Atlantic Basin Tropical Cyclones

Tropical Storm Victor Forecast Discussion


554 
WTNT45 KNHC 011452
TCDAT5

Tropical Storm Victor Discussion Number   9
NWS National Hurricane Center Miami FL       AL202021
1100 AM AST Fri Oct 01 2021

Since the last advisory, Victor's deep convection has become limited 
to the northern portion of its circulation. Convective outflow is 
limited to the south, which indicates that the changes in the 
structure of the tropical storm are due at least in part to 
southerly wind shear. Microwave and ASCAT data between 0800 and 1200 
UTC also indicate that the center of Victor has become elongated, 
and may be trying to reform to the north, closer to the convection. 
Even with that reformation, an 1128 ASCAT-B overpass revealed that 
the center of Victor is located substantially south of previous 
estimates, which has necessitated a significant change to the track 
forecast. 

With the new position, the initial motion estimate is now 295/13 kt. 
The tropical storm is still generally expected to turn northwestward 
over the weekend and then continue on that heading through early 
next week, steered by the southwest periphery of a mid-level ridge 
centered over the eastern Atlantic. Nearly all of the dynamical 
models are showing this turn occuring slightly later than earlier 
forecasts, which results in a track well to the west of the previous 
NHC forecast. Combined with the updated analysis of Victor's 
position, the new NHC forecast has been shifted over 100 n mi to the 
southwest by day 4. However, this is still on the far east side of 
the guidance envelope so additional changes to the track forecast 
might be needed this afternoon.

The aforementioned ASCAT data showed peak winds near 50 kt, which 
supports an intensity of 55 kt, assuming a little undersampling due 
to the resolution of the instrument. The intensity analysis is also 
supported by the latest TAFB Dvorak estimate. Despite the 
large changes to the track forecast, no change of note was made to 
the intensity forecast.  Increasing shear and a dry surrounding 
environment should cause Victor to weaken during the next few days. 
Some models even indicate it could dissipate before the end of the 
forecast period. The NHC forecast is based on the intensity model 
consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 11.5N  33.5W   55 KT  65 MPH
 12H  02/0000Z 12.0N  34.8W   55 KT  65 MPH
 24H  02/1200Z 13.1N  36.4W   50 KT  60 MPH
 36H  03/0000Z 14.7N  38.1W   45 KT  50 MPH
 48H  03/1200Z 16.6N  40.0W   45 KT  50 MPH
 60H  04/0000Z 18.7N  42.1W   40 KT  45 MPH
 72H  04/1200Z 20.6N  43.9W   35 KT  40 MPH
 96H  05/1200Z 23.6N  46.5W   30 KT  35 MPH
120H  06/1200Z 27.1N  46.9W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster D. Zelinsky




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