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Tropical Storm Gabrielle Discussion Number 6
NWS National Hurricane Center Miami FL AL082019
1100 PM AST Wed Sep 04 2019
South to southwesterly shear is affecting the overall organization
of Gabrielle this evening. A recent scatterometer pass indicated
that the low-level center was located on the southern edge of
weakening convection, and to the south of a mid-level circulation
apparent in infrared satellite imagery. This same scatterometer pass
showed an expanded wind field in the northwest quadrant as well as
45-kt peak winds, and this initial intensity is in agreement with
the latest subjective satellite intensity estimate from TAFB.
The shear is not expected to abate for the next 48 hours, and sea
surface temperatures are forecast to remain marginal through 36
hours. Therefore little to no change in intensity is expected from
Gabrielle during the next couple of days. After 48 hours, shear is
expected to decrease for a few days while the cyclone moves over
waters warmer than 28 C. This should allow for some gradual
intensification, and Gabrielle is forecast to become a hurricane by
Sunday. The official intensity forecast is close to the previous
one and very near the intensity from the corrected consensus HCCA.
Gabrielle has been moving northwestward or 325/6 kt. This motion
should continue for the next day or so as the cyclone is steered by
a subtropical ridge to its northeast. After that time, a mid- to
upper-level low is forecast to develop to the west of Gabrielle,
which will help to increase the forward motion late this week and
over the weekend. There was a notable westward shift in the guidance
beyond 72 hours possibly due to the interaction of the cyclone with
the aforementioned upper low. After 96 hours, an approaching
mid-latitude trough will begin to turn Gabrielle to the north then
northeast. The official forecast track is very similar to the
previous one through 72 hours, and was shifted slightly westward
thereafter.
FORECAST POSITIONS AND MAX WINDS
INIT 05/0300Z 21.5N 34.4W 45 KT 50 MPH
12H 05/1200Z 22.4N 35.2W 45 KT 50 MPH
24H 06/0000Z 23.7N 36.6W 45 KT 50 MPH
36H 06/1200Z 25.4N 38.3W 45 KT 50 MPH
48H 07/0000Z 27.3N 40.2W 45 KT 50 MPH
72H 08/0000Z 30.8N 44.6W 55 KT 65 MPH
96H 09/0000Z 34.0N 48.0W 65 KT 75 MPH
120H 10/0000Z 37.5N 48.0W 65 KT 75 MPH
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Forecaster Latto
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