000 WTNT43 KNHC 181456 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 1100 AM AST SAT OCT 18 2014 Gonzalo's convective canopy is becoming ragged and substantially asymmetric with the cold clouds primarily seen in the northern semicircle. Subjective Dvorak and the objective Advanced Dvorak Technique suggest a range from 65 to 77 kt for the maximum sustained winds, while the CIMSS Advanced Microwave Sounding Unit estimate indicates about 85 kt. A blend of these gives 80 kt for the initial intensity, a considerable drop from the previous advisory. As Gonzalo will be moving north of the warm Gulf Stream waters and experiencing increasingly hostile vertical wind shear over the next day, the hurricane should steadily weaken. In about a day, extratropical transition should occur, consistent with the FSU Cyclone Phase Space and SHIPS diagnostic analyses. However, rather than getting a baroclinic kick after ET, Gonzalo is anticipated by the global model guidance to continue weakening until dissipation in about three days. The NHC intensity forecast is based upon the IVCN multi-model intensity consensus while a tropical cyclone and upon the GFS and ECMWF global models while the system is extratropical. Gonzalo is moving toward the north-northeast at 22 kt, as it is being advected along in the south-southwesterlies north of the subtropical ridge. The system should accelerate as it gets picked up by the core of the jet stream and becomes extratropical. The NHC track forecast is based upon the tightly clustered TVCN multi-model consensus and is just slightly westward of the previous advisory. The initial tropical storm and hurricane-force wind radii were analyzed to be larger than previously indicated based on a 0922Z AMSU pass, as indicated by the CIRA size analyses. The post-tropical portion of the forecast has been coordinated with the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 36.8N 61.7W 80 KT 90 MPH 12H 19/0000Z 40.8N 58.3W 70 KT 80 MPH 24H 19/1200Z 47.0N 50.5W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 20/0000Z 51.3N 38.7W 55 KT 65 MPH...POST-TROP/EXTRATROP 48H 20/1200Z 53.5N 23.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 21/1200Z...DISSIPATED $$ Forecaster Landsea