{"id": "1218139883296882691", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-12T15:00:00Z", "msg": "872\nWTPZ45 KNHC 121459\nTCDEP5\n \nHurricane Simon Discussion Number  21\nNWS National Hurricane Center Miami FL       EP202026\n800 AM MST Mon Oct 12 2026\n \nSimon's interaction with the coast of Mexico has made it a very \ncompact hurricane. The satellite presentation this morning consists \nof a very small central dense overcast with a warm spot in the \ncenter which still appears to be a small eye. The convection is also \nvery electrically active, with substantial lightning occurring in \nthe eastern eyewall. A 1110 UTC GPM microwave pass showed that \nSimon's inner core remains intact, though with the eye open on the \nnorthwest side. This structure is consistent with some mid-level \neasterly shear that appears to be undercutting the outflow layer, \nlooking at some area-average soundings from the HAFS-A/B \ninitialization this morning. Satellite intensity estimates have a \nlarge range this morning, as low as CI 4.1/67 kt from the UW-CIMSS \nADT, or as high as CI 5.5/102 kt from the latest subjective Dvorak \nfix. The initial intensity is lowered slightly to 95 kt for this \nadvisory, favoring a blend of the latest SATCON (100 kt) and D-MINT \n(85-90 kt) estimates.\n \nBased on satellite images, Simon continues to move very slowly to \nthe northwest, with an estimated motion of 315 degrees at 3 kt. This \nvery slow motion is the result of competing steering influences from \na distant mid-level ridge centered over the Texas Gulf coast, and \nanother weaker mid-level ridge placed southwest of Simon over the \neastern Pacific. In general the steering imparted by the ridge to \nthe northwest should be a little stronger, and thus Simon is \nexpected to maintain a very slow northwestward motion over the next \n24-36 h. After that period, a large trough with an embedded \nshort-wave is expected to amplify and move into the southwestern \nUnited States, and this trough is expected to extend far enough \nsouthward to impart a little more westerly flow that should \nultimately turn Simon to the north-northeast in the 48-72 hour time \nframe. With that said, the track guidance is not at all in agreement \non how quickly this turn will occur. The latest 06 UTC GFS and \nHAFS-A/B runs almost immediately move Simon northward and then \nnorth-northeast, resulting in a much faster landfall back in \nmainland Mexico. By contrast, the 06 UTC ECMWF run shows a \nshort-term westward track that meanders offshore to the southeast of \nthe Baja California Peninsula before it turns northward and moves up \ninto the Gulf of California. The ensemble guidance is also all over \nthe place, resembling a squashed spider with substantial spread from \nthe southwest to northeast direction. The latest NHC track forecast \nhas been shifted westward and is quite a bit slower, following the \nlatest trends in the track guidance. However, this track is not \nnearly as slow or as far west as the latest Google DeepMind ensemble \nmean (GDMI) or its newer Weather Next Model (WN3I). Given the large \nspread in solutions, this remains a low confidence track forecast.\n \nBased on the earlier microwave images, Simon still appears to have a\nsmall inner core, and that is an important consideration to take\ninto account in the forecast over the next few days. While the\nhurricane appears to be currently dealing with some mid-level\neasterly shear and that may result in a little more short-term\nweakening, this shear is expected to subside over the next 24 h as\nSimon traverses very warm 30-31 C sea-surface temperatures. In fact,\nthe latest HMON and HAFS-A/B runs show the small core of Simon\nrecovering and re-intensifying back into a major hurricane later\nthis week. Thus, the latest NHC intensity forecast starts to show\nsome restrengthening after 24 h. Small storms like Simon can also\nbe prone to rapid changes in intensity, both up or down, which\nmakes the intensity forecast also more uncertain than usual. This\nforecast is initially close to the middle of the guidance but ends\nup on the higher side after 48 h. Rapid weakening is still\nanticipated when Simon eventually makes landfall later this week\ntowards the end of the forecast.\n \nKey Messages:\n \n1. Tropical Storm winds are still likely along a portion of the\nwest-central coast of Mexico for a few more hours, where a Tropical\nStorm Warning is in effect.\n \n2. Simon is expected to approach the coast of western Mexico later\nthis week, where hurricane conditions are possible. A Hurricane\nWatch is in effect from Cabo Corrientes to Bahia Tempehuaya.\n \n3. Heavy rainfall associated with Simon will impact portions of\nsouthwestern and west-central Mexico over the next few days. This\nrainfall will produce life-threatening flooding and mudslides,\nespecially in areas of steep terrain.\n \n4. Large swells will affect portions of the southwestern and\nwest-central coasts of Mexico over the next few days. These swells\nare 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  12/1500Z 20.1N 106.5W   95 KT 110 MPH\n 12H  13/0000Z 20.4N 106.8W   85 KT 100 MPH\n 24H  13/1200Z 20.9N 107.3W   80 KT  90 MPH\n 36H  14/0000Z 21.3N 107.7W   85 KT 100 MPH\n 48H  14/1200Z 21.6N 107.7W   90 KT 105 MPH\n 60H  15/0000Z 22.2N 107.4W   90 KT 105 MPH\n 72H  15/1200Z 23.2N 106.9W   90 KT 105 MPH\n 96H  16/1200Z 24.1N 106.3W   45 KT  50 MPH...INLAND\n120H  17/1200Z...DISSIPATED\n \n"}