[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 241455
TCDAT3

Tropical Storm Gaston Discussion Number  17
NWS National Hurricane Center Miami FL       AL082022
300 PM GMT Sat Sep 24 2022

Gaston has lost most of its deep convection and it is currently an
exposed low-level circulation.  The closest relatively deep
convective activity is south of Pico Island over 100 miles away
from the center and likely terrain-induced. Though a recent
scatterometer pass missed the center of Gaston, it did show an area
of tropical-storm-force winds of around 35 kt to the east of the
center.  Therefore, the initial intensity has been lowered to 40
kt, slightly higher than the satellite intensity estimates.

Hostile environmental conditions have weakened Gaston considerably.
The strong vertical wind shear and dry mid-level humidities are not
expected to improve for the remainder of the forecast period, and
additional weakening is likely.  The official forecast is similar to
the previous prediction and still shows Gaston becoming fully
post-tropical within 12 hours.  A couple of the global models,
however, indicate a mid-latitude shortwave trough/baroclinic zone
interacting with post-tropical Gaston early Sunday morning could
develop isolated deep convection, but this should be a short-lived
event.

The storm is moving west-southwestward at an estimated 245/8 kt.  A
building mid-level ridge to the north is expected to steer Gaston
to the west through Monday morning, and to the west-southwest
until it dissipates near the end of the week.  The NHC forecast
track is shifted slightly south of the previous advisory track,
likely due to the southern shift of the initial position.


Key Messages:

1. Tropical storm conditions over the western and central Azores
today should diminish today as Gaston moves away from the islands.

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


FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 38.0N  30.8W   40 KT  45 MPH
 12H  25/0000Z 38.2N  32.5W   40 KT  45 MPH...POST-TROPICAL
 24H  25/1200Z 38.4N  35.1W   35 KT  40 MPH...POST-TROPICAL
 36H  26/0000Z 38.2N  37.0W   35 KT  40 MPH...POST-TROPICAL
 48H  26/1200Z 37.5N  39.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  27/0000Z 36.7N  40.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  27/1200Z 35.6N  43.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  28/1200Z 33.0N  48.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  29/1200Z...DISSIPATED

$$
Forecaster Bucci
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