Official Discussion issued by the National Hurricane Center

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

Copy of official data

Hurricane Delta Discussion Number  18
NWS National Hurricane Center Miami FL       AL262020
1000 PM CDT Thu Oct 08 2020

Reports from Air Force and NOAA Hurricane Hunter aircraft
investigating Delta indicate that the hurricane strengthened a
little more this evening.  Peak flight-level winds were 120 kt, and
the highest SFMR-observed surface winds were 98 kt.  Using a blend
of adjusted flight-level and surface wind observations, the current
intensity estimate is set at 105 kt.  The eye became obscured on
satellite images a couple of hours ago, but recently it has become
apparent again.  Delta could intensify a little more within the next
6 hours or so.  Thereafter, sharply decreasing oceanic heat content,
significantly increasing west-southwesterly shear, and drier
mid-level air should cause weakening.  The official intensity
forecast through landfall is above most of the model guidance.
However, even 24-hour tropical cyclone intensity forecasts are 
still subject to an uncertainty of 1 Saffir-Simpson category, so 
one should not focus on the exact official landfall intensity 
forecast.  Moreover, even if Delta weakens some, it will still have 
serious storm surge impacts due to its large size.

Aircraft and satellite center fixes show that the hurricane is
gradually turning toward the right.  The motion is now
north-northwestward, or 340/10 kt.  Delta should turn northward on
Friday as it moves on the western side of a mid-tropospheric high
pressure area.  Later on Friday, a 500-mb shortwave trough over the
southern United States is likely to cause the tropical cyclone to
turn north-northeastward and cross the northern Gulf of Mexico
coast.  Delta should then move northeastward on the eastern side of
the trough over the southeastern United States for the next day or
two before dissipating near Kentucky.  The official track forecast
is very close to the previous NHC track, and in very good agreement
with the various consensus track predictions.


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 a relatively large 
hurricane.

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  09/0300Z 25.7N  93.6W  105 KT 120 MPH
12H  09/1200Z 27.4N  93.7W  105 KT 120 MPH
24H  10/0000Z 29.8N  93.0W   85 KT 100 MPH...INLAND
36H  10/1200Z 32.0N  91.9W   45 KT  50 MPH...INLAND
48H  11/0000Z 33.5N  90.2W   25 KT  30 MPH...INLAND
60H  11/1200Z 34.9N  88.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
72H  12/0000Z 36.5N  87.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
96H  13/0000Z...DISSIPATED

$$
Forecaster Pasch/Berg