[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 230237
TCDAT3

Tropical Storm Gaston Discussion Number  11
NWS National Hurricane Center Miami FL       AL082022
300 AM GMT Fri Sep 23 2022

Gaston's cloud pattern is showing signs of disruption by westerly
shear with the center located near the western edge of the main
area of convection.  This was confirmed by a recent scatterometer
overpass, which showed that the intensity was, somewhat
surprisingly, still near 55 kt.  This intensity is also in
agreement with a Dvorak classification from TAFB, and so the
advisory's initial wind speed is held at that value.

The storm has continued to slow its forward speed, with the latest
initial motion estimated to be eastward at around 10 kt.
During the next day or so, Gaston is expected to move on a
clockwise loop along the southern side of a blocking mid-level
ridge.  The official track forecast follows the multi-model
consensus prediction.  This is fairly close to the previous NHC
forecast, except shifted a little northward in the latter part of
the period.

Gaston is expected to remain in an environment of dry air, over
relatively cool SSTs, and under the influence of strong westerly
shear for the next couple of days.  These factors should lead to
gradual weakening and loss of tropical characteristics in 48 hours
or so.  The official intensity forecast is similar to the previous
one and is close to the latest Decay-SHIPS prediction.


Key Messages:

1. Tropical storm conditions are occurring over portions of the
western Azores, and will likely spread to the central Azores later
today.

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


FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 41.0N  31.0W   55 KT  65 MPH
 12H  23/1200Z 40.4N  29.4W   55 KT  65 MPH
 24H  24/0000Z 39.3N  29.3W   50 KT  60 MPH
 36H  24/1200Z 38.7N  30.4W   50 KT  60 MPH
 48H  25/0000Z 38.9N  32.3W   50 KT  60 MPH...POST-TROPICAL
 60H  25/1200Z 39.4N  34.4W   45 KT  50 MPH...POST-TROPICAL
 72H  26/0000Z 39.8N  36.4W   40 KT  45 MPH...POST-TROPICAL
 96H  27/0000Z 40.9N  38.0W   35 KT  40 MPH...POST-TROPICAL
120H  28/0000Z 41.5N  39.0W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Pasch
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