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Tropical Depression Eta Forecast Discussion Number 22
2020-11-06 03:54:23| National Hurricane Center (Atlantic)
Issued at 900 PM CST Thu Nov 05 2020 000 WTNT44 KNHC 060254 TCDAT4 Tropical Depression Eta Discussion Number 22 NWS National Hurricane Center Miami FL AL292020 900 PM CST Thu Nov 05 2020 Eta has not become any better organized during the past several hours, and a specific center is hard to locate. It is estimated that the center is near a growing area of deep convection located east of the Belize. While it is possible the system has degenerated into a broad low or trough, there isn't enough evidence to break continuity, so Eta remains a 30-kt tropical depression on this advisory. Scatterometer data will probably come in overnight to provide a better look at the low-level circulation. The initial motion is an uncertain 360/7 kt. Eta should move northeastward on Friday around a developing mid- to upper-level trough over the Gulf of Mexico, then turn northward on Sunday and west-northwestward early next week as the trough cuts off into a closed low. The details of this sinuous path, however, are pretty fuzzy and small differences in the tropical cyclone position could lead to large errors down the line. The most notable change tonight is that the GFS-based guidance (including HWRF and HMON) have generally shifted northward and faster. The new forecast is moved eastward near Cuba, and then northward near the Florida Keys in response to this guidance and the 18Z ECMWF. It should be stressed this is a fairly uncertain forecast due to the strong trough interaction. Eta should begin to strengthen on Friday due to the low-level circulation forecast to become better defined in a fairly conducive environment. While vertical wind shear could increase this weekend, it is expected that upper-level divergence and trough dynamics will overwhelm the negative factors and cause continued intensification until the system reaches Cuba. The new forecast is raised from the previous one, but still lies below the NOAA corrected-consensus model HCCA. There isn't a lot of agreement on the intensity after Cuba, however, and the forecast hinges on how tropical it will remain after the trough interaction. The new forecast flattens out the intensity near Florida as a compromise between the various solutions, but I don't have much confidence in the forecast at that range. Key Messages: 1. Through Monday morning, 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, the Cayman Islands and western Cuba. 2. Eta is forecast to regain tropical storm strength over the northwestern Caribbean Sea on Friday. Although the details of the future track and intensity of Eta are uncertain, there is an increasing risk of impacts from wind and rainfall in portions of the Cayman Islands, Cuba, southern Florida and the Florida Keys and the northwestern Bahamas this weekend and early next week. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 16.6N 87.8W 30 KT 35 MPH 12H 06/1200Z 17.5N 87.2W 35 KT 40 MPH 24H 07/0000Z 18.8N 85.4W 40 KT 45 MPH 36H 07/1200Z 19.7N 83.2W 45 KT 50 MPH 48H 08/0000Z 20.8N 81.0W 55 KT 65 MPH 60H 08/1200Z 22.6N 79.8W 50 KT 60 MPH...INLAND 72H 09/0000Z 24.2N 80.4W 55 KT 65 MPH...OVER WATER 96H 10/0000Z 25.0N 83.0W 55 KT 65 MPH 120H 11/0000Z 25.5N 85.0W 55 KT 65 MPH $$ Forecaster Blake
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