Official Discussion issued by the National Hurricane Center

Delta (AL262020) DATA RELEASED: 10/8/2020 4:00:00 PM UTC

Copy of official data

Hurricane Delta Discussion Number  17
NWS National Hurricane Center Miami FL       AL262020
400 PM CDT Thu Oct 08 2020

Delta is strengthening.  In satellite imagery, an eye is now seen in 
the cold cloud tops of the central dense overcast.  On the aircraft 
side, just received reports from an Air Force Reserve Hurricane 
Hunter aircraft included 700-mb flight-level winds of 119 kt, SFMR 
winds estimates near 90 kt, and a central pressure of 959 mb inside 
a 30 n mi wide eye.  A blend of the flight-level and SFMR wind 
estimates give an initial intensity of 100 kt, and Delta is again a 
major hurricane.

The initial motion is now northwestward or 320/10 kt.  There is no 
change to the track forecast philosophy and little change to the 
track forecast from the previous advisory.  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 30 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 remains very 
tightly clustered in terms of direction, and the new forecast track 
is near the various consensus models.

Shear, sea surface temperature, and moisture conditions appear 
favorable for strengthening during the next 12 h or so, and based on 
this additional intensification is expected tonight. A short period 
of rapid intensification remains possible given current trends, 
although the various rapid intensification indices are not 
enthusiastic about the possibilities of this,  After 12 h, the 
global models again forecast strong southwesterly shear developing 
over the hurricane before landfall, and based on this some weakening 
is forecast.  Rapid weakening is expected after landfall.  The 
system is expected to weaken to a depression no later than 60 h and 
degenerate to a remnant low by 72 h, with dissipation following 
shortly thereafter.  The intensity forecast lies at or above the 
upper edge of the intensity guidance.

Recent scatterometer data indicates that Delta is growing in size
as it approaches the Louisiana coast. The NHC wind radii forecast
again follows a combination of the data and the forecasts from
global and hurricane regional models.

Key Messages:

1. Life-threatening storm surge is expected near and east of where 
Delta makes landfall 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 Morgan City, 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. Heavy rainfall will lead to significant flash flooding and minor 
to major river flooding in parts of Louisiana Friday and Saturday. 
Additional flooding is expected across portions of the central Gulf 
Coast into the Lower Mississippi Valley. 

FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 24.8N  93.4W  100 KT 115 MPH
12H  09/0600Z 26.3N  93.9W  110 KT 125 MPH
24H  09/1800Z 28.6N  93.5W  105 KT 120 MPH
36H  10/0600Z 31.0N  92.5W   65 KT  75 MPH...INLAND
48H  10/1800Z 32.9N  91.1W   40 KT  45 MPH...INLAND
60H  11/0600Z 34.3N  89.2W   30 KT  35 MPH...INLAND
72H  11/1800Z 35.8N  87.2W   20 KT  25 MPH...POST-TROP/INLAND
96H  12/1800Z...DISSIPATED

$$
Forecaster Beven