{"id": "1212829417913483271", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-23T21:00:00Z", "msg": "996\nWTPZ42 KNHC 232049\nTCDEP2\n \nHurricane Polo Discussion Number  13\nNWS National Hurricane Center Miami FL       EP172026\n300 PM CST Wed Sep 23 2026\n \nSatellite imagery this afternoon suggests that Polo seems to be at\nor near the end of its eyewall replacement cycle, as the eyewall\ncloud tops have gotten colder during the past several hours, and the\neye is gradually becoming more distinct. The various satellite\nintensity estimates are lower than they were six hours ago, but they\nare no longer falling. The initial intensity is lowered to 125 kt,\nand for the moment that could still be a little generous. The\nhurricane's outer rainbands continue to affect the coast of Mexico.\n \nThe hurricane is now moving faster toward the northwest at 310/6 kt. \nWater vapor imagery suggests a mid-level ridge is building over \nTexas and northern Mexico, and the dynamical models forecast this \nridge to build westward to the north of Polo starting on Thursday as \nan upper-level trough near Baja California weakens and lifts out. \nThis evolution should result in Polo moving northwestward for 12 h \nor so, followed by a west-northwestward motion with some increase in \nforward speed. There have been changes in the forecast guidance \nsince the last advisory for the forecast period after 60 h. The \ncluster of models that was forecasting a northward motion has \nshifted a touch to the west, while the cluster that was forecasting \na more northwestward motion has shifted more northward. So, while \nthere is still spread and uncertainty, the guidance is a little more \nclustered than before. The biggest changes are the ECMWF and the \nUKMET, which are now part of the northward moving cluster.  The new \nforecast track for this period follows the northward cluster to a \nposition west of Baja California by 120 h.  Overall, the new track \nis similar to the previous track through 72 h and a little west of \nthe previous track after that.\n\nThe intensity guidance continues to suggest a little decrease in \nintensity during the next 12-24 h followed by slight strengthening. \nHowever, since Polo is completing its eyewall replacement, it is \npossible that intensification could occur at any time. So, the new \nintensity forecast now shows re-intensification during the next 24 \nh.  After 48 h, the environment gradually becomes less favorable \ndue to slightly stronger shear and the possibility of some dry air \nentrainment. The guidance forecasts slow weakening during this \ntime, and the new intensity forecast follows suit. The new forecast \nis again near the upper edge of the guidance for the first 60 h and \nthen lies closer to the middle of the guidance envelope.\n \nWhile the center of Polo is forecast to remain offshore, outer\nrainbands should spread across southwestern Mexico during the next\nday or so, producing areas of heavy rain and tropical-storm-force\nwinds.\n \nKey Messages:\n \n1. Heavy rainfall associated with Polo will impact coastal portions \nof southwest Mexico through Thursday. This rainfall may produce \nlife-threatening flooding and mudslides, especially in areas of \nsteep terrain.\n \n2. A Tropical Storm Warning is in effect for portions of \nsouthwestern Mexico from Tecpan de Galeana to Punta San Telmo, and \na Tropical Storm Watch is in effect west of that to Playa Perula. \nInterests in these areas should closely monitor updates to the \nforecast.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  23/2100Z 15.7N 102.4W  125 KT 145 MPH\n 12H  24/0600Z 16.2N 103.4W  130 KT 150 MPH\n 24H  24/1800Z 16.7N 105.0W  135 KT 155 MPH\n 36H  25/0600Z 16.9N 106.9W  135 KT 155 MPH\n 48H  25/1800Z 17.2N 108.9W  130 KT 150 MPH\n 60H  26/0600Z 17.7N 110.6W  125 KT 145 MPH\n 72H  26/1800Z 18.9N 112.0W  120 KT 140 MPH\n 96H  27/1800Z 22.2N 113.4W  105 KT 120 MPH\n120H  28/1800Z 24.3N 113.4W   90 KT 105 MPH\n \n"}