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Tropical Storm Zeta Discussion Number  13
NWS National Hurricane Center Miami FL       AL282020
400 PM CDT Tue Oct 27 2020
 
Visible satellite images show that the low-level center of the storm 
is slightly displaced to the north of the main area of deep 
convection.  Since the organization of the tropical cyclone has not 
yet improved, the current intensity is held at 55 kt, which is a 
blend of subjective and objective Dvorak estimates.  Zeta should 
move over warm waters and through a moist, low-shear environment 
through tomorrow morning, so strengthening is anticipated, and the 
cyclone is likely to regain hurricane intensity within the next 6-12 
hours. The NHC intensity forecast is on the high side of the model 
guidance suite. Zeta is expected to interact with a frontal zone 
and become an extratropical cyclone as it approaches the eastern 
United States in a couple of days. After moving off the U.S. east 
coast, the system is forecast to become absorbed by the same frontal 
system.
 
Zeta continues to move northwestward, or at about 310/12 kt.  The 
expected large-scale steering flow evolution remains about the same 
as before.  Zeta is expected to turn northward and move along the 
western side of a mid-level anticyclone centered east of Florida 
through Wednesday morning.  Then, a vigorous 500-mb shortwave trough 
approaching from the west should cause Zeta to accelerate north- 
northeastward and move inland along the central Gulf Coast by late 
Wednesday.  The cyclone should continue to accelerate ahead of the 
trough and move over the southeastern and eastern U.S. through 
Thursday.  The official track forecast was nudged just slightly 
westward in 24 to 36 hours to be in better agreement with the latest 
GFS and ECMWF explicit model fields.
 
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. Localized heavy rainfall from Zeta will continue tonight in 
portions of the Yucatan Peninsula of Mexico and western Cuba where 
additional flash flooding is possible in urban areas. Tonight 
through Thursday heavy rainfall is expected from portions of the 
central U.S. Gulf Coast into the Ohio Valley and Mid-Atlantic 
States. This rainfall will lead to flash, urban, small stream, and 
minor river flooding.

FORECAST POSITIONS AND MAX WINDS
 
INIT  27/2100Z 22.7N  90.3W   55 KT  65 MPH
 12H  28/0600Z 24.5N  91.3W   70 KT  80 MPH
 24H  28/1800Z 27.9N  91.0W   70 KT  80 MPH
 36H  29/0600Z 32.4N  87.8W   45 KT  50 MPH...INLAND
 48H  29/1800Z 37.2N  81.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
 60H  30/0600Z 40.0N  70.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  30/1800Z...DISSIPATED
 
$$
Forecaster Pasch
 
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