Hour-by-Hour impact of Hurricane Lowell reconstructed by University of Hawaiʻi team

Hurricane Lowell brought 100+ mph winds, heavy rainfall to Kauaʻi, Niʻihau

Hurricane Lowell’s close passage west of Kauaʻi and Niʻihau brought damaging winds, heavy rainfall with more than 23 inches recorded on Mount Waiʻaleʻale, and dangerous surf. To understand the storm’s full impact, a University of Hawaiʻi team reconstructed Hurricane Lowell hour by hour across Kauaʻi and the state using observations from the Hawaiʻi Mesonet, a statewide network of weather stations, alongside experimental high-resolution mapping tools.

Users can visit the newly launched Hurricane Lowell website to explore interactive wind and rainfall maps, station observations and satellite storm replays.

The most striking weather signal during the storm was the wind. At Līhuʻe Airport, the highest measured hourly average wind speed reached 56 mph late on September 7. However, because Kauaʻi’s weather stations are concentrated primarily at lower elevations, experimental high-resolution modeling was used to estimate conditions across remote terrain. The models suggest that winds over exposed high-elevation ridges were much stronger, locally exceeding 100 mph as the island’s steep topography accelerated airflow over ridges and through valleys.

Rainfall on Windward Oahu, Mount Waiʻaleʻale, Kauaʻi’s north shore

Rainfall across the western islands was also substantial throughout the event. On September 6, rainfall amounts of 5 inches or more along the Koʻolau Ridge sent flood waters down Waikāne and Waiahole Valleys on Oʻahu, forcing the closure of Kamehameha Highway. 

On September 7, nearly all of Kauaʻi received more than 2 inches of rain, with many areas exceeding 5 inches. High-elevation and north shore sensors show Mount Waiʻaleʻale recorded more than 23 inches of rain on September 7, accumulating nearly 36 inches over the full three-day storm period. Meanwhile, on Kauaʻi’s north shore, where rising river waters forced the closure of Hanalei Bridge, the Hawaiʻi Mesonet stations at Waipā and Lower Limahuli recorded more than 14 and 17 inches of rainfall, respectively, during the storm.

Coastal impacts and interactive storm replay

The report also references information from Pacific Islands Ocean Observing System (PacIOOS) on the significant coastal hazards brought by the storm. Large surf and storm surge impacted south- and west-facing shores of Kauaʻi as the hurricane tracked to the west.

To make these complex meteorological observations accessible to the public and emergency responders, the UH team launched a dedicated Hurricane Lowell website. The site features interactive graphics that allow users to follow Lowell’s winds and rainfall through time, compare ground station observations with mapped estimates, and replay the storm using Hawaiʻi Mesonet measurements integrated with Geostationary Operational Environmental Satellite-West satellite imagery.