State of Hawaii

MONTH: January 2009

PREPARED: February 3, 2009

State: [Text data table for rain gages]

The new year began with the final phase of a very wet weather pattern that hit the Hawaiian Islands in December 2008. From January 1 through January 3, an upper level low pressure system southwest of the state helped produce heavy rainfall over portions of Kauai, Niihau, Oahu, and the Big Island. Fortunately, this concluding phase did not produce significant flood-related damages.

During the second week of January, north Pacific weather transitioned to a more progressive pattern with a series of quick cold front passages which produced brief periods of heavy rains and cool temperatures across the island chain. Frontal passages occurred on January 10, 16, 20, and 26, each preceded by south to southwest winds and followed by cool northwest to north winds. From a rainfall perspective, the January 16 cold front was the most active featuring a few 2 to 4 inch totals and single 24-hour total of 9.74 inches at Kaupo Gap on the southeast slope of Haleakala, Maui. Minor flooding problems accompanied these fronts but no significant damages occurred.

While the passage of the cold fronts helped ease drought conditions in some parts of the state, significant areas of drought continue to persist, especially over the leeward sections of the Big Island and Maui County. The combination of December and January rainfall has helped eliminate drought areas on Kauai and Oahu.

Island of Kauai : [January 2009 map]

Following the very wet conditions in December, most of the rain gages across Kauai recorded below normal totals for the month of January with many totals in the range of 40 to 70 percent of normal. The U.S. Geological Survey (USGS) gage on Mount Waialeale recorded the state’s highest monthly total of 22.39 inches (59 percent of normal) though the Kokee gage posted the highest daily total of 3.54 inches during the January 16 cold front passage.

Island of Oahu: [January 2009 map]

Most of the gages on Oahu recorded below normal rainfall during the month of January. Many gage totals fell within the range of 40 to 70 percent of normal similar to the situation on Kauai. The USGS’ Poamoho 2 rain gage posted the highest Oahu total of 11.61 inches (50 percent of normal), which was fourth highest in the state, and the highest daily total of 2.42 inches on January 2. Honolulu Airport’s 3.69 inches (137 percent of normal) stood out as Oahu’s sole monthly total above normal. Most of this amount fell during the cold front passage on January 11 with 2.00 inches recorded in 24-hours.

Maui County: [Maui January 2009 map] [Molokai/Lanai January 2009 map]

January rainfall totals across Maui County displayed the familiar wide range of conditions, from 28 percent of normal at Hana (2.41 inches) to 167 percent of normal at Kula (5.84 inches). The gage at Kaupo Gap recorded the highest monthly total of 14.62 inches (141 percent of normal), which was somewhat unusual since Puu Kukui normally posts the highest total in the county. Most of the Kaupo Gap total occurred on January 16 when 9.74 inches fell within moist pre-frontal southerly low level flow.

Island of Hawaii: [January 2009 map]

Most of the gages on the Big Island posted below normal rainfall totals for the month of January. The gage at Laupahoehoe recorded the highest monthly total of 9.25 inches (69 percent of normal) while the gage at Glenwood registered the highest daily total of 3.27 inches on January 2. Drought-plagued areas in the leeward portions of the island received needed rainfall during the cold front passages but the totals remained well off the normal pace for January.

Data Sources: Data used in this report are largely from National Weather Service sources including climate network weather observation stations at Lïhue, Honolulu, Kahului, and Hilo, the Hydronet state network of automated rain gages, and selected Cooperative Observer sites. Additional data come from automated rain gages operated by the State of Hawai‘i Department of Land and Natural Resources, the US Geological Survey, the US Bureau of Land Management, the US National Park Service, the Department of Defense, and the US Fish and Wildlife Service. Data presented here are not certified and should be used for information purposes only.

Kevin R. Kodama
Senior Service Hydrologist
NOAA/NWS Weather Forecast Office Honolulu