State of Hawaii
Seasonal Precipitation Summary

Following a wet December 2007, the first month of 2008 started off with drier conditions over most of the state. Strong thunderstorms over the Hana area of east Maui on January 18 prompted a flash flood warning, but no significant damages or injuries were reported. Heavy showers fell again over the windward slopes of Maui and the Big Island on January 29 and 30, producing minor flooding problems. These showers helped saturate the ground and set the stage for much more significant flooding in the Hilo area of the Big Island, as an upper level trough destabilized the underlying moist trade winds in early February. For the east Big Island residents, the early February deluge was the most significant flood event since the intense November 1-2, 2000 severe flood event. Initial assessments by Hawaii County officials indicated 100 to 150 homes were damaged, primarily due to the overflow of Waiakea Stream and nearby drainage ditches. Fortunately, officials reported no significant injuries or deaths due to the storm. Heavy rains over Kauai on February 3 forced the closure of both the Wainiha and Hanalei Bridges along Kuhio Highway. The USGS gage on the Makaweli River indicated a new (unofficial) record water level of 15.56 ft., just beating the previous record of 15.51 ft set on January 31, 1975. High water levels in Hanapepe River forced the evacuation of some residents in Hanapepe Valley and came close to overflowing a levee protecting Hanapepe town.

On February 6, Oahu received its turn when thunderstorms generated heavy rains over the central Koolau Range during the evening hours. Substantial runoff from afternoon thunderstorms over central and southwest Oahu on February 7 resulted in 3 to 4 feet of water in the west-bound lanes of the H-1 Freeway near Makakilo during peak afternoon traffic hours. Activity later shifted to east Molokai where heavy rains and flooding briefly forced the closure of the Kamehameha V Highway. A final burst of heavy rains occurred over the South Kona slopes of the Big Island on the afternoon of February 8. A flash flood warning was issued, but fortunately only minor flooding problems were reported.

An overall dry, stable weather pattern that started on February 9 continued through March 11 with a low level ridge of high pressure near the island chain keeping winds light and rainfall sparse. The ridge shifted northward on March 12, bringing windward showers and some needed relief, especially to those residents relying on water catchment systems. On March 17 and 18, thunderstorms over the Big Island and east Maui produced 1 to 2 inches of rain but no flooding problems. Enhanced shower activity over Kauai on March 20 and 21 elevated water levels in the Hanalei River, although no flooding occurred. The remainder of March, — normally one of the wettest months of the year for windward locations — was relatively tranquil, with daily rain gage totals of mostly less than an inch across the state.

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, 1st Quarter 2008

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

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

Rainfall during the April-May-June, May-June-July and June-July-Aug 2008 seasons has equal chances of being below normal, near normal, or above normal at all Hawaii stations…”