (call sign PJRP) reported 39-kt winds at 0600 UTC 30 October.

Rainfall totals as high as 250–500 mm were observed over portions of Honduras, with a maximum total of 554.2 mm at Trujillo. However, it is not certain whether all of these rains were directly associated with Beta. There are no meteorological reports available near the point of landfall in Nicaragua. Puerto Cabezas, Nicaragua, had a storm-total rainfall of 162.3 mm with 131.1 mm falling in a 6-h period on 29 October.

3) Casualty and damage statistics

Beta reportedly caused extensive damage on the Colombian island of Providencia; however, details of these impacts are unknown. The government of Nicaragua reported roofs were removed from numerous dwellings as well as moderate storm-surge flooding near the landfall location. Major flooding occurred in Honduras, but it cannot be determined how much of it was directly associated with Beta. There are no reported deaths due to Beta.