{"id": "1216935825592090631", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-08T09:00:00Z", "msg": "992\nWTPZ45 KNHC 080855\nTCDEP5\n \nTropical Storm Simon Discussion Number   4\nNWS National Hurricane Center Miami FL       EP202026\n300 AM CST Thu Oct 08 2026\n \nThis evening's conventional satellite imagery and a recent ASCAT\noverpass and a 0323 UTC MetOp-SG1 MI indicate that Simon is\ndeveloping a compact inner core structure.  There are also curved\nbands with -73C to -82C cold cloud tops forming in the west and\nnortheast portions of the cyclone.  The TAFB subjective satellite\nintensity estimate is T3.0/45 kt and a blend of the UW-CIMSS\nobjective estimates (41-47 kt) yield an initial intensity of 45 kt.\n \nThe shear is low, the atmosphere is moist, and the ocean is warm\nwith high heat content values, all contributing to a high\nprobability of Simon quickly intensifying during the next couple of\ndays.  The upper wind pattern is also quite favorable with \nimpressive diffluent easterly flow ventilating the western portion \nof the cyclone.  The latest SHIPS RI Index shows a 63 percent \nchance of a 55 kt increase in 48 hrs, while the UW-CIMSS AI-RI \nindicates a similar likelihood of rapid intensification.  The \nofficial forecast shows Simon becoming a major hurricane in 48 hrs \nwith a peak intensity of 115 kt on Saturday, and this is based on \nthe HFIP-HCCA and slightly above the Google DeepMind ensemble \nguidance.\n \nSimon's initial motion is estimated to be due west, or 270 degrees \nat 6 kt.  This general motion should continue through today while \nbeing steered by high pressure north of the cyclone over central \nMexico.  On Friday, the system should turn west-northwestward to \nnorth-northwestward in response to a mid-tropospheric trough \napproaching Baja California.  Toward the end of the period, Simon is \nexpected to move northward ahead of and on the southeastern side of \nthe aforementioned trough and approach the southwestern coast of \nMexico over the weekend.  The GFS and the ECMWF HiRes global models \nstill show outlier tracks to the left of the NHC forecast but have \nbeen trending eastward, aligning more with the better-performing \nHCCA and Google DeepMind TC ensemble mean aids, which the official \nforecast leans toward.\n \nSimon's 34 kt wind radii were decreased a bit based on a 0403 UTC\nMETOP-B ASCAT pass.\n \n \nKey Messages:\n \n1. Simon is expected to strengthen into a hurricane by early Friday \nand approach the west-central coast of Mexico as a major hurricane \non Saturday. Tropical storm conditions are possible within the \ntropical storm watch area early Friday. There is also risk of \ndangerous wind and storm surge impacts along portions of this coast \nover the weekend and into early next week and additional watches \nwill likely be required for portions of southwestern Mexico.\n \n2. Heavy rainfall associated with Simon will impact portions of \nsouthwestern Mexico later this week and into the weekend. This \nrainfall may produce life-threatening flooding and mudslides, \nespecially in areas of steep terrain.\n \n3. Swells will affect portions of the southwestern and west-central\ncoast of Mexico through the weekend.  These swells are likely to\ncause life-threatening surf and rip current conditions.  Please\nconsult products from your local weather office.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  08/0900Z 15.4N 103.1W   45 KT  50 MPH\n 12H  08/1800Z 15.4N 104.1W   60 KT  70 MPH\n 24H  09/0600Z 15.9N 105.1W   75 KT  85 MPH\n 36H  09/1800Z 16.6N 105.5W   95 KT 110 MPH\n 48H  10/0600Z 17.4N 105.6W  110 KT 125 MPH\n 60H  10/1800Z 18.3N 105.4W  115 KT 130 MPH\n 72H  11/0600Z 19.3N 105.3W  110 KT 125 MPH\n 96H  12/0600Z 21.8N 105.7W   80 KT  90 MPH\n120H  13/0600Z 24.3N 106.1W   55 KT  65 MPH...INLAND\n \n"}