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Post-Tropical Cyclone HERMINE Forecast Discussion Number 34
2016-09-05 22:42:58| National Hurricane Center (Atlantic)
Issued at 500 PM AST MON SEP 05 2016 000 WTNT44 KNHC 052042 TCDAT4 POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER 34 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 500 PM AST MON SEP 05 2016 The satellite presentation of Hermine remains non-tropical, with a rather linear band of deep convection situated north and northwest of the estimated center. There continues to be multiple low-level swirls over the inner part of the circulation. Overall, the appearance of the system is gradually losing organization. The advisory intensity remains at 60 kt based on earlier reconnaissance data and a ship report from this afternoon. The system is forecast to move over SSTs of 23 to 24 deg C on Tuesday and these cooler waters should cause weakening. The official intensity forecast is close to the model consensus and, although this guidance may not be very valid for a post-tropical cyclone, the NHC forecast is also consistent with the trends shown by the global models. Some of these models, such as the ECMWF suggest that the cyclone could dissipate within 72 hours. Earlier aircraft center fixes and a more recent satellite-derived fix result in a motion estimate of 300/6 kt. A weak mid-level ridge to the north of Hermine should maintain the west-northwestward motion overnight. After that, the ridge breaks down and the cyclone is expected to become trapped in a region of weak steering currents. This should result in a slow and erratic motion through 48 hours. By the end of the forecast period, if the cyclone survives, a faster east-northeastward motion could occur due to the influence of the mid-latitude westerlies. The official track forecast is a little to the west of the previous one but generally to the right of the latest dynamical model consensus. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 39.3N 69.5W 60 KT 70 MPH...POST-TROPICAL 12H 06/0600Z 39.7N 70.6W 55 KT 65 MPH...POST-TROPICAL 24H 06/1800Z 39.9N 71.3W 50 KT 60 MPH...POST-TROPICAL 36H 07/0600Z 40.0N 71.5W 45 KT 50 MPH...POST-TROPICAL 48H 07/1800Z 40.3N 71.3W 35 KT 40 MPH...POST-TROPICAL 72H 08/1800Z 42.0N 69.0W 25 KT 30 MPH...POST-TROPICAL 96H 09/1800Z...DISSIPATED $$ Forecaster Pasch
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