[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 302042
TCDAT5

Tropical Storm Victor Discussion Number   6
NWS National Hurricane Center Miami FL       AL202021
500 PM AST Thu Sep 30 2021

Victor has been relatively steady in strength during the past
several hours.  Satellite images continue to show that the storm has
a large circulation with numerous curved bands surrounding the
center. However, recent microwave images indicate that the cyclone
has yet to develop a well-defined inner core, which is likely why
the system has not strengthened much despite the favorable
environmental conditions.  The Dvorak classifications are again
unchanged and range from 35 to 45 kt, and on this basis, the initial
intensity is held at 40 kt.

Victor is still moving west-northwestward, or 290 degrees, at 12 kt.
The storm is forecast to continue on that same general track for
about another day 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 by early next week when it is forecast to move in
the flow between the ridge and the low.  The GFS has shifted
westward this cycle and is now not far from the ECMWF track.  The
new NHC forecast track is nudged westward toward a consensus of the
GFS, ECMWF, UKMET, and HMON models.  The standard consensus aids
could be too far to the east since the latest run of the HWRF, which
is a member of those models, is a significant outlier to the east.

As mentioned above, although the storm has been in favorable
conditions for strengthening during the past day or so, it has not
taken full advantage likely due to its broad structure.  The
favorable environment for Victor should persist for about another 24
hours, so gradual strengthening is possible during that time period.
However, by the weekend, the models show Victor moving into a region
of moderate to strong southwesterly shear and a progressively drier
airmass.  These negative factors for the storm along with slightly
cooler SSTs should cause Victor to lose strength this weekend and
early next week.  In fact, some of the models suggest that Victor
could dissipate by the end of the forecast period.  The new NHC
intensity forecast is again a little lower than the previous one,
trending toward the HCCA, IVCN, and IVDR consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z  9.9N  30.0W   40 KT  45 MPH
 12H  01/0600Z 10.6N  31.4W   45 KT  50 MPH
 24H  01/1800Z 11.6N  33.1W   55 KT  65 MPH
 36H  02/0600Z 12.9N  34.6W   50 KT  60 MPH
 48H  02/1800Z 14.5N  36.2W   45 KT  50 MPH
 60H  03/0600Z 16.4N  38.0W   40 KT  45 MPH
 72H  03/1800Z 18.9N  40.0W   35 KT  40 MPH
 96H  04/1800Z 23.6N  42.7W   30 KT  35 MPH
120H  05/1800Z 28.0N  42.9W   30 KT  35 MPH

$$
Forecaster Cangialosi
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