MONTHLY PRECIPITATION SUMMARY

State of Hawaii

MONTH: November 2010

PREPARED: December 6, 2010

State: [Text data table for rain gages]

The November weather pattern across the main Hawaiian Islands involved trade winds on most of the days. There were a few breaks in the trade wind pattern, one of which involved the first significant cold front of the wet season to reach the island chain. This cold front moved over Kauai on November 3 and reached Maui County before dissipating on November 4. The remnant frontal cloud band lingered near Maui and the Big Island, producing nearly continuous rainfall over the windward slopes of both islands. Maui received the highest event totals with the U.S. Geological Survey’s (USGS) West Wailuaiki gage recording nearly 14 inches on November 4 and 5 and their Puu Kukui gage recording just over 20 inches over the same 2-day period. Fortunately, hourly rain rates were mostly less than half an inch per hour so there were no flooding problems reported.

The second significant weather system was an upper level disturbance which triggered a band of heavy showers and thunderstorms that swept across Kauai and Oahu late on November 18 before dissipating over Maui County early on November 19. Kauai and west Oahu gages reported totals as much as 1 to 2 inches with a quarter to half an inch recorded over central and east Oahu. While gage totals were rather modest, radar-based estimates of rainfall were significantly higher west of Kauai and southwest of Oahu.

Following a period of light winds from November 20 through 22, the trade winds resumed on November 23 and persisted until November 28. Abundant trade wind showers affected windward areas but brought only limited amounts of rainfall to drought-plagued leeward areas of the Big Island and Maui.

Island of Kauai : [November 2010 map] [Year-to-date map]

Several of the windward gages on Kauai recorded near to above normal rainfall for the month of November while most leeward sites showed below normal totals. The USGS’ Mount Waialeale gage recorded 33.49 inches (96 percent of normal), the island’s highest total and second highest statewide. This gage also recorded the highest daily total of 5.13 inches on November 6 associated with remnant cold front moisture.

Rainfall totals for 2010 through the end of November were below normal at most of the gages on Kauai. The Mount Waialeale total of 246.75 inches (65 percent of normal) remained the highest year-to-date total in the state but was on pace to end the year with its second lowest annual total on record. Most of the remaining gages on the island had totals in the range of 40 to 70 percent of normal.

Island of Oahu: [November 2010 map] [Year-to-date map]

Many of the gages on Oahu recorded below normal rainfall totals for the month of November. However, several sites along the slopes of the Koolau Range from Niu Valley to Kahana Valley recorded near to above normal totals. The highest amount from this group was 26.07 inches recorded by the U.S. Fish and Wildlife Service’s Oahu Forest National Wildlife Refuge (NWR) gage. This gage recorded 15.49 inches from November 3 through 6 as a result of a cold front passage and the subsequent return of its remnant moisture. The maximum daily total from this 4-day period was 4.93 inches on November 4.

Most of the rainfall totals for 2010 through the end of November stayed well within the below normal range. The Oahu Forest NWR gage had the highest year-to-date total of 159.03 inches (86 percent of normal). The remaining gage totals were mostly within the 40 to 70 percent of normal range.

Maui County: [Maui November 2010 map] [Year-to-date map] [Molokai/Lanai November 2010 map] [Year-to-date map]

Gages exposed to trade wind rainfall recorded near to above normal totals for the month of November. The highest monthly total was 34.75 inches (105 percent of normal) from the USGS gage on Puu Kukui. Included within the monthly total was a 2-day accumulation of 20.14 inches on November 4 and 5. The USGS’ West Wailuaiki gage recorded 13.71 inches during the same 2-day period. In contrast, many leeward areas were very dry with most of the gages in these areas showing less than 50 percent of normal rainfall.

Rainfall totals for 2010 through the end of November were in the below normal range at most of the gages across Maui County. The USGS’ Puu Kukui gage had the highest year-to-date total of 224.28 inches (64 percent of normal) and was second highest statewide. Many of the remaining totals were below 50 percent of normal.

Island of Hawaii: [November 2010 map] [Year-to-date map]

Many of the windward gages on the Big Island posted near to above normal monthly rainfall totals. However, most of the leeward areas recorded amounts at less than 50 percent of normal. The USGS’ gage at Kawainui Stream had the highest monthly total of 16.92 inches (136 percent of normal) and the highest daily total of 5.08 inches on November 5. At the South Point gage within the drought-plagued Kau District, the 1.74 inches from November was the highest monthly total since March 2009.

Most of the Big Island gages had below normal rainfall totals for 2010 through the end of November. Windward totals remained mainly in the range of 40 to 60 percent of normal while leeward totals were mostly less than 30 percent of normal. The rain gage at Kawainui Stream had the highest year-to-date total of 157.13 inches (104 percent of normal) and ranked fifth highest in the state. Both Hilo Airport and Kapapala Ranch stayed within reach of setting new records for the driest year. However, rainfall over the past couple of months have made it less likely at both locations.

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