Tropical Cyclone Discussion
961 WTPA42 PHFO 242056 TCDCP2 Tropical Storm Nolo Discussion Number 17 NWS Central Pacific Hurricane Center Honolulu HI EP152026 Issued by NWS National Hurricane Center Miami FL 1100 AM HST Thu Sep 24 2026 Nolo continues to become better organized, with a ragged eye on satellite imagery and a primitive eyewall noted on the latest microwave pass. The initial intensity is set to 60 kt, at the high end of the various estimates due to the improved organization on conventional satellite and microwave imagery. An Air Force Reserve Hurricane Hunter aircraft is scheduled to be in the storm this afternoon for a more precise estimate. The storm has been moving erratically during the day, but appears to finally be moving slowly northward. There is no change the synoptic reasoning with a mid-latitude trough near the northwestern Hawaiian Islands causing Nolo to accelerate north-northeastward during the next day or so. The trough should move away by the weekend and be replaced by a ridge, forcing a sharp westward turn on Saturday. The northward trend during the last couple of model cycles has stopped and is actually trending southward, led by the ECMWF model. The new forecast is a touch south of the last one, but really all these track changes are quite small. This remains an uncertain forecast with some model ensemble tracks still over the Big Island, though most are south. This forecast necessitates a Tropical Storm Warning for the Big Island, and a closer track could substantially increase the threat of damaging winds, particularly over higher terrain, along exposed ridges, and in areas downwind of the ridges. Rapid intensification is expected during the next day or so now that an inner core has formed, combined with warm warm SSTs, low shear and high mid-level moisture. Nolo is likely to become a hurricane by tonight and reach major hurricane strength as it nears the Big Island on Saturday. The new forecast is similar to the previous one for the first few days, close to the HCCA aid. At long range, vertical wind shear is forecast to cause Nolo to weaken, and the NHC intensity prediction is lowered at that time. Key Messages: 1. Nolo is expected to pass near or just south of the Big Island of Hawaii on Saturday as a major hurricane. Tropical storm conditions are expected to begin on the Big Island Friday night with hurricane conditions possible on Saturday, particularly in areas of steep terrain. Residents should follow advice given by local officials, including evacuating if told to do so. 2. The time to finish preparations for significant heavy rain and flooding impacts on the Big Island is now as heavy rain increases in both coverage and intensity today and Friday. Periods of heavy rain are expected to continue across the Big Island and Maui through the weekend. Life-threatening, catastrophic flooding and mudslides are possible, especially in areas of steep terrain across the Big Island and Maui. Across the remainder of Hawaii, lesser rainfall totals are expected, with isolated flooding possible. 3. Large and damaging waves are likely along portions of the Big Island's coastline into the weekend. 4. A Tropical Storm Watch is in effect for Maui County where tropical storm conditions are possible beginning on Saturday. Interests elsewhere in Hawaii should closely monitor the latest forecast updates and ensure that they have their preparedness plans in place. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 14.9N 156.1W 60 KT 70 MPH 12H 25/0600Z 15.4N 156.0W 70 KT 80 MPH 24H 25/1800Z 16.4N 155.6W 85 KT 100 MPH 36H 26/0600Z 17.2N 155.5W 95 KT 110 MPH 48H 26/1800Z 17.7N 156.0W 100 KT 115 MPH 60H 27/0600Z 17.8N 157.3W 105 KT 120 MPH 72H 27/1800Z 17.8N 159.2W 105 KT 120 MPH 96H 28/1800Z 19.5N 163.0W 95 KT 110 MPH 120H 29/1800Z 22.5N 165.2W 80 KT 90 MPH