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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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