Official Discussion issued by the National Hurricane Center

Zeta (AL282020) DATA RELEASED: 10/27/2020 10:00:00 AM UTC

Copy of official data

Tropical Storm Zeta Discussion Number  12
NWS National Hurricane Center Miami FL       AL282020
1000 AM CDT Tue Oct 27 2020

High-resolution GOES-16 visible satellite images indicate that the 
center of Zeta has moved just offshore of the northern coast of 
Yucatan.  Based on Air Force and NOAA aircraft observations a little 
while ago, after the cyclone's interaction with the Yucatan, the 
maximum winds had decreased to near 55 kt.  The cloud pattern of the 
storm is well organized, with a small Central Dense Overcast and 
numerous banding features.  Given this, Zeta is likely to 
restrengthen as it moves over the warm waters of the southern Gulf 
of Mexico and in a low-shear environment today through tomorrow 
morning.  When the cyclone nears the northern Gulf Coast in 30-36 
hours, decreasing oceanic heat content and possibly stronger shear 
will likely halt the intensification process.  The official 
intensity forecast shows slight weakening near landfall, but Zeta is 
likely to be at or near hurricane strength when it crosses the 
coastline.  The NHC intensity forecast is close to the model 
consensus and a blend of the LGEM and Decay-SHIPS guidance.

The storm continues its generally northwestward motion, or at around 
305/12 kt.  Zeta will move northwestward to northward around the 
southwestern and western periphery of a mid-level high pressure area 
centered east of Florida for the next 24 hours or so.  Then, a 
strong 500-mb shortwave trough approaching from the west should 
cause Zeta to accelerate north-northeastward to northeastward by 
late Wednesday and Thursday.  This will bring Zeta across the 
north-central Gulf coast late Wednesday and over the southeastern 
United States on Thursday.  Aside from some speed differences, the 
track models are in good agreement and have shown good run-to-run 
consistency.  The official track forecast is about the same as the 
previous one and close to the model consensus.

Given Zeta's acceleration near landfall, strong winds are likely 
to spread well inland along the northern Gulf coast Wednesday 
night. 

KEY MESSAGES:

1. A life-threatening storm surge is expected along portions of the 
northern Gulf Coast by late Wednesday, with the highest inundation 
occurring somewhere between the Mouth of the Pearl River and Dauphin 
Island, Alabama.  Residents in the Storm Surge Warning area should 
follow any advice given by local officials.

2. Hurricane conditions are expected by late Wednesday within 
portions of the Hurricane Warning area between Morgan City, 
Louisiana, and the Mississippi/Alabama border.  Damaging winds, 
especially in gusts, will spread well inland across portions of 
southeast Mississippi and southern Alabama Wednesday night due to 
Zeta∆s fast forward speed. 

3. Between tonight and Thursday, heavy rainfall is expected from 
portions of the central U.S. Gulf Coast into the Ohio Valley and 
Mid-Atlantic States near and in advance of Zeta.  This rainfall 
will lead to flash, urban, small stream, and minor river flooding.

4. Tropical storm conditions will continue in portions of the 
northern Yucatan Peninsula of Mexico during the next few hours. 
Heavy rainfall is expected across the Yucatan Peninsula, the Cayman 
Islands, and western Cuba today, which will lead to flash flooding 
in urban areas.

FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 21.6N  89.5W   55 KT  65 MPH
12H  28/0000Z 23.1N  90.9W   70 KT  80 MPH
24H  28/1200Z 25.7N  91.6W   75 KT  85 MPH
36H  29/0000Z 29.3N  89.9W   70 KT  80 MPH
48H  29/1200Z 34.2N  85.2W   30 KT  35 MPH...INLAND
60H  30/0000Z 38.5N  76.5W   30 KT  35 MPH...INLAND
72H  30/1200Z 41.0N  66.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
96H  31/1200Z...DISSIPATED

$$
Forecaster Pasch