Official Discussion issued by the National Hurricane Center

Delta (AL262020) DATA RELEASED: 10/8/2020 10:00:00 AM UTC

Copy of official data

Hurricane Delta Discussion Number  16
NWS National Hurricane Center Miami FL       AL262020
1000 AM CDT Thu Oct 08 2020

Satellite imagery shows that Delta is better organized this 
morning, with the center well embedded in a cold central dense 
overcast and a hint of a eye developing in the overcast.  Reports 
from Air Force Reserve and NOAA Hurricane hunter aircraft indicate 
that the central pressure has fallen to 968 mb inside a 35 n mi wide 
eye, along with flight-level and SFMR winds that support an initial 
intensity of 90 kt.

The initial motion remains northwestward or 305/12 kt.  The track 
forecast is reasonably straightforward.  During the next 12-24 h, 
Delta should turn to the north between a mid- to upper-level ridge 
over the Florida Peninsula and eastern Gulf of Mexico and a mid- to 
upper-level level trough over the U.S. Southern Plains.  This 
should be followed by a north-northeastward motion that is expected 
to bring the center near or over the northern Gulf coast, most 
likely in southwestern Louisiana, in about 36 h.  After landfall, 
the cyclone should move northeastward through the Lower Mississippi 
and Tennessee Valleys along the southern edge of the mid-latitude 
westerlies until it dissipates.  The track guidance is very tightly 
clustered in terms of direction, and the new forecast track has 
only minor tweaks from the previous one.

Shear, sea surface temperature, and moisture conditions appear 
favorable for strengthening during the next 12-24 h or so, and 
based on this Delta is expected to regain major hurricane strength.  
Rapid intensification cannot be ruled out, although the various 
rapid intensification indices do not suggest a high chance, and 
the first 24 h of the forecast is already above the intensity 
guidance.  The global models forecast strong southwesterly shear 
developing over the hurricane during the last 12 h before landfall, 
and based on this some weakening is forecast.  Rapid weakening is 
expected after landfall, with Delta forecast to degenerate to a 
remnant low by 72 h and dissipate shortly after that. It should be 
noted that the NHC 1-2 day intensity forecasts are subject to errors 
of around 1 Saffir-Simpson category.

Delta is expected to grow in size as it approaches the Louisiana 
coast. The NHC wind radii forecast again follows a consensus of the 
global and hurricane regional models.

Key Messages:

1. Life-threatening storm surge is expected near and east of where
Delta makes landfall on Friday, and a Storm Surge Warning is in
effect from High Island, Texas, to Ocean Springs, Mississippi. The
highest inundation of 7 to 11 feet is expected somewhere between
Rockefeller Wildlife Refuge and Port Fourchon, Louisiana. Residents
in the warning area should promptly follow advice given by local 
officials. The storm surge risk remains high despite the forecast 
decrease in intensity before landfall since Delta is expected to 
grow in size.

2. Hurricane-force winds are expected Friday afternoon and evening
somewhere within the Hurricane Warning area between High Island,
Texas, and Morgan City, Louisiana. Hurricane-force winds will also
spread inland across portions of southern Louisiana near the path of
Delta∆s center Friday evening and Friday night.

3. Significant flash flooding and minor to moderate river flooding
are likely in parts of Louisiana Friday and Saturday, with 
additional flooding in portions of the central Gulf Coast into the 
Lower Mississippi Valley.

FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 24.0N  92.7W   90 KT 105 MPH
12H  09/0000Z 25.4N  93.6W   95 KT 110 MPH
24H  09/1200Z 27.5N  93.8W  100 KT 115 MPH
36H  10/0000Z 29.8N  93.1W   90 KT 105 MPH...ON THE COAST
48H  10/1200Z 32.4N  91.7W   45 KT  50 MPH...INLAND
60H  11/0000Z 34.0N  90.0W   30 KT  35 MPH...INLAND
72H  11/1200Z 35.6N  87.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
96H  12/1200Z...DISSIPATED

$$
Forecaster Beven