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Tropical Storm Elsa Forecast Discussion Number 18
2021-07-04 22:43:48| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Sun Jul 04 2021 000 WTNT45 KNHC 042043 TCDAT5 Tropical Storm Elsa Discussion Number 18 NWS National Hurricane Center Miami FL AL052021 500 PM EDT Sun Jul 04 2021 Elsa continues to exhibit some well-defined convective banding features over the northern and eastern portions of the circulation. Dvorak current intensity estimates from TAFB and SAB are 45 and 55 kt respectively,so the advisory intensity remains at 50 kt. Although the cirrus-level outflow over the area looks fairly impressive, the SHIPS output diagnoses about 20 kt of vertical shear over the cyclone, which may be inhibiting strengthening. Another negative factor could be blockage of the low-level inflow by the land masses surrounding the cyclone. The storm has turned toward the northwest, and the initial motion estimate is now 310/12 kt. There is little change to the track forecast reasoning from the previous advisory package. Elsa should move around the western periphery of a mid-level subtropical high pressure area during the next 3 days or so. Thereafter, the system should accelerate northward to northeastward over the eastern United States and the northwest Atlantic. No significant changes have been made to the NHC track forecast, which remains close to the simple and correct model consensus solutions. Some strengthening could occur as the storm approaches the south coast of Cuba and although not explicitly shown in the official forecast, Elsa could strengthen to near 60 kt before landfall in that country. Over the eastern Gulf of Mexico, southwesterly shear is expected to limit strengthening. The official intensity forecast remains on the high side of the numerical model guidance. 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 through 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. 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 04/2100Z 19.8N 77.9W 50 KT 60 MPH 12H 05/0600Z 21.1N 79.4W 55 KT 65 MPH 24H 05/1800Z 22.7N 81.2W 50 KT 60 MPH...INLAND 36H 06/0600Z 24.2N 82.4W 50 KT 60 MPH...OVER WATER 48H 06/1800Z 25.8N 83.0W 50 KT 60 MPH 60H 07/0600Z 27.9N 83.0W 50 KT 60 MPH 72H 07/1800Z 30.5N 82.3W 30 KT 35 MPH...INLAND 96H 08/1800Z 34.9N 78.0W 30 KT 35 MPH...INLAND 120H 09/1800Z 40.0N 69.0W 35 KT 40 MPH...OVER WATER $$ Forecaster Pasch
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