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March 2013 Precipitation Summary
State of Hawaii
MONTH: March 2013
PREPARED: April 3, 2013
Note: This summary uses the arithmetic mean, or average, for “normal” rainfall values.
State: [Text data table for rain gages]
After several months of unseasonably persistent trade winds, March brought an unusual absence of trade winds with only a quarter of the days having large scale winds from the east to northeast. Normally March has about 60 percent of the days coming from the trade wind direction. In its place, four cold fronts affected the main Hawaiian Islands during the month bringing periods of heavy rainfall and some flash flooding.
The most significant heavy rain event occurred following a cold front passage over the west half of the state on March 22. While the passage of the front itself was largely uneventful, remnant frontal moisture lingered over the central and western portions of the island chain. An upper level disturbance moving over Oahu from the southwest on March 24 tapped into this moisture and brought widespread rainfall with totals in the range of 1 to 3 inches. The rainfall was steady and spread out over time which resulted in only minor flooding problems. A stronger upper level trough dropped in from the northwest on the night of March 26 and enhanced showers associated with the frontal remnant over Kauai. Heavy rainfall initially focused on the north-facing slopes with flash flooding in Hanalei River inundating Kuhio Highway west of the Hanalei Bridge overnight and into the morning of March 27. High water levels in Hanakapiai Stream on the Na Pali Coast stranded 12 hikers overnight and all were rescued by helicopter the following morning. In the early morning hours of March 27, heavy rainfall shifted to the northeastern quadrant of Kauai. Flash flooding in Kapaa Stream inundated a portion of Hauaala Road near Kapaa for about 4 hours, and a small tributary to Opaekaa Stream temporarily closed Puupilo Road in Wailua Homesteads. Rainfall totals for the 24-hours from 2 PM HST, March 26 to 2 PM HST, March 27 ranged from 10 to 15 inches in the northeast to almost 22 inches in the northwest. Some heavy