Monthly Precipitation
State of Hawaii Summary and Outlook

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

October: As the first month of the Hawaiian wet season, October produced several heavy rain events and wetter than normal conditions for many areas of the island chain…The first significant heavy rain event of the month was a continuation of heavy rains that began on September 30 resulting from the low level remnant of Hurricane Kenneth passing beneath a strong upper level low pressure system. Mainly moderate to fresh trade winds dominated … from October 2 through October 18. … On October 22 and 23, a shear line, the first of the 2005-2006 wet season, brought wet trades to many areas of the state. This event was followed on October 24 by a trade wind disturbance…Finally, during the early morning hours of October 31, terrain-induced heavy rains in southeasterly low level winds produced nearly 11 inches of rain in the Punaluu area of windward Oahu and 1 to 6 inches of rain along other areas of the Koolaus.

November: November 2005 produced a relatively stable weather pattern over most of the island chain with only one very localized flash flood event squeezing in on November 30 [on windward Oahu]. The rest of the month can be broken into two parts...trades and no trades. From November 1 through 18, mainly moderate trade winds affected the state…. Starting on November 19 and continuing through the end of the month, a series of strong north Pacific storms pushed the low level high pressure ridge southward over the island chain, producing a light wind pattern dominated by local land and sea breezes… the November 23 front marked the first cold front of the 2005-2006 wet season and its occurrence is about one month later than normal.

December: While the first week of December provided some active weather over the Hawaiian Islands, the airmass became quite stable for the remainder of the month to produce very dry conditions for most areas of the state….The island of Kauai experienced record-setting dryness …with all gages reporting below normal totals and most at less than 10 percent of normal.. All gages on Oahu recorded well below normal totals..and more than half of the sites posted totals at less than 10 percent of normal…[Most gauges on Maui and the Big Island were well below normal.] Following a period of moderate trades from December 9 through December 14, the subtropical ridge of high pressure settled over the island chain, pushed southward by a series of strong storms in the northwest Pacific. The presence of the ridge over the state resulted in very stable conditions, little or no rain, and winds dominated by local land and sea breezes. This stable weather pattern persisted for the rest of the month.

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

Climate Outlook:
According to the IRI’s 90 day and the Climate Prediction Center's official forecast for Hawaii, dynamical and statistical tools predict a tendency towards warmth [warmer than normal air temperatures] from FMA (February-March-April) 2006 to MMJ (May-June-July) 2006. Dynamical and statistical tools also indicate a tendency towards above median precipitation from FMA to MAM 2006. For the FMA and MAM all four Hawaii stations have a 40% chance of having above normal rainfall.

Based upon this and other statistical and dynamic models PEAC’s forecast is as follows: