Issued at 200 AM MST Tue Oct 13 2026
000 WTPZ45 KNHC 130842 TCDEP5 Hurricane Simon Discussion Number 24 NWS National Hurricane Center Miami FL EP202026 200 AM MST Tue Oct 13 2026 Simon remains a very small hurricane. Synthetic aperture radar (SAR) data from around 01 UTC showed its compact wind field, with a 5-n-mi radius of maximum wind and tropical-storm-force winds that extended only 30-40 n mi from the center. Satellite images reveal Simon has maintained a small central dense overcast tonight, with a sharper edge to the cloud tops on the northeastern side, perhaps the result of some vertical wind shear. Given the small size of Simon, it is possible that conventional satellite estimates are struggling to represent its true intensity. The initial intensity is set at 80 kt, which lies in between the latest Dvorak CI number from TAFB (4.5/77 kt) and the earlier SAR data. The hurricane is moving slowly northwestward (310/3 kt) around a subtropical ridge over the southern United States. During the next couple of days, Simon is forecast to become caught in weak steering currents between this ridge and another ridge that should build to the northwest over the eastern Pacific. As a result, most of the track guidance now shows little net motion of the storm through 60 h, although Simon meanders in several different directions in the various global models and ensembles. Given the lack of a clear model signal, the new NHC forecast attempts to maintain some continuity by using a blend of the latest Google DeepMind, AI-GFS, and ECMWF track aids through 72 h. Once again, the trend is slower and farther west than the previous prediction. A general northward motion is shown at 96-120 h as the system (if it survives that long) should become steered by a cutoff upper low to its northwest. Needless to say, the lack of model agreement makes this a very low confidence forecast. Simon's intensity forecast is also very challenging and highly sensitive to its uncertain track. The small system is forecast to be within a generally low shear environment over very warm SSTs for the next couple of days. However, the slow forward speed of Simon could lead to upwelling of cooler waters, and its proximity to land could make it susceptible to intrusions of drier air from mainland Mexico. Much of the guidance shows little intensity change or even some weakening through midweek, and the NHC forecast remains on the higher end of the intensity guidance. By Thursday, the model consensus favors more steady weakening through the rest of the period due to increased vertical wind shear, and the latter half of the NHC forecast has been lowered notably from the previous one. It is worth emphasizing that this is a very low confidence forecast, and interests in west-central Mexico should continue to closely monitor the latest updates. Changes to watches and warnings may be required later today based on the latest forecast trends. Key Messages: 1. Hurricane conditions are likely on Las Islas Marias over the next day or so, where a Hurricane Warning remains in effect. 2. Simon could approach the coast of western Mexico later this week at or near hurricane strength, and a Hurricane Watch remains in effect for a portion of the area. 3. Heavy rainfall associated with Simon will impact portions of 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 several days. These swells are likely to cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 20.6N 107.2W 80 KT 90 MPH 12H 13/1800Z 20.7N 107.4W 75 KT 85 MPH 24H 14/0600Z 20.9N 107.7W 75 KT 85 MPH 36H 14/1800Z 21.0N 107.8W 75 KT 85 MPH 48H 15/0600Z 21.2N 107.9W 75 KT 85 MPH 60H 15/1800Z 21.8N 108.0W 70 KT 80 MPH 72H 16/0600Z 23.0N 108.1W 65 KT 75 MPH 96H 17/0600Z 24.2N 108.1W 55 KT 65 MPH 120H 18/0600Z 25.4N 108.2W 30 KT 35 MPH...POST-TROP/INLAND $$ Forecaster Reinhart
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