ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM POST-TROPICAL CYCLONE JOAQUIN DISCUSSION NUMBER 42 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 PM AST WED OCT 07 2015 Satellite imagery indicates that the system no longer resembles a tropical cyclone, with a disorganized area of multi-layered cloudiness sheared off well to the northeast of the ill-defined low-level center. However, model analyses and surface data indicate that the cyclone is not yet embedded within a frontal zone, and therefore is not extratropical at this time. Nonetheless, since the system lacks sufficient organized deep convection to qualify as a tropical cyclone, Joaquin is being declared as a post- tropical cyclone, and advisories are being terminated. Cyclone phase space analyses from Florida State University indicate that the system will become extratropical in about 12 hours, and this is also shown in the official forecast. The current intensity is set at 55 kt in agreement with a recent scatterometer overpass. Global models show a gradual spindown of the cyclone over the next several days, and so does the official forecast. Post-tropical Joaquin continues to move rapidly toward the east, or 080/30 kt, while embedded in strong mid-latitude westerlies. The steering current is forecast to gradually weaken as a mid-level trough deepens near the Greenwich meridian, and the cyclone should move at a progressively slower forward speed over the period. In 2-3 days, the system is forecast to turn southeastward ahead of the abovementioned trough. There is fairly good agreement among the global models on this scenario. The track, intensity, and wind radii forecasts are primarily based upon guidance provided by the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 42.0N 37.0W 55 KT 65 MPH...POST-TROPICAL 12H 08/1200Z 42.5N 32.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 24H 09/0000Z 42.8N 26.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 09/1200Z 42.5N 22.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 10/0000Z 42.5N 19.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 11/0000Z 42.0N 14.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 12/0000Z 40.5N 11.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 13/0000Z 39.0N 10.5W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch NNNN
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