{"id": "1213113021534044167", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-24T21:00:00Z", "msg": "909\nWTPZ42 KNHC 242051\nTCDEP2\n \nHurricane Polo Discussion Number  17\nNWS National Hurricane Center Miami FL       EP172026\n300 PM CST Thu Sep 24 2026\n \nA NOAA Hurricane Hunter aircraft has investigated Polo during the\npast few hours, and its data indicates that the eyewall replacement\ncycle mentioned in the previous advisory is almost complete. The \nfirst aircraft pass reported concentric eyewalls of 15 and 30 n mi \ndiameters. Subsequent passes reported that the inner eyewall \ndissipated, while the remaining outer eyewall contracted to 25 n mi \ndiameter. In addition, 700-mb flight level winds in the northeast \neyewall increased by about 15 kt during the mission, with the \nmaximum winds of 147 kt.  The central pressure also started to fall \nduring the mission, and the estimated value from data on the last \npass is near 935 mb. Based on these data, the initial intensity is \nset at 130 kt. It should be noted that the strengthening observed \nby the aircraft has not yet been fully reflected in satellite \nimagery.\n \nPolo is now moving west-northwestward or 285/9 kt. There is little \nchange to the track forecast reasoning from the previous advisory. \nA mid-level ridge building westward from northern Mexico should \nsteer the hurricane generally westward for the next 24-36 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 is \ngenerally in good agreement with this scenario, although there \nremains some spread in the forward speed between the slower HAFS \nmodels and the faster GFS and HCCA models. The new track, which is \nan update of the previous forecast, takes the center away from the \nsouthwestern coast of Mexico this evening and then has it moving \nacross Baja California into northwestern mainland Mexico in 96-120 \nh.\n \nThe new intensity forecast now calls for Polo to strengthen for the\nnext 12 h or so after the end of the eyewall replacement, and Polo\nis expected to regain Category 5 strength tonight or Friday\nmorning. After that, a slow weakening is expected through 96 h as\nPolo encounters somewhat increased shear, with the caveat that\nthere could be some fluctuations due to additional eyewall\nreplacement cycles. Rapid weakening is expected when the cyclone\ncrosses Baja California and moves into mainland Mexico. The new\nforecast again lies near the upper edge of the intensity guidance.\n\nIt should be noted that moisture from Hurricane Polo and Odalys \nwill be carried a long distance into the southwestern United States \nthis weekend and early next week, and may indirectly contribute to \na heavy rainfall and flash flood threat in the region. See products \nissued by the Weather Prediction Center for more information.\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. Wind gusts to tropical storm force may occur along portions of \nthe southwestern coast of Mexico this evening.\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  24/2100Z 17.1N 105.5W  130 KT 150 MPH\n 12H  25/0600Z 17.2N 106.8W  140 KT 160 MPH\n 24H  25/1800Z 17.4N 108.8W  135 KT 155 MPH\n 36H  26/0600Z 17.8N 110.5W  130 KT 150 MPH\n 48H  26/1800Z 18.7N 112.0W  125 KT 145 MPH\n 60H  27/0600Z 20.3N 113.1W  120 KT 140 MPH\n 72H  27/1800Z 22.0N 113.4W  110 KT 125 MPH\n 96H  28/1800Z 25.2N 112.8W   95 KT 110 MPH\n120H  29/1800Z 27.9N 109.9W   60 KT  70 MPH...INLAND\n \n"}