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Tropical Storm Kevin Discussion Number   8
NWS National Hurricane Center Miami FL       EP112021
300 AM MDT Mon Aug 09 2021
 
Kevin is a sheared tropical cyclone. Satellite imagery indicates the 
low-level center lies near the edge of the dense overcast, which has 
a sharp border in the northeastern quadrant of the cyclone. The 
associated deep convection is displaced well to the southwest of 
Kevin's partially exposed center. Recent scatterometer data only 
show 25 to 30-kt winds near the center, but the full southwestern 
quadrant where the most intense convection is occurring was not 
sampled. The initial intensity is lowered to 45 kt for this 
advisory, in best agreement with the subjective final Dvorak 
T-numbers from TAFB and SAB. This estimate could still be generous, 
however.

The cyclone has turned west-northwestward during the past 12 h, and 
its estimated motion is now 290/6 kt. The track forecast reasoning 
is unchanged, as Kevin is expected to move west-northwestward for 
most of the forecast period along the southwestern periphery of a 
mid-level ridge. The official NHC track forecast has been adjusted a 
bit northward again this cycle, following the trend of the latest 
multi-model consensus aids.

Although Kevin has been embedded within a favorable thermodynamic 
environment, 15 to 20 kt of northeasterly shear has thus far limited 
its rate of strengthening. This shear is expected to persist for the 
next couple of days, so it seems likely that Kevin will continue to 
struggle intensifying, despite warm SSTs and a moist, unstable 
environment. By the time the vertical wind shear diminishes, Kevin 
will have gained enough latitude that the underlying SSTs will be 
unfavorable for further strengthening. The new intensity guidance is 
much lower than previous cycles, and so the latest NHC intensity 
forecast has been reduced by 5 to 10 kt at all forecast hours. Thus, 
Kevin is no longer forecast to become a hurricane. By day 5, the 
system is expected to become a post-tropical remnant low over sub-22 
deg C waters.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/0900Z 16.3N 110.9W   45 KT  50 MPH
 12H  09/1800Z 16.8N 111.9W   50 KT  60 MPH
 24H  10/0600Z 17.6N 113.3W   50 KT  60 MPH
 36H  10/1800Z 18.4N 115.0W   55 KT  65 MPH
 48H  11/0600Z 19.2N 116.5W   55 KT  65 MPH
 60H  11/1800Z 20.1N 118.2W   50 KT  60 MPH
 72H  12/0600Z 21.0N 120.2W   45 KT  50 MPH
 96H  13/0600Z 22.5N 124.5W   30 KT  35 MPH
120H  14/0600Z 24.0N 129.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Reinhart/Pasch
 
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