Atlantic Basin Tropical Cyclones

Subtropical Storm Wanda Forecast Discussion


000
WTNT41 KNHC 010927 CCA
TCDAT1

Subtropical Storm Wanda Discussion Number   6...Corrected
NWS National Hurricane Center Miami FL       AL212021
900 AM GMT Mon Nov 01 2021

Corrected initial position

Wanda is now located to the west of the axis of the upper-level
trough that it is embedded in.  As a result, significant northerly
vertical wind shear has developed over the storm, and between this
and continuing dry air entrainment the associated convection is
less organized than 24 h ago.  Various subjective and objective
satellite intensity estimates are in the 40-50 kt range, and based
on continuity from earlier ASCAT data the initial intensity is held
at 45 kt.

After the earlier southwestward motion, Wanda is now turning
southeastward with the initial motion of 125/6.  The storm and the
upper-level trough should move northeastward later today and then
northward by 36-48 h as southerly flow between a large
mid-latitude trough over the northwestern Atlantic and a
ridge east of Wanda becomes the dominant steering mechanism. After
72 h, another mid-latitude ridge is expected to build between Wanda
and the western Atlantic trough, and as a result the cyclone is
expected to turn eastward and then southward.  The latest track
guidance shows a more northward motion than the previous guidance
between 36-60 h, and a more southward motion after 96 h.  The new
forecast track has been nudged in those directions.

The intensity guidance suggests little change in strength during
the next several days as dry air and relatively cool SSTs continue
to affect the system.  However, the current shear is expected to
decrease during the next 24-36 h, and this should help the system
to transition to a tropical cyclone.  By 120 h, Wanda is expected
to become a post-tropical low as cooler sea surface temperatures
and an even dryer air mass cause the convection to dissipate.  The
new intensity forecast is unchanged from the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 34.5N  43.9W   45 KT  50 MPH
 12H  01/1800Z 34.3N  43.3W   45 KT  50 MPH
 24H  02/0600Z 34.9N  42.1W   45 KT  50 MPH...TROPICAL CYCLONE
 36H  02/1800Z 36.2N  41.3W   45 KT  50 MPH
 48H  03/0600Z 38.2N  40.9W   45 KT  50 MPH
 60H  03/1800Z 40.1N  40.7W   45 KT  50 MPH
 72H  04/0600Z 41.5N  40.0W   45 KT  50 MPH
 96H  05/0600Z 43.0N  36.5W   45 KT  50 MPH
120H  06/0600Z 41.0N  33.5W   40 KT  45 MPH...POST-TROPICAL

$$
Forecaster Beven



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