[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 230831
TCDAT5

Tropical Storm Don Discussion Number  37
NWS National Hurricane Center Miami FL       AL052023
500 AM AST Sun Jul 23 2023

Don is moving over much cooler water, and its structure is
rapidly deteriorating.  While the latest satellite pictures still
show a well-defined center, the eyewall convection has fallen apart
and become more fragmented.  Dvorak estimates are falling quickly,
and the initial wind speed is lowered to 55 kt.  Don should
continue to rapidly weaken as it moves over very cool waters with
increasing shear, and it should lose any remaining deep convection
within 24 hours and become a post-tropical cyclone. The new
forecast is lower than the previous one, closest to the GFS model.

The storm continues moving north-northeast, now at 14 kt.  Don
should move faster to the northeast today and east-northeast on
Monday due steering flow mostly around the northern side of
the subtropical ridge.  Guidance is tightly packed around the
previous forecast, and little change was made for this advisory,
except to move up dissipation 12 hours based on the global model
fields.

If you were thinking Don has been around a while considering the
time of year, you'd be right.  The storm is moving up the list of
longest-lasting tropical cyclones on record for July (including
subtropical stages). Preliminarily, Don is tied for 10th, and the
cyclone could make the top 5 longest-lasting for July if it lasts
through early Monday.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 42.6N  48.9W   55 KT  65 MPH
 12H  23/1800Z 44.5N  47.5W   45 KT  50 MPH
 24H  24/0600Z 46.4N  44.2W   35 KT  40 MPH...POST-TROPICAL
 36H  24/1800Z 47.5N  39.5W   30 KT  35 MPH...POST-TROPICAL
 48H  25/0600Z...DISSIPATED

$$
Forecaster Blake
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