{"id": "1221957658025000963", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-26T03:00:00Z", "msg": "664\nWTPZ42 KNHC 260237\nTCDEP2\n \nTropical Storm Vance Discussion Number  19\nNWS National Hurricane Center Miami FL       EP222026\n900 PM CST Sun Oct 25 2026\n \nVance's structure continues to degrade as seen in visible satellite\nimagery and the GPM and AMSR3 microwave passes, due to strong\nvertical wind shear and relatively dry mid-level air. Convection\ncontinues to develop to the northeast of the center, but it is\nmostly limited to that quadrant. The TAFB Dvorak fix was T3.5/55 kt\nand the objective intensity estimates from UW-CIMSS are in 37-52 kt\nrange.  Based on that data, the initial intensity has been lowered\nto 55 kt.\n \nVance is currently moving toward the northwest, 305/6 kt. The\ntropical storm is being steered by a mid-level ridge centered over\nthe south-central United States, along with a closed upper-level low\nmoving across the southwestern United States. The cyclone is\nexpected to continue to move toward the northwest to west-northwest\nwith a decrease in forward speed as the steering currents weaken. A\nturn back to the north is expected by the middle of the week as an\namplified mid to upper-level trough moves over the eastern Pacific.\nThe current NHC track forecast has been adjusted a little to the\nwest of the previous one. Future adjustments to the west are likely\nif the guidance trends continue.\n \nThe combination of southwesterly wind shear and relatively dry\nmid-level air are expected to continue to gradually weaken the\nstorm. By the middle of this week, an upper-level trough will\nfurther enhance the wind shear, resulting in additional weakening.\nBoth the GFS and ECMWF simulated satellite imagery suggest that\nVance will struggle to hold on to organized deep convection by late\nthis week. The current intensity forecast still calls for Vance\nto become post-tropical at 96 h and degenerate into a remnant low by\n120 h. However, the current intensity forecast is on the upper end\nof the guidance envelope, as most of the guidance shows the rate of\nweakening much faster than what is currently forecast. It is\ncertainly possible that the cyclone could weaken faster, which will\nmean that it could become a remnant low sooner than what is\nforecasted.\n \nKey Messages:\n \n1. Although the threat to southwest Mexico is decreasing\nas the forecast track shifts westward away from the coast,\ninterests there should continue to monitor Vance's progress.\n \n2. Periods of heavy rainfall associated with Vance will impact\nportions of western Mexico during much of this week. This rainfall\nmay produce flooding and mudslides across Colima, Nayarit, and\nSinaloa, along with western portions of Michoac\u00e1n, Jalisco, and\nDurango, especially in areas along steep terrain.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  26/0300Z 15.0N 104.7W   55 KT  65 MPH\n 12H  26/1200Z 15.3N 105.3W   50 KT  60 MPH\n 24H  27/0000Z 15.7N 106.0W   45 KT  50 MPH\n 36H  27/1200Z 16.5N 106.8W   40 KT  45 MPH\n 48H  28/0000Z 17.4N 107.3W   40 KT  45 MPH\n 60H  28/1200Z 18.5N 107.6W   40 KT  45 MPH\n 72H  29/0000Z 20.0N 107.7W   40 KT  45 MPH\n 96H  30/0000Z 22.0N 107.8W   35 KT  40 MPH...POST-TROPICAL\n120H  31/0000Z 24.0N 107.9W   30 KT  35 MPH...POST-TROP/REMNT LOW\n \n"}