{"id": "1221536150313992194", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-24T15:00:00Z", "msg": "199\nWTPZ42 KNHC 241454\nTCDEP2\n \nHurricane Vance Discussion Number  13\nNWS National Hurricane Center Miami FL       EP222026\n900 AM CST Sat Oct 24 2026\n\nThe satellite appearance of Vance has deteriorated a bit during the \npast few hours, likely due to the combined effects of colder sea \nsurface temperatures near the center and increasing southwesterly \nshear. While the eyewall cloud tops remain quite cold, the eye has \nbecome less distinct and the central dense overcast has become more \nragged. The subjective and objective satellite intensity estimates \nhave nudged downward, and the initial intensity is reduced to 90 kt.\n\nThe intensity forecast is still problematic and low confidence. \nVance is likely to weaken during the next 24 h as it crosses a pool \nof colder water with temperatures near 27C that has been upwelled by \nseveral previous tropical cyclones, and at the same time \nsouthwesterly shear is forecast to increase to near 20-25 kt. The \ncyclone is likely to take 24 h or so to cross the cold pool, then it \nis expected to move over sea surface temperatures near 29C closer to \nthe coast of Mexico. This should allow intensification if the shear \nis light enough. The GFS and ECMWF both show a period of reduced, \nbut still marginal, shear that could allow some intensification, and \nthis is reflected in the intensity forecast. The new intensity \nforecast has some adjustments from the previous forecast, \nparticularly after 60 h. There are three issues that should be noted \nfor this forecast. First the 06Z GFS calls for Vance to make \nlandfall along the Mexican coast as a hurricane, although at the \nmoment no other guidance explicitly shows this. Second, it is \npossible that Vance could weaken more than currently forecast during \nthe next 24 h as it passes over the cold pool. Third, it is possible \nthat the shear may increase to the point where no re-intensification \ncould occur, as the UKMET and Canadian models show stronger shear \nthan the GFS and ECMWF.\n\nThe initial motion is 340/5 kt.  Vance is being steered by a weak \nlow- to mid-level ridge over eastern Mexico, and it is approaching a \nlarge mid-latitude trough over the western United States and \nnorthwestern Mexico. While neither of these features will change \nmuch during the next few days, Vance is likely to move into an area \nof lighter steering currents near the base of the trough and slow \nits forward motion during the next 24-36 h.  The track forecast \nafter 36 h is dependent on how strong Vance is and how well Vance \nmaintains its vertical structure. A weaker system that shears apart \nlike shown in the UKMET and Canadian is likely to move \nwest-northwestward to northwestward before resuming a more northerly \nmotion, while a stronger and vertically deeper system is likely to \ncontinue slowly northward.  The new forecast track is on the east \nside of the guidance envelope near the HFIP corrected consensus, \nGoogle DeepMind, and Florida State Superensemble, and it has only \nminor adjustments from the previous forecast.\n\nKey Messages:\n\n1. Due to the uncertainties in both the track and intensity \nforecasts, it is too early to say what wind and storm surge  \nimpacts Vance may cause along the coast of Mexico. Interests in \nsouthwestern Mexico should continue to monitor the progress of the \nhurricane.\n\n2. Heavy rainfall associated with slow-moving Hurricane Vance will \nimpact the western coast of Mexico from Michoac\u00e1n to Jalisco during \nmuch of next week. This rainfall may produce life-threatening \nflooding and mudslides across Colima and western portions of \nMichoac\u00e1n and Jalisco, especially in areas along steep terrain.\n\n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  24/1500Z 12.9N 103.0W   90 KT 105 MPH\n 12H  25/0000Z 13.6N 103.3W   85 KT 100 MPH\n 24H  25/1200Z 14.6N 103.6W   80 KT  90 MPH\n 36H  26/0000Z 15.5N 104.0W   80 KT  90 MPH\n 48H  26/1200Z 16.0N 104.3W   85 KT 100 MPH\n 60H  27/0000Z 16.3N 104.4W   90 KT 105 MPH\n 72H  27/1200Z 16.7N 104.4W   80 KT  90 MPH\n 96H  28/1200Z 17.7N 104.5W   65 KT  75 MPH\n120H  29/1200Z 18.7N 104.7W   50 KT  60 MPH\n \n"}