State of Hawaii

MONTH: July 2008

PREPARED: August 4, 2008

State: [Text data table for rain gages]

Trade wind showers finally returned to expected summer levels during July helping improve or at least stabilize drought conditions along the windward slopes of the Hawaiian Islands. Through July 15, low level wind speeds stayed mainly in the light to moderate range allowing land and sea breezes to dominate local wind conditions. This pattern allowed for heavy afternoon showers to occur over leeward areas and even some minor flooding over the leeward Kohala and Waianae slopes on July 9 and over the Ulupalakua area on July 14 and 15.

The trade winds increased to moderate to fresh levels from July 16 through the end of the month and brought in the remnant of former tropical cyclone Elida to the Big Island and Maui on July 22 and 23. Frequent showers from the Elida remnant deposited 2- to 6-inch accumulations along the east-facing slopes of both islands but no reports of significant flooding problems. Enhanced trade showers also occurred over the windward Hamakua and Kohala areas of the Big Island resulting in elevated stream levels but no flooding problems. Agriculture interests in both areas have been hard hit by the ongoing drought conditions so the onset of rainfall brought welcome relief.

Despite the return of trade wind showers, water use conservation notices and restrictions remained in place across the state. This includes a mandatory 30 percent reduction in irrigation water use for the Waimanalo Reservoir system and a mandatory 20 percent reduction for the Kualapuu Reservoir system in west Molokai. On Maui, residents of central and Upcountry Maui have been asked to voluntarily reduce water use by 10 and 5 percent, respectively. The ranching industry has been hit especially hard by the drought due to severely degraded pasture conditions. The ongoing drought prompted the U.S. Department of Agriculture to declare the State of Hawaii a primary disaster area on August 1 for agriculture interests.

Island of Kauai : [July 2008 map] [Year-to-date map]

Most of the gages on Kauai recorded near to above normal rainfall during July. The U.S. Geological Survey (USGS) gage on Mount Waialeale recorded the highest monthly total statewide at 30.30 inches (91 percent of normal) and the highest daily total of 3.49 inches on July 5. Lower elevation windward gages at Kapahi and Wailua posted at least 0.01 inch totals every day of the month. The regular windward showers helped restore agriculture reservoir water supplies to adequate levels over northeast Kauai.

Although conditions improved in many areas, rain totals for 2008 through the end of July remained at below normal levels at most locations on Kauai. Mount Waialeale’s 188.06 inches (77 percent of normal) continued to lead all totals statewide by more than 60 inches.

Island of Oahu: [July 2008 map] [Year-to-date map]

Most of the gages across the island of Oahu recorded near to above normal rain totals during July and several sites recorded the highest monthly totals since February. The U.S. Fish and Wildlife Service’s gage in the Oahu Forest National Wildlife Refuge (NWR) recorded the highest total on the island at 10.78 inches (72 percent of normal). The Manoa Lyon gage posted the highest daily total of 1.12 inches on July 20.

Rain totals for 2008 through the end of July remained in the below normal range at most of the gages on Oahu. The sole exception is the USGS gage at the South Fork Kaukonahua Stream site which pushed up into the near normal range on 87 percent of normal rain for the year-to-date. Most of the remaining sites remained in the 30 to 60 percent of normal range. The Oahu Forest NWR gage has recorded the highest year-to-date total on the island at 76.34 inches (63 percent of normal) but ranked only 9th statewide. Normally, this gage ranks in the top 5 in the state.

Maui County: [Maui July 2008 map] [Year-to-date map] [Molokai/Lanai July 2008 map] [Year-to-date map]

Half of the gages in Maui County recorded below normal rain totals for the month of July while the other half recorded near to well above normal rainfall. The USGS gage on Puu Kukui lived up to expectation as the second wettest spot in the state by having the second highest total of 26.67 inches (79 percent of normal) below only Mount Waialeale’s 30.30 inches. This gage also recorded the highest daily total of 5.49 inches on July 23. For several sites, the July totals marked the highest monthly rainfall since February.

Ulupalakua Ranch is particularly noteworthy since its monthly total of 6.25 inches set a new record for the wettest July with data going back to 1955 despite being surrounded by drought conditions in the Kula and Kaupo areas. An explanation for this may be the prevalence of light to moderate trade wind days during the first half of July which enabled a well-developed afternoon upslope flow to produce rainfall. From July 1 through 17, the Ulupalakua Ranch gage recorded at least 0.01 inches on 10 days compared with just 2 days from July 18 through 31 when significant trades resumed.

Molokai Airport also had wetter than normal conditions with its 1.45 inches (207 percent of normal) marking the second wettest July total on record. The standing July record for this gage is 1.53 inches in 1965.

Most of the rain totals for 2008 through the end of July remained in the below normal range across Maui County. Record-breaking July rains at Ulupalakua Ranch have pushed its year-to-date total into near normal territory with West Wailuaiki and Oheo Gulch. Puu Kukui’s 127.50 inches (54 percent of normal) led all Maui County totals and ranked second statewide.

Island of Hawaii: [July 2008 map] [Year-to-date map]

The Big Island had a wide range of rainfall conditions ranging from 3 percent of normal at Keahole Airport (0.02 inches) to 317 percent of normal at South Point (3.80 inches). The highest monthly total on the island came from the Glenwood gage with 13.96 inches (141 percent of normal), followed closely by Waiakea Uka’s 13.87 inches (101 percent of normal). Rainfall from the remnant of tropical cyclone Elida helped boost windward totals on July 22 and 23. For the 24-hours ending at 2 PM HST on July 23, Glenwood received 4.01 inches, Waiakea Uka had 3.91 inches, and the Hakalau gage recorded 3.52 inches.

Most of the Hilo, Puna, and Kau gages continued to indicate near to above normal rain totals for 2008 through the end of July. The remaining gages showed below normal totals mainly in the range of 30 to 60 percent of normal. Waiakea Uka’s 96.01 inches (91 percent of normal) led all Big Island totals and continued to rank fourth 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