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Hurricane Zeta Discussion Number  15
NWS National Hurricane Center Miami FL       AL282020
400 AM CDT Wed Oct 28 2020
 
The satellite presentation of Zeta has improved significantly 
overnight with deep convection wrapping around an eye that at times 
as been fairly well defined.  An Air Force Reserve Hurricane Hunter 
aircraft that has just began its reconnaissance mission into Zeta 
has reported a pressure that has fallen to 982 mb and a 25-30 
n-mi-wide eye during it first pass through the center. It is 
somewhat surprising that the plane did not report stronger winds 
during its northeast eyewall pass given the improved satellite 
presentation, and using a blend of the aircraft data and recent 
objective and subjective satellite estimates yields and initial 
intensity of 75 kt.  It is possible the winds have yet to catch up 
to the improved satellite appearance, but since Zeta will moving 
over warm waters and in a light wind shear environment this morning 
some additional strengthening is likely.   Although cooler waters 
and increasing southwesterly upper-level winds over the northern 
Gulf of Mexico are likely to cause the cyclone's intensity to 
level-off or even come down slightly, Zeta is expected to reach the 
northern Gulf coast as significant hurricane by late this afternoon. 
The NHC intensity forecast is at the upper-end of the guidance, a 
little above the latest HWRF prediction. After landfall, Zeta will 
weaken while it moves over the southeastern United States, but the 
cyclone is forecast to become an extratropical gale-force low 
pressure area off the Mid-Atlantic coast Thursday night.  The 
post-tropical cyclone should be absorbed by frontal boundary over 
the western Atlantic on Friday.
 
Zeta has turned north-northwestward and has begun to accelerate as
anticipated.  A vigorous upper-level low moving into west Texas
will cause Zeta to accelerate north-northeastward today, which will
bring the center of the hurricane over southeastern Louisiana by
late this afternoon.  The cyclone is expected to continue to
accelerate ahead of the trough over the southeastern United States
tonight and Thursday. The dynamical model are in very good
agreement and the latest NHC track is a blend of the various global
models. The new track forecast is very close the previous official
forecast.
 
Given Zeta's acceleration near landfall, strong winds are likely
to spread well inland along the northern Gulf coast this evening
and tonight.
 
KEY MESSAGES:
 
1. A life-threatening storm surge is expected along portions of the
northern Gulf Coast by late today, 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 this afternoon 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 and central Alabama tonight due to Zeta's fast forward 
speed.

3. Through Thursday, heavy rainfall is expected from portions of the 
central U.S. Gulf Coast into the Tennessee Valley, Ohio Valley, 
Southern to Central Appalachians, and Mid-Atlantic States near and 
in advance of Zeta. This rainfall will lead to flash, urban, small 
stream, and minor river flooding.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/0900Z 25.1N  91.8W   75 KT  85 MPH
 12H  28/1800Z 27.9N  91.1W   85 KT 100 MPH
 24H  29/0600Z 32.8N  87.5W   50 KT  60 MPH...INLAND
 36H  29/1800Z 37.5N  79.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  30/0600Z 40.5N  67.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 60H  30/1800Z...DISSIPATED
 
$$
Forecaster Brown
 
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