Tropical Cyclone Discussion
337 WTPZ45 KNHC 142055 TCDEP5 Hurricane Simon Discussion Number 30 NWS National Hurricane Center Miami FL EP202026 200 PM MST Wed Oct 14 2026 Simon is showing how small tropical cyclones can undergo rapid weakening as well as rapid intensification. A synthetic aperture radar (SAR) overpass near 13Z showed winds in the eyewall of 65-75 kt, suggesting that the intensity in the previous advisory was too high. An Air Force Reserve Hurricane Hunter aircraft has just reported that the storm is now weaker, with no hurricane-force winds present so far at 700 mb. The central pressure is near 989 mb based on a dropsonde with a surface pressure of 993 mb and surface winds of 41 kt. The initial intensity is reduced to 65 kt based mainly on the central pressure, and it is likely that this is generous. The aircraft reported a 16-nm wide eye open to the southwest and a larger radius of maximum wind than shown by the earlier SAR data. The hurricane continues drifting southwest or 235/3 kt. For the next day or so, Simon should continue drifting southwestward or southward in an area of light steering currents, with the center remaining well offshore. After that time, there remains some spread in the track guidance models. While all of the global models agree that a mid- to upper-level trough should form west of Baja California near and after 48 h, there remains disagreement on how this will affect Simon's track. The HAFS models keep the cyclone moving southward through 72 h, while the GFS model does not show any northward turn until 48 h. The remainder of the guidance forecasts a turn toward the northwest or north-northwest around 36 h, with that motion continuing through the end of the forecast period. The new track forecast follows the latter scenario in anticipation that the center will try to follow convective bursts displaced to the north by southerly shear. Overall, the track guidance envelope has shifted westward since the previous advisory, and so has the track forecast. Simon is currently experiencing light to moderate northerly shear and dry air entrainment, and this combination has at least temporarily disrupted the eyewall convection. The shear is likely to subside during the next 6-18 h, and based on this the intensity forecast keeps the cyclone as a minimal hurricane. After 36 h, increasing southerly and southwesterly upper-level winds between the trough to the northwest and Tropical Storm Trudy to the southeast should cause significant shear over Simon. The intensity forecast shows steady weakening during this time, and there is a possibility that Simon could weaken faster and dissipate sooner than currently forecast. Key Messages: 1. Interests in Baja California Sur should continue to closely monitor the latest updates. Watches or warnings could be required for portions of Baja California Sur over the next day or two. 2. Large swells will likely affect portions of the coast of west-central Mexico and Baja California Sur over the next several days. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 19.3N 108.3W 65 KT 75 MPH 12H 15/0600Z 19.2N 108.5W 65 KT 75 MPH 24H 15/1800Z 19.1N 108.4W 65 KT 75 MPH 36H 16/0600Z 19.5N 108.6W 65 KT 75 MPH 48H 16/1800Z 20.3N 109.5W 60 KT 70 MPH 60H 17/0600Z 21.5N 110.5W 55 KT 65 MPH 72H 17/1800Z 22.8N 111.5W 45 KT 50 MPH 96H 18/1800Z 24.9N 113.2W 30 KT 35 MPH 120H 19/1800Z 26.7N 114.2W 25 KT 30 MPH...POST-TROP/REMNT LOW