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Tropical Storm Gabrielle Discussion Number 21
NWS National Hurricane Center Miami FL AL082019
1100 AM AST Sun Sep 08 2019
Gabrielle continues to show signs of becoming better organized.
Deep convection now wraps about two-thirds of the way around the
center of circulation, and microwave imagery shows a distinct curved
band on the western semicircle. A blend of the various satellite
intensity estimates support holding the initial intensity at 50 kt.
However, this value may be a little conservative.
The tropical storm will continue to be in a moderately favorable
environment for intensification over the next 24 hours or so. And,
based on the improving presentation of Gabrielle since late
last night, some intensification seems likely during that time.
After 24 to 36 hours, increasing southwesterly shear will begin to
impact the cyclone as a mid-latitude trough approaches the region,
and the system will move over cooler waters. This should cause a
gradual weakening trend to begin. After 48 hours, Gabrielle is
expected to merge with a cold front and become an extratropical
cyclone. The official forecast intensity has been increased slightly
through 36 hours out of respect for the near term likelihood for
intensification. Otherwise, the forecast is similar to the previous
one, and is in agreement with the various consensus aids.
The initial motion is 330/10kt. Gabrielle will turn to the north
later today and then northeast by Monday as the system rounds the
western periphery of a mid-level ridge centered near the Azores.
Once Gabrielle turns northeastward, it will become embedded in the
increasing southwesterly flow ahead of the approaching mid-latitude
trough, which will accelerate the cyclone's forward motion. The
official forecast is little changed from the previous one, and is
near the tightly clustered track guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 08/1500Z 33.8N 49.0W 50 KT 60 MPH
12H 09/0000Z 35.6N 49.1W 60 KT 70 MPH
24H 09/1200Z 38.4N 47.5W 60 KT 70 MPH
36H 10/0000Z 41.2N 43.8W 60 KT 70 MPH
48H 10/1200Z 43.7N 39.0W 55 KT 65 MPH
72H 11/1200Z 50.1N 24.7W 45 KT 50 MPH...POST-TROP/EXTRATROP
96H 12/1200Z 57.8N 5.3W 35 KT 40 MPH...POST-TROP/EXTRATROP