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Tropical Storm Eta Forecast Discussion Number 35
2020-11-09 03:54:56| National Hurricane Center (Atlantic)
Issued at 1000 PM EST Sun Nov 08 2020 000 WTNT44 KNHC 090254 TCDAT4 Tropical Storm Eta Discussion Number 35 NWS National Hurricane Center Miami FL AL292020 1000 PM EST Sun Nov 08 2020 Although deep convection has waned near the center of Eta since this afternoon, radar imagery continues to show a ring of low-topped convection around the center, with some deep convection returning over the northeastern portion of the circulation. Doppler radar velocities of 64-68 kt around 5000 ft, and recent NOAA reconnaissance aircraft observations support maintaining the 55 kt initial intensity. The aircraft reported a minimum pressure of around 993 mb. Since Eta has a fairly large radius of maximum winds and a dry slot that has wrapped into the inner core, it appears that any short-term strengthening should be slow to occur. As a result, the new NHC intensity forecast calls for a little less strengthening until Eta moves into the southeastern Gulf of Mexico in about 24 hours. Regardless of whether Eta becomes a hurricane near the Florida Keys, there is little difference in impacts between a 55-to-60-kt tropical storm and a 65-kt hurricane. After 24 hours, Eta is forecast to move over warmer sea surface temperatures in the southeastern Gulf of Mexico and the vertical shear is forecast to decrease. This is expected to allow for some strengthening and Eta is forecast re-gain hurricane strengthen by Tuesday. Gradual weakening is predicted between 72-120 hours due to increasing southwesterly shear and the entrainment of dry mid-level air. The updated NHC intensity forecast is near the SHIPS/LGEM models during the first couple of days, and in good agreement with the HFIP corrected consensus model thereafter. Eta has turned northwestward this evening around the north side of a cut-off low located just south of western Cuba. The tropical cyclone should turn west-northwestward to westward overnight, and a southwestward motion is expected on Tuesday as Eta pivots around the upper-low. In 36-48 h, Eta is expected to slow down and possibly stall over the southeastern Gulf of Mexico as the steering currents weakening. In about 3 days, Eta should begin moving northward between a mid-level ridge over the western Atlantic and a broad trough over the central United States. The models that maintain Eta has a deeper system show a faster northeastward motion late in the period, whereas models that weaken Eta slow its northward progression by day 5. The NHC track forecast lies near the model consensus at 96 and 120 h, and is similar to the previous advisory. Key Messages: 1. Heavy rainfall from Eta will continue across portions of Cuba, Jamaica, the Bahamas, and southern Florida and spread north into central Florida. Life-threatening flash flooding is possible across the urban areas of southeast Florida. Significant, life-threatening flash flooding and river flooding is possible in Cuba, and significant flash and urban flooding are possible for Jamaica, the Bahamas and the remainder of southern Florida, along with potential minor river flooding in central Florida. 2. Hurricane conditions are expected tonight and early Monday across portions of the Florida Keys, and are possible across portions of southern Florida. Tropical storm conditions will extend well away from Eta's center across the southern and central portions of the Florida peninsula. 3. There is a danger of life-threatening storm surge in portions of the Florida Keys. Life-threatening storm surge is possible along portions of the southern coast of the Florida peninsula. Residents in these areas should follow any advice given by local officials. 4. Eta is forecast to approach the Florida Gulf Coast later this week as a tropical storm, and could bring impacts from rain, wind, and storm surge. Interests in this area should monitor the progress of Eta and updates to the forecast this week. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 24.6N 80.5W 55 KT 65 MPH 12H 09/1200Z 24.9N 82.6W 60 KT 70 MPH 24H 10/0000Z 24.2N 84.3W 60 KT 70 MPH 36H 10/1200Z 23.6N 85.1W 65 KT 75 MPH 48H 11/0000Z 24.2N 85.1W 65 KT 75 MPH 60H 11/1200Z 25.5N 84.9W 65 KT 75 MPH 72H 12/0000Z 26.6N 84.6W 60 KT 70 MPH 96H 13/0000Z 28.2N 83.6W 55 KT 65 MPH 120H 14/0000Z 30.0N 82.0W 45 KT 50 MPH...INLAND $$ Forecaster Brown
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