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Tropical Storm Elsa Forecast Discussion Number 19
2021-07-05 04:58:57| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Sun Jul 04 2021 000 WTNT45 KNHC 050258 TCDAT5 Tropical Storm Elsa Discussion Number 19 NWS National Hurricane Center Miami FL AL052021 1100 PM EDT Sun Jul 04 2021 Similar to this time last night, Elsa has undergone another convective bursting pattern, except that tonight this has translated into at least some slight strengthening. An Air Force Reserve reconnaissance aircraft investigating the cyclone this evening has found maximum 850-mb flight-level winds of 55 kt and reliable SFMR surface winds of about 55 kt. Although there have been SFMR winds of 60 kt or more reported northeast and north of the center, those values appear to be contaminated by shoaling and/or breaking waves owing to the shallow water flowing in and around the offshore Cayo Anclitas and Cayo Pingues archipelagos. The estimated center pressure of 1004 mb based on dropsonde data also does a higher intensity of 60 kt. Therefore, based on the most reliable data, the intensity has been increased to 55 kt. The initial motion estimate is 310/13 kt. There remains no significant change to the previous few track forecasts and synoptic reasonings. Elsa is expected to move northwestward and then northward around the western periphery of a mid-level subtropical ridge during the next 3 days, followed by acceleration toward the northeast on days 4 and 5 as the cyclone moves near the southeast U.S. coast and then over the northwestern Atlantic. The new NHC track forecast is basically just an update and extension of the previous advisory track, and lies close to a blend of the tightly packed corrected consensus model HCCA and the simple consensus models TVCA and GFEX. Cuban radar data from Pilan and Camaguey have occasionally revealed an eye-like feature in the low -and mid-levels of the cyclone where cloud top temperatures have been colder than -80C and also where significant lightning activity has been occurring. Given that the circulation centers have become better aligned and the upper-level outflow pattern is well-established and steadily improving, some additional strengthening during the next 12 h is forecast, which calls for Elsa to be near hurricane strength before landfall occurs along the south-central coast of Cuba tomorrow. Over the eastern Gulf of Mexico late Monday and Tuesday, some restrengthening is forecast after Elsa clears Cuba, but southwesterly vertical wind shear is expected to hinder the intensification process. The official intensity forecast remains on the high side of the numerical model guidance, and follows a blend of the HCCA intensity consensus model, and the LGEM and and Decay-SHIPS statistical-dynamical models. Key Messages: 1. Widespread heavy rain will continue to affect portions of Jamaica tonight where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba tonight into Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and coastal Georgia Monday through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding. Mid to late week, heavy rains across coastal South Carolina may result in isolated flash flooding. 2. Tropical storm conditions and a dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba tonight. Tropical storm conditions are expected in portions of central and western Cuba tonight and Monday, and will spread into portions of the Florida Keys by late Monday. 3. Tropical Storm and Surge Surge Watches are in effect for portions of the west coast of the Florida peninsula where tropical storm conditions and a dangerous storm surge are possible beginning as early as Monday night and continuing into Tuesday. 4. There is a risk of tropical storm conditions, storm surge, and rainfall impacts along the remainder of the Florida Peninsula Tuesday night through Wednesday and the coasts of Georgia and the Carolinas Wednesday and Thursday. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 20.6N 79.2W 55 KT 65 MPH 12H 05/1200Z 21.9N 80.7W 60 KT 70 MPH 24H 06/0000Z 23.5N 82.1W 50 KT 60 MPH 36H 06/1200Z 25.1N 82.9W 50 KT 60 MPH 48H 07/0000Z 27.1N 83.2W 50 KT 60 MPH 60H 07/1200Z 29.2N 82.8W 45 KT 50 MPH...INLAND 72H 08/0000Z 31.5N 81.6W 35 KT 40 MPH...INLAND 96H 09/0000Z 36.0N 76.0W 35 KT 40 MPH...INLAND 120H 10/0000Z 41.0N 66.8W 40 KT 45 MPH...OVER WATER $$ Forecaster Stewart
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