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Hurricane Delta Discussion Number 20
NWS National Hurricane Center Miami FL AL262020
1000 AM CDT Fri Oct 09 2020
Reports from NOAA and Air Force Reserve Hurricane Hunter aircraft
indicate that Delta has weakened a little since the last advisory.
The central pressure has risen to 962 mb, and the strongest 700-mb
flight-level winds reported by the NOAA plane were 107 kt. In
addition, SFMR wind estimates have been in the 85-95 kt range.
Based on these data, the initial intensity is lowered to 100 kt.
Delta is moving northward or 360/11 kt between a deep-layer ridge
over the eastern Gulf of Mexico and a mid- to upper-level trough
over the U.S. Southern Plains. A turn toward the north-northeast
is expected during the next few hours, and the center is forecast
to cross the southwestern coast of Louisiana late this afternoon
or this evening. After landfall, a continued north-northeastward
motion should bring the center across central and northeastern
Louisiana by the 24 h point. Thereafter, Delta is expected to move
generally northeastward through the lower Mississippi and Tennessee
Valleys until it dissipates. The track forecast guidance remains
tightly clustered, and the new forecast track is little changed
from the previous forecast.
Increasing vertical shear and decreasing oceanic heat content along
the forecast track should cause Delta to continue to weaken before
landfall. However, there will still be significant impacts from
winds and storm surge (see Key Messages below). After landfall,
rapid weakening is anticipated, with Delta expected to weaken to a
tropical storm tonight and to a tropical depression by Saturday
afternoon or evening. The cyclone is forecast to dissipate
between 60-72 h based on the consensus of the global models.
1. Life-threatening storm surge is expected near and east of where
Delta makes landfall this evening, and a Storm Surge Warning is in
effect from High Island, Texas, to the Mouth of the Pearl River.
The highest inundation of 7 to 11 feet is expected somewhere
between Rockefeller Wildlife Refuge and Morgan City, Louisiana.
Water levels in this area will rise quickly this afternoon and
evening as Delta approaches and efforts to protect life and
property should be rushed to completion.
2. Hurricane-force winds are expected this afternoon and evening
within portions of the Hurricane Warning area, especially along the
coast of southwest Louisiana. Hurricane force winds will also
spread inland across portions of southern Louisiana near the path of
Delta’s center this evening and tonight.
3. Heavy rainfall will lead to significant flash flooding and minor
to major river flooding in parts of Louisiana today and Saturday.
Additional flooding is expected across portions of the central Gulf
Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS
INIT 09/1500Z 28.0N 93.8W 100 KT 115 MPH
12H 10/0000Z 30.0N 93.0W 90 KT 105 MPH...INLAND
24H 10/1200Z 32.2N 91.8W 50 KT 60 MPH...INLAND
36H 11/0000Z 33.7N 90.2W 30 KT 35 MPH...INLAND
48H 11/1200Z 35.0N 88.4W 25 KT 30 MPH...INLAND
60H 12/0000Z 36.7N 86.2W 20 KT 25 MPH...POST-TROP/REMNT LOW