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Hurricane SEYMOUR Forecast Discussion Number 12
2016-10-26 04:53:09| National Hurricane Center (East Pacific)
Issued at 800 PM PDT TUE OCT 25 2016 000 WTPZ45 KNHC 260252 TCDEP5 HURRICANE SEYMOUR DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016 800 PM PDT TUE OCT 25 2016 Seymour has continued to rapidly intensify since the last advisory. The eye is about 10-15 nmi wide in infrared satellite imagery, but is less than 10 nmi wide in a recent 0005Z SSMI/S microwave image, indicating that the eye diameter has contracted since the previous advisory. The initial intensity is increased to 130 kt for this advisory based on satellite intensity estimates of T6.5/127 kt from both TAFB and SAB, and a T6.7/132 kt from UW-CIMSS ADT. The initial motion is now 285/13 kt. The global and regional models remain in excellent agreement on Seymour moving steadily west-northwestward around the southwestern periphery of a deep-layer ridge for the next 24 hours, followed by a turn toward the northwest in 36 hours as a strong shortwave trough significantly erodes the western portion of the ridge. By 48 hours, Seymour is expected to slow down appreciably and turn north-northwestward as the cyclone rapidly weakens and becomes more vertically shallow. After that time, the shallow post-tropical low is forecast to turn back toward the west-northwest under the influence of the low-level trade wind flow. The official forecast track is similar to the previous advisory, and lies close to blend of the TVCX and HCCA consensus models. Some additional slight strengthening is possible during the next 6-12 hours due to the small eye, low shear conditions, and warm SSTs. After that time, increasing southwesterly vertical wind shear, cooler waters, including significant cold upwelling by 24 hours and beyond, should cause steady to rapid weakening. Seymour is expected to drop below hurricane status shortly after 48 hours, degenerate into a post-tropical low by 72 hours, and dissipate by 120 hours. The new intensity forecast is similar to the previous forecast, and is close to the IVCN intensity consensus model. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 16.1N 117.7W 130 KT 150 MPH 12H 26/1200Z 16.7N 119.4W 125 KT 145 MPH 24H 27/0000Z 17.9N 121.1W 110 KT 125 MPH 36H 27/1200Z 19.2N 122.2W 95 KT 110 MPH 48H 28/0000Z 20.2N 122.6W 70 KT 80 MPH 72H 29/0000Z 21.1N 122.9W 40 KT 45 MPH...POST-TROPICAL 96H 30/0000Z 21.7N 123.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 31/0000Z...DISSIPATED $$ Forecaster Stewart
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