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Tropical Storm Wanda Discussion Number 26
NWS National Hurricane Center Miami FL AL212021
900 AM GMT Sat Nov 06 2021
Wanda's convective structure has continued to evolve this morning,
with two earlier bands situated east and west of the well-defined
center now having consolidated into a solid band of convection with
cloud tops of -50C to -57C wrapping around the eastern semicircle.
The initial intensity remains 45 kt for this advisory based on
continuity with earlier 40-45 kt ASCAT data and the recently
improved convective structure.
The initial motion estimate is southward or 180/04 kt. Wanda is
expected to slow down further this morning and then turn sharply
northeastward this afternoon as a narrow mid-/upper-level shortwave
ridge passes to the north of the cyclone. A strong deep-layer trough
and associated frontal system are then forecast to approach Wanda
from the west by tonight, causing the cyclone to accelerate
northeastward on Sunday and Monday. The front is forecast to catch
up with Wanda in the 36-48-h period, resulting in extratropical
transition before the system is absorbed by a large, deepening
extratropical cyclone over the northern Atlantic early next week.
The latest NHC model guidance is in excellent agreement on this
developing forecast track scenario, and the official forecast track
lies very near the the middle of the tightly packed simple- and
corrected-consensus guidance envelope.
Wanda's is now over what will be the warmest water for the remainder
of the cyclone's lifetime. The deep-layer shear is forecast to
remain around 10-15 kt for the next 24 h or so, while colder
aloft overspreads the cyclone, creating a little more instability.
This combination of positive environmental factors should continue
to produce deep convection near Wanda's center, possibly resulting
in some slight strengthening before the system becomes an
extratropical cyclone. The new NHC intensity forecast is basically
identical to the previous advisory, and closely follows a blend of
the various intensity consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 06/0900Z 37.4N 38.3W 45 KT 50 MPH
12H 06/1800Z 37.5N 37.7W 45 KT 50 MPH
24H 07/0600Z 39.4N 35.0W 45 KT 50 MPH
36H 07/1800Z 43.6N 29.5W 50 KT 60 MPH
48H 08/0600Z 48.7N 22.2W 50 KT 60 MPH...POST-TROP/EXTRATROP
60H 08/1800Z 54.2N 12.8W 40 KT 45 MPH...POST-TROP/EXTRATROP