{"id": "1212333541791596551", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-22T03:00:00Z", "msg": "893\nWTPZ42 KNHC 220247\nTCDEP2\n \nHurricane Polo Discussion Number   6\nNWS National Hurricane Center Miami FL       EP172026\n900 PM CST Mon Sep 21 2026\n \nPolo continues to rapidly intensify (RI) this evening. On \ngeostationary satellite, the hurricane's structure is becoming \nincreasingly impressive, with the earlier ragged eye clearing out as \nvery cold cloud tops (-80 C and below) wrap around. In addition, an \nF17 SSMIS microwave pass at 0105 UTC suggests the earlier eyewall \nreplacement cycle (ERC) observed from the NOAA-P3 aircraft has \ncompleted. Not surprisingly, satellite intensity estimates are \nquickly rising, with the latest subjective Dvorak estimate from TAFB \nup to T5.0/90 kt, with the DMINT estimate associated with that \nrecent SSMIS pass at 96 kt. Given the continued improvement of Polo \non satellite, the initial intensity is being increased to 95 kt for \nthis advisory.\n\nThe intensifying hurricane continues to move a little south of due \neast, with its estimated motion at 105 degrees at 4 kt. This \nshort-term motion is expected to continue for the next 12-18 h \nbefore mid- to upper-level ridging over Mexico intensifies. The net \nresult of this synoptic pattern change is that the primary steering \nshould flip in about 24 h, causing Polo to make a sharp turn to the \nnorthwest and then west-northwest in the 36-60 h time frame, \nbringing the core of the hurricane near, but just offshore of, the \ncoast of southwestern Mexico. Finally, toward the end of the \nforecast period, Polo will likely be reaching the westward extent of \nthe deep-layer ridge. In addition, Polo may also be approaching \nTropical Storm Odalys that is forecast to be positioned west of \nPolo, and much of the track guidance responds to this evolution by \nshowing the hurricane turning more northward by 120 h. There \ncontinues to be quite a bit of cross-track uncertainty, both in \nterms of how sharp Polo's turn to the northwest will be in the next \n48 h, and also toward the end of the forecast when Polo could \nexperience binary interaction with Odalys. The NHC track forecast \ncontinues to favor a blend of the HFIP Corrected Consensus Approach \n(HCCA) and Google DeepMind ensemble mean (GDMI) aids, but the track \nuncertainly remains high in the 3-5 day period. \n\nNow that it appears the earlier ERC has completed, it is hard to see \nwhat could prevent Polo from continuing to RI for the next day or \nso. Shear remains low, analyzed at 6 kt by UW-CIMSS, and there is \nample deep-layer moisture. Sea-surface temperatures are also very \nwarm (31 C) and extend vertically down 50-100 meters along the \nshort-term track of Polo per a ARGO profiler, which should limit \ncooler ocean upwelling despite the slow motion of the hurricane. \nSHIPS RI indices continue to be very high, with DTOPS showing an 81 \npercent chance of at least a 40 kt increase in intensity over the \nnext 24 h. Thus, the NHC intensity forecast will continue to show \nRI, and now shows a 140-kt peak in 24 h. This intensity forecast \nagrees with the HCCA intensity aid, and is also close to the 18z \nHAFS-B forecast which also shows a 140-kt peak in its raw output in \n24 h. Beyond that time, inner-core fluctuations related to \nadditional ERCs will likely lead to intensity oscillations, and both \nthe GFS- and EC-SHIPS guidance does show a marked increase in \neasterly shear beyond 48 h. Therefore, slow weakening is shown in \nthe day 3-5 period, though it still remains a bit higher than the \nintensity guidance consensus aside from HCCA. Regardless, Polo is \nexpected to remain a major hurricane through the entire forecast \nperiod.\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 and \nhas been extended to Manzanillo. \n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  22/0300Z 15.0N 102.3W   95 KT 110 MPH\n 12H  22/1200Z 14.9N 101.8W  115 KT 130 MPH\n 24H  23/0000Z 15.1N 101.7W  140 KT 160 MPH\n 36H  23/1200Z 15.6N 102.2W  140 KT 160 MPH\n 48H  24/0000Z 16.5N 103.2W  135 KT 155 MPH\n 60H  24/1200Z 17.3N 104.5W  130 KT 150 MPH\n 72H  25/0000Z 17.7N 106.0W  125 KT 145 MPH\n 96H  26/0000Z 18.6N 109.2W  115 KT 130 MPH\n120H  27/0000Z 20.1N 111.7W  105 KT 120 MPH\n \n"}