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Hurricane Leslie Forecast Discussion Number 67
2018-10-13 04:37:55| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Fri Oct 12 2018 000 WTNT43 KNHC 130237 TCDAT3 Hurricane Leslie Discussion Number 67 NWS National Hurricane Center Miami FL AL132018 1100 PM AST Fri Oct 12 2018 Although Leslie continues to produce a compact area of deep convection, microwave data since the previous advisory indicate that the mid-level center is becoming more separated from the low-level center due to increasing shear. Dvorak final-T numbers have begun to decrease a bit, and the initial intensity is therefore set at 70 kt. A cold front is beginning to wrap around the western side of Leslie's circulation, and the global models indicate that the cyclone should lose its warm core and become fully embedded within the frontal zone by 24 hours, if not sooner. Despite sea surface temperatures of 17-23 degrees Celsius ahead of Leslie, baroclinic forcing is likely to maintain the system's intensity as it becomes extratropical. As a result, Leslie is forecast to reach the Iberian Peninsula as a hurricane-force extratropical low, with the NHC intensity forecast most closely following the GFS guidance. Rapid weakening is forecast once the low moves inland, and the system should dissipate over the higher terrain of Spain in about 48 hours. The forward motion is east-northeastward, or 075/31 kt. Located within the base of a progressive trough, Leslie should maintain this trajectory, slowing down only a little bit before it reaches Portugal and Spain in 24-36 hours. Except for the UKMET model, which shows Leslie turning more northeastward toward the northwestern Iberian Peninsula, the rest of the track guidance is tightly clustered and brings the center inland across central Portugal and western Spain. Because most of the models are in good agreement and are close to the previous official forecast, no significant changes were made to the NHC forecast on this cycle. Based on coordination from earlier today, the meteorological services of Portugal and Spain will handle hazard information for their respective countries via local weather products. Key Messages: 1. Leslie is expected to bring near hurricane-force winds to portions of Portugal late Saturday as a powerful post-tropical cyclone. Gale-force winds are also likely to affect portions of western Spain Saturday night and Sunday. 2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1 to 3 inches) with isolated amounts as high as 100 mm (4 inches) across portions of Portugal and Spain, which could cause flash flooding. 3. For more information on Leslie, interests in Portugal should refer to products from the Portuguese Institute for Sea and Atmosphere at www.ipma.pt. Interests in Spain should refer to products from the State Meteorological Agency at www.aemet.es. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 34.7N 20.7W 70 KT 80 MPH 12H 13/1200Z 36.5N 15.4W 65 KT 75 MPH 24H 14/0000Z 38.9N 9.4W 65 KT 75 MPH...POST-TROP/EXTRATROP 36H 14/1200Z 41.0N 5.1W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 15/0000Z 42.3N 1.1W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 16/0000Z...DISSIPATED $$ Forecaster Berg
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