Tropical Cyclone Discussion
317 WTPZ42 KNHC 262034 TCDEP2 Hurricane Polo Discussion Number 25 NWS National Hurricane Center Miami FL EP172026 200 PM MST Sat Sep 26 2026 SAR data valid this morning that arrived after the issuance of the last advisory indicated that Polo's inner-core has expanded, possibly due to an eyewall replacement cycle. A combination of a slight increase in easterly wind shear over the past 12 hours (10-15 kt according to both SHIPS diagnostics and UW-CIMSS analysis) and the likely eyewall replacement cycle are likely causing Polo to weaken. Intensity estimates vary greatly, from a 105 kt estimate with that SAR pass to over 140 kt from the ADT. Taking the available data as a whole, the intensity is set at 125 kt for this advisory, which is also fairly close to recent estimates from of the newer techniques from UW-CIMSS: AiDT, DPRINT and DMINT. A NOAA Hurricane Hunter aircraft is scheduled to investigate Polo later today, which should provide more information about the structure and intensity of the hurricane. The hurricane has turned northwestward as it moves around the western end of a mid-level ridge centered over northern Mexico. Polo will gradually turn northward, and then northeastward over the next two days as it continues to move around the ridge and is steered increasingly by a mid- to upper-level trough approaching from the northwest. There is an unusually large spread in the track models, primarily associated with Polo's forward speed. The AI guidance, including GDM, show a notably faster forward motion than many of the dynamical models, with some of the hurricane regional models even forecasting the hurricane to stall offshore of the west coast of the Baja California peninsula. No changes of note were made to the track forecast with this advisory and the NHC forecast still leans toward the AI models and HCCA, but confidence in that forecast is not particularly high due to the high model spread. The models have better agreement on the intensity forecast and nearly unanimously depict Polo steadily weakening over the next 48 hours. Some short-term intensity fluctuations will be possible during that period, but a combination of moderate shear and a drier environment along the forecast track should prevent it from significantly restrengthening. It is worth noting that Polo is still expected to be a strong hurricane when it approaches Baja California Sur. More rapid weakening is likely beyond 60 hours, as the shear is expected to increase substantially and Polo is forecast to begin interacting with land. Polo is expected to become a remnant low and then dissipate before it reaches the southern U.S., but distant moisture associated with it and Odalys will be transported into the southwestern United States late this weekend and early next week, and may indirectly contribute to a heavy rainfall and flash flood threat in the region. See products issued by the Weather Prediction Center for more information. Key Messages: 1. Polo is forecast to approach the west coast of the Baja California peninsula on Monday as a hurricane, and a Hurricane Watch is in effect for that region. Tropical storm conditions could reach portions of the coast as soon as Sunday night or early Monday, making further preparations difficult. A storm surge will be possible, especially in areas of onshore winds. 2. Heavy rainfall associated with Polo may begin to impact Baja California Sur Sunday night into Tuesday. This rainfall may produce life-threatening flooding and mudslides, especially in areas of steep terrain. 3. Dangerous surf and rip currents are likely along portions of the northwest coast of Mexico and Baja California for the next several days. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 18.7N 112.5W 125 KT 145 MPH 12H 27/0600Z 19.8N 113.4W 115 KT 130 MPH 24H 27/1800Z 21.4N 114.0W 105 KT 120 MPH 36H 28/0600Z 23.2N 114.0W 95 KT 110 MPH 48H 28/1800Z 24.8N 113.3W 85 KT 100 MPH 60H 29/0600Z 26.4N 111.9W 70 KT 80 MPH...INLAND 72H 29/1800Z 28.0N 110.2W 50 KT 60 MPH...INLAND 96H 30/1800Z 31.2N 105.7W 20 KT 25 MPH...POST-TROP/INLAND 120H 01/1800Z...DISSIPATED