Tropical Cyclone Discussion
141 WTPZ42 KNHC 212052 TCDEP2 Hurricane Polo Discussion Number 5 NWS National Hurricane Center Miami FL EP172026 300 PM CST Mon Sep 21 2026 Satellite images show that Polo has a ragged eye on both visible and infrared images, with very deep convection starting to wrap around a broken eyewall. The NOAA Hurricane Hunter aircraft has been providing valuable data that show the cyclone undergoing an early-stage eyewall cycle, with two wind maxes on the TDR radar. The plane recently reported 0.5 km winds up to 92 kt, with higher winds and lower central pressure on each fix, dropping about 1 mb per hour. These winds convert to roughly 75 kt at the surface, and that will be the initial wind speed this advisory. While the current eyewall replacement could slightly hinder intensification, the last aircraft pass through Polo already showed that the old inner eyewall was fading. Thus, given the very warm waters, light shear and moist environment, a high-end rapid intensification event is expected. The latest model guidance are even higher than the last cycle, and the new NHC intensity forecast follows the trend, but is still below the NOAA HCCA corrected- consensus aid. An increase in easterly wind shear could cause some weakening in the medium-range period, though Polo should be a small and powerful hurricane throughout the forecast period. The storm is drifting east-southeastward and should move in that general direction for about a day before a mid-level ridge intensifies over Mexico. This ridge should cause the cyclone to turn sharply towards the northwest and west-northwest on Wednesday and Thursday, bringing the core of the storm near or south of the coast of southwestern Mexico. Eventually there is enough troughing over the eastern Pacific to cause the system to bend more northwestward at long range towards the Baja California peninsula. The details, however, are pretty sketchy with a potential binary interaction with Tropical Storm Odalys looming, which is helping to cause a large north-south spread in the guidance. No big changes were made to the NHC forecast, but it is a little farther west at and beyond 72 hours where uncertainty is high. Key Messages: 1. Heavy rainfall associated with Polo will impact coastal portions of southwest Mexico through Thursday. This rainfall may produce life-threatening flooding and mudslides, especially in areas of steep terrain. 2. Polo is forecast to strengthen to a major hurricane while it moves closer to the coast of southwestern Mexico during the next few days. Although the core of the hurricane is forecast to stay offshore, it is too soon to determine the exact location or magnitude of impacts. Residents in southwestern Mexico should closely monitor its progress and updates to the forecast. A Tropical Storm Watch is in effect for portions of southwestern Mexico. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 15.1N 102.7W 75 KT 85 MPH 12H 22/0600Z 14.9N 102.3W 100 KT 115 MPH 24H 22/1800Z 14.9N 102.0W 125 KT 145 MPH 36H 23/0600Z 15.4N 102.2W 140 KT 160 MPH 48H 23/1800Z 16.1N 102.9W 145 KT 165 MPH 60H 24/0600Z 17.0N 104.0W 140 KT 160 MPH 72H 24/1800Z 17.7N 105.5W 140 KT 160 MPH 96H 25/1800Z 18.6N 108.6W 130 KT 150 MPH 120H 26/1800Z 20.5N 111.2W 120 KT 140 MPH