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North Carolina coast and Lili was a rare December hurricane. 1. Introduction There were twelve named tropical cyclones during 1984 in the North Atlantic-Caribbean--Gulf of Mexico region. Five reached hurricane force and the remaining seven were tropical storms. In addition, there was one subtropical storm. These numbers compare with a long-term average of ten named tropical cyclones,- of which six reach hurricane force. Statistics for this year are given in Table 1. Figure I shows this
North Carolina coast and Lili was a rare December hurricane. 1. Introduction There were twelve named tropical cyclones during 1984 in the North Atlantic-Caribbean--Gulf of Mexico region. Five reached hurricane force and the remaining seven were tropical storms. In addition, there was one subtropical storm. These numbers compare with a long-term average of ten named tropical cyclones,- of which six reach hurricane force. Statistics for this year are given in Table 1. Figure I shows this
wave’s “intrinsic” potential for development (e.g., its observed size, cloud and circulation structure, convective nature) when it crosses the west coast of Africa, and 2) the characteristics of the eastern Atlantic atmospheric and oceanic environment that it then encounters. While satellite signatures, surface pressure analyses, and circulation features derived from rawindsonde data provide some clues about tropical waves departing Africa, a reliable quantitative measure of point 1 above remains
wave’s “intrinsic” potential for development (e.g., its observed size, cloud and circulation structure, convective nature) when it crosses the west coast of Africa, and 2) the characteristics of the eastern Atlantic atmospheric and oceanic environment that it then encounters. While satellite signatures, surface pressure analyses, and circulation features derived from rawindsonde data provide some clues about tropical waves departing Africa, a reliable quantitative measure of point 1 above remains
25 November, satellite pictures showedthat a circular convective cloud mass about 100 nmi in diameter had formed near the low center. Theeye was well-defined, implying that a small tropicalsystem had developed within the larger extratropical cyclone. Satellite intensity estimates were at 65 kt--minimal hurricane force--by 1800 GMT of that day, atwhich time the system was centered 600 n mi westsouthwest of the Azores. Given the name Karl, thehurricane strengthened slightly for the next 24 h
25 November, satellite pictures showedthat a circular convective cloud mass about 100 nmi in diameter had formed near the low center. Theeye was well-defined, implying that a small tropicalsystem had developed within the larger extratropical cyclone. Satellite intensity estimates were at 65 kt--minimal hurricane force--by 1800 GMT of that day, atwhich time the system was centered 600 n mi westsouthwest of the Azores. Given the name Karl, thehurricane strengthened slightly for the next 24 h
short time later the Teverya,, 60 mi to thenorthwest, sent a special report of a force 10 south windwith a pressure of 998 mb and moderate t,o heavy south-west smell. The beginnings of a vortex arrangement ofhighly active convective clouds had been shown by ESSA6 about 1520 GMT. On that picture one heavy cloud mass150 mi in diamet,er was found to the east of the raggedopen cent,er, two cloud masses about 60 mi in diamet,eron the south side, and two bands of c,umulonimbus in arcsaround the northwest
short time later the Teverya,, 60 mi to thenorthwest, sent a special report of a force 10 south windwith a pressure of 998 mb and moderate t,o heavy south-west smell. The beginnings of a vortex arrangement ofhighly active convective clouds had been shown by ESSA6 about 1520 GMT. On that picture one heavy cloud mass150 mi in diamet,er was found to the east of the raggedopen cent,er, two cloud masses about 60 mi in diamet,eron the south side, and two bands of c,umulonimbus in arcsaround the northwest
415 n mi west of Cabo San Lucas. A swirl of low clouds persisted in this area for several days thereafter. Flight-level and dropwindsonde observations were made from about 1900 to 2200 UTC on 20 June from a Hurricane Hunter flight of the 53d Weather Reconnaissance Squadron of the U.S. Air Force Reserve Command. A comparison of aircraft and satellite-based intensity estimates shows that the satellite intensity estimates were larger by 15–20 kt. The Dvorak-based maximum wind estimate was about 105
415 n mi west of Cabo San Lucas. A swirl of low clouds persisted in this area for several days thereafter. Flight-level and dropwindsonde observations were made from about 1900 to 2200 UTC on 20 June from a Hurricane Hunter flight of the 53d Weather Reconnaissance Squadron of the U.S. Air Force Reserve Command. A comparison of aircraft and satellite-based intensity estimates shows that the satellite intensity estimates were larger by 15–20 kt. The Dvorak-based maximum wind estimate was about 105
