Official Discussion issued by the National Hurricane Center

Twenty (AL202020) DATA RELEASED: 9/13/2020 9:00:00 AM UTC

Copy of official data

Tropical Depression Twenty Discussion Number   3
NWS National Hurricane Center Miami FL       AL202020
500 AM AST Sun Sep 13 2020

The depression remains poorly organized and elongated from 
northeast-to-southwest. Convection mainly consists of small curved 
but fragmented bands in the southern semicircle. Satellite intensity 
estimates remain unchanged as a result, so the initial intensity 
will also remain unchanged at 30 kt.

The initial motion estimate is 295/09 kt. The ridge to the north 
and east of the tropical depression is forecast to remain intact 
for the next 5 days, keeping the cyclone on a general 
west-northwestward track through 72 hours, followed by a 
northwestward motion toward the weakness in the ridge on days 4 and 
5. The latest NHC guidance remains in very good agreement on this 
developing track scenario and, thus, no significant changes were 
made to the previous advisory track.

Due to the negative influence of the long low-level westerly fetch 
associated with the monsoon trough that the cyclone is embedded 
within, it will likely another 24 hours or so for the low-level 
wind field to become better organized. However, once that occurs, 
environmental conditions are expected to be favorable for steady 
strengthening on days 2-4, followed by gradual weakening on ay 5 
due to increasing southwesterly vertical wind shear. The new NHC 
intensity forecast is similar to the previous advisory forecast, and 
lies near the upper end of the intensity guidance envelope.


INIT  13/0900Z 12.2N  35.5W   30 KT  35 MPH
12H  13/1800Z 12.6N  36.9W   30 KT  35 MPH
24H  14/0600Z 13.2N  39.2W   40 KT  45 MPH
36H  14/1800Z 13.7N  41.5W   50 KT  60 MPH
48H  15/0600Z 14.4N  43.8W   60 KT  70 MPH
60H  15/1800Z 15.3N  45.7W   70 KT  80 MPH
72H  16/0600Z 16.3N  46.9W   80 KT  90 MPH
96H  17/0600Z 19.0N  49.6W   90 KT 105 MPH
120H  18/0600Z 21.5N  51.8W   85 KT 100 MPH

Forecaster Stewart