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James L. Franklin, Richard J. Pasch, Lixion A. Avila, John L. Beven II, Miles B. Lawrence, Stacy R. Stewart, and Eric S. Blake

dropwindsondes ( Hock and Franklin 1999 ), but more frequently are estimated from flight-level winds using empirical relationships derived from a 3-yr sample of GPS dropwindsonde data ( Franklin et al. 2003 ). During NOAA reconnaissance missions, surface winds can be estimated remotely using the Stepped-Frequency Microwave Radiometer (SFMR) instrument ( Uhlhorn and Black 2003 ). When available, satellite and reconnaissance data are supplemented by conventional land-based surface and upper-air observations

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John L. Beven II, Lixion A. Avila, James L. Franklin, Miles B. Lawrence, Richard J. Pasch, and Stacy R. Stewart

basin at least since 1966 when reliable satellite observations began. Five cyclones made landfall on the Pacific coast of Mexico. Ignacio and Marty made landfall as hurricanes over the Baja California peninsula, causing 14 deaths. Carlos and Olaf came ashore as tropical storms in mainland Mexico, while Nora made landfall as a tropical depression in mainland Mexico. Jimena, which formed in the eastern North Pacific basin, threatened portions of the Hawaiian Islands. As seen in past seasons, tropical

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Lixion A. Avila, Richard J. Pasch, John L. Beven II, James L. Franklin, Miles B. Lawrence, and Stacy R. Stewart

May. The low moved little and dissipated by 0000 UTC 26 May. Special Sensor Microwave Imager (SSM/I) and Tropical Rainfall Measuring Mission (TRMM) images of Agatha from around 1400 UTC 22 May through 0230 UTC 23 May revealed a ring of precipitation resembling an eyewall. One of these images is shown in Fig. 5 . The presence of the convective ring suggests that Agatha’s peak intensity was probably higher than indicated by the 35–45-kt winds suggested by the Dvorak estimates, although no technique

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Miles B. Lawrence, Lixion A. Avila, John L. Beven, James L. Franklin, Richard J. Pasch, and Stacy R. Stewart

northward, the low produced sporadic bursts of central convection. After turning northwestward, the low looped back toward the southeast on 20 April. The central convection became better organized and the low separated from the frontal system. It is estimated the low became Subtropical Storm Ana at 0600 UTC 20 April about 215 n mi west of Bermuda. Based on satellite microwave data showing a warm core, it is estimated that Ana became a tropical storm near 0000 UTC 21 April with winds of 50 kt (1 kt = 0

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Michael J. Brennan, Richard D. Knabb, Michelle Mainelli, and Todd B. Kimberlain

geostationary and low-earth orbiting satellites, aircraft reconnaissance, weather radar, buoys, and conventional land-based surface and upper-air observations ( Dvorak 1984 ; Hebert and Poteat 1975 ; Hawkins et al. 2001 ; Brueske and Velden 2003 ; Demuth et al. 2006 ; Brennan et al. 2009 ). In 2007, during all NOAA WP-3D aircraft missions and a subset of the U.S. Air Force Reserve C-130 aircraft flights, surface winds were remotely estimated using the Stepped-Frequency Microwave Radiometer (SFMR

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James L. Franklin, Lixion A. Avila, Jack L. Beven, Miles B. Lawrence, Richard J. Pasch, and Stacy R. Stewart

the extratropical stage. For storms east of 55°W, or those not threatening land, the primary (and often sole) source of information is Geostationary Operational Environmental Satellite (GOES) and polar-orbiting weather satellite imagery, interpreted using the Dvorak (1984) technique. For systems posing a threat to land, in situ observations are also generally available from aircraft reconnaissance flights conducted by the 53d Weather Reconnaissance Squadron (“Hurricane Hunters”) of the Air Force

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James L. Franklin and Daniel P. Brown

-air observations supplement the satellite and reconnaissance data. In key forecast situations, the kinematic and thermodynamic structure of the storm environment is obtained from dropsondes released during operational “synoptic surveillance” flights of NOAA’s Gulfstream IV jet aircraft ( Aberson and Franklin 1999 ). Several satellite-based technologies play an important role in the analysis of tropical weather systems. Foremost of these is multichannel passive microwave imagery [e.g., from the Tropical

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James L. Franklin, Lixion A. Avila, John L. Beven II, Miles B. Lawrence, Richard J. Pasch, and Stacy R. Stewart

, the primary (and often sole) source of information is Geostationary Operational Environmental Satellite (GOES) and polar-orbiting weather satellite imagery, interpreted using the Dvorak (1984) technique. Several other satellite-based remote sensors play an important part in the analysis of tropical weather systems. Foremost of these is multichannel passive microwave imagery, which over the past decade has provided radarlike depictions of systems' convective structure ( Hawkins et al. 2001 ), and

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Richard D. Knabb, Lixion A. Avila, John L. Beven, James L. Franklin, Richard J. Pasch, and Stacy R. Stewart

this section. Observations of eastern North Pacific tropical cyclones are mostly limited to satellite data, primarily from the Geostationary Operational Environmental Satellites (GOES). GOES-East and GOES-West provide the visible and infrared imagery that serves as input for intensity estimates via the Dvorak (1984) technique. This imagery is supplemented by occasional microwave satellite data and imagery from National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites

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Richard J. Pasch, Eric S. Blake, Lixion A. Avila, John L. Beven, Daniel P. Brown, James L. Franklin, Richard D. Knabb, Michelle M. Mainelli, Jamie R. Rhome, and Stacy R. Stewart

the center of Norman on 15 October is uncertain. Conventional satellite imagery suggests the center may have moved inland east of Manzanillo. However, surface observations do not support a landfall, and the center was too disorganized to be easily tracked in microwave satellite imagery. Therefore, the best estimate is that the center dissipated over water as it approached Manzanillo. While Norman produced some locally heavy rains over portions of southwestern Mexico, there were no reports of

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