{"id": "1222028539491876867", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-26T09:00:00Z", "msg": "336\nWTPZ42 KNHC 260838\nTCDEP2\n \nTropical Storm Vance Discussion Number  20\nNWS National Hurricane Center Miami FL       EP222026\n300 AM CST Mon Oct 26 2026\n\nVance has not changed significantly in organization over the past \nseveral hours.  There are disorganized bursts of deep convection \nnear and east of the estimated center, but convective banding \nfeatures are not well defined.  Upper-level outflow is mainly over \nthe northern semicircle of the system.  The advisory intensity is \nheld at 55 kt for now, which is in agreement with a subjective \nDvorak estimate from TAFB and a little higher than most of the \nobjective estimates from UW-CIMSS.  \n\nAlthough the center is difficult to locate, it is estimated to be \nsituated near the western side of the main area of convection.  The \nstorm appears to still be moving slowly northwestward, with an \ninitial motion estimate of around 305/5 kt.  A slow \nwest-northwestward track is likely over the next 36 hours or so due \nto a weak mid-level ridge to the north of the system.  In a couple \nof days, a broad mid-level trough near the Baja California peninsula \nshould induce a turn toward the north, and the weakening cyclone \nshould then move northward and approach mainland Mexico later this \nweek.  The official track forecast is shifted somewhat to the west \nof the previous one, but not as far west as much of the model \nguidance.  Additional westward adjustments may be required in \nsubsequent advisory packages.\n\nVance remains in an environment of strong westerly vertical wind \nshear and in a somewhat dry mid-level air mass.  The SHIPS guidance \nindicates that the strong shear should persist for the next few \ndays.  Therefore weakening is anticipated as in the previous NHC \nforecast.  Simulated satellite imagery from the ECMWF global model \noutput shows Vance losing most of its deep convection after 72 \nhours.  Thus, the system is expected to become a post-tropical \nremnant low by late this week.  The official forecast is on the high \nside of the intensity model guidance suite.\n\n\nKey Messages:\n \n1. Although the threat to southwest Mexico is decreasing as the \nforecast track shifts westward away from the coast, interests there \nshould 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 Sinaloa and along western \nportions of Jalisco, Nayarit and Durango, especially in areas along \nsteep terrain.\n\n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  26/0900Z 15.3N 105.1W   55 KT  65 MPH\n 12H  26/1800Z 15.6N 105.9W   50 KT  60 MPH\n 24H  27/0600Z 16.1N 106.9W   45 KT  50 MPH\n 36H  27/1800Z 17.2N 107.6W   40 KT  45 MPH\n 48H  28/0600Z 18.5N 108.0W   40 KT  45 MPH\n 60H  28/1800Z 19.9N 108.1W   40 KT  45 MPH\n 72H  29/0600Z 21.4N 108.0W   35 KT  40 MPH\n 96H  30/0600Z 23.2N 107.9W   30 KT  35 MPH...POST-TROP/REMNT LOW\n120H  31/0600Z 24.5N 108.0W   30 KT  35 MPH...POST-TROP/REMNT LOW\n \n"}