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Tropical Storm Karina Discussion Number   5
NWS National Hurricane Center Miami FL       EP162020
800 PM PDT Sun Sep 13 2020
 
Karina's satellite presentation is not terribly impressive, with the
deep convection sheared well south of what appears to be a somewhat
elongated low-level center by 15 to 20 kt of northerly shear. The
subjective Dvorak Final-T numbers have decreased a little in the
last 6 hours, but overall a blend of the objective and subjective
satellite estimates yields an intensity of 40 kt for this advisory.
 
Karina only has a limited window for strengthening, with SSTs
forecast to cool to 26C along the forecast track within 36 hours.
With the shear forecast to persist during until the waters cool and
the atmosphere dries out, the intensity guidance has trended
downward again this cycle, and so has the NHC prediction, which is
close to or a little above HCCA and higher than the simple
consensus aids. Karina should become a remnant low in about 4 days
and is expected to dissipate by day 5.
 
The initial motion estimate is 285/11. Karina should be steered
generally west-northwestward for the next several days, followed by
a turn toward the west in the low-level flow by 96 hours. The new
NHC track forecast is similar to the previous one and lies near the
middle of the guidance envelope.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0300Z 18.2N 117.1W   40 KT  45 MPH
 12H  14/1200Z 18.7N 118.1W   40 KT  45 MPH
 24H  15/0000Z 19.4N 119.7W   45 KT  50 MPH
 36H  15/1200Z 20.2N 121.0W   45 KT  50 MPH
 48H  16/0000Z 21.0N 122.1W   40 KT  45 MPH
 60H  16/1200Z 21.8N 123.3W   35 KT  40 MPH
 72H  17/0000Z 22.3N 124.5W   30 KT  35 MPH
 96H  18/0000Z 22.5N 126.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  19/0000Z...DISSIPATED
 
$$
Forecaster Brennan
 
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