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Tropical Depression Four-E Discussion Number   3
NWS National Hurricane Center Miami FL       EP042023
200 PM PDT Fri Jul 21 2023
 
Tropical Depression Four is currently struggling to produce deep 
convection within a highly sheared environment. Convection has waned 
since this morning, with cloud tops continuing to warm this 
afternoon. The low-level center has also become more exposed with  
remaining convection to the east of the center. Subjective and 
objective Dvorak satellite estimates from TAFB, SAB, and CIMMS ADT 
and AiDT range from 25 to 35 knots. Given the current structure, a 
blend of satellite estimates and recent visible satellite trends 
yields an initial intensity of 30 kt for this advisory.
 
The depression continues to be in an environment of strong 
upper-level westerly wind shear.  The system has crossed into 
cooler sea surface temperatures as well, with SSTs continuing to 
cool along the forecast track. Given these parameters it is likely 
the depression will gradually weaken, becoming a remnant low by 
tomorrow, and dissipating by 60 hours. 
 
The system is moving west-northwestward at 12 kt.  A ridge centered 
over the southwestern United States should continue to steer the 
depression on this general heading and speed for the next 24 hours. 
Afterward, the shallow remnant low is expected to turn more westward 
in the low-level flow.  The NHC track forecast lies near the 
previous forecast track.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/2100Z 15.8N 124.9W   30 KT  35 MPH
 12H  22/0600Z 16.4N 126.6W   30 KT  35 MPH
 24H  22/1800Z 17.0N 128.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  23/0600Z 17.4N 130.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  23/1800Z 17.7N 132.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  24/0600Z...DISSIPATED
 
$$
Forecaster Kelly/Brown
 
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