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Tropical Storm VANCE
ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM VANCE DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212014 800 PM PDT SAT NOV 01 2014 Vance's convective organization has improved considerably since the previous advisory with a central dense overcast feature having developed during the past few hours. In addition, recent SSMI/S and WindSat microwave satellite imagery indicate that a small precursor eye feature with a diameter 10-12 nmi has developed. The initial intensity has been increased to 45 kt based on consensus satellite intensity estimates of T3.0/45 kt from TAFB, SAB, and UW-CIMSS ADT. The initial motion estimate remains 290/11 kt. For the next 24 hours or so, Vance is expected to move west-northwestward along the southern periphery of a deep-layer ridge located to its north. After that, a turn to the north is forecast as the cyclone moves around the ridge and ahead of an approaching mid-tropospheric trough that will be moving across Baja California in the 48-72 hour time frame. By late in the forecast period, Vance is expected to weaken rapidly, with the low- and upper-level circulations decoupling. The remnant low is forecast to meander off of the southwestern coast of Mexico and the southern tip of Baja California. The NHC forecast track is similar to the previous advisory track, and lies close to the multi-model consensus TVCE. The mid-level moisture has apparently increased based on the recent development of significant inner-core convection. With such low vertical shear conditions and the aforementioned eye-like feature, rapid intensification is a very distinct possibility during the next 24-36 hours. The NHC official intensity forecast has been increased above the previous advisory forecast through 48 hours, which is above the intensity consensus model ICON and is about midway between the GFDL and HWRF intensity forecasts. After that, the intensity forecast is unchanged from the previous advisory due to expected strong southwesterly vertical shear conditions of at least 35-40 kt, which should result in rapid weakening of Vance and degeneration into a remnant low on Days 4 and 5. FORECAST POSITIONS AND MAX WINDS INIT 02/0300Z 10.2N 105.4W 45 KT 50 MPH 12H 02/1200Z 11.2N 107.4W 55 KT 65 MPH 24H 03/0000Z 12.6N 109.6W 65 KT 75 MPH 36H 03/1200Z 14.3N 110.8W 75 KT 85 MPH 48H 04/0000Z 16.0N 110.9W 65 KT 75 MPH 72H 05/0000Z 18.8N 109.5W 45 KT 50 MPH 96H 06/0000Z 21.0N 108.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 07/0000Z 22.0N 108.1W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart NNNN