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Tropical Storm Don Discussion Number  27
NWS National Hurricane Center Miami FL       AL052023
900 PM GMT Thu Jul 20 2023
 
A band of deep convection has developed over the eastern portion of
Don's circulation since the previous advisory, however, there has
been little overall change in the cyclone's organization today.
The latest subjective Dvorak CI numbers from SAB and TAFB were
unchanged from this morning so the initial intensity remains 45 kt.
Although that could be a little generous based on the earlier
scatterometer data, it is best to hold the intensity steady until
the next ASCAT overpass this evening.
 
Recent satellite fixes indicate that Don continues to move
west-northwestward (290 degrees) but at a slightly faster forward
speed of 9 kt.  A strong low- to mid-level ridge that is currently
located to the north of Don is forecast to shift eastward during
the next 2 to 3 days.  This should cause Don to turn northwestward
on Friday and then northward ahead of a broad mid-level trough over
the western Atlantic later this weekend.  After that time, the
cyclone is forecast to turn northeastward in the low- to mid-level
southwesterly flow ahead of the aforementioned trough.  The
dynamical model envelope has again shifted to the west and the NHC
track forecast has been adjusted accordingly.
 
Marginal sea surface temperatures, moderate shear, and nearby dry
mid-level have prevented additional strengthening today.  Those
conditions are not forecast to change much during the next couple of
days and therefore, little overall change in strength is expected
during that period.  Don is forecast to move north of the Gulf
stream and over much cooler waters in 60 to 72 hours, and it is
likely to become post-tropical shortly thereafter. The global
models show the system becoming an open trough in 4 to 5 days and
the official forecast calls for dissipation by that time.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/2100Z 34.7N  43.7W   45 KT  50 MPH
 12H  21/0600Z 35.1N  45.1W   45 KT  50 MPH
 24H  21/1800Z 36.2N  47.1W   45 KT  50 MPH
 36H  22/0600Z 37.8N  49.0W   45 KT  50 MPH
 48H  22/1800Z 39.7N  50.4W   45 KT  50 MPH
 60H  23/0600Z 42.1N  51.2W   40 KT  45 MPH
 72H  23/1800Z 44.6N  50.4W   35 KT  40 MPH
 96H  24/1800Z 49.7N  42.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  25/1800Z...DISSIPATED
 
$$
Forecaster Brown
 
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