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Tropical Storm Victor Forecast Discussion

WTNT45 KNHC 292043

Tropical Storm Victor Discussion Number   2
NWS National Hurricane Center Miami FL       AL202021
800 PM CVT Wed Sep 29 2021

The cloud pattern continues to exhibit a large circulation with 
numerous curved bands surrounding the center.  The strongest 
thunderstorms remain on the system's west side. The latest Dvorak 
estimates from TAFB and SAB have both increased to 2.5/35 kt, and on 
that basis, the cyclone has been upgraded to a 35-kt tropical storm.

Victor is still on a west-northwest course at about 11 kt. There has 
been little change to the track forecast reasoning.  The cyclone is 
expected to continue west-northwestward during the next couple of 
days as it remains steered by the flow on the south side of a 
deep-layer ridge.  By late Friday, however, the models show the 
western periphery of the ridge being eroded due to a mid- to 
upper-level low over the subtropical central Atlantic.  As a result, 
the cyclone should turn northwestward by Friday night and then 
northward late this weekend or early next week.  There remains a 
fair amount of spread in the timing and location of the northward 
turn with the GFS and HWRF still on the right side of the guidance 
envelope and the ECMWF showing the slowest and westernmost solution. 
Overall, the consensus models have not changed much and neither has 
the official track forecast.

The storm is expected to remain in conducive environmental 
conditions for strengthening during the next couple of days.  During 
that time period, Victor is forecast to move over 28-29 deg C 
waters while embedded within a moist airmass with very low wind 
shear (less than 10 kt).  Rapid intensification sometimes occurs 
when conditions are this favorable, however, since the storm is 
broad and does not yet have an inner core, gradual strengthening 
seems more reasonable. The NHC forecast brings Victor to hurricane 
intensity in 36 hours. In a few days, however, the models show a 
pronounced increase in southwesterly shear and a notably drier 
atmosphere. These unfavorable conditions should end the opportunity 
for strengthening and promote a weakening trend.  The NHC intensity 
forecast is similar to the previous one and remains near a blend of 
the HCCA, IVCN, and IVDR consensus models.


INIT  29/2100Z  8.3N  25.5W   35 KT  40 MPH
 12H  30/0600Z  8.8N  26.9W   45 KT  50 MPH
 24H  30/1800Z  9.5N  28.9W   55 KT  65 MPH
 36H  01/0600Z 10.3N  30.8W   65 KT  75 MPH
 48H  01/1800Z 11.4N  32.4W   70 KT  80 MPH
 60H  02/0600Z 12.8N  34.1W   70 KT  80 MPH
 72H  02/1800Z 14.7N  35.8W   60 KT  70 MPH
 96H  03/1800Z 19.3N  38.9W   50 KT  60 MPH
120H  04/1800Z 24.9N  40.9W   40 KT  45 MPH

Forecaster Cangialosi

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