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February 2012 Precipitation Summary
State of Hawaii
MONTH: February 2012
PREPARED: March 15, 2012
State: [Text data table for rain gages]
February started with a more winter-like pattern as the trade winds broke down on February 3 prior to a weak cold front passage on February 5. A more significant front followed on February 7 accompanied by cool northwest winds in the moderate to fresh range. The first front brought less than an inch of rainfall while the second front dropped 1- to 3-inch totals. Oahu had some minor flooding during the February 7 frontal passage. Trade winds returned on February 10 and persisted mainly in the moderate to fresh range through February 23 with only a brief deviation to southeasterlies on February 14 and 15.
The weather pattern changed over the central North Pacific from February 24 and brought unsettled conditions to the main Hawaiian Islands during the next two weeks. The island of Kauai took the brunt of the initial storm system which came in the form of a kona low centered far northwest of Niihau. Unstable conditions over Kauai produced heavy rainfall with Mount Waialeale recording 13.07 inches and many locations recording 5- to 8-inch totals during the 3-day period from February 24 through 26. Flash flooding on February 26 caused road closures in several areas including Waimea, Kekaha, and Koloa. The portion of Kuhio Highway leading into Hanalei town was closed for more than 6 hours. Although the kona low weakened and opened up into an upper level trough, lingering instability brought heavy rainfall to northeast Kauai on February 29. Gages recorded 1 to 3 inches of rainfall but impacts were minimal.
Over the east end of the state, periods of moist low level winds from the east to east-southeast during the latter half of the month resulted in above normal totals over the windward slopes. An upper level low near the Big Island helped enhance showers resulting in 3 to 5 inches of rainfall on February 21 and 22 and minor flooding problems.
Despite the wet conditions along the east-facing slopes of the Big Island, drier than normal conditions prevailed for many of the leeward areas and maintained drought for yet another month in the wet season. For more information on the ongoing drought, please refer to the latest Drought Information Statement.
Island of Kauai : [February 2012 map] [Year-to-date map]
All of the available rain gages across the island recorded near to well above normal rainfall totals for the month of February. The U.S. Geological Survey’s (USGS) Mount Waialeale gage recorded 45.47 inches (186 percent of normal), the state’s highest monthly total and the highest February total for this site since 2006. Most of the remaining gages measured more than 10 inches of rain during the month and all of the leeward totals were more than double the monthly normal. Anahola had the highest daily total of 7.68 inches on February 26, of which 6.84 inches occurred during the 6-hour period from 3 AM to 9 AM HST.
Most of the gages across Kauai had near to above normal rainfall totals for 2012 through the end of February. Mount Waialeale’s 64.66 inches (131 percent of normal) surpasses all other year-to-date totals in the state by a wide margin.
Island of Oahu: [February 2012 map] [Year-to-date map]
Most of the rain gages on Oahu recorded below normal rainfall totals for the month of February. Many monthly totals were in the range of 30 to 70 percent of normal. The U.S. Fish and Wildlife Service’s Oahu Forest National Wildlife Refuge (NWR) gage had the highest monthly total of 9.95 inches (62 percent of normal) followed closely by Nuuanu’s 9.91 inches (121 percent of normal). The USGS rain gage in the headwaters of Moanalua Valley recorded the highest daily total of 2.16 inches on February 24.
All of the gages on Oahu had below normal rainfall totals for 2012 through the end of February. The Oahu Forest NWR gage had the highest year-to-date total of 14.08 inches (42 percent of normal). Most of the totals across the island were below 50 percent of normal.
Maui County: [Maui February 2012 map] [Year-to-date map] [Molokai/Lanai February 2012 map] [Year-to-date map]
A majority of gages across Maui County posted below normal rainfall totals for the month of February. Two sites on the southeast slope of Haleakala, the USGS’ Kepuni gage and the National Park Service’s gage at Kaupo Gap, were the only gages that indicated near to above normal monthly totals. Puu Kukui had the highest monthly total of 15.42 inches (58 percent of normal) and the highest daily total of 2.91 inches on February 7.
All of the gages in Maui County indicated below normal totals for 2012 through the end of February. The USGS’ Puu Kukui gage had the highest year-to-date total of 18.92 inches (33 percent of normal) but this didn’t break into the top 10 statewide.
Island of Hawaii: [February 2012 map] [Year-to-date map]
Another wet month for the east-facing slopes of the Big Island where 9 gages recorded more than 10 inches of rain. In fact, South Hilo and Puna District gages at Piihonua, Waiakea Uka, Waiakea Experiment Station, and Mountain View logged more than 20 inches of rainfall in 3 out of the last 4 months. Waiakea Uka had the highest monthly total of 22.57 inches (203 percent of normal) while the Waiakea Experiment Station had the highest daily total of 5.63 inches on February 19. In contrast, most of the leeward sites continued to have very low rainfall totals with many February totals at less than 50 percent of normal.
February rainfall helped offset the very dry conditions in January to help push most of the windward totals to near normal levels for 2012. However, rainfall deficits increased at most of the leeward sites with most year-to-date totals below 50 percent of normal. The gage at Mountain View had the highest year-to-date total on the Big Island with 25.57 inches (99 percent of normal) and was fourth highest in the state.
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