[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

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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