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HURRICANE GASTON DISCUSSION NUMBER  42
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072016
1100 PM AST THU SEP 01 2016

The low-level center of Gaston is becoming exposed in infrared
satellite imagery, with about 25 kt of westerly shear pushing the
deep convection out ahead of the cyclone.  Dvorak CI numbers remain
4.5/77 kt from TAFB and 4.0/65 kt from SAB, while the objective ADT
has dropped well into tropical storm territory.  The initial winds
are only lowered to 65 kt to allow for a gradual spin down of the
circulation, but this estimate could be generous.  Due to
progressively colder sea surface temperatures and persistent shear,
continued weakening is forecast.  Gaston could lose its deep
convection in about 36 hours after it has passed the Azores, and
that's when it is expected to become post-tropical.  Dissipation is
still forecast by day 3. The NHC intensity forecast is an update of
the previous one and most closely follows the LGEM.

Now that Gaston's center is exposed, there is more confidence in
the initial motion (075/20 kt).  Gaston is expected to move
eastward or east-northeastward at a slower forward speed near the
western and central Azores during the next 36 hours.  After that
time, the shallow remnant low should turn northeastward ahead of an
approaching cold front.  The track guidance remains in good
agreement, and the NHC forecast is close to the TVCN multi-model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 38.3N  36.0W   65 KT  75 MPH
 12H  02/1200Z 38.8N  33.0W   55 KT  65 MPH
 24H  03/0000Z 39.4N  29.8W   45 KT  50 MPH
 36H  03/1200Z 40.6N  27.0W   35 KT  40 MPH...POST-TROPICAL
 48H  04/0000Z 42.7N  23.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  05/0000Z...DISSIPATED

$$
Forecaster Berg

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