State of Hawaii

MONTH: August 2007

PREPARED: September 7, 2007

State: [Text data table for rain gages]

Hurricane Flossie provided the month’s most significant weather event as it approached the island chain from the southeast before turning west and quickly weakening to a tropical depression while passing south of the state on August 14 and 15. Forecasted heavy rains over the southeast-facing slopes of the Big Island never materialized as Flossie veered away before low level southeasterly winds could produce mountain-enhanced rainfall in the Kau District. The north- and east-facing slopes managed to catch some of Flossie’s outer shower bands as the hurricane approached with 1 to 2 inches reported by gages in the Hamakua, South Hilo , and Puna Districts. The outer shower bands progressed westward over the next 24-hours, dropping 1 to 3 inches over windward Maui and 2 to 4 inches over the Koolau Range on Oahu. Despite the scare to the State of Hawaii , Flossie did not produce any significant wind- or flood-related damages. Large surf did impact the southeast-facing shores but Hawaii County Civil Defense reported only minor coastal inundation problems.

The following week, an upper level low pressure system destabilized the local airmass enough to support brief heavy showers during the afternoon of August 25. A thunderstorm over the Poamoho area of Oahu dropped 1.70 inches in an hour which prompted the issuance of a Flash Flood Warning but did not produce significant damage. Another thunderstorm over the Waianae Range in West Oahu dropped 0.79 inches in 15-minutes before dissipating. On the Big Island , heavy showers developed over a small section of the Puna District near Glenwood and Mountain View producing over 3 inches of rain but no flooding problems.

Moderate trades dominated the local weather pattern for the rest of August. The low level remnant of former Tropical Storm Erick passed south of the Big Island on August 5 with no rainfall impacts.

Sufficient rainfall, completion of backup water source projects, and water use conservation measures helped improve the drought situation over portions of the South Kohala and Hamakua Districts on the Big Island . The Hawaii County Department of Water Supply eased water restrictions from a mandatory 25 percent water use cutback to a voluntary 10 percent reduction in daily use. On the other hand, drought conditions worsened over Maui with the area coverage spreading from Upcountry Maui to also include the Central Maui Water System. Upcountry water restrictions remain at a mandatory 10 percent cutback level while the Central Maui notice calls for a voluntary 10 percent reduction in use. Drought conditions also worsened over east Oahu resulting in a mandatory 30 percent reduction in water use as of September 6 for farms supplied by the Waimanalo Irrigation System.

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

Most of the gages on Kauai recorded near to below normal rain totals for August. Only the Makaha Ridge gage’s 3.15 inches represented an above normal total (158 percent), most of which occurred on August 25 and 26 (2.64 inches). Mount Waialeale ’s below normal total of 23.50 inches (60 percent of normal) led all August totals statewide. Kauai ’s highest 24-hour total of 2.42 inches also came from Mount Waialeale on August 15 as Tropical Storm Flossie’s outer rain band swept by the Garden Isle. The Lihue Airport total of 0.44 inches (23 percent of normal) marked the lowest August rain total on record for this location. The previous record was 0.46 inches set in 2000.

Most of the Kauai gage totals for 2007 through the end of August remain in the below normal range. Mount Waialeale ’s 238.11 inches for the year continues to be the highest total in the state and the only near normal site on the island. All other gage totals fall within the range of 40 to 80 percent of normal.

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

Oahu once again received a wide range of rainfall conditions from well below normal totals along the lower elevations of the eastern Koolau Range to near normal amounts in the interior Koolaus, and well above normal totals over a few spots in the north central and west sections of the island. The Oahu Forest National Wildlife Refuge (NWR) total once again led all island totals with 12.75 inches (78 percent of normal) and was fifth highest statewide. Many lower elevation stations on both windward and leeward sides of the island continue to see very dry conditions. Over east Oahu, the Kaneohe Marine Corps Base, Bellows Air Force Station, and the Hawaii Kai Golf Course all recorded less than 40 percent of normal rainfall. Over the south side of the island, Kunia, Kalaeloa Airport, and Honolulu Airport all recorded less than 0.20 inches of rain, or 30 percent of normal or less for all 3 sites.

Most of the Oahu rain totals for 2007 through the end of August continue to fall in the below normal range. The Oahu Forest NWR total of 111.79 inches (82 percent of normal) leads all island totals and ranks second in the state behind Mount Waialeale.

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

Maui County experienced a wide variety of rainfall conditions, ranging from 0 ( Lanai 1) to 560 (Kaunakakai) percent of normal. A majority of the sites recorded below normal totals, especially over West Maui and the windward slopes of Haleakala. The highest percent of normal values came from normally dry locations where just a couple of inches of rain translated to well above normal percentages. Puu Kukui had the highest monthly total of 14.56 inches (45 percent of normal), followed closely by West Wailuaiki’s 14.41 inches (73 percent of normal). Normally considered the second wettest spot in the state, Puu Kukui has not recorded a near normal total since May 2006. West Wailuaiki recorded the highest daily total of 2.79 inches on August 14 when one of Hurricane Flossie’s outer rain bands brushed by the windward side of Maui.

Most of the gages across Maui County continue to show below normal totals for 2007 through the end of August. Oheo Gulch is the only site with near to above normal rainfall. Puu Kukui’s 110.03 inches (41 percent of normal) continues to rank third statewide.

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

Most of the gages on the windward side of the Big Island recorded below normal rainfall during August. Glenwood in upper Puna was the sole exception with its 14.63 inches registering at 128 percent of normal and was the highest Big Island total. The Glenwood gage also recorded the highest daily total of 3.41 inches on August 25 as a result of afternoon showers induced by an upper level trough. Kapapala Ranch in the Kau District indicated wetter than normal conditions with 4.37 inches (125 percent of normal) during the month. Interestingly, none of this rain came from Hurricane Flossie.

Rain totals for 2007 through the end of August remain at below normal levels at most locations on the Big Island. Glenwood is one of the exceptions and its 100.78 inches (91 percent of normal) leads all Big Island totals and is fifth highest in the state. The remaining gage totals are mostly within the range of 40 to 80 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