{"id": "1212263735648714759", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-21T21:00:00Z", "msg": "141\nWTPZ42 KNHC 212052\nTCDEP2\n \nHurricane Polo Discussion Number   5\nNWS National Hurricane Center Miami FL       EP172026\n300 PM CST Mon Sep 21 2026\n \nSatellite images show that Polo has a ragged eye on both visible\nand infrared images, with very deep convection starting to wrap\naround a broken eyewall.  The NOAA Hurricane Hunter aircraft has\nbeen providing valuable data that show the cyclone undergoing an\nearly-stage eyewall cycle, with two wind maxes on the TDR radar.\nThe plane recently reported 0.5 km winds up to 92 kt, with\nhigher winds and lower central pressure on each fix, dropping about \n1 mb per hour.  These winds convert to roughly 75 kt at the \nsurface, and that will be the initial wind speed this advisory.\n \nWhile the current eyewall replacement could slightly hinder \nintensification, the last aircraft pass through Polo already showed \nthat the old inner eyewall was fading.  Thus, given the very warm \nwaters, light shear and moist environment, a high-end rapid \nintensification event is expected.  The latest model guidance are \neven higher than the last cycle, and the new NHC intensity forecast \nfollows the trend, but is still below the NOAA HCCA corrected- \nconsensus aid.  An increase in easterly wind shear could cause some \nweakening in the medium-range period, though Polo should be a small \nand powerful hurricane throughout the forecast period.\n \nThe storm is drifting east-southeastward and should move in that \ngeneral direction for about a day before a mid-level ridge \nintensifies over Mexico.  This ridge should cause the cyclone to \nturn sharply towards the northwest and west-northwest on Wednesday \nand Thursday, bringing the core of the storm near or south of the \ncoast of southwestern Mexico.  Eventually there is enough troughing \nover the eastern Pacific to cause the system to bend more \nnorthwestward at long range towards the Baja California peninsula.  \nThe details, however, are pretty sketchy with a potential binary \ninteraction with Tropical Storm Odalys looming, which is helping to \ncause a large north-south spread in the guidance.  No big changes \nwere made to the NHC forecast, but it is a little farther west at \nand beyond 72 hours where uncertainty is high.  \n \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. Polo is forecast to strengthen to a major hurricane while it\nmoves closer to the coast of southwestern Mexico during the next few\ndays. Although the core of the hurricane is forecast to stay\noffshore, it is too soon to determine the exact location or\nmagnitude of impacts. Residents in southwestern Mexico should\nclosely monitor its progress and updates to the forecast. A Tropical\nStorm Watch is in effect for portions of southwestern Mexico.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  21/2100Z 15.1N 102.7W   75 KT  85 MPH\n 12H  22/0600Z 14.9N 102.3W  100 KT 115 MPH\n 24H  22/1800Z 14.9N 102.0W  125 KT 145 MPH\n 36H  23/0600Z 15.4N 102.2W  140 KT 160 MPH\n 48H  23/1800Z 16.1N 102.9W  145 KT 165 MPH\n 60H  24/0600Z 17.0N 104.0W  140 KT 160 MPH\n 72H  24/1800Z 17.7N 105.5W  140 KT 160 MPH\n 96H  25/1800Z 18.6N 108.6W  130 KT 150 MPH\n120H  26/1800Z 20.5N 111.2W  120 KT 140 MPH\n \n"}