[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

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
This weather bulletin was brought to you by:
www.nashvilleweather.net