State of Hawaii

MONTH: July 2007

PREPARED: August 2, 2007

State: [Text data table for rain gages]

Uninterrupted trade winds continued to blow across the main Hawaiian Islands throughout the month of July. Trade wind strength stayed mainly at moderate levels with a brief foray into the fresh to strong range on July 20 and 21, in part due to the passage of Tropical Depression Cosme about 225 miles south of Hilo. Rain bands associated with Cosme reached the east and southeast slopes of the Big Island during the afternoon of July 20 and generated 2-day event totals 6.94 inches at Hakalau and 6.68 inches at Glenwood. Much needed rain also fell across most of the leeward Kohala sections of the Big Island though totals stayed below an inch. Hawaii County Civil Defense did not report any significant flooding as a result of Cosme’s passage.

In addition to Cosme, the island chain also received an unseasonal visit from a weak shear line which produced a boost in trade wind showers from July 14 through 16. Some of the gages along the windward slopes recorded 1- to 3-inch daily totals associated with the shear line passage.

While many windward and upslope areas of the state received near normal rainfall totals, many leeward areas continue to see drought conditions. Mandatory water restrictions remain in place in Upcountry Maui (10 percent reduction) and portions of the South Kohala and Hamakua Districts on the Big Island (25 percent reduction). The low reservoir level in the Waimanalo Irrigation System also translates to a continuation of the mandatory 20 percent cut in irrigation water use. Lastly, brush fires continue to be a problem across the state, including a small but significant fire on Waahila Ridge (the slopes above the Honolulu Forecast Office).

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

Several gages on Kauai , especially along the east-facing slopes, recorded near to above normal rainfall during July while gages across the rest of the island posted below normal totals. Most of the below normal totals fell within the range of 40 to 80 percent of normal. Mount Waialeale ’s near normal total of 32.31 inches led all monthly amounts statewide and its 24-hour total of 3.69 inches on July 2 led all daily totals on the island.

Most of the Kauai gage totals for 2007 through the end of July are in the below normal range. Mount Waialeale ’s 214.61 inches for the year represents the sole near normal site on the island and is the highest year-to-date total statewide. All other gage totals fall within the range of 40 to 80 percent of normal.

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

Oahu received a wide range of rainfall conditions during July with many gages along the slopes of the Koolau Range recording near to above normal rainfall. However, many leeward coastal sites such as Honolulu Airport, Kalaeloa Airport, and all of the Waianae sites continued to see very dry conditions with July totals at less than 15 percent of normal. The Honolulu Airport total of 0.05 inches marks the second driest July on record, beaten only by the 0.03 inches recorded in July 1950. Meanwhile, just 12 miles away, the Oahu Forest National Wildlife Refuge (NWR) gage recorded 19.54 inches which was the second highest total in the state and 130 percent of its normal value for July. The Manoa Lyon Arboretum gage posted the highest daily total of 1.81 inches on July 21 and also recorded measurable rain (0.01 inches or greater) every day.

Most of the Oahu rain totals for 2007 through the end of July continue to fall in the below normal range. The Oahu Forest NWR total of 99.04 inches (82 percent of normal) leads all island-wide totals and ranks second highest in the state behind only Mount Waialeale.

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

Most of the windward gages on the island of Maui recorded near to above normal rain totals for July. Leeward gages continued to see dry conditions and below normal totals. Puu Kukui recorded the highest countywide total of 17.85 inches but this amount was only 53 percent of normal. Normally regarded as the second wettest spot in the state, Puu Kukui has not recorded a near normal monthly total since May 2006. However, this site did manage to record Maui County’s highest daily total of 5.88 inches on July 21 associated with moisture in the outer fringe of Tropical Depression Cosme. With the exception of the Kamalo gage, all sites on Molokai and Lanai recorded below normal rainfall.

Most locations throughout Maui County have below normal totals for 2007 through the end of July. Only Oheo Gulch and Kaupo Gap on the southeast side of Maui have near to above normal totals at 108 and 81 percent of normal, respectively. Puu Kukui’s 95.47 inches (41 percent of normal) for the year-to-date ranks third statewide, followed closely by West Wailuaiki’s 93.04 inches (78 percent of normal).

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

Most of the gages in the Kau, North Kona, and South Kona Districts of the Big Island recorded near to above normal rainfall for July while many of the remaining gages posted near to below normal totals. Despite receiving a boost of rain from Tropical Depression Cosme on July 20 and 21, most of the South Hilo and Puna District gages did not record near normal totals. The exception was the Glenwood gage which recorded a Big Island-leading total of 11.12 inches, or 112 percent of normal. Keahole Airport’s total of 2.10 inches is noteworthy since it is 300 percent of normal and marks the second consecutive month with well above normal rainfall.

Rain totals for 2007 through the end of July remain at below normal levels at most spots on the Big Island. The exceptions are Keahole Airport and Glenwood which have recorded amounts at 113 and 87 percent of normal, respectively. Glenwood’s 86.15 inches leads all Big Island totals and ranks fifth statewide.

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