Third Quarter
Monthly Precipitation
State of Hawaii Summary

The following summaries are excerpted from the NOAA NWS Honolulu Forecast Office's Monthly Precipitation Summaries.

July:Weaker than normal trade winds and an unusually stable airmass during the middle of the month resulted in drier than normal conditions for most areas of the state during July. The main exception was the Kona area of the Big Island which experienced a period of heavy rains from July 23 through July 26. Localized flooding on July 23 resulted in the evacuation of several homes and damaged classrooms at Konawaena Middle School in Kealakekua. No significant injuries or deaths were reported.

August:Thanks to the remnant of Hurricane Darby, August proved to be a very wet month for many areas of the state. Darby crossed into the central Pacific (longitude 140W) as a weakening tropical depression on July 31 and declared a dissipated tropical cyclone in less than 24 hours. However, the remnant circulation still contained ample low level moisture which passed beneath a significant upper level trough over the Hawaiian Islands. The combination of warm, moist low level conditions, cool temperatures aloft, and jet stream support triggered thunderstorms and heavy rains over the Big Island on August 3. The area of thunderstorms and heavy rains progressed slowly westward across the island chain through August 4. Flash flooding occurred over the Kona area of the Big Island, the southeast flank of Haleakala on Maui, and over several areas of Oahu. Minor flooding occurred on Molokai, Lanai, and Kauai. The heavy rains over Oahu during the early morning hours of August 4 were reminiscent of some of the heavy rain events that occurred in January and February this year, causing major problems during the morning rush hour commute. Fortunately, no significant flood-related injuries were reported. For additional details, please refer to [NWS HFO's] online Darby Storm Summary.

The rest of August saw mainly moderate trade winds over the island chain. A temporary break in the trades on August 16-19 allowed for well-developed sea breezes. Heavy showers occurred over central Oahu during the afternoon of August 18 and over Kona during the afternoon of August 19. These showers produced minor flooding on both days.

September: Moderate trade winds dominated the weather pattern over the main Hawaiian Islands for the month of September, producing daily showers over Kauai and Oahu. However, Maui County and the Big Island experienced much less rainfall, which was somewhat unexpected under the persistent trade wind conditions.

Upper level troughs helped destabilize the airmass over the state from September 2 through 5 and September 25 through 28, producing brief heavy showers but no flood related problems.

Kevin R. Kodama, Senior Service Hydrologist
National Weather Service Forecast Office, Honolulu, Hawaii