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#806105 (Received by flhurricane at: 10:45 AM 07.Oct.2015) TCDAT1 TROPICAL STORM JOAQUIN DISCUSSION NUMBER 40 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 AM AST WED OCT 07 2015 Satellite images indicate that Joaquin continues to slowly weaken. The low-level center is now about half a degree west of the mid-level circulation, with an area of deep convection noted. Dvorak estimates are lower, so the initial wind speed is reduced to 60 kt. A gradual spin-down of the cyclone is expected while Joaquin moves over colder waters north of the Gulf Stream. Deep convection should probably disappear tonight when the SSTs drop below 20C, so the intensity forecast calls for Joaquin to become post-tropical at that time. The cyclone will likely become a more classic extratropical low on Thursday when frontal features are forecast to form near the center. The official intensity forecast is very close to the previous one, and is in closest agreement with the GFS forecast. Joaquin continues moving rapidly east-northeastward as it is embedded in strong westerly flow north of the subtropical ridge. This motion should continue for another 24 hours or so. After that time, the guidance is in good agreement that the cyclone should decelerate and turn east-southeastward due to it coming under the influence of a developing deep-layer trough over western Europe. The official forecast is adjusted southward, and is near a blend of the GFS and the ECMWF models. The track, intensity, and wind radii forecasts for 12 hours and beyond are primarily based upon guidance provided by the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 41.0N 45.6W 60 KT 70 MPH 12H 08/0000Z 41.8N 39.6W 55 KT 65 MPH...POST-TROPICAL 24H 08/1200Z 42.6N 32.1W 50 KT 60 MPH...POST-TROPICAL 36H 09/0000Z 43.5N 26.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 09/1200Z 44.2N 21.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 10/1200Z 43.5N 15.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 11/1200Z 42.5N 11.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 12/1200Z...DISSIPATED $$ Forecaster Blake |