Tropical Cyclone Discussion
816 WTPZ42 KNHC 280235 TCDEP2 Tropical Storm Vance Discussion Number 27 NWS National Hurricane Center Miami FL EP222026 800 PM MST Tue Oct 27 2026 The structure of Vance continues to be heavily sheared and ragged based on the current visible satellite imagery. Some of the most recent images have shown that a small convective burst has occurred near the center, however it is also being blown away by the westerly wind shear at this point. In addition to the shear, there is dry air that is getting into the core of the storm, which is keeping the center of Vance fully exposed. The most recent objective intensity estimates from UW-CIMSS are in the range of 28-33 kt, while the latest TAFB Dvorak fix is a T2.0/30 kt. Given the available data the initial intensity has been held at 35 kt for this advisory. Vance is moving northwestward at 310/07 kt, as the storm is being steered by a low-level ridge centered over the south-central United States. A gradual turn toward the north is forecast over the next few days due to a strong mid-level trough moving across the U.S. West Coast. As a result, Vance should move toward the Gulf of California by Thursday. The current NHC track forecast is very similar to the previous one, with some minor adjustments being made based on the latest HCCA and GDMI forecast aids. The intensity portion of the forecast has plenty of uncertainties due to a variety of variables. The cyclone is over warm waters of 29-30 C for the next several days, but the wind shear is expected to be around 40 kt based on the GFS and ECMWF SHIPS guidance. This could allow for convection to develop near the center, but that convection will then be blown away by the shear. This could also mean that there could be brief fluctuations in intensity at times due to the convection. The most recent GFS and ECMWF simulated satellite guidance shows that there could be one or two more convective bursts from Vance due to some upper-level divergence sometime tomorrow. However, the impacts that this convection could have on the storm are still uncertain. At this point, the cyclone is still expected to become post-tropical around 36 h. By 60 h, it is expected to be a post-tropical remnant low, and finally by 72 h the circulation of Vance is forecast to dissipate. If the storm cannot maintain organized deep convection, it is possible that Vance could transition to a post-tropical cyclone sooner than currently forecast. Key Messages: 1. Periods of heavy rainfall associated with Vance will impact portions of western Mexico during much of this week. This rainfall may produce flooding and mudslides across central and southern Sinaloa, western Durango, and northwestern Nayarit, especially in areas along steep terrain. 2. Interests along the southwestern and west-central coasts of Mexico and the southern Baja California Peninsula should monitor the progress of Vance. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 17.3N 108.4W 35 KT 40 MPH 12H 28/1200Z 18.5N 108.7W 35 KT 40 MPH 24H 29/0000Z 20.2N 108.5W 35 KT 40 MPH 36H 29/1200Z 21.7N 108.1W 35 KT 40 MPH...POST-TROPICAL 48H 30/0000Z 23.5N 107.7W 35 KT 40 MPH...POST-TROPICAL 60H 30/1200Z 25.3N 107.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 31/0000Z...DISSIPATED