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Tropical Storm Karina Discussion Number  10
NWS National Hurricane Center Miami FL       EP162020
200 AM PDT Tue Sep 15 2020
 
Karina has continued to become a little better organized tonight
with a concentrated area of deep convection near and over the
estimated low-level center.  The latest satellite intensity
estimates range from 45 to 55 kt, and the initial wind
speed is nudged up to 50 kt based on that data.
 
Karina is approaching the 26 C isotherm, and it should be moving 
over progressively cooler waters during the next several days. These 
less favorable oceanic conditions combined with a drier and more 
stable air mass should promote gradual weakening beginning by 
tonight, and Karina is forecast to become a post-tropical remnant 
low in about 60 hours.  In addition to the cool waters and dry air, 
an increase in southerly shear should cause the remnant low to 
dissipate in 4 to 5 days.  The intensity guidance is in good 
agreement, and the NHC forecast is near the middle of the guidance 
envelope.
 
The tropical storm is moving northwestward at 10 kt.  A continued
northwestward motion on the southwestern periphery of a mid-level
ridge is expected for the next couple of days.  After that time, a
turn to the west and a decrease in forward speed are forecast as
the weak and shallow system moves in the low-level flow.
 
The initial 34-kt wind radii have been reduced based on partial
ASCAT overpasses.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0900Z 19.8N 120.6W   50 KT  60 MPH
 12H  15/1800Z 20.8N 121.7W   50 KT  60 MPH
 24H  16/0600Z 22.0N 123.3W   45 KT  50 MPH
 36H  16/1800Z 23.0N 124.8W   40 KT  45 MPH
 48H  17/0600Z 23.7N 125.9W   35 KT  40 MPH
 60H  17/1800Z 24.0N 126.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  18/0600Z 23.9N 127.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  19/0600Z 23.1N 129.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  20/0600Z...DISSIPATED
 
$$
Forecaster Cangialosi
 
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