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Tropical Storm Victor Forecast Discussion

WTNT45 KNHC 301454

Tropical Storm Victor Discussion Number   5
NWS National Hurricane Center Miami FL       AL202021
200 PM CVT Thu Sep 30 2021

Victor remains a sprawling tropical storm with numerous curved bands
surrounding the center.  The associated convection remains most
organized on the storm's west side.  The latest Dvorak estimates are
largely unchanged and range from 35 to 45 kt.  In addition, an
ASCAT-B pass from around 12Z showed maximum winds in the 35-40 kt
range.  Based on all of this data, the initial intensity is held at
40 kt.  The ASCAT data also showed that the wind field is quite
broad with tropical-storm-force winds extending about 90 n mi north
of the center.

Victor is still moving west-northwestward, or 290 degrees, at 12 kt.
The storm is forecast to continue on that same general track for
another day or so as it remains on the south side of a deep-layer
ridge over the subtropical eastern Atlantic.  By late Friday, a mid-
to upper-level low is expected to form over the central Atlantic,
and that feature should erode the western portion of the ridge.  As
a result, Victor is expected to turn northwestward by the weekend
and then northward early next week when it is forecast to move in
the flow between the ridge and the low.  The model tracks have
converged compared to yesterday, but the ECMWF remains the slowest
and westernmost solution and the HWRF is still the easternmost
model.  The NHC track forecast is nudged to the west of the
previous one and lies close to the various consensus aids and is in
fair agreement with the GFS.

The storm has about another 36 hours in conducive environmental 
conditions of very low wind shear, a moist mid-level airmass, and 
warm 28-29 degree C SSTs.  Therefore, intensification seems likely 
during that time period, but given the broad nature of the system's 
wind field, Victor will likely gain strength slowly during that time 
period.  However, in a couple of days, the models show a significant 
increase in southwesterly shear and a progressively drier airmass.  
These negative factors for the storm along with slightly cooler SSTs 
should cause Victor to lose strength.  In fact, some of the models 
suggest that Victor could dissipate by the end of the forecast 
period.  The new NHC intensity forecast is a little lower than the 
previous one.  It should be noted that although this forecast no 
longer explicitly shows Victor becoming a hurricane, it could occur 
in a day or two before conditions become hostile.  This forecast 
lies near the high end of the model guidance.


INIT  30/1500Z  9.5N  28.9W   40 KT  45 MPH
 12H  01/0000Z 10.2N  30.4W   50 KT  60 MPH
 24H  01/1200Z 11.1N  32.3W   60 KT  70 MPH
 36H  02/0000Z 12.4N  34.0W   60 KT  70 MPH
 48H  02/1200Z 13.9N  35.5W   55 KT  65 MPH
 60H  03/0000Z 15.7N  37.2W   50 KT  60 MPH
 72H  03/1200Z 17.9N  39.0W   45 KT  50 MPH
 96H  04/1200Z 23.2N  41.8W   35 KT  40 MPH
120H  05/1200Z 28.0N  42.4W   30 KT  35 MPH

Forecaster Cangialosi

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