{"id": "1222596334534459399", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-28T09:00:00Z", "msg": "593\nWTPZ42 KNHC 280846\nTCDEP2\n \nTropical Storm Vance Discussion Number  28\nNWS National Hurricane Center Miami FL       EP222026\n200 AM MST Wed Oct 28 2026\n \nVance's low-level circulation remains partially exposed due to \nstrong westerly vertical wind shear affecting the cyclone. However, \nsatellite imagery indicates that deep convection has expanded near \nthe center and across the eastern semicircle of the circulation \nearly this morning, with cloud-top temperatures as cold as -85 C. \nThis increase in convection could be partly associated with the \nnocturnal convective maximum, despite the persistent strong westerly \nshear. A 0411 UTC Metop-C scatterometer pass indicated that Vance's \nlow-level circulation was not as well defined and had become \nelongated from east to west, with peak winds of 30 to 35 kt east of \nthe center. Given these observations and the recent convective \npresentation, the initial intensity is held at 35 kt.\n\nThe initial motion is northward, or 360/10 kt. A gradual turn toward \nthe north-northeast is expected today as the low- to mid-level ridge \nto the northeast of Vance erodes in response to a series of \nshortwave troughs rotating through a broad mid- to upper-level \ntrough deepening over the West Coast of the United States. The track \nguidance remains in good agreement with this scenario, bringing \nVance west of the Islas Marias tonight or early Thursday, followed \nby a forecast landfall along the coast of Mexico north of Mazatlan \non Thursday. The latest NHC track forecast is essentially unchanged \nfrom the previous prediction and lies near the GDMI and HCCA aids.\n\nStrong westerly to southwesterly vertical wind shear associated with \nthe subtropical jet is expected to increase further as Vance moves \nnorthward toward the deepening upper-level trough. This shear, \ncombined with dry mid-level air, should continue to inhibit \nsustained organization of deep convection near the center despite \nwarm sea surface temperatures along the forecast track. Global model \nguidance generally supports this scenario, depicting intermittent \nconvective bursts primarily displaced east of the circulation. \nHowever, some intensity guidance suggests that Vance could maintain \nits strength or even strengthen slightly during the next day or so, \npossibly due to enhanced upper-level divergence associated with the \ninteraction between the subtropical jet and upper trough. Given this \npossibility, the NHC forecast maintains Vance's intensity at 35 kt \nthrough 24 h, followed by gradual weakening thereafter. The \nincreasingly elongated and less well-defined low-level circulation \nsuggests that Vance could degenerate into a post-tropical remnant \nlow sooner than previously forecast, and the latest forecast \nindicates this transition by 36 h. Given the forecast weakening and \nexpected loss of tropical characteristics, the threat of tropical \nstorm conditions over land remains low at this time. The latest NHC \nintensity forecast is very similar to the previous prediction and \nlies near the middle of the guidance envelope.\n\n\nKey Messages:\n\n1. 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 central and southern \nSinaloa, western Durango, and northwestern Nayarit, especially in \nareas along steep terrain.\n\n2. Interests along the southwestern and west-central coasts of \nMexico and the southern Baja California Peninsula should monitor the \nprogress of Vance.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  28/0900Z 18.6N 108.6W   35 KT  40 MPH\n 12H  28/1800Z 20.0N 108.7W   35 KT  40 MPH\n 24H  29/0600Z 21.6N 108.3W   35 KT  40 MPH\n 36H  29/1800Z 23.1N 108.0W   30 KT  35 MPH...POST-TROP/REMNT LOW\n 48H  30/0600Z 25.2N 107.1W   25 KT  30 MPH...POST-TROP/INLAND\n 60H  30/1800Z...DISSIPATED\n \n"}