[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 212031
TCDAT3

Tropical Storm Gaston Discussion Number   6
NWS National Hurricane Center Miami FL       AL082022
Issued by the NWS Weather Prediction Center College Park MD
900 PM GMT Wed Sep 21 2022

There has been little change associated with Gaston during the past
several hours.  The system continues to produce an area of deep
convection near the center and exhibits well-defined outflow over
the western semicircle.  However, drier air is entraining into
the eastern portion of the circulation.  The Dvorak CI-numbers from
TAFB and SAB continue to support an initial intensity of 55 kt.

Gaston continues to track northeastward over the north-central
Atlantic, with the latest initial motion estimated to be 045/12 kt.
Although there is no significant change to the forecast reasoning,
there is a considerable amount of model spread in the details of the
future steering pattern.  An amplifying ridge associated with Fiona
is expected to trap Gaston's circulation late this week and this
weekend.  This could result in a clockwise loop and an eventual
turn westward.  The new NHC track forecast is a little to the south
and faster than the previous one, trending toward the latest
consensus models.

It appears that the opportunity for strengthening has ended.  A slow
weakening trend should begin in the next day or so when Gaston moves
over cooler waters and into a region of drier air and slightly
stronger westerly vertical wind shear.  An approaching mid-level
trough should aid in the system's transition to an extratropical
cyclone in a couple of days or so.  The NHC intensity forecast
remains near the middle of the guidance envelope.

Interests in the Azores should continue to monitor the forecast for
Gaston.  For additional information, see warnings and products
issued by the meteorological service in the Azores.


FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 39.0N  40.0W   55 KT  65 MPH
 12H  22/0600Z 40.0N  37.4W   55 KT  65 MPH
 24H  22/1800Z 40.8N  33.9W   55 KT  65 MPH
 36H  23/0600Z 40.9N  31.2W   50 KT  60 MPH
 48H  23/1800Z 40.4N  30.0W   50 KT  60 MPH
 60H  24/0600Z 39.8N  30.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  24/1800Z 39.6N  31.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  25/1800Z 40.3N  34.7W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  26/1800Z 41.0N  37.0W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi/Wegman/Carbin
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