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Tropical Storm KARINA Forecast Discussion Number 33
2014-08-21 04:47:06| National Hurricane Center (East Pacific)
Issued at 800 PM PDT WED AUG 20 2014 000 WTPZ41 KNHC 210247 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 33 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 PM PDT WED AUG 20 2014 After looking fairly robust on the previous advisory, 25-30 kt of vertical wind shear has left the convective cloud pattern looking rather disheveled over the past several hours. A 20/2318 UTC AMSU overpass indicated that the strong shear had displaced the mid-level circulation at least 45 nmi southwest of the now fully exposed low-level center. Satellite intensity estimates from both TAFB and SAB have decreased, yielding an average intensity estimate of 50 kt, which is the initial intensity used for this advisory. As expected, the steering currents have collapsed and Karina has been meandering in the same general area for the past 12 hours or so. Little motion is expected tonight, with a drift to the east or east-southeast forecast to begin on Thursday. After that, Karina is expected to begin moving slowly northeastward as it comes under the influence of the large circulation of Tropical Storm Lowell located well to the east of the cyclone. As the distance between the two systems decreases, smaller Karina is expected to accelerate northeastward and then northward within the eastern portion of Lowell's circulation, gradually getting drawn closer to the center of Lowell. NHC guidance remains in excellent agreement on this developing track scenario, and the official forecast is similar to but a little east of the consensus model TVCE in order to maintain a reasonable physical distance between the centers of the two tropical cyclones. Fluctuations in the amount of Lowell-induced shear that will affect Karina will also result in fluctuations in the cyclone's intensity for the 72 hours while it remains over 26C and warmer SSTs. But overall, no significant intensity changes are expected for the next 2 to 3 days. After that, however, increasing shear as Karina moves closer to Lowell's center, plus sharply decreasing sea-surface temperatures, will induce weakening on Days 4 and 5. Karina is expected to become a post-tropical remnant low pressure system by 96 hours, but given the rather small size of the cyclone, it is possible that the system could degenerate into an open trough as it interacts with the larger circulation of Tropical Storm Lowell. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 15.9N 136.4W 50 KT 60 MPH 12H 21/1200Z 15.7N 136.3W 50 KT 60 MPH 24H 22/0000Z 15.5N 135.8W 50 KT 60 MPH 36H 22/1200Z 15.6N 135.1W 50 KT 60 MPH 48H 23/0000Z 16.3N 134.1W 50 KT 60 MPH 72H 24/0000Z 18.3N 131.0W 40 KT 45 MPH 96H 25/0000Z 21.4N 128.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 26/0000Z 27.0N 129.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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