444
WTNT43 KNHC 272041
TCDAT3

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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