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Hurricane SEYMOUR Forecast Discussion Number 15
2016-10-26 22:39:37| National Hurricane Center (East Pacific)
Issued at 200 PM PDT WED OCT 26 2016 000 WTPZ45 KNHC 262039 TCDEP5 HURRICANE SEYMOUR DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016 200 PM PDT WED OCT 26 2016 Seymour has begun to quickly weaken. The hurricane's central dense overcast has taken on a distorted appearance, and the deep convection associated with the cyclone's circulation has become noticeably asymmetric. The eye has also become cloud-filled and has cooled rather dramatically in the last few hours. The recent deterioration of the cloud pattern is associated with a considerable increase of southwesterly shear over the cyclone. Dvorak T-numbers have decreased to T5.5/102 kt from both satellite agencies, and these estimates averaged with Dvorak CI-numbers, are used to lower the initial intensity to 110 kt. The shear, currently analyzed in the 15 to 20 kt range, is forecast to increase tremendously over Seymour during the next 24 to 36 hours as a strong mid- to upper-level tropospheric trough approaches the cyclone from the west. Since Seymour is a small tropical cyclone and will be traversing cooler waters by that time, the weakening trend should become increasingly more rapid. Global models show the vortex decoupling as a result of the strong deep-layer shear in 30 to 36 hours, and the official forecast shows Seymour degenerating into a remnant low by 48 hours. The NHC track forecast represents an update of the previous one and is near the various model consensus aids. Seymour continues to gain a greater northward component of motion, and the initial motion estimate is 300/11. The cyclone is forecast to turn even more poleward and slow down during the next 24 to 36 hours as it rounds the western periphery of a mid-level high located west of the Baja California peninsula. While the vortex remains intact, the strong south-southwesterly flow associated with the upstream trough should cause Seymour to turn north-northeastward before shearing off and eventually dissipating. The NHC intensity forecast is not much different than the previous one and near the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 17.5N 121.2W 110 KT 125 MPH 12H 27/0600Z 18.8N 122.2W 85 KT 100 MPH 24H 27/1800Z 20.6N 123.0W 60 KT 70 MPH 36H 28/0600Z 22.3N 122.6W 40 KT 45 MPH 48H 28/1800Z 23.5N 121.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 29/1800Z...DISSIPATED $$ Forecaster Kimberlain
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