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Tropical Storm Karina Discussion Number 12
NWS National Hurricane Center Miami FL EP162020
Issued by NWS Central Pacific Hurricane Center Honolulu HI
200 PM PDT Tue Sep 15 2020
Latest satellite images show little significant change in the
organization of deep convection associated with Karina since the
previous advisory. Although the thunderstorms are primarily
limited to the southwest semicircle, they remain over the center,
and outflow in the northeast semicircle appears somewhat improved
in the last couple of hours. A blend of subjective Dvorak current
intensity estimates of 3.0/45 kt from SAB/HFO and 3.5/55 kt from
TAFB supports maintaining an initial intensity of 50 kt.
Karina is crossing the 26C isotherm with an initial motion estimate
of 305/10 kt, and much cooler waters lie along the forecast track.
Karina is being steered by a mid- and upper-level ridge to the
centered to the northeast and north respectively, and the short
term forecast anticipates some relaxation of the recent
northeasterly shear as Karina rounds the ridges. This should lead to
slow weakening in the short term, and as south to southwesterly
shear increases after about 24 hours, Karina will continue
to weaken. Simulated satellite imagery based on HWRF guidance
indicates the cyclone will become convection-free within about 48
hours, with dissipation following soon thereafter. As Karina
weakens and becomes increasingly shallow, it will be steered by
the low-level northeasterly trade wind flow supplied by a surface
high centered to the distant northwest.
The updated track forecast lies along the same trajectory as the
previous, but is shifted slightly southward due to recent observed
motion, and is near the middle of guidance envelope. The intensity
forecast is essentially unchanged and closely follows trends
presented by SHIPS and FSSE.
FORECAST POSITIONS AND MAX WINDS
INIT 15/2100Z 20.7N 122.1W 50 KT 60 MPH
12H 16/0600Z 21.6N 123.3W 45 KT 50 MPH
24H 16/1800Z 22.5N 124.8W 40 KT 45 MPH
36H 17/0600Z 23.2N 126.0W 35 KT 40 MPH
48H 17/1800Z 23.5N 127.2W 30 KT 35 MPH
60H 18/0600Z 23.3N 128.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 18/1800Z 22.5N 129.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/1800Z...DISSIPATED
$$
Forecaster Birchard
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