[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 222048
TCDAT3

Tropical Storm Gaston Discussion Number  10
NWS National Hurricane Center Miami FL       AL082022
Issued by the NWS Weather Prediction Center College Park MD
900 PM GMT Thu Sep 22 2022

Gaston is beginning to approach the Azores Islands. An observation
on Flores in the western Azores recently showed wind gusts to
tropical storm strength in an outer band of the storm.  Satellite
images indicate that Gaston has been relatively steady in strength
through the day with deep convection persisting near the center and
strong outflow continuing in the northern semicircle.  Since the
Dvorak estimates are unchanged, the initial intensity remains 55 kt
for this advisory.

The storm has slowed down slightly, with the latest initial motion
estimated to be east-northeastward at 15 kt.  A turn to the east and
an additional reduction in forward speed are expected overnight,
followed by a clockwise loop near or over the central and western
Azores on Friday and Saturday as the storm moves on the south side
of a building ridge.  The models have trended northward at days 4
and 5, and the NHC track forecast has been adjusted in that
direction for those time periods.

Despite moderate to strong shear, relatively dry air, and cool
SSTs, Gaston has been maintaining its strength.  Given that these
conditions are only expected to gradually worsen for the system, a
slow weakening trend seems likely.  The models all show a similar
theme, and the NHC intensity forecast lies near the middle of the
guidance envelope.  Gaston is expected to become post-tropical on
Saturday when it merges with an approaching shortwave trough.

Key Messages:

1. Tropical storm conditions are expected to begin later tonight in
the western Azores and will likely spread to the central Azores on
Friday.

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


FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 41.1N  32.0W   55 KT  65 MPH
 12H  23/0600Z 40.9N  30.1W   55 KT  65 MPH
 24H  23/1800Z 40.1N  29.2W   55 KT  65 MPH
 36H  24/0600Z 39.2N  29.5W   50 KT  60 MPH
 48H  24/1800Z 38.8N  30.9W   50 KT  60 MPH...POST-TROPICAL
 60H  25/0600Z 39.1N  33.1W   50 KT  60 MPH...POST-TROPICAL
 72H  25/1800Z 39.3N  35.0W   45 KT  50 MPH...POST-TROPICAL
 96H  26/1800Z 39.3N  37.8W   35 KT  40 MPH...POST-TROPICAL
120H  27/1800Z 40.5N  40.0W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Cangialosi/Churchill/Hamrick
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