On Wednesday evening, a hurricane warning was issued for Hawaii for the first time in 22 years. Despite signs that the hurricane was weakening, Iselle strengthened slightly on Wednesday and is now forecast to hit the Big Island as a Category 1 hurricane on Thursday. If it does so, this will be the first hurricane landfall on the Big Island in recorded history.
As of the 2 a.m. Hawaii time advisory, Iselle still has 85 mph sustained winds and was located 350 miles east-southeast of Hilo. Landfall is expected later this evening, Hawaii time, or in the early morning hours of Friday, Eastern time. The impacts will likely be severe for two reasons: it’s a hurricane with destructive winds and a massive amount of rain, and the infrastructure in Hawaii is not designed for such conditions since they occur so infrequently.
Hawaii’s Big Island is home to Mauna Loa and Mauna Kea, the former rising to an elevation of nearly 14,000 feet. As with any mountainous area, this storm will generate a LOT of rain which will result in flash flooding and mudslides. Rainfall totals of six to 12 inches will probably not be uncommon, and isolated areas near the highest terrain could see up to 24 inches of rain. The higher elevations will also experience the strongest winds. Long radar loops are available to help monitor the storm as it approaches.