Issued at 800 AM MST Mon Oct 12 2026
821 WTPZ45 KNHC 121459 TCDEP5 Hurricane Simon Discussion Number 21 NWS National Hurricane Center Miami FL EP202026 800 AM MST Mon Oct 12 2026 Simon's interaction with the coast of Mexico has made it a very compact hurricane. The satellite presentation this morning consists of a very small central dense overcast with a warm spot in the center which still appears to be a small eye. The convection is also very electrically active, with substantial lightning occurring in the eastern eyewall. A 1110 UTC GPM microwave pass showed that Simon's inner core remains intact, though with the eye open on the northwest side. This structure is consistent with some mid-level easterly shear that appears to be undercutting the outflow layer, looking at some area-average soundings from the HAFS-A/B initialization this morning. Satellite intensity estimates have a large range this morning, as low as CI 4.1/67 kt from the UW-CIMSS ADT, or as high as CI 5.5/102 kt from the latest subjective Dvorak fix. The initial intensity is lowered slightly to 95 kt for this advisory, favoring a blend of the latest SATCON (100 kt) and D-MINT (85-90 kt) estimates. Based on satellite images, Simon continues to move very slowly to the northwest, with an estimated motion of 315 degrees at 3 kt. This very slow motion is the result of competing steering influences from a distant mid-level ridge centered over the Texas Gulf coast, and another weaker mid-level ridge placed southwest of Simon over the eastern Pacific. In general the steering imparted by the ridge to the northwest should be a little stronger, and thus Simon is expected to maintain a very slow northwestward motion over the next 24-36 h. After that period, a large trough with an embedded short-wave is expected to amplify and move into the southwestern United States, and this trough is expected to extend far enough southward to impart a little more westerly flow that should ultimately turn Simon to the north-northeast in the 48-72 hour time frame. With that said, the track guidance is not at all in agreement on how quickly this turn will occur. The latest 06 UTC GFS and HAFS-A/B runs almost immediately move Simon northward and then north-northeast, resulting in a much faster landfall back in mainland Mexico. By contrast, the 06 UTC ECMWF run shows a short-term westward track that meanders offshore to the southeast of the Baja California Peninsula before it turns northward and moves up into the Gulf of California. The ensemble guidance is also all over the place, resembling a squashed spider with substantial spread from the southwest to northeast direction. The latest NHC track forecast has been shifted westward and is quite a bit slower, following the latest trends in the track guidance. However, this track is not nearly as slow or as far west as the latest Google DeepMind ensemble mean (GDMI) or its newer Weather Next Model (WN3I). Given the large spread in solutions, this remains a low confidence track forecast. Based on the earlier microwave images, Simon still appears to have a small inner core, and that is an important consideration to take into account in the forecast over the next few days. While the hurricane appears to be currently dealing with some mid-level easterly shear and that may result in a little more short-term weakening, this shear is expected to subside over the next 24 h as Simon traverses very warm 30-31 C sea-surface temperatures. In fact, the latest HMON and HAFS-A/B runs show the small core of Simon recovering and re-intensifying back into a major hurricane later this week. Thus, the latest NHC intensity forecast starts to show some restrengthening after 24 h. Small storms like Simon can also be prone to rapid changes in intensity, both up or down, which makes the intensity forecast also more uncertain than usual. This forecast is initially close to the middle of the guidance but ends up on the higher side after 48 h. Rapid weakening is still anticipated when Simon eventually makes landfall later this week towards the end of the forecast. Key Messages: 1. Tropical Storm winds are still likely along a portion of the west-central coast of Mexico for a few more hours, where a Tropical Storm Warning is in effect. 2. Simon is expected to approach the coast of western Mexico later this week, where hurricane conditions are possible. A Hurricane Watch is in effect from Cabo Corrientes to Bahia Tempehuaya. 3. Heavy rainfall associated with Simon will impact portions of southwestern and west-central Mexico over the next few days. This rainfall will produce life-threatening flooding and mudslides, especially in areas of steep terrain. 4. Large swells will affect portions of the southwestern and west-central coasts of Mexico over the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 20.1N 106.5W 95 KT 110 MPH 12H 13/0000Z 20.4N 106.8W 85 KT 100 MPH 24H 13/1200Z 20.9N 107.3W 80 KT 90 MPH 36H 14/0000Z 21.3N 107.7W 85 KT 100 MPH 48H 14/1200Z 21.6N 107.7W 90 KT 105 MPH 60H 15/0000Z 22.2N 107.4W 90 KT 105 MPH 72H 15/1200Z 23.2N 106.9W 90 KT 105 MPH 96H 16/1200Z 24.1N 106.3W 45 KT 50 MPH...INLAND 120H 17/1200Z...DISSIPATED $$ Forecaster Papin
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