{"id": "1213039964446457863", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-24T15:00:00Z", "msg": "463\nWTPZ42 KNHC 241440\nTCDEP2\n \nHurricane Polo Discussion Number  16\nNWS National Hurricane Center Miami FL       EP172026\n900 AM CST Thu Sep 24 2026\n\nSatellite imagery shows that while Polo remains a powerful \nhurricane, there have been some structural changes during the past \nfew hours. First, an AMSR3 overpass a few hours ago showed a new \nouter eyewall was forming, indicating that the hurricane is about \nto begin another eyewall replacement cycle. Second, while the eye \nand the central convective features remain well defined, there is \nnow an outer band in the southwestern semicircle with infrared cloud \ntop temperatures colder than those currently seen in the inner core. \nThe various satellite intensity estimates have nudged downward, and \nthe initial intensity of 135 kt is at the upper edge of the \nestimates.\n\nPolo is turning more westward with the initial motion now 295/9 kt. \nA mid-level ridge building westward from northern Mexico should \nsteer the hurricane generally westward for the next 36 h or so.  \nAfter that, a mid-latitude trough moving eastward across the \nnortheastern Pacific should prevent the ridge from building farther \nwest, with Polo likely to recurve northward and northeastward \naround the western end of the ridge.  The track guidance has come \ninto much better agreement on this scenario, although there are \nsignificant differences in how fast the storm will move during the \nrecurvature. One on side, the GFS, HCCA, Google DeepMind, and \nFlorida State Super Ensemble are faster, and the official forecast \nleans towards them. On the other, the UKMET and the regional \nhurricane models are notably slower with their forward speed. \nOverall, the new forecast track is near the center of the guidance \nenvelope and is similar to the previous forecast. The new track \ntakes the center away from the southwestern coast of Mexico today \nand then has it passing over Baja California Sur in 96-120 h.\n\nFluctuations in strength seem likely over the next day or so while\nPolo undergoes this new eyewall replacement and remains in \nfavorable environmental conditions. The intensity forecast shows \nlittle change in strength at 12 h and some slight strengthening at \n24 h to try to account for the cycle.  After 24 h, a slow weakening \nis expected through 96 h as Polo encounters somewhat increased \nshear. The new forecast shows a sharp drop in intensity by 120 h \nas Polo crosses the Baja California peninsula. The new forecast \nlies near the upper edge of the intensity guidance.\n\n\nKey Messages:\n \n1. Heavy rainfall associated with Polo will impact coastal portions \nof southwest Mexico today. This rainfall may produce \nlife-threatening flooding and mudslides, especially in areas of \nsteep terrain.\n \n2. Tropical storm conditions are expected across portions of the \ncoast within the warning area from Tecpan de Galeana to Manzanillo \nfor a few more hours.\n \n3. Polo is forecast to approach the Baja California Peninsula early\nnext week as a hurricane. Interests there should closely monitor\nthe latest updates and ensure that they have their preparedness\nplan in place.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  24/1500Z 16.8N 104.4W  135 KT 155 MPH\n 12H  25/0000Z 17.0N 105.8W  135 KT 155 MPH\n 24H  25/1200Z 17.1N 107.8W  140 KT 160 MPH\n 36H  26/0000Z 17.4N 109.6W  135 KT 155 MPH\n 48H  26/1200Z 18.2N 111.2W  130 KT 150 MPH\n 60H  27/0000Z 19.4N 112.5W  125 KT 145 MPH\n 72H  27/1200Z 21.1N 113.3W  115 KT 130 MPH\n 96H  28/1200Z 24.4N 113.3W  100 KT 115 MPH\n120H  29/1200Z 27.0N 111.1W   75 KT  85 MPH...GULF OF CALIFORNIA\n \n"}