[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 030232
TCDAT1

Tropical Storm Wanda Discussion Number  13
NWS National Hurricane Center Miami FL       AL212021
300 AM GMT Wed Nov 03 2021

Bands of convection have continued to wax and wane around the
center of Wanda over the past 6-12 hours, with a band currently
located over the western portion of the cyclone.  A timely 2320 UTC
ASCAT-B overpass detected peak winds of around 40 kt and given the
known undersampling of that instrument for small tropical cyclones,
the 45-kt initial intensity is maintained.  That is also supported
by a recent SATCON intensity estimate of 42 kt.  The ASCAT data did
show that the area of tropical-storm-force winds has increased in
size over the eastern semicircle and now extends outward up to about
80 n mi in that portion of the storm.

Wanda is moving northward or 010/8 kt. The cyclone should continue
moving northward ahead of an approaching mid-latitude trough during
the next 24-36 hours.  After that time however, the trough is
expected to weaken and lift northward causing Wanda to slow down
and turn eastward.  After 48 hours, the track guidance has
continued its southward shift when a narrow ridge is forecast to
build to the northwest of the system. The NHC track forecast is
again shifted southward in the 60 to 96 h time period.  By late in
the period, Wanda is forecast to accelerate northeastward ahead of
yet another mid-latitude trough. There is a bit more confidence in
the latest track prediction as the dynamical model guidance has
come into a bit better agreement, however additional southwestward
or westward adjustments during the middle portion of the forecast
period could be required.

Little overall change in strength is anticipated over the next
several days.  As Wanda moves northward during the next day or so,
it will be moving over slightly cooler waters which could cause
the cyclone to struggle to produce deep convection. After day 2,
there are indications of increasing shear, but a nearby baroclinic
zone could help the system maintain its intensity.  Later in the
period, shear and decreasing mid-level relative humidity are
likely to cause Wanda to become post-tropical, and by day 5 the
guidance indicates Wanda will merge with a frontal boundary and
become extratropical.


FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 37.3N  40.3W   45 KT  50 MPH
 12H  03/1200Z 38.5N  40.0W   45 KT  50 MPH
 24H  04/0000Z 40.1N  39.9W   45 KT  50 MPH
 36H  04/1200Z 41.2N  39.8W   45 KT  50 MPH
 48H  05/0000Z 41.2N  39.2W   45 KT  50 MPH
 60H  05/1200Z 40.2N  38.1W   45 KT  50 MPH
 72H  06/0000Z 38.5N  37.7W   45 KT  50 MPH
 96H  07/0000Z 38.0N  36.0W   45 KT  50 MPH...POST-TROPICAL
120H  08/0000Z 43.5N  29.5W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown
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