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Tropical Storm Eta Forecast Discussion Number 15
2020-11-04 09:56:35| National Hurricane Center (Atlantic)
Issued at 400 AM EST Wed Nov 04 2020 000 WTNT44 KNHC 040856 TCDAT4 Tropical Storm Eta Discussion Number 15 NWS National Hurricane Center Miami FL AL292020 400 AM EST Wed Nov 04 2020 Eta still has a well-organized cloud pattern while it moves over northern Nicaragua, but there has been a considerable decrease in deep convection as evidenced by the warming cloud tops. Assuming an inland weakening rate as given by the Decay-SHIPS model, the current intensity is reduced to 60 kt. Continued weakening will occur over the next 48 hours or so, and the system should degenerate into remnant low tomorrow. In fact, the surface circulation could lose its identity in a day or two. However, the upper-level circulation is likely to remain intact, and a surface cyclone is predicted to regenerate once the system moves into the northwestern Caribbean Sea on Friday. Some strengthening is forecast thereafter, in line with the intensity model consensus. However, the global models show the system interacting with a strong upper-level trough in 3-5 days, so the cyclone may have some hybrid or subtropical characteristics by that time. Eta continues westward, or at about 270/7 kt. A mid-level ridge to the north of the cyclone should steer it on a generally west-northwestward track during the next 48 hours. Thereafter, a 500-mb trough/low dropping into the Gulf of Mexico is expected to cause the cyclone to move northeastward in 3-4 days. By the end of the forecast period, the system is expected to rotate cyclonically around the eastern side of the low. The official track forecast is quite close to the latest corrected consensus, HCCA, prediction which is usually a good performer. There is still significant uncertainty as to the details of the track in the 3- to 5-day time frame. Of more immediate concern are the torrential rains that Eta will continue to produce over portions of Central America. Key Messages: 1. Through Friday evening, heavy rainfall from Eta will lead to catastrophic, life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Flash and river flooding is also possible across Jamaica, southeast Mexico, El Salvador, southern Haiti, and the Cayman Islands. 2. Eta is forecast to regain tropical storm strength before it moves across portions of Cuba and approaches southern Florida this weekend. While it is too soon to determine the exact timing, magnitude, and location of possible impacts from wind and rainfall, interests in Cuba, southern Florida and the Florida Keys should monitor the progress of Eta through the week. FORECAST POSITIONS AND MAX WINDS INIT 04/0900Z 13.8N 84.7W 60 KT 70 MPH 12H 04/1800Z 14.0N 85.5W 40 KT 45 MPH...INLAND 24H 05/0600Z 14.6N 87.0W 30 KT 35 MPH...INLAND 36H 05/1800Z 15.5N 88.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 06/0600Z 16.5N 88.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 06/1800Z 17.6N 87.6W 30 KT 35 MPH...OVER WATER 72H 07/0600Z 19.0N 85.5W 35 KT 40 MPH 96H 08/0600Z 22.6N 81.8W 45 KT 50 MPH 120H 09/0600Z 25.0N 81.5W 50 KT 60 MPH $$ Forecaster Pasch
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