Tropical Cyclone Discussion
134 WTPZ45 KNHC 112059 TCDEP5 Hurricane Simon Discussion Number 18 NWS National Hurricane Center Miami FL EP202026 300 PM CST Sun Oct 11 2026 Simon is still a Category 4 hurricane, but appears to be feeling the effects of the nearby high terrain of the Serra Madre Mountains as the inner core is brushing up against the Mexican coast. The eye remains observed on geostationary satellite imagery, but is more cloud filled than earlier with warmer surrounding cloud tops. While the 18 UTC subjective Dvorak fix was still at T6.5/125 kt, the objective intensity estimates have continued to fall, with values now in the 109-115 kt range. Therefore, the initial intensity is being lowered to 115 kt for this advisory. An earlier Synthetic Aperture Radar (SAR) RCM-1 pass was very useful to adjust the 34- 50- and 64-kt radii of Simon as the hurricanes wind field continues to shrink in size. Simon has stubbornly maintained a north-northwestward motion, roughly parallel to the coastline, estimated at 335/5 kt. It is now looking increasingly likely that Simon will avoid making a direct landfall in the short-term, though its eastern inner core will likely produce hurricane conditions as the storm continues to move north-northwestward from Playa Perula to Cabo Corrientes this afternoon and evening. The steering ridge centered over the Texas coast is likely to maintain this motion now for the next several days, though with some slowdown in the motion due to a weaker but competing ridge located to Simon's southwest. On Tuesday into Wednesday, a large short-wave trough is forecast to move across the southwestern United States and this feature should provide enough southwesterly environmental flow to turn the hurricane to the northeast, finally reaching the coast of Mexico in 60-72 h. Compared to this morning, the guidance has shifted westward and slower once again, and there remain some outlier solutions like the GFS that want to turn Simon southwestward beyond 48 h. However, the majority of the ensemble guidance (European-EPS, Google DeepMind) do show this slow recurving solution back into Mexico. The NHC track forecast is a little bit west and slower for the first 36-48 h, but then bends back to the previous forecast track thereafter, still showing Simon moving inland and dissipating in the day 3-4 period. This forecast still remains low confidence. Intensity wise, it is now looking more likely that Simon will not weaken as much as originally expected, now that it is only brushing up against the coast instead of part of its inner core moving inland. Still, the high topography in Jalisco should still have a negative effect, which has already been seen in Simon's wind field shrinking in size. The hurricane-regional models still show significant weakening over the next 12-24 h, even the ones that only skirt the coast of Mexico, and the NHC intensity forecast still shows a fast rate of weakening during that time. However, other environmental conditions remain very favorable, as shear stays under 10 kt, and sea-surface temperatures warm to 31-32 C as Simon passes north of Cabo Corrientes and enters waters that have been unaffected by recent tropical cyclones (Polo and Rachel). However, there will be a significant amount of nearby dry air and it remains to be seen how intact Simon's inner core will remain over the next 24 h of near land interaction. The latest NHC intensity forecast now shows Simon maintaining hurricane intensity, and this forecast could still be low if the inner core remains more robust than the hurricane regional models are forecasting. This forecast is now on the higher end of the intensity guidance aids, but is under the SHIPS guidance this cycle, and also remains low confidence. Key Messages: 1. Catastrophic wind and life-threatening storm surge impacts are likely along a portion of the west-central coast of Mexico, and a Hurricane Warning is in effect from Punta San Telmo to El Roblito. Residents should continue to shelter in a safe room to ride out the storm as the most significant hazards with Simon are now ongoing. 2. Simon is now expected to approach the coast of west Mexico later this week, where Hurricane conditions are now possible along the coast of El Roblito to Bahia Tempehuaya. A Hurricane Watch is now in effect for this region. 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. Swells will affect portions of the southwestern and west-central coast 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 11/2100Z 19.6N 105.8W 115 KT 130 MPH 12H 12/0600Z 20.2N 106.1W 90 KT 105 MPH 24H 12/1800Z 21.0N 106.6W 80 KT 90 MPH 36H 13/0600Z 21.6N 106.9W 75 KT 85 MPH 48H 13/1800Z 22.2N 107.1W 75 KT 85 MPH 60H 14/0600Z 22.8N 107.0W 75 KT 85 MPH 72H 14/1800Z 23.4N 106.6W 75 KT 85 MPH 96H 15/1800Z 24.0N 105.9W 30 KT 35 MPH...POST-TROP/INLAND 120H 16/1800Z...DISSIPATED