State of Hawaii

MONTH: October 2007

PREPARED: November 5, 2007

State: [Text data table for rain gages]

Trade winds persisted at mainly moderate to fresh levels through most of October. The only break occurred from October 20 through 22 when the subtropical ridge moved over the island chain to produce a light wind pattern dominated by local land and sea breezes. A weak shear line brushed the island of Kauai on October 23 causing a small increase in rainfall before lifting back toward the north.

A bit unusual was the lack of heavy rains. October normally has the second highest flash flood frequency but there were no events during the entire month. Moderate to heavy rains over the Kona slopes during the afternoon of October 4 produced minor flooding but did not warrant the issuance of a flash flood warning.

The lack of heavy rains resulted in the persistence of drought conditions across several areas of the state. An increase in trade wind showers helped ease water supply concerns for Upcountry Maui but did not persist enough to allow removal of water use restrictions that have been in place since June 13. Dry conditions also continued over east Oahu where a mandatory 30 percent reduction in water use has been in place since September 6 for farms utilizing the Waimanalo Irrigation System.

Island of Kauai : [October 2007 map] [Year-to-date map]

While a few gages recorded near to above normal rainfall, most sites posted below normal totals for the month of October. The Hanalei River gage had the highest available total at 7.44 inches (88 percent of normal). Mount Waialeale probably had a higher October total but data remained unavailable from this site.

The Lihue Airport gage recorded only 0.39 inches (9 percent of normal) of rain resulting in the third consecutive month with a record low monthly total. The previous October record was 0.98 inches set back in 1998. Not surprisingly, the persistent dry conditions also set new records for the driest 3-month (1.27 inches) and 6-month (3.14 inches) periods since establishment of the site in 1950.

All of the available gage totals for 2007 through the end of October are in the below normal range. Wailua has the highest total of 50.07 inches (77 percent of normal).

Island of Oahu: [October 2007 map] [Year-to-date map]

The persistent trades and the lack of heavy rain events in October resulted in below normal totals at most of the gages across Oahu. The Oahu Forest National Wildlife Refuge (NWR) gage had the highest monthly of 14.24 inches (84 percent of normal) and the highest daily total of 2.20 inches on October 31. Lower elevation gages in leeward Oahu continued to indicate very dry conditions with Honolulu Airport, Kalaeloa Airport, Kunia, Waianae, and Waianae Boat Harbor all reporting less than 10 percent of normal rainfall.

Most of the gage totals from Oahu continue to register in the below normal range for 2007 through the end of October. The Oahu Forest NWR total of 138.33 inches (82 percent of normal) leads all Oahu totals and remains fourth highest statewide behind Mount Waialeale, Puu Kukui, and West Wailuaiki.

Maui County: [Maui October 2007 map] [Year-to-date map] [Molokai/Lanai October 2007 map] [Year-to-date map]

Maui County rainfall totals ranged from 0 (Kaunakakai and Kihei) to 166 (Oheo Gulch) percent of normal. The Puu Kukui gage logged 20.85 inches of rain (78 percent of normal) which was the highest county-wide monthly total. The highest daily total also came from the Puu Kukui gage with 3.54 inches recorded on October 1. Windward gages showed the totals closest to normal due to the persistent trade winds and this helped Upcountry Maui water supplies. All Molokai and Lanai totals fell into the below normal category.

Most of the Maui County gage totals remained at below normal levels for 2007 through the end of October. Only West Wailuaiki and Oheo Gulch have totals in the near to above normal range at 87 and 119 percent of normal, respectively. Puu Kukui has recorded 161.71 inches of rain so far (51 percent of normal) and this total is second highest statewide behind Mount Waialeale.

Island of Hawaii: [October 2007 map] [Year-to-date map]

Persistent trades once again helped bring sufficient showers to the windward side of the Big Island and pushed gage totals into the near to above normal range. However, most leeward areas indicated below normal rainfall, the exceptions being Pohakuloa West (3.31 inches, 221 percent of normal) and Honaunau (6.72 inches, 129 percent of normal). Most of the Honaunau monthly total occurred on 3 separate afternoons where brief heavy showers dropped 1 to 2 inches of rain. The Glenwood gage logged the highest monthly total of 12.62 inches (124 percent of normal) with measurable rain on 30 out of 31 days.

Rain totals for 2007 through the end of October remained below normal at most locations on the Big Island. Glenwood’s 126.80 inches (98 percent of normal) leads all Big Island totals and is fifth highest in the state. Most of the remaining totals are in the range of 30 to 70 percent of normal.

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