Tropical Cyclone Discussion
684 WTPZ45 KNHC 090846 TCDEP5 Hurricane Simon Discussion Number 8 NWS National Hurricane Center Miami FL EP202026 300 AM CST Fri Oct 09 2026 Simon has quickly strengthened this morning. A EUMETSAT METOP-B Microwave Humidity Sounder (MHS) image revealed a small banding eye feature, and the IR-BD curve enhancement indicates -83C cold cloud tops associated with a small central dense overcast over the surface center. Water vapor imagery and satellite wind data indicate developing cyclonic outflow above 200 mb. Based on the much improved cloud pattern and the TAFB subjective intensity estimate of T4.5 (77 kt), the initial intensity is increased to 80 kt. Simon's small, intense inner core, favorable environmental conditions, low shear, very warm oceanic temperatures, and high mid-level moisture content all support a rapid intensification event, which appears to be well underway. Further significant strengthening is expected, and the cyclone is forecast to be a very dangerous major hurricane when it approaches the coast of Mexico. The guidance also shows compact Simon quickly weakening and over the high mountainous terrain by early next week. The NHC forecast is once again hedged toward the high end of the guidance, in best agreement with the HFIP-HCCA model. Simon's initial motion is estimated to be northwestward, or 315/4 kt. A northward motion is forecast by early Saturday while high pressure over central Mexico weakens and shifts eastward, in response to an amplifying mid-tropospheric trough approaching Baja California. The HiRes global models (ECM/GFS/CMC/UKM), HAFS hurricane models and the NOAA GEFS AI ensemble mean continue to agree more with Simon approaching the west-central coast of Mexico on Sunday. The HCCA and the Google DeepMind ensemble mean have been somewhat inconsistent during the past 2 cycles, windshield-wipering with a track either inland or just offshore beyond the 48-hour period. Additionally, the along-track forward speeds have also become inconsistent, which has slightly affected the wind impact timing. To minimize these track forecast inconsistencies, the NHC forecast blends the various consensus aids and is nudged to the right of the HCCA and GDM ensemble mean solutions. Key Messages: 1. Simon is expected to approach the west-central coast of Mexico as a major hurricane on Saturday. 2. Life-threatening wind and storm surge impacts are expected along a portion of the west-central coast of Mexico, and a Hurricane Warning is in effect from Punta San Telmo to Punta Mita. Preparations to protect life and property should be completed by late Friday. 3. Heavy rainfall associated with Simon will impact portions of southwestern Mexico through this weekend. This rainfall may 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 through the weekend. 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 09/0900Z 15.8N 104.5W 80 KT 90 MPH 12H 09/1800Z 16.1N 104.7W 100 KT 115 MPH 24H 10/0600Z 16.7N 104.9W 120 KT 140 MPH 36H 10/1800Z 17.6N 105.0W 125 KT 145 MPH 48H 11/0600Z 18.6N 105.1W 120 KT 140 MPH 60H 11/1800Z 19.9N 105.3W 110 KT 125 MPH...INLAND 72H 12/0600Z 21.4N 105.4W 80 KT 90 MPH...OVER WATER 96H 13/0600Z 23.7N 106.0W 60 KT 70 MPH...INLAND 120H 14/0600Z 24.9N 106.3W 35 KT 40 MPH...INLAND