{"id": "1222947433691873282", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-29T15:00:00Z", "msg": "062\nWTPZ42 KNHC 291432\nTCDEP2\n \nTropical Storm Vance Discussion Number  33\nNWS National Hurricane Center Miami FL       EP222026\n800 AM MST Thu Oct 29 2026\n \nDeep convection near the center yesterday evening produced \ntropical-storm-force winds in Vance's northern and eastern \nsemicircles.  Strong (50 kt) west-southwesterly vertical wind shear \nhas been pushing the deep convection farther and farther away from \nthe center over the past 9 to 12 hours, and now the convection is \nlocated more than 90 n mi east and northeast of the center.  Recent \nsurface observations from Islas Marias are 20 kt gusting to 30 kt \nwhile located underneath some of the deepest convection for the past \nfew hours, so the winds are likely decreasing, but it is still \npossible that a small area of winds to tropical-storm-force exists \nin that convection, so Vance will be held at 35 kt for this \nadvisory.  Scatterometer passes expected within the next couple of \nhours should give us a better assessment of Vance's strength.\n \nThe UW-CIMSS shear analysis and the latest SHIPS guidance are both \nanalyzing about 50 kt of west-southwesterly vertical wind shear \ncurrently impacting Vance.  The shear is forecast to increase to \naround 55 kt over the next 6 h or so.  Vance is also located within \na drier environment than it was yesterday, with mid-level relative \nhumidity values in the 40 to 50 percent range. Therefore, deep \nconvection, which is currently located well east of the center and \nmoving farther away, is unlikely to return, and the GFS and ECMWF \nsimulated satellite products do not forecast any new convection to \nform near the center.  Therefore, the timing of post-tropical \ntransition has been moved up to hour 12 in the official forecast. \nMost of the models then show the remnant low dissipating in about 18 \nto 24 hours over the southern Gulf of California.  Although gradual \nweakening is forecast until dissipation, gusts to \ntropical-storm-force are still likely today within the deep \nconvection well east of the center.\n \nVance has been moving northward, or 350/7 kt.  A generally northward \nmotion at about the same speed is expected until Vance degenerates \ninto a trough of low pressure over the southern Gulf of California \nin about 18 to 24 hours.  The new NHC forecast is nudged a bit to \nthe left of the previous one and is near the latest HCCA and GDMI. \nIt should be emphasized that the main threat with Vance is the very \nheavy rainfall and high rain rates near the areas of very deep \nconvection near the Islas Marias and west-central Mexico.\n \n \nKey Messages:\n \n1. Periods of heavy rainfall associated with Vance will impact\nportions of western Mexico during the next day or two. This rainfall\nmay produce flooding and mudslides across central and southern\nSinaloa, far southwestern Durango, and far northwestern Nayarit,\nespecially in areas along steep terrain.\n \n2. Moisture carried northeastward from Vance will produce heavy rain\nacross portions of the U.S. Southern Plains and New Mexico today\ninto Friday.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  29/1500Z 21.6N 108.8W   35 KT  40 MPH\n 12H  30/0000Z 22.9N 108.5W   25 KT  30 MPH...POST-TROP/REMNT LOW\n 24H  30/1200Z...DISSIPATED\n \n"}