associated cloud spiraland on November 6 a US. Air Force reconnaissanceflight found that an eye had formed with surroundingwinds of 55 m.p.h.Lois commenced a slow east-northeastward course whilesteadily increasing toward hurricane intensity, which wasachieved on the afternoon of November 7. Thereafter,hurricane Lois accelerated on a northeastward track, adirection it was to maintain during the next four days and2,000 mi. Throughout this period the hurricane waskept under surveillance by reconnaissance
associated cloud spiraland on November 6 a US. Air Force reconnaissanceflight found that an eye had formed with surroundingwinds of 55 m.p.h.Lois commenced a slow east-northeastward course whilesteadily increasing toward hurricane intensity, which wasachieved on the afternoon of November 7. Thereafter,hurricane Lois accelerated on a northeastward track, adirection it was to maintain during the next four days and2,000 mi. Throughout this period the hurricane waskept under surveillance by reconnaissance
satellite view of the stormat 1534 GMT on the 9th is shown in Fig. 16. Well-defined cloud characteristics--such as centraldense overcast and low-le, vel banding or strong outflow pattern--were never in evidence. Also theminimum pressure of 1006 mb does not ordinarilysupport tropical storm intensity for ariy length oftime. However, surface pressure anomalies werewell above normal over the western North Atlanticand this provided the necessary pressure gradientfor sustained gale-force winds
satellite view of the stormat 1534 GMT on the 9th is shown in Fig. 16. Well-defined cloud characteristics--such as centraldense overcast and low-le, vel banding or strong outflow pattern--were never in evidence. Also theminimum pressure of 1006 mb does not ordinarilysupport tropical storm intensity for ariy length oftime. However, surface pressure anomalies werewell above normal over the western North Atlanticand this provided the necessary pressure gradientfor sustained gale-force winds
dissipated over land near Cabo Corrientes, Mexico, without consequence. The 1998 eastern North Pacific hurricane season also featured United States Air Force Reserve (USAFR) reconnaissance flights into Hurricanes Lester and Madeline, which threatened the coast of Mexico. These flights were coordinated through the government of Mexico and served to test flight clearance procedures in Mexican airspace. The average numbers of tropical storms and hurricanes per year in the eastern North Pacific basin are 16
dissipated over land near Cabo Corrientes, Mexico, without consequence. The 1998 eastern North Pacific hurricane season also featured United States Air Force Reserve (USAFR) reconnaissance flights into Hurricanes Lester and Madeline, which threatened the coast of Mexico. These flights were coordinated through the government of Mexico and served to test flight clearance procedures in Mexican airspace. The average numbers of tropical storms and hurricanes per year in the eastern North Pacific basin are 16
investigated by comparing mean large-scale surface and upper-air environments of null- andactive-MCC periods of both years. Results confirmed the primary importance to MCC development of stronglow-level thermal forcing, as well as proper vertical phasing of favorable lower- and midtropospheric environments. A cursory survey of MCCs documented outside of the United States reveals that MCCs, or MCC-type storms,are a warm-season phenomenon of midlatitude, subtropical, and low-latitude regions around the
investigated by comparing mean large-scale surface and upper-air environments of null- andactive-MCC periods of both years. Results confirmed the primary importance to MCC development of stronglow-level thermal forcing, as well as proper vertical phasing of favorable lower- and midtropospheric environments. A cursory survey of MCCs documented outside of the United States reveals that MCCs, or MCC-type storms,are a warm-season phenomenon of midlatitude, subtropical, and low-latitude regions around the
hurricane hunt'er plnnc rcnchetlthe center of the st'orm, found a circulnr rye well defined,central pressure 994 mb., surface winds in ewess of hurri-cane force, and the wall cloud around the eye S mi. wide.This observation indicated that hurrictme I'lorn wtw thrmost concentrated and best organized t,ropicd cyclone ofthe past two years. The San Juan KerLtlrer Ruretluoffice issued a bulletin at 9 a.m., and tlw first formtdhurricane advisory on Flora at 11 a.m., EST.The eye of hurricane Flora pnssed over
hurricane hunt'er plnnc rcnchetlthe center of the st'orm, found a circulnr rye well defined,central pressure 994 mb., surface winds in ewess of hurri-cane force, and the wall cloud around the eye S mi. wide.This observation indicated that hurrictme I'lorn wtw thrmost concentrated and best organized t,ropicd cyclone ofthe past two years. The San Juan KerLtlrer Ruretluoffice issued a bulletin at 9 a.m., and tlw first formtdhurricane advisory on Flora at 11 a.m., EST.The eye of hurricane Flora pnssed over
