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#1022561 (Received by flhurricane at: 11:12 AM 25.Oct.2020)
TCDAT3

Tropical Storm Zeta Discussion Number 4
NWS National Hurricane Center Miami FL AL282020
1100 AM EDT Sun Oct 25 2020

Although the cloud pattern of the storm is not well-organized and
somewhat elongated zonally, the system is producing very vigorous
deep convection, particularly over the southern portion of the
circulation. Cirrus cloud motions show that the upper-level
outflow is well-defined. The current intensity estimate remains at
35 kt in agreement with Dvorak values from both TAFB and SAB, and
pending another Hurricane Hunter mission into the system this
afternoon.

The center is difficult to locate at this time, and the best
estimate for motion is quasi-stationary. A high pressure area
developing near Florida should induce a general northwestward
motion over the next couple of days. Later, a shortwave trough
approaching from the west is likely to cause Zeta to turn northward
and north-northeastward while it nears the northern Gulf Coast in
72-84 hours. The official track forecast lies between the GFS
solution which is farther east and the ECMWF prediction which lies
farther south and west.

Given the favorable upper-level outflow pattern and very high
oceanic heat content over the northwestern Caribbean, strengthening
is likely until the center moves near or over the Yucatan Peninsula
late tomorrow. Zeta should be near or at hurricane strength when it
approaches the Yucatan. The official intensity forecast for the
next 36 hours is close to the model consensus. After Zeta moves
into the central Gulf of Mexico, increasing southwesterly shear and
diminishing oceanic heat content are expected to prevent
strengthening. The NHC intensity forecast over the Gulf is above
the latest model consensus. Although not explicitly shown in the
official forecast, the unfavorable atmospheric and oceanic
conditions over the northern Gulf of Mexico could cause Zeta
to weaken by the time the center nears the northern Gulf coast.
However, users are reminded that these intensity forecasts are
subject to uncertainty.

KEY MESSAGES:

1. Tropical storm conditions are expected in portions of the
northern Yucatan Peninsula of Mexico Monday night and early Tuesday,
with hurricane conditions possible. Tropical storm conditions
could occur over extreme western Cuba on Monday.

2. Through Wednesday, heavy rainfall is expected from Zeta across
portions of central and western Cuba, the Cayman Islands, Jamaica,
the northeast Yucatan peninsula of Mexico, southern Florida and the
Keys. This rainfall may lead to flash flooding in urban areas.

3. Zeta could be at or just below hurricane strength when it
approaches the northern Gulf Coast on Wednesday, and could bring
storm surge, rainfall, and wind impacts to areas from Louisiana to
the Florida Panhandle. Residents in these areas should monitor the
progress of Zeta and updates to the forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 25/1500Z 17.8N 83.8W 35 KT 40 MPH
12H 26/0000Z 18.4N 84.1W 40 KT 45 MPH
24H 26/1200Z 19.2N 85.1W 50 KT 60 MPH
36H 27/0000Z 20.3N 86.7W 60 KT 70 MPH
48H 27/1200Z 21.9N 88.7W 65 KT 75 MPH
60H 28/0000Z 24.0N 90.3W 65 KT 75 MPH
72H 28/1200Z 27.0N 90.5W 65 KT 75 MPH
96H 29/1200Z 35.0N 85.5W 25 KT 30 MPH...INLAND
120H 30/1200Z...DISSIPATED

$$
Forecaster Pasch