{"id": "1218280597857107971", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-13T03:00:00Z", "msg": "377\nWTPZ45 KNHC 130255\nTCDEP5\n \nHurricane Simon Discussion Number  23\nNWS National Hurricane Center Miami FL       EP202026\n800 PM MST Mon Oct 12 2026\n \nSimon's convection has degraded quite a bit since the last advisory.\nGiven how much of this weakening has been concentrated across the\neastern half of the storm, it is possible that Simon has been\ningesting dry, high terrain air into its center. Regardless of the\nphysical mechanism, however, both subjective and objective Dvorak\nintensity estimates have picked up on this weakening trend, as the\nTAFB Dvorak classification rates Simon at 5.0/90 kt and UW-CIMSS\nestimates range from 51 to 72 kt. As a result of these data, Simon's\ninitial intensity has been lowered to 85 kt.\n \nThe storm motion remains very slow at 305/3 kt. Simon is riding the\nwestern flank of a high pressure ridge centered over the\nsoutheastern US, with high pressure building to the storm's west as\nwell in the wake of a deep trough currently enveloping the\nIntermountain West. Simon is battling a multitude of features\ninfluencing its motion as a result, and track guidance continues to\nexhibit a wide spread of solutions. Thus, confidence in the track\nforecast remains low. The global models, however, do seem to agree\nthat the high anchored over the southeastern US will remain for at\nleast the next 48 hours, so the current forecast thinking is that\nSimon will not make a turn toward land in the meantime. What becomes\nof that high once the aforementioned trough moves eastward across\nthe US is what will ultimately determine Simon's path.\n \nLooking at the global models, the GFS depicts the trough doing\nlittle to erode the southeastern high, leaving Simon to become\ncaught in a col as it is wedged between two high pressure systems,\nthus causing it to become nearly stationary over the next couple of\ndays. The ECMWF, however, seems to suggest that the trough will dig\ndeep enough to cause a turn to the northeast toward land over the\nnext 48 hours. More skilled guidance like the HCCA and GDMI,\nhowever, seem to favor a due northwest track, likely stemming from\nthe southeastern US high remaining fixed in place and the high to\nthe west not building enough to affect Simon's motion. The latest\nNHC track forecast favors this solution, while still depicting a\nturn to the northeast after a couple of days should this Pacific\nhigh strengthen enough to nudge Simon off its current trajectory.\n \nShould Simon continue to move northwestward, as is currently\nforecast, gradual re-strengthening should follow. The environment\njust off the coast of west-central Mexico continues to be defined by\nlow vertical wind shear, anomalously warm SSTs, and ample mid-level\nmoisture. Should the storm become nearly stationary as some models\nsuggest, however, re-intensification could be inhibited by Simon\nchurning up cooler waters from deep below the sea surface. It should\nbe noted that the current consensus across the guidance does not\nfavor a period of rapid intensification, so the latest NHC intensity\nforecast continues to reflect a more gradual upward trend in\nstrength, before dropping off sharply once Simon makes its\nforecasted approach to land. With confidence lacking in the track\nforecast, however, Simon's intensity forecast confidence is only low\nto moderate.\n \nKey Messages:\n \n1. Hurricane conditions are likely on Las Islas Marias over the\nnext day or so, where a Hurricane Warning remains in effect.\n \n2. Simon could approach the coast of western Mexico later this week,\nwhere hurricane conditions are possible.\n \n3. Heavy rainfall associated with Simon will impact portions of\nwest-central Mexico over the next few days. This rainfall will\nproduce life-threatening flooding and mudslides, especially in areas\nof steep terrain.\n \n4. Large swells will affect portions of the southwestern and\nwest-central coasts of Mexico over the next several days. These\nswells are likely to cause life-threatening surf and rip current\nconditions. Please consult products from your local weather office.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  13/0300Z 20.4N 107.0W   85 KT 100 MPH\n 12H  13/1200Z 20.7N 107.3W   75 KT  85 MPH\n 24H  14/0000Z 21.0N 107.7W   70 KT  80 MPH\n 36H  14/1200Z 21.3N 108.0W   70 KT  80 MPH\n 48H  15/0000Z 21.8N 108.0W   75 KT  85 MPH\n 60H  15/1200Z 22.5N 107.9W   80 KT  90 MPH\n 72H  16/0000Z 23.2N 107.8W   85 KT 100 MPH\n 96H  17/0000Z 24.0N 107.6W   85 KT 100 MPH\n120H  18/0000Z 24.8N 107.3W   30 KT  35 MPH...POST-TROP/INLAND\n \n"}