Nearly a Foot of Rain Fell in Parts of Hawaiʻi Island. Nolo’s Flood Risk Remains

Nearly a foot of rain had fallen in some places on Hawaiʻi’s Big Island by September 26. That is a substantial amount of water before the storm is done—not an island-wide total, and not a measure of flooding. National Hurricane Center director Michael Brennan said another eight to ten inches was possible, particularly in the south and east. On September 27, CNN reported that heavy rain was intensifying and that flooding and mudslides could be life-threatening. No checked report establishes that catastrophic flooding occurred. ⁷²

The change in Nolo’s track was welcome but easy to misread. The hurricane was expected to move west, away from a direct strike, and Hawaiʻi Island’s hurricane watch was canceled on September 26. A tropical-storm warning for Hawaiʻi County and a flood watch across the island remained in effect when the watch was canceled. Their status later Sunday has not been verified. The canceled watch concerned the prospect of hurricane conditions; it did not mean rain had stopped or saturated slopes were safe. ³⁸

Brennan described tropical-storm conditions already occurring on the Big Island, with gusts of 50 to 60 miles per hour in some places, especially near higher mountains. His Saturday update placed Nolo’s center a little more than 150 miles south of the island and not moving closer. He expected conditions to improve from Saturday night, especially Sunday and Monday, as the storm moved west. That improvement was a forecast, not a verified account of conditions in every affected community. ⁷

Friday’s alarm rested on a formidable forecast. Nolo was then reported as a Category 2 hurricane with sustained winds of 105 miles per hour, moving at about five miles per hour. Forecasters projected 10 to 25 inches of rain across affected areas, locally more than two feet; Maui, then under a tropical-storm watch, could receive up to ten inches. An early discussion allowed for Nolo to strengthen to Category 4, with winds up to 140 miles per hour. That was a possibility, not a strength the checked reports establish it reached. ¹

The estimates shifted as the track developed. NBC meteorologist Bill Karins said one rainfall ceiling had come down from as much as three feet to around two feet, while other early reporting still allowed for more than two feet in some Big Island areas. None of those ceilings is a measured storm total. Saturday’s more useful distinction was between the nearly one foot Brennan said had already fallen in some places and the further eight to ten inches he said could fall. Similarly, a forecast of gusts up to 75 miles per hour should not be confused with the 50-to-60-mile-per-hour gusts Brennan said had occurred. ⁸¹⁰⁷⁶

Reports of Nolo’s strength also describe different times, not two simultaneous storms. NBC reported Category 2 winds above 100 miles per hour in an earlier September 26 account, then Category 1 winds above 90 miles per hour in a later one. The latter is the latest clearly dated intensity in the checked reporting; a September 27 official advisory was not available to establish its Sunday strength or position. An early Saturday weather bulletin’s coordinates and winds are likewise a historical reading, not a Sunday fix. ⁵⁴¹³

In Hilo, people told the Associated Press they had prepared and were hunkering down; one speaker said many events had been canceled as a precaution. Shelters opened in Hawaiʻi and Maui counties. State and county offices, public schools and University of Hawaiʻi campuses on the Big Island were set to close September 24 and 25, with Maui County closures expanding on Friday. State parks, campsites, forest reserves and state-managed trails also closed on specified dates across Hawaiʻi Island, Maui and Molokaʻi. Those dated decisions do not establish which facilities were still closed on Sunday. ³¹⁶⁶⁴⁶

President Donald Trump approved a pre-landfall federal emergency declaration on September 25, covering Hawaiʻi, Kauaʻi and Maui counties and the City and County of Honolulu. It authorizes federal assistance for eligible emergency protective measures, including direct federal assistance, at a 75 percent federal cost share. That is preparation for possible impacts, not a damage assessment or a promise to reimburse 75 percent of every loss. ²⁸²⁹

The storm’s reach was not confined to the Big Island: a September 27 local report described strong winds and rough surf on Oʻahu, including around Waikīkī and Diamond Head, without establishing specific damage or a measured surge there. A separate report mentioned a closed Big Island mountain highway, but the checked material does not establish its name, cause or reopening time; it cannot support a claim that a landslide damaged the road. ⁴⁹²²

When we reported on September 10, we described another offshore hurricane, Lowell, damaging Kauaʻi and Niʻihau without landfall. Nolo is a separate storm, and its unresolved danger is rain on the Big Island after a westward turn. Final rainfall totals, verified flooding or mudslide damage, any injuries or deaths, and subsequent warning changes have not been established in the checked reports. The near-foot observation is real; the feared additional rain and its consequences remain questions.