794
WTNT44 KNHC 011500
TCDAT4

Tropical Storm Eta Discussion Number 4
NWS National Hurricane Center Miami FL AL292020
1000 AM EST Sun Nov 01 2020

Eta appears to be gradually becoming better organized this morning.
A small area of persistent, deep convection near and over the center
has supported the development of a small central dense overcast.
Meanwhile, a larger convective band with limited curvature is noted
well northeast and east of the storm center. Objective intensity
estimates from UW-CIMSS and subjective Dvorak classifications from
TAFB and SAB support an initial intensity of 35 kt. It should be
noted that the center was relocated a bit farther south this morning
based on overnight microwave imagery. A NOAA Hurricane Hunter
aircraft is scheduled to investigate Eta this afternoon.

Weak vertical wind shear and high oceanic heat content should
support steady strengthening over the next couple of days. The SHIPS
Rapid Intensification Index still indicates the potential for rapid strengthening, and the official NHC intensity forecast lies on the
higher end of the guidance envelope. The current forecast shows Eta
becoming a hurricane by 36 h, and continued strengthening is
forecast through landfall. Once inland, Eta should quickly weaken
over the mountainous terrain of Central America.

The tropical storm is moving westward at around 13 kt. A westward or west-southwestward motion with a gradual decrease in forward speed
is expected over the next several days, as Eta is steered by a
mid-level ridge positioned to its north and northwest. The track
guidance remains fairly tightly clustered through about 72 h, and
the only change with this forecast is a slight southward correction
based on the relocated center position. The official NHC forecast
now brings Eta inland over Central America by 60 h. There is
increased uncertainty in the track forecast post-landfall, with a
range of plausible outcomes. While much of the guidance suggests Eta
will spin down and weaken over Central America or possibly cross
into the eastern Pacific, some model solutions indicate the
potential for Eta or its remnants to re-emerge over the northwestern
Caribbean Sea at or beyond day 5. For now, the official NHC forecast
remains close to the previous one and the corrected consensus aid
HCCA, which keeps the cyclone inland over Central America through
day 5.


Key Messages:

1. Eta is expected to strengthen to a hurricane before it reaches
the coast of Central America early Tuesday, and there is a risk of
storm surge, hurricane-force winds, and heavy rainfall for portions
of Nicaragua and Honduras, where Hurricane and Tropical Storm
Warnings have been issued.

2. Through Thursday afternoon, heavy rainfall from Eta may lead to life-threatening flash flooding and river flooding across portions
of Jamaica, the Cayman Islands, and Central America, along with
landslides in areas of higher terrain.


FORECAST POSITIONS AND MAX WINDS

INIT 01/1500Z 14.8N 77.2W 35 KT 40 MPH
12H 02/0000Z 14.9N 78.9W 45 KT 50 MPH
24H 02/1200Z 14.9N 80.6W 55 KT 65 MPH
36H 03/0000Z 14.5N 81.9W 65 KT 75 MPH
48H 03/1200Z 14.2N 82.7W 75 KT 85 MPH
60H 04/0000Z 13.9N 83.6W 70 KT 80 MPH...INLAND
72H 04/1200Z 13.8N 84.4W 45 KT 50 MPH...INLAND
96H 05/1200Z 14.1N 86.7W 30 KT 35 MPH...INLAND
120H 06/1200Z 14.6N 88.2W 25 KT 30 MPH...INLAND

$$
Forecaster Reinhart/Brown/Berg
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