Tropical Cyclone Discussion
169 WTPZ45 KNHC 082032 TCDEP5 Tropical Storm Simon Discussion Number 6 NWS National Hurricane Center Miami FL EP202026 300 PM CST Thu Oct 08 2026 Simon is almost a hurricane. The storm continues to have a very compact inner core with some signs of an eye becoming apparent in satellite images. There are also numerous spiral bands beyond the inner core region, with the outermost band in the far northeast quadrant still affecting portions of southwestern Mexico. The latest satellite intensity estimates have increased a little from earlier and now range from about 50 to 65 kt. Based on that data, the initial intensity is nudged up to 60 kt. A 17Z ASCAT-C pass was used to adjust the initial wind radii. The tropical storm is moving slowly westward at about 5 kt, steered by a weak mid-level ridge to its north. A turn to the northwest is expected tonight or early Friday, followed by a northward motion later that day when the ridge weakens and shifts eastward, in response to an approaching mid- to upper-level trough. Although the models generally agree on the large-scale steering pattern evolution, there are very important differences in where and when the system makes that turn. There has been a notable shift to the east this cycle, and given the westward bias often seen in the models for this region, the NHC track forecast has been again nudged eastward. It should be noted that the best-performing models of the year so far are east of the official forecast, and additional adjustments might be needed if this trend continues. This forecast brings the core of the system inland over southwestern and west-central Mexico Saturday afternoon or Saturday night. Simon is in near ideal environmental conditions of low wind shear, high moisture, and over very warm waters. The SHIPS model shows more than a 70 percent chance that the system will rapidly intensify over the next 24 hours. In fact, the storm's compact inner core structure makes it even more likely that it will capitalize on the favorable conditions. Therefore, the NHC intensity forecast continues to call for rapid strengthening into a very dangerous category 4 hurricane before Simon reaches the coast of west-central Mexico. This forecast lies near the high end of the guidance, in best agreement with the HCCA model. Based on the new forecast, the government of Mexico has issued a Hurricane Warning for a portion of the coast of southwestern and west-central Mexico. Key Messages: 1. Simon is expected to strengthen to a hurricane by tonight and 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 now in effect from Punta San Telmo to Playa Perula. 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 08/2100Z 15.7N 103.9W 60 KT 70 MPH 12H 09/0600Z 16.1N 104.4W 75 KT 85 MPH 24H 09/1800Z 16.8N 104.9W 95 KT 110 MPH 36H 10/0600Z 17.7N 105.0W 115 KT 130 MPH 48H 10/1800Z 18.8N 104.9W 115 KT 130 MPH 60H 11/0600Z 19.9N 104.9W 65 KT 75 MPH...INLAND 72H 11/1800Z 21.1N 104.8W 35 KT 40 MPH...INLAND 96H 12/1800Z 23.2N 105.0W 25 KT 30 MPH...POST-TROP/INLAND 120H 13/1800Z...DISSIPATED