State of Hawaii

MONTH: November 2007

PREPARED: December 14, 2007

State: [Text data table for rain gages]

November began with the development of a kona storm north of the main Hawaiian Islands. Note that in this usage, the word “kona” is used in its adjective form for “leeward” rather than as a proper noun for the location on the Big Island. A strong associated rain band developed within the Kauai Channel and moved eastward over Oahu producing thunderstorms, very heavy rain, and flash flooding. Several gages along windward Oahu recorded 8 to 10 inches of rain while many spots over the rest of the island recorded 3 to 6 inch totals. Flash flooding briefly forced the closure of Kamehameha Highway at Waikane Stream and inundated homes along low-lying areas near Kailua Beach Park. After drenching Oahu, the area of heavy rain continued eastward to Molokai and dropped 3 to 6 inches of rain. Heavy runoff, mud, and debris at Kawela Gulch closed the Kamehameha V Highway for several hours.

After the kona storm drifted west of the state and weakened, trade winds returned at mainly moderate levels then persisted through the Thanksgiving weekend. An upper level trough east of the island chain helped trigger heavy showers over the southern portion of the Big Island on November 19 but presented no serious flooding issues.

On November 26, trade winds veered to a southeasterly direction drawing up deep tropical moisture over the Hawaiian Islands. A strong upper level trough moved over the state from the northwest, tapped into the low level tropical moisture, and rapidly generated an area of heavy showers and thunderstorms near Kauai on the afternoon of November 27. As the rain area progressed eastward across the state, heavy showers produced flash flooding over portions of Kauai, minor urban flooding over Oahu, and significant flash flooding over the Kona slopes of the Big Island. The Kona flash floods damaged several homes and forced the closure of Highway 11 in several spots between mile markers 103 and 109. Rainfall totals over 2 days from this storm ranged from 5 to 8 inches on Kauai, 1 to 2 inches on Oahu, 1 to 3 inches on Maui, and 5 to 7 inches on the Big Island.

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

Most of the gages on Kauai recorded near to above normal rainfall during November. The U.S. Geological Survey’s (USGS) gage on Mount Waialeale was the main exception at 57 percent of normal, though its 19.78 inches still led all island-wide totals. The normally dry side of the island provided the highest daily total with the Hanapepe gage recording 5.21 inches during the November 28 heavy rain event. Of this total, 2.44 inches occurred during the 2-hour period from 1:30 to 3:30 AM. At Lihue Airport, the monthly total still came in below normal but at least no records were broken. Monthly totals for August, September, and October each set new records for low rainfall totals at the airport.

While the wet conditions pushed a couple of spots into the near normal range, most of the available totals for 2007 through the end of November remain in the below normal range. Mount Waialeale’s 291.17 inches leads all totals statewide and is 77 percent of normal.

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

In contrast to the dry conditions of October, the month of November produced near to well above normal rain totals at most locations across Oahu. The highest total came from the U.S. Fish and Wildlife Service’s gage at the Oahu Forest National Wildlife Refuge (NWR) where its 23.73 inches (142 percent of normal) led all totals statewide. Waihee Pump had the highest daily total of 10.32 inches on November 4 associated with a kona storm. More than half of this amount (5.76 inches) occurred during the 3-hour period from 12:15 and 3:15 AM. For Honolulu Airport, more rain fell during November (5.46 inches) than the rest of the year combined (January through October, 3.43 inches).

Wet November conditions have helped push 2007 totals into the near normal range at several locations. However, many gage totals remain below normal in the range of 50 to 80 percent. The Oahu Forest NWR gage leads all Oahu totals with 162.06 inches (87 percent of normal) and has passed Maui’s West Wailuaiki for third highest in the state behind Mount Waialeale and Puu Kukui.

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

Most gages across Maui County recorded near to well above normal rainfall for November. As usual, Puu Kukui and West Wailuaiki had the highest totals at 12.72 and 8.87 inches, respectively but interestingly had the lowest percent of normal values at 39 and 48 percent. Gages on Molokai and Lanai had the highest percent of normal values with Kaunakakai’s 6.12 inches registering at 383 percent and Lanai City’s 7.43 inches at 240 percent. More than half of the Molokai and Lanai rainfall occurred during the kona storm rainfall on November 4. In fact, Kaunakakai’s daily rainfall on November 4 (3.44 inches) and November 5 (2.38 inches) exceeded its monthly normal value of 1.60 inches.

Rain totals for 2007 through the end of November remained below normal at most gage locations throughout Maui County. The wet conditions of November helped push the Kaunakakai total into the near normal range after being below normal all year. Puu Kukui’s 174.43 inches (50 percent of normal) leads all Maui County totals and is second highest in the state behind only Mount Waialeale.

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

Most of the windward locations on the Big Island posted below normal rain totals for November while most of the leeward sites showed near to well above normal totals. The Pahoa gage total of 14.82 inches (111 percent of normal) topped all Big Island totals which is somewhat unusual since Glenwood often has the highest total. Gages in the South Kona District showed very wet conditions due mostly to very heavy rains during the afternoon of November 28. On this day, the Honaunau gage recorded 6.09 inches of which 5.60 inches occurred during the 3-hour period from 1:00 to 4:00 PM. A burst of heavy rain from 1:45 to 2:00 PM produced 0.93 inches.

Rain totals for 2007 through the end of November remained below normal at most locations on the Big Island. Glenwood’s 138.08 inches (93 percent of normal) leads all Big Island totals and remains fifth highest in the state. Most of the remaining totals are in the range of 40 to 80 percent of normal which is an increase since last month when most were in the range of 30 to 70 percent.

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