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Tropical Storm Karina Forecast Discussion Number 12
2020-09-15 22:59:29| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Tue Sep 15 2020 000 WTPZ41 KNHC 152059 TCDEP1 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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