Tropical Storm VICTOR Advisory vie, 01-10

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Tropical Storm Victor Discussion Number   8
NWS National Hurricane Center Miami FL       AL202021
500 AM AST Fri Oct 01 2021

Infrared and microwave satellite imagery indicate that Victor has
continued to become a little better organized, with a 0342Z AMSR2
overpass showing that a 75-percent-closed mid-level eye feature had
formed. However, both data sources also revealed that a pronounced
dry slot has formed in the southeastern quadrant. Upper-level
outflow remains well established in all quadrants except to the
south where it is somewhat restricted. Despite the slightly improved
satellite signatures, subjective and objective intensity
classifications have not changed since the previous advisory, so the
intensity remains at 50 kt for this advisory.

The initial motion estimate is 305/13 kt. Victor has made a slight
jog toward the northwest, but this is likely a temporary motion due
to redevelopment of the center farther into the convective cloud
shield. The cyclone should resume a west-northwestward motion later
today and maintain that motion for another day or so as Victor moves
along the southwestern periphery of a strong subtropical ridge
situated over the east-central Atlantic. The latest model runs
continue to show a broad mid- to upper-level low developing over the
central Atlantic to the west of Victor in the 24-72-h forecast
period, which will act to erode the western portion of the ridge and
create a deep-layer southerly flow pattern across the cyclone.  As a
result, Victor is forecast to turn northwestward by the weekend and
then move northward by early next week. Owing to a more robust
mid-/upper-level low forecast to develop than previously expected,
the latest NHC track guidance has made a significant westward shift
by at least 100 nmi at 72 h and nearly 200 nmi on days 4 and 5. This
westward shift is due to Victor now forecast to weaken faster and
become more vertically shallow, with the dominant steering flow
shifting to low-level easterlies. The new NHC track forecast has
also been shifted westward, but not as far west as the tightly
packed consensus models, all of which lie well to the east of the
westernmost GFS solution.

Victor is expected to remain in a somewhat favorable environment for
the next 18 h or so, which should allow for at least some slight
strengthening to occur.  Thereafter, however, southwesterly
deep-layer vertical wind shear is forecast by the GFS and ECMWF
models to increase to 20-25 kt in 24 hours and 30-35 kt by 72 h.
These hostile shear conditions, in conjunction with a drier air
mass, should result in gradual weakening during the 24-120-h period,
with Victor becoming a remnant low on day 5. The new official
intensity forecast is a little below the previous advisory, but it
is above the consensus intensity models ICON, HCCA, and FSSE, due to
the recent development of the aforementioned primitive eye feature.


FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 11.7N  32.3W   50 KT  60 MPH
 12H  01/1800Z 12.4N  33.6W   55 KT  65 MPH
 24H  02/0600Z 13.4N  35.3W   55 KT  65 MPH
 36H  02/1800Z 14.9N  36.8W   50 KT  60 MPH
 48H  03/0600Z 16.7N  38.6W   45 KT  50 MPH
 60H  03/1800Z 19.0N  40.5W   40 KT  45 MPH
 72H  04/0600Z 21.0N  42.0W   35 KT  40 MPH
 96H  05/0600Z 24.0N  44.0W   30 KT  35 MPH
120H  06/0600Z 28.0N  45.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart