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Last advisory issued for Isaias as it moves over Quebec. Other than 94L (which looks like it won't develop) Atlantic is quiet for a bit.
Days since last H. Landfall - US: Any 3 (Isaias) , Major: 666 (Michael) Florida - Any: 666 (Michael) Major: 666 (Michael)
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#1010605 (Received by flhurricane at: 11:03 AM 01.Aug.2020)

Hurricane Isaias Discussion Number 18
NWS National Hurricane Center Miami FL AL092020
1100 AM EDT Sat Aug 01 2020

Data from an Air Force Reserve reconnaissance aircraft around 1410
UTC indicated that the center of the eye of Isaias was located
along the southern coast of northern Andros Island about 15 nmi
south-southwest of Andros Town. The eye appearance in Bahamas and
aircraft radar data, along with the visual reports from the flight
crew, has gone from nearly closed a few hours ago to open in the
southwestern quadrant more recently. However, the diameter of the
eye has been has been holding steady between 20-22 nmi, an
indication that Isaias has been able to fight off some modest
southwesterly wind shear. The initial intensity has been lowered
to 70 kt based on maximum 700-mb flight-level winds of 77 kt, which
equals about 70-kt surface wind speed, and the central pressure
fluctuating between 987-990 mb.

The initial motion estimate remains 315/10 kt. The latest NHC model
guidance is now tightly packed about the previous 18-h worth of
official track forecasts, and as a result, no significant changes
were made to the previous advisory track. The global and regional
models have come into much better agreement compared to 24 hours ago
in taking Isaias northwestward slowly for the next 36 h or so, and
moving the center near or keeping it just offshore the east-central
Florida coast. By 48 hours, the hurricane is expected to turn
northward around the western portion of the Bermuda-Azores ridge
that will slowly be eroded by an approaching mid-level shortwave
trough currently situated over the central United States. By 60 h
and beyond, the aforementioned trough is expected to gradually
accelerate Isaias northeastward near or along the coast from
South Carolina to New England. The new NHC track forecast is
basically an extension of the previous one, and lies very close to
an average of the simple consensus model TVCA, and the corrected-
consensus models NOAA-HCCA and FSSE.

In the near term, Isaias could weaken a little bit this afternoon
while passing over northern Andros Island. However, the still
impressive vertical structure of the cyclone should allow for some
re-strengthening after the center moves back over the warm Gulf
Stream by this evening. The current SHIPS analyzed westerly
vertical wind shear of 25 kt could be too high due to the model
incorporating some of the storm's outflow. The models forecast the
shear to weaken somewhat over the next 36 h while Isaias is moving
over the Gulf Stream, and the 06Z UKMET shows Isaias moving
underneath a 200-mb anticyclone, which would normally favor some
strengthening. Given all of these factors, the official forecast
maintains a steady intensity through Monday night. Slow weakening
is forecast when Isais encounters more significant southwesterly
vertical wind shear ahead of a strong upper-level trough that will
be approaching the U.S. east coast on days 3-5.

Key Messages:

1. Hurricane conditions and dangerous storm surge will continue in
portions of the northwest Bahamas today and tonight.

2. Hurricane conditions are expected along portions of the Florida
east coast by late tonight and Sunday. Preparations to protect life
and property should be rushed to completion.

3. Dangerous storm surge is possible along the Florida east coast
from Jupiter Inlet to Ponte Vedra Beach where water rises of 2 to 4
feet above ground level are possible along the immediate coastline
and adjacent waterways. Residents there should follow advice given
by local emergency officials.

4. Isaias will produce heavy rains and potentially life-threatening
flash flooding in the Bahamas, and flash urban flooding, especially
in low-lying and poorly drained areas, in eastern Florida, and from
the Carolinas to the mid-Atlantic and Northeast U.S. Minor river
flooding is possible across portions of the Carolinas and Virginia
early next week.

5. Tropical storm watches and warnings are in effect for portions
of the northeast Florida and southern Georgia coasts. Additional
watches and warnings will likely be issued later today and Sunday
along the U.S. east coast as the risk of wind, heavy rainfall, and
storm surge impacts continues to increase.


INIT 01/1500Z 24.7N 77.9W 70 KT 80 MPH
12H 02/0000Z 25.7N 78.8W 70 KT 80 MPH
24H 02/1200Z 27.1N 79.7W 70 KT 80 MPH
36H 03/0000Z 28.5N 80.3W 70 KT 80 MPH
48H 03/1200Z 30.1N 80.4W 65 KT 75 MPH
60H 04/0000Z 32.6N 79.4W 60 KT 70 MPH
72H 04/1200Z 36.0N 76.9W 50 KT 60 MPH...INLAND
96H 05/1200Z 43.3N 69.7W 45 KT 50 MPH...OVER WATER
120H 06/1200Z 49.0N 57.9W 40 KT 45 MPH...POST-TROP/EXTRATROP

Forecaster Stewart