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Hurricane SEYMOUR Forecast Discussion Number 6
2016-10-24 16:33:26| National Hurricane Center (East Pacific)
Issued at 900 AM MDT MON OCT 24 2016 000 WTPZ45 KNHC 241433 TCDEP5 HURRICANE SEYMOUR DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016 900 AM MDT MON OCT 24 2016 Seymour's cloud pattern continues to increase in organization. The cyclone's small central dense overcast has become circular and increasingly symmetric since the last advisory, with plenty of cold-topped deep convection, particularly near the center. Dvorak satellite classifications were T3.5/55 kt and T4.0/65 kt at 1200 UTC, while UW-CIMSS ADT values were around T4.5. Since that time, the cloud pattern has continued to exhibit greater organization. Thus, the initial intensity is raised to 65 kt, toward the higher end of the subjective estimates. For the next 36 hours or so, Seymour should be embedded in a nearly ideal environment for intensification, characterized by low vertical wind shear, warm waters, strong upper-level divergence and a sufficiently moist atmosphere. SHIPS model output continues to indicate the likelihood of rapid intensification during the next 24 hours, and so does the official forecast. Around 48 hours, southwesterly shear associated with a vigorous trough northwest of Seymour should begin to increase and induce weakening. The shear should become prohibitively high in 3 to 4 days and result in rapid weakening, and then a decoupling of the cyclone toward the end of the forecast period. Remnant low status is predicted in 5 days, but it very likely could be sooner. The NHC intensity forecast is largely an update of the previous one and is slightly above the multi-model consensus, close to the FSU Superensemble and the NOAA corrected consensus model, HCCA. The initial motion is 290/13. Seymour is being steered west- northwestward on the south side of deep-layer ridge near the southern tip of the Baja California peninsula. When the cyclone reaches the western edge of this ridge in about 2 days, it should encounter the flow associated with the deep-layer trough upstream of Seymour. This should result in a decrease in forward speed while the cyclone's heading turns northwestward and then sharply northward. Once a completely shallow system, Seymour or its remnants should turn north-northeast and lose its identity well west of the Baja California peninsula. The new track forecast has been adjusted westward in response to a shift of the guidance in that direction, but not as far left as the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 15.2N 109.8W 65 KT 75 MPH 12H 25/0000Z 15.8N 111.9W 75 KT 85 MPH 24H 25/1200Z 16.2N 114.5W 95 KT 110 MPH 36H 26/0000Z 16.6N 116.9W 105 KT 120 MPH 48H 26/1200Z 17.4N 119.0W 95 KT 110 MPH 72H 27/1200Z 20.5N 121.8W 75 KT 85 MPH 96H 28/1200Z 23.9N 121.5W 45 KT 50 MPH 120H 29/1200Z 26.2N 120.2W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Kimberlain
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