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Tropical Storm Vicky Discussion Number   3
NWS National Hurricane Center Miami FL       AL212020
800 PM CVT Mon Sep 14 2020
 
Vicky is severely sheared by strong upper-level westerly winds. The 
initial intensity is held at 40 kt based on earlier ASCAT data, but 
it is entirely possible the cyclone has weakened since this morning 
and all recent intensity estimates are lower. The shear is the main 
factor in Vicky's forecast; it is expected to increase substantially 
(up to 60 kt in 24 h in GFS-SHIPS diagnostics) and should cause the 
cyclone to weaken. The NHC forecast now shows Vicky becoming a 
remnant low in 36 hours, and it would not be surprising if it 
happens sooner than that given the very hostile environment. After 
Vicky loses all of its convection, the dynamical models suggest that 
it will take a couple more days for the remnant low to spin down and 
open into a trough.
 
Vicky's movement has been somewhat erratic since it formed, but a 
long-term motion estimate is 325/6 kt. A continued northwestward 
motion is forecast for the next 12 to 24 hours, followed by a turn 
toward the west as Vicky weakens and is increasingly steered by 
low-level easterly winds. The NHC track forecast is based on the 
TVCN and HCCA consensus aids and is practically on top of the 
previous forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/2100Z 19.3N  29.5W   40 KT  45 MPH
 12H  15/0600Z 20.1N  30.3W   35 KT  40 MPH
 24H  15/1800Z 21.2N  31.9W   35 KT  40 MPH
 36H  16/0600Z 22.0N  33.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  16/1800Z 22.5N  35.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  17/0600Z 22.9N  38.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  17/1800Z 23.0N  39.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  18/1800Z 23.1N  43.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  19/1800Z...DISSIPATED
 
$$
Forecaster Zelinsky
 
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