000 WTPZ41 KNHC 010844 TCDEP1 TROPICAL STORM VANCE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212014 200 AM PDT SAT NOV 01 2014 Vance's structure has been improving since the last advisory. A cluster of deep convection has developed near the center, and more defined curved bands are forming on the outer edges of the circulation. The maximum winds are held at 35 kt based on a consensus of subjective and objective satellite intensity estimates. The first three days of the forecast are fairly straightforward. Vance is expected to turn west-northwestward later today, accelerate northwestward toward a deepening mid-level trough west of 110W by day 2, and curve toward the north on day 3. The track guidance remains tightly clustered but has shifted westward after 36 hours. Therefore, the updated NHC track forecast is a little left of the previous one from 36 to 72 hours. While Vance turns northward, light vertical shear, warm sea surface temperatures, and a moistening mid-level troposphere should allow the storm to reach hurricane strength in 2-3 days. This part of the forecast closely follows the SHIPS, HWRF, and Florida State Superensemble guidance. The forecast is a little more complex after day 3. Once Vance begins to recurve, it will encounter southwesterly shear that increases from 20-25 kt on day 3 to well over 40 kt on days 4 and 5. This environment is likely to cause the cyclone to decouple, with the mid-level circulation being sheared off toward Mexico and the low-level circulation being left behind south of the Baja California peninsula. While the operational GFS brings Vance to the coast of Mexico in 96 hours, the parallel run of GFS and the ECMWF model have much slower and weaker solutions and do not bring the surface center to the Mexican coast. As additional support for this scenario, most of the GFS and European ensemble members show Vance lingering or even dissipating offshore. At this time, the operational GFS is considered an outlier solution, and the NHC track forecast is closer to a blend of the European and parallel GFS models. Due to the shear, Vance is expected to weaken rapidly after day 3, possibly becoming a remnant low near or offshore the coast of Mexico by day 5. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 9.4N 102.7W 35 KT 40 MPH 12H 01/1800Z 9.7N 104.1W 40 KT 45 MPH 24H 02/0600Z 10.5N 106.3W 50 KT 60 MPH 36H 02/1800Z 11.6N 108.6W 55 KT 65 MPH 48H 03/0600Z 13.2N 110.4W 65 KT 75 MPH 72H 04/0600Z 17.1N 110.8W 65 KT 75 MPH 96H 05/0600Z 20.5N 109.0W 35 KT 40 MPH 120H 06/0600Z 23.5N 106.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg