Atlantic Basin Tropical Cyclones

Tropical Storm Wanda Forecast Discussion


000
WTNT41 KNHC 040847
TCDAT1

Tropical Storm Wanda Discussion Number  18
NWS National Hurricane Center Miami FL       AL212021
900 AM GMT Thu Nov 04 2021

Wanda continues to exhibit bands of moderately deep convection, and 
these bands are strongest most numerous over the western portion of 
the circulation.  The upper-level outflow has become better 
defined, also over the western semicircle.  Overall, however, the 
intensity of the convection has diminished slightly over the past 
several hours.  The advisory intensity is held at 45 kt, which is 
in agreement with Dvorak Current Intensity numbers from both SAB 
and TAFB.  This is also in good agreement with earlier 
scatterometer measurements.

The initial motion continues to be just east of north, or 010/8 kt 
along the eastern side of a mid-latitude shortwave trough.  This 
trough is expected to weaken very soon and Wanda should slow its 
forward speed later this morning.  During the next 48 hours, a 
narrow ridge is forecast to build to the northwest of the cyclone 
and force it to turn eastward tonight and then southward on Friday. 
By 72 hours, another mid-latitude trough approaching Wanda should 
finally cause the system to begin to accelerate northeastward.  The 
dynamical model guidance is in reasonably good agreement on the 
evolution of the steering pattern over the next several days.  
There has been little change to the official track forecast, which 
remains close to the model consensus, and near the middle of the 
guidance envelope.

Although Wanda is located over cool 20-21 deg C sea surface 
temperatures, it has been able to maintain some deep convection and 
winds of 45 kt.  On its projected path during the next day or two, 
water temperatures beneath Wanda are not likely to get much cooler 
and the upper-tropospheric temperatures are forecast to decrease 
somewhat.  This could allow for some slight strengthening, as 
indicated by the official intensity forecast.  In 4 to 5 days, the 
global models show the system becoming embedded in a frontal zone 
over the north Atlantic, so the NHC forecast calls for Wanda to 
revert back to extratropical status by that time.


FORECAST POSITIONS AND MAX WINDS

INIT  04/0900Z 41.5N  39.5W   45 KT  50 MPH
 12H  04/1800Z 42.1N  39.3W   50 KT  60 MPH
 24H  05/0600Z 41.7N  38.2W   50 KT  60 MPH
 36H  05/1800Z 40.1N  37.5W   50 KT  60 MPH
 48H  06/0600Z 38.4N  37.5W   50 KT  60 MPH
 60H  06/1800Z 38.2N  37.0W   45 KT  50 MPH
 72H  07/0600Z 39.8N  35.0W   45 KT  50 MPH
 96H  08/0600Z 47.0N  26.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  09/0600Z 52.0N  16.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch



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