Gordon - 91L

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DoctorMu
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Gordon - 91L

Post by DoctorMu » Mon Sep 03, 2018 4:09 pm

Gordon now projected to reach hurricane strength (CAT 1) at landfall:


Tropical Storm Gordon Discussion Number 6
NWS National Hurricane Center Miami FL AL072018
500 PM EDT Mon Sep 03 2018

Data from an earlier Air Force Reserve reconnaissance mission, along
with Doppler velocity data from the Miami radar, indicate that
Gordon has strengthened a little more, with some these data
supporting an intensity of about 50 kt. However, since the earlier
5-n mi-diameter eye has eroded and inner-core convection has become
somewhat ragged, the initial intensity remains 45 kt.

The initial motion estimate is 300/15 kt. The latest model guidance
is still in excellent agreement on Gordon maintaining a west-
northwestward to northwestward motion for the next 48-72 hours right
up until landfall as a strong ridge to the north of the cyclone is
forecast to remain locked in place over the southeastern U.S. and
mid-Atlantic states. Although the guidance has shifted slightly back
to the left, no appreciable changes were made to the previous
forecast track since the models have been 'windshield-wipering' back
and forth over the past 24 hours. The new NHC track forecast is
similar to or a little north of the latest consensus models.

Overall, Gordon's presentation in both radar and satellite imagery
has steadily improved since the previous advisory. Although the
inner-core structure has eroded somewhat, outer banding features
have improved and now extend as far north as central and northern
Florida. The GFS- and ECMWF-based SHIPS intensity models continue to
indicate that westerly to northwesterly wind shear of 10-15 kt is
expected to affect Gordon for the next 36 hours, a flow pattern that
would generally hinder development. However, the global models'
upper-level wind fields show Gordon remaining near or underneath a
synoptic-scale upper-level anticyclone, a more favorable pattern
that supports at least steady strengthening. Since Gordon will be
moving over very warm sea-surface temperatures of about 30 C, the
cyclone is forecast to reach hurricane strength in 24-36 hours, just
before landfall. For that reason, a Hurricane Warning has been
issued for portions of the central Gulf Coast. The NHC intensity
forecast is a little above the previous advisory, and is close to a
blend of the consensus models HCCA, FSSE, and IVCN.

Key Messages:

1. Gordon is expected to bring life-threatening storm surge and
hurricane conditions to portions of the central Gulf Coast where a
Storm Surge Warning and Hurricane Warning are in effect. Residents
in these areas should listen to advice from their local officials.
All preparations to protect life and property should be rushed to
completion, as tropical storm conditions are expected to arrive in
the warning areas Tuesday afternoon or evening.

2. Heavy rainfall from Gordon will affect southern Alabama, southern
Mississippi and Louisiana, where totals could reach as high as 8
inches. This rainfall could cause flash flooding.

3. Rainfall will continue across portions of South Florida and the
Florida Keys through early Tuesday, where totals could reach as high
as 8 inches.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 26.2N 82.6W 45 KT 50 MPH
12H 04/0600Z 27.3N 84.8W 50 KT 60 MPH
24H 04/1800Z 28.9N 87.2W 60 KT 70 MPH
36H 05/0600Z 30.6N 89.3W 65 KT 75 MPH...INLAND
48H 05/1800Z 32.1N 91.1W 35 KT 40 MPH...INLAND
72H 06/1800Z 34.1N 93.5W 25 KT 30 MPH...INLAND
96H 07/1800Z 35.5N 94.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1800Z 38.2N 94.8W 20 KT 25 MPH...POST-TROP/REMNT LOW