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Tropical Depression Twenty-One-E Discussion Number   3
NWS National Hurricane Center Miami FL       EP212020
100 AM PST Wed Nov 18 2020
 
The curved band feature that was prominent in earlier satellite 
images has dissipated, likely due to very dry air surrounding the 
cyclone. The depression now consists of a small central dense 
overcast (CDO) that has just recently become established in the past 
few hours. Earlier ASCAT data indicated that the strongest winds 
were occurring to the west of the center of the depression, near the 
curved band that existed at that time, while winds of 20-25 kt were 
occurring around the center. The nearest sampling by a scatterometer 
tonight was by the ASCAT-A, which did pass over some of the same 
area that had the strongest winds earlier, with peak winds now only 
20 kt. Assuming the reorganizing of the convection near the center 
has helped to increased the winds somewhat there, the initial 
intensity is being held at 30 kt. 
 
If the current CDO feature persists this morning, then the 
depression will likely strengthen to a tropical storm later today. 
By early Thursday, moderate west-southwesterly shear, cooler 
oceanic temperatures, and the presence of a very dry and stable air 
mass should cause the cyclone to begin weakening, and by Thursday 
night the system is expected to degenerate to a remnant low. The 
latest NHC intensity forecast is unchanged from the previous one and 
is in agreement with the various multimodel consensus aids. 
 
The initial motion continues to be west-northwestward at 10 kt. The 
depression is moving to the south of a mid-level ridge, and the 
cyclone is expected to continue in this general motion through 
tonight. A turn to the west within the low-level easterly trade 
wind flow is expected on Thursday as the system loses its deep 
convection and becomes shallow. The track forecast was nudged a 
little to the left of the previous advisory track due to a shift in 
the model guidance in that direction. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0900Z 15.7N 115.2W   30 KT  35 MPH
 12H  18/1800Z 16.1N 116.8W   35 KT  40 MPH
 24H  19/0600Z 16.5N 118.9W   35 KT  40 MPH
 36H  19/1800Z 16.7N 120.9W   30 KT  35 MPH
 48H  20/0600Z 16.8N 123.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  20/1800Z 16.8N 125.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  21/0600Z...DISSIPATED
 
$$
Forecaster Latto
 
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