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Hurricane Leslie Forecast Discussion Number 65
2018-10-12 16:38:48| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Fri Oct 12 2018 000 WTNT43 KNHC 121438 TCDAT3 Hurricane Leslie Discussion Number 65 NWS National Hurricane Center Miami FL AL132018 1100 AM AST Fri Oct 12 2018 Leslie's cloud pattern continues to feature a central dense overcast, but with only hints of an eye in visible imagery. A partial northern eyewall was noted on a 0910Z SSMIS overpass. Dvorak intensity estimates have decreased slightly, and based on this, the initial intensity has been conservatively nudged down to 75 kt. The wind field is quite large, especially south of the center, as confirmed by a pair of recent ASCAT passes, and the initial wind radii have been adjusted using those data. The initial motion estimate is now 070/28. Leslie is moving quickly east-northeastward on the southern side of a powerful longwave trough centered over the north Atlantic. The track forecast reasoning has changed since the last advisory, with the GFS, ECMWF, and now the 06Z run of the UKMET all showing a more eastward motion of Leslie toward the Iberian Peninsula as the cyclone is picked up by the aforementioned trough. The new NHC track forecast has been adjusted significantly to the north and east, especially beyond 24 hours, but still lies to the south of and is slower than the GFS and ECMWF. Once the system moves inland, the low-level center should dissipate over the high terrain, but a 72 hour remnant low point is included for continuity purposes. Needless to say, confidence in the official track forecast beyond 24 hours is quite low given the recent shift in the models, and further adjustments will likely be necessary. The intensity forecast shows Leslie only slowly weakening as a tropical cyclone during the next 24 hours due to a combination of cool SSTs and increasing shear from the trough. However, simulated satellite imagery and model fields suggest that Leslie will transition to a powerful post-tropical cyclone by 36 hours, likely still at hurricane intensity as shown by the global models. Weakening is expected after the trough passes Leslie by, and the mid-level circulation will likely be sheared away by strong upper-level winds. Leslie is expected to bring significant rain and wind impacts to portions of Portugal and Spain by Sunday, and residents in those areas should refer to products from their local meteorological services for more information on these hazards. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 33.0N 28.0W 75 KT 85 MPH 12H 13/0000Z 34.2N 23.0W 70 KT 80 MPH 24H 13/1200Z 35.4N 17.0W 65 KT 75 MPH 36H 14/0000Z 36.0N 12.5W 65 KT 75 MPH...POST-TROPICAL 48H 14/1200Z 36.3N 9.1W 50 KT 60 MPH...POST-TROPICAL 72H 15/1200Z 37.0N 4.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 16/1200Z...DISSIPATED $$ Forecaster Brennan
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