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Hurricane SEYMOUR Forecast Discussion Number 7
2016-10-24 23:05:03| National Hurricane Center (East Pacific)
Issued at 300 PM MDT MON OCT 24 2016 000 WTPZ45 KNHC 242104 CCA TCDEP5 HURRICANE SEYMOUR DISCUSSION NUMBER 7...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016 300 PM MDT MON OCT 24 2016 CORRECTED 120H STATUS Seymour is rapidly intensifying. A pinhole eye has formed within a small, nearly symmetric, central dense overcast (CDO) during the last several hours. In addition, a long curved band coils inward toward the center with a dry slot between it and the CDO. Dvorak classifications are T4.5/77 kt from TAFB and SAB, and the latest UW-CIMSS ADT value is T4.7/82 kt. A blend of these is used to raise the initial intensity estimate to 80 kt. Seymour has another 24 hours to strengthen under nearly ideal environmental conditions, consisting of low vertical wind shear, warm waters, strong upper-level divergence, and a sufficiently moist atmosphere. By 36 to 48 hours, an uptick in the southwesterly vertical shear associated with a mid- to upper-tropospheric trough approaching Seymour from the northwest should induce a weakening trend. With the waters cooling substantially and the shear becoming prohibitively high after that time, rapid weakening is likely. Seymour is now forecast to become a post-tropical remnant low by 96 hours, if not perhaps sooner, as depicted in global model guidance. The new intensity forecast is generally above the the guidance through 48 hours, closest to the FSU Superensemble and NOAA Corrected Consensus HCCA model output, and just above the multi- model consensus after that time. The initial motion estimate is 285/14 kt. Seymour should maintain a west-northwestward motion with some decrease in forward speed for the next 36 to 48 hours as it nears the western periphery of a mid-level ridge located to the south of Baja California. The trough upstream of Seymour should erode the ridge further in about 48 hours and cause the cyclone to turn northwestward and northward while it decelerates. The guidance has again shifted toward the left during the next few days, and the official forecast is adjusted in that direction but lies on the eastern side of the guidance envelope. The model guidance is now much slower after that time, around the time Seymour decouples and becomes a remnant low. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 15.3N 111.3W 85 KT 100 MPH 12H 25/0600Z 15.6N 113.3W 100 KT 115 MPH 24H 25/1800Z 16.0N 115.9W 110 KT 125 MPH 36H 26/0600Z 16.7N 118.3W 110 KT 125 MPH 48H 26/1800Z 17.6N 120.4W 100 KT 115 MPH 72H 27/1800Z 20.7N 122.4W 70 KT 80 MPH 96H 28/1800Z 22.3N 122.4W 35 KT 40 MPH...POST-TROP/REMNT LOW 120H 29/1800Z...DISSIPATED $$ Forecaster Kimberlain
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