Atlantic Basin Tropical Cyclones

Tropical Storm Don Forecast Discussion

WTNT45 KNHC 230831

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 

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.  


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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