[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 231457
TCDAT3

Tropical Storm Gaston Discussion Number  13
NWS National Hurricane Center Miami FL       AL082022
300 PM GMT Fri Sep 23 2022

Gaston is improving in satellite presentation this morning.
Convection is re-forming and wrapping around the northern and
western sides of the circulation.  A recent scatterometer pass
showed that Gaston was slightly stronger than the previous advisory
and the initial intensity has been increased to 55 kt.  The
tropical-storm-force wind field was also expanded, especially in the
northwestern quadrant based on these data.

The cyclone has managed to retain its tropical characteristics for
now.  Global model guidance suggests moderate to strong vertical
wind shear should gradually strip away convection from the core over
the next day or so.  In spite of the relatively hostile conditions,
Gaston has managed to maintain its strength, therefore only gradual
weakening is forecast until the storm merges with a shortwave trough
in about 36 hours and becomes a post-tropical cyclone.  The official
intensity forecast has been shifted slightly higher than the
previous advisory due to the initial intensity and is slightly
stronger than the consensus model aids.

The storm is moving east-southeastward at an estimated 120/6 kt.  A
sharp turn to the south is expected shortly while Gaston traverses
the periphery of a mid-level ridge building to the north.
Afterward, the cyclone should generally move toward the
west-southwest and west, completing an anticyclone turn, through the
end of the period.  The NHC forecast has been nudged slightly
northward once again from the previous forecast and lies between the
HCCA and TVCN multi-model consensus aids.

Key Messages:

1. Tropical storm conditions are occurring over portions of the
western Azores, and are spreading to the central Azores.

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


FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 40.2N  29.1W   55 KT  65 MPH
 12H  24/0000Z 39.4N  29.0W   55 KT  65 MPH
 24H  24/1200Z 38.7N  30.2W   50 KT  60 MPH
 36H  25/0000Z 38.7N  32.3W   50 KT  60 MPH...POST-TROPICAL
 48H  25/1200Z 38.9N  34.8W   50 KT  60 MPH...POST-TROPICAL
 60H  26/0000Z 39.0N  36.7W   45 KT  50 MPH...POST-TROPICAL
 72H  26/1200Z 39.0N  38.6W   40 KT  45 MPH...POST-TROPICAL
 96H  27/1200Z 38.9N  42.0W   35 KT  40 MPH...POST-TROPICAL
120H  28/1200Z 37.7N  46.2W   30 KT  35 MPH...POST-TROPICAL

$$
Forecaster Bucci
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