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Tropical Storm Eta Discussion Number  39
NWS National Hurricane Center Miami FL       AL292020
900 PM CST Mon Nov 09 2020
 
Eta's convective structure appears to be gradually becoming better 
organized this evening. The center is located near the northern edge 
of a band that wraps around the southeastern and southern portions 
of the circulation.  Recent subjective Dvorak data T-numbers were 
3.0, which still support an initial intensity of 45 kt. With Eta's 
structure gradually improving and a forecast for the cyclone to 
remain over SSTs of around 28C and in generally low vertical wind 
shear conditions, some re-strengthening is likely during the next 
24-36 hours. Although the NHC intensity forecast shows Eta remaining 
just below hurricane strength, there is a possibility that the storm 
will briefly regain hurricane status over the southeastern Gulf of 
Mexico within the next day or so.  By 48 hours, when the cyclone 
moves over the east-central Gulf of Mexico, increasing vertical wind 
shear and dry mid-level air are likely to result in weakening, and 
like the previous forecast, the new NHC forecast indicates that Eta 
could weaken to a tropical depression by the end of the period. Some 
of the global model guidance suggests that Eta could weaken even 
faster than indicated below after 72 hours. 

Recent satellite fixes indicate that Eta is moving southwestward but 
a little slower than before at around 8 kt. Eta should slow its 
forward progress overnight and then meander over the southeastern 
Gulf of Mexico on Tuesday as steering current collapse. In 36-48 
hours, Eta should begin moving northward between a mid-level ridge 
over the western Atlantic and a broad trough over the central United 
States. After 72 hours, the spread in the guidance increases when 
Eta is expected to be weaker and be steered by the low-level flow.  
Most of the guidance shows a northwestward to northward motion at 
that time period but have varying forward speed. The NHC track shows 
a slow north-northwest motion late in the period to account for 
these differences.  There is lower than normal confidence in the 
latter portion of the track forecast given the large spread in the 
guidance. 

Key Messages:
 
1. Heavy rainfall from Eta will continue across portions of Cuba, 
the Bahamas, and southern Florida and spread north into central 
Florida.  Additional flash and urban flooding, especially across 
previously inundated areas, will be possible in South Florida 
tonight. Flash and urban flooding will also be possible for Cuba, 
the Bahamas and the remainder of southern Florida over the next 
several days.
 
2. Eta could approach the Florida Gulf Coast later this week as a
tropical storm, and possibly bring impacts from rain, wind, and
storm surge. Interests in this area should continue to monitor 
the progress of Eta and updates to the forecast this week.


FORECAST POSITIONS AND MAX WINDS
 
INIT  10/0300Z 23.2N  85.2W   45 KT  50 MPH
 12H  10/1200Z 22.8N  85.5W   50 KT  60 MPH
 24H  11/0000Z 23.4N  85.5W   60 KT  70 MPH
 36H  11/1200Z 24.6N  85.3W   60 KT  70 MPH
 48H  12/0000Z 25.8N  85.2W   55 KT  65 MPH
 60H  12/1200Z 26.6N  85.2W   50 KT  60 MPH
 72H  13/0000Z 27.0N  85.3W   45 KT  50 MPH
 96H  14/0000Z 27.7N  85.6W   35 KT  40 MPH
120H  15/0000Z 29.0N  86.0W   30 KT  35 MPH
 
$$
Forecaster Brown
 
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