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Tropical Storm Gaston Forecast Discussion


172 
WTNT43 KNHC 242106 CCA
TCDAT3

Tropical Storm Gaston Discussion Number  18...Corrected
NWS National Hurricane Center Miami FL       AL082022
900 PM GMT Sat Sep 24 2022

Corrected Rainfall Statement In Key Messages

Gaston still lacks any deep convection near the center of its 
circulation.  There is a burst of convection, mentioned in the 
previous advisory, that is now northwest of Faial island and over a 
hundred miles from the center of the storm. The subjective and 
objective Dvorak classifications have decreased to 30-40 kt. 
Thus, the initial intensity has been lowered to 35 kt to be a blend 
of these estimates.

Strong vertical wind shear and dry environmental conditions 
continue to weaken Gaston.  These adverse atmospheric conditions 
are not expected to improve for the remainder of the forecast 
period, and the storm should gradually weaken.  The official 
forecast is slightly lower than the previous prediction due to the 
decrease in initial intensity.  Gaston is still expected to become 
fully post-tropical within 12 hours.  Global model simulated 
satellite imagery, however, indicate a mid-latitude shortwave 
trough interacting with post-tropical Gaston early Sunday morning 
could develop isolated deep convection, but this should be a 
short-lived event.

Gaston has made its turn to the west and is moving 280/10 kt.  The 
storm should continue to move generally westward for the next day 
or so as it is steered by a building ridge to the north.  The ridge 
is then expected to turn the cyclone to the west-southwest and 
southwest through the end of the forecast period.  The model 
guidance has shifted to the north this forecast cycle.  The 
official track forecast follows the northward guidance trend and 
now lies on the south side of the guidance, though north of the 
previous advisory.


Key Messages:

1. Tropical storm conditions over the western Azores should 
diminish overnight as Gaston moves away from the islands.

2. Gaston is expected to produce heavy rainfall over the western and 
central Azores through early Sunday.  This rainfall may result in 
landslides and areas of flooding.


FORECAST POSITIONS AND MAX WINDS

INIT  24/2100Z 38.2N  31.8W   35 KT  40 MPH
 12H  25/0600Z 38.6N  33.7W   35 KT  40 MPH...POST-TROPICAL
 24H  25/1800Z 38.6N  36.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  26/0600Z 38.3N  38.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  26/1800Z 38.0N  39.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  27/0600Z 37.5N  42.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  27/1800Z 37.0N  45.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  28/1800Z...DISSIPATED

$$
Forecaster Bucci




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