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Tropical Depression Eta Forecast Discussion Number 26
2020-11-07 03:53:42| National Hurricane Center (Atlantic)
Issued at 900 PM CST Fri Nov 06 2020 000 WTNT44 KNHC 070253 TCDAT4 Tropical Depression Eta Discussion Number 26 NWS National Hurricane Center Miami FL AL292020 900 PM CST Fri Nov 06 2020 A NOAA Hurricane Hunter aircraft that flew a tail-Doppler radar mission earlier this evening reported that Eta's circulation remained elongated, and that there had not been any significant increase in winds since this afternoon. There has been some increase in deep convection near and to the east of the estimated center, but there has been little overall change in organization. Therefore, the initial intensity remains 30 kt for this advisory. Eta is expected to strengthen over the next 24 to 48 hours while it moves over warm waters and within an area of strong upper-level divergence to the southeast of a mid- to upper-level trough over the Gulf of Mexico. Eta's structure is likely to take on characteristics of a subtropical cyclone as it merges with the cutoff low late Sunday and Monday. As this occurs, Eta's wind field is expected to increase in size. By 72 hours and beyond, dry air entrainment is likely to cause some weakening. The new NHC intensity forecast is close to the previous one. Eta is moving toward northeastward at a faster forward speed of around 10 kt. An additional increase in forward speed should occur overnight as Eta moves northeastward around the southeastern portion of a developing mid- to upper-level trough over the Gulf of Mexico. This feature should continue to steer Eta northeastward during the next 24 hours, but after that time the trough is forecast to cut-off, with Eta turning northward, and then northwestward around and into the mid- to upper-level closed low. The merged system is likely to move northwestward or northward later in the period. The latest runs of the dynamical models have trended toward a more northward track on Sunday and Monday with some of them showing a track near or over the southern portion of the Florida peninsula in 48 to 60 hours. The new NHC track forecast has been adjusted slightly northward during that time and lies between the TVCA multi-model consensus and the HFIP corrected consensus aid. Since Eta's wind field is forecast to expand when it moves north of Cuba, tropical-storm-force winds are expected to cover a large area to the north and northeast of the center regardless of the exact track of the center. The new forecast track requires a Tropical Storm Watch for the northwestern Bahamas, the southern Florida peninsula, and the Florida Keys. Additional watches for the Florida peninsula may be required overnight or on Saturday morning. Key Messages: 1. Heavy rainfall is diminishing across portions of Central America, although the threat of life-threatening flooding may continue, along with landslides in areas of higher terrain. Heavy rainfall from Eta will move into the Cayman islands and portions of Cuba, resulting in significant, life-threatening flash flooding and river flooding in Cuba. Flash and urban flooding will also be possible for the Cayman Islands, Jamaica, southeast Mexico, the Bahamas and Southern Florida. 2. Tropical storm conditions are expected this weekend in portions of the Cayman Islands and Cuba, where a Tropical Storm Warning is in effect. 3. There is an increasing risk of impacts from wind and flash and urban flooding due to heavy rainfall in portions of southern Florida, the Florida Keys, and portions of the Bahamas this weekend and early next week. Tropical Storm Watches have been issued for portions of these areas and additional watches may be required overnight or on Saturday morning. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 18.0N 85.2W 30 KT 35 MPH 12H 07/1200Z 19.0N 83.2W 40 KT 45 MPH 24H 08/0000Z 20.3N 81.1W 45 KT 50 MPH 36H 08/1200Z 21.9N 79.9W 50 KT 60 MPH...INLAND 48H 09/0000Z 24.0N 79.9W 55 KT 65 MPH...OVER WATER 60H 09/1200Z 25.0N 81.3W 55 KT 65 MPH 72H 10/0000Z 25.2N 82.6W 50 KT 60 MPH 96H 11/0000Z 26.0N 84.3W 45 KT 50 MPH 120H 12/0000Z 27.0N 84.7W 45 KT 50 MPH $$ Forecaster Brown
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