State of Hawaii
Seasonal Precipitation Summary

Despite brief interludes of heavy rainfall, the second quarter of 2008 was marked by dry conditions and drought across the almost the entire state. Most of the state has been extremely dry for the entire first half of 2008 (see Figures 1a, 1b). Enhanced shower activity over the island chain on April 9-10 brought minor flooding to windward slopes of the Kauai, Maui, Lanai and the Big Island. Unstable upper level conditions on April 25 and 26 helped support heavy showers and isolated thunderstorms over the islands, with the heaviest rainfall occurring over the Kailua and Waimanalo areas of windward Oahu during the afternoon of April 25.

Dry conditions continued to prevail through May. A breakdown in the trade wind pattern from May 12 - 20 resulted in light winds and stable conditions with little rainfall. On May 21 and 22, low level convergence of winds southeast of a nearby cold front brought showers to Kauai and Oahu. Moderate trade winds resumed on May 24, but stable conditions did not allow for much rainfall to occur during the remainder of the month. The lack of sufficient rainfall aggravated drought conditions across Oahu, Molokai, Maui, and the Big Island in May, with impacts mainly felt by the agriculture sector. Residents in the Upcountry area of Maui were asked to voluntarily cut back on water use by 5 percent.

On June 12, an upper level trough provided sufficient instability to produce heavy rains over windward sections of Oahu. Fortunately, the rains produced only minor flooding problems, although runoff forced the closure of beaches at Bellows Air Force Station due to high levels of bacteria. The rains brought temporary relief to drought conditions over east Oahu where users of Waimanalo irrigation water have been suffering under mandatory 20 perpercent restrictions on water use. Most of the rain gages on Kauai recorded near to above normal rain totals for the month of June. While there was a wide range of conditions reported across Maui County and Hawaii County, most locations in there recorded below normal rain totals for the month of June.

Windward areas of the Big Island have seen below normal summer rainfall and have been placed under moderate drought. Degraded pasture conditions are severely affecting livestock, and brush fire danger is also very high. Drought conditions across Maui range from moderate to severe, and sugar planting in central Maui has been suspended due to lack of water. In west Molokai, users of irrigation water from the Kualapu’u Reservoir remain under a mandatory 20% reduction on water use. On east Oahu, extreme drought conditions have developed. Irrigation water levels continue to drop in the Waimanalo Reservoir, where officials have placed a 30% mandatory restriction on irrigation water use. The latest long-lead Hawaiian Outlook issued by the NOAA Climate Prediction Center continued to project below-normal rainfall in the Hawaiian Islands through December 2008, which is deep into the islands’ normal wet season.

Additional individual rainfall station information and specific island information for Hawaii can be found in the Monthly Precipitation Summaries.

Hawaii Rainfall Summary for Select Stations, 2nd Quarter and 1st Half 2008

Climate Outlook: The following is in excerpt from the Climate Prediction Center’s official Seasonal Outlook Discussion for Hawaii ...

“NCEP Models predict a tendency for below normal temperature for Hilo and Kahului from June-July-August through Oct-Nov-Dec 2008… and for Honolulu and Lihue from June-July-Aug to Sept-Oct-Nov 2008. Models also predict below normal rainfall for all Hawaii locations from June-July-Aug to Aug-Sept-Oct 2008.”