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Post-Tropical Cyclone HERMINE Forecast Discussion Number 33
2016-09-05 17:30:54| National Hurricane Center (Atlantic)
Issued at 1100 AM AST MON SEP 05 2016 000 WTNT44 KNHC 051530 TCDAT4 POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER 33...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 1100 AM AST MON SEP 05 2016 Corrected for initial motion in second paragraph Hermine continues to exhibit a non-tropical cloud pattern with a broad curved band of showers to the north of the center. High-resolution visible images show multiple low-level swirls rotating around the broad center of the cyclone. An Air Force reconnaissance plane found highest unflagged SFMR-observed surface winds of 52 kt, and highest 850 mb flight-level winds were 69 kt, both north of the center. The initial intensity estimate remains 60 kt. Although Hermine is currently over rather warm waters, the system should be passing over cooler SSTs by early Tuesday and this should result in a weakening trend. The official intensity forecast is consistent with the trend depicted by the global models. These models, especially the ECMWF, suggest that the system will open up to a trough by the end of the forecast period and this is also reflected in the official forecast. The center is not particularly well defined, and using a mean center position from the multiple swirls leads to a motion estimate of 325/5 kt, which is rather uncertain. Hermine is in a weak steering environment. A narrow mid-level ridge to the north of the cyclone should induce a continued northwestward motion at a slow forward speed during the next 24 hours or so. As this ridge breaks down by Tuesday night, the system should turn northward. Later in the forecast period, the mid-latitude westerlies should carry Hermine off to the east-northeast and northeast. The track forecast has been shifted west of the previous NHC track, but lies a little to the east of the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 38.8N 68.8W 60 KT 70 MPH...POST-TROPICAL 12H 06/0000Z 39.2N 69.5W 60 KT 70 MPH...POST-TROPICAL 24H 06/1200Z 39.7N 70.5W 55 KT 65 MPH...POST-TROPICAL 36H 07/0000Z 40.0N 70.7W 45 KT 50 MPH...POST-TROPICAL 48H 07/1200Z 40.5N 70.5W 40 KT 45 MPH...POST-TROPICAL 72H 08/1200Z 41.0N 69.0W 35 KT 40 MPH...POST-TROPICAL 96H 09/1200Z 44.5N 62.0W 30 KT 35 MPH...POST-TROPICAL 120H 10/1200Z...DISSIPATED $$ Forecaster Pasch
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