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Hurricane NICOLE Forecast Discussion Number 40
2016-10-14 04:34:46| National Hurricane Center (Atlantic)
Issued at 1100 PM AST THU OCT 13 2016 000 WTNT45 KNHC 140234 TCDAT5 HURRICANE NICOLE DISCUSSION NUMBER 40 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 1100 PM AST THU OCT 13 2016 The satellite presentation of Nicole has degraded substantially this evening, with the area of cold convective tops shrinking in size and become less symmetric. The low-level center is difficult to locate in geostationary imagery, but recent microwave data suggest it is located to the southwest of the coldest convective tops. This structure is consistent with the 40-45 kt of southwesterly shear analyzed over Nicole by the SHIPS model and UW-CIMSS. The initial intensity has been lowered to 85 kt, which is between the latest Dvorak estimates from TAFB and SAB. Nicole should continue to weaken in the next 12 hours due to the persistent strong shear and cooling SSTs. However, from 24-48 hours, forcing associated with a shortwave trough should cause Nicole to remain a powerful cyclone, and the intensity is maintained at 75 kt through that time. After the shortwave moves past Nicole, slow decay is expected late in the period. The new NHC intensity forecast is lower than the previous one in the first 12-24 hours, following the trend of the latest hurricane intensity guidance. After that time, the intensity forecast is based on global model guidance. Note that the structure of Nicole is quite uncertain during the forecast period, since the cyclone does not appear to complete extratropical transition, with the global models showing the cyclone acquiring a warm seclusion structure. A 2201Z WindSat pass suggested that the center of Nicole was located a little south of previous estimates. The initial motion is estimated to be 060/18, as Nicole is now embedded in the mid- latitude southwesterly flow ahead of a longwave trough moving off the U.S. east coast. This pattern should steer Nicole generally east-northeastward for the next 48 hours, although the forward speed will decrease by 36 hours as Nicole interacts with the aforementioned shortwave. The trough moves east of Nicole by 72 hours, leaving the cyclone in a region of weaker steering flow until a high-latitude trough approaches from the northwest in 4-5 days, and cause Nicole to accelerate northeastward by the end of the forecast period. The new NHC track forecast is a little south of the previous one due to the initial position and is close to a blend of the GFS and ECMWF models through the period. The post-tropical portion of Nicole's track, intensity, and wind radii forecast has been coordinated with the NOAA Ocean Prediction Center. Note that swells from Nicole will affect Bermuda and portions of the U.S. east coast and Atlantic Canada during the next couple of days. By early next week, wave models suggest that long-period swell from Nicole will radiate outward and affect much of the North Atlantic basin. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 34.4N 61.2W 85 KT 100 MPH 12H 14/1200Z 35.6N 58.5W 75 KT 85 MPH 24H 15/0000Z 36.9N 54.3W 75 KT 85 MPH 36H 15/1200Z 38.1N 51.0W 75 KT 85 MPH 48H 16/0000Z 38.6N 49.0W 75 KT 85 MPH...POST-TROPICAL 72H 17/0000Z 39.0N 47.0W 65 KT 75 MPH...POST-TROPICAL 96H 18/0000Z 41.0N 44.0W 65 KT 75 MPH...POST-TROPICAL 120H 19/0000Z 47.0N 37.0W 60 KT 70 MPH...POST-TROPICAL $$ Forecaster Brennan
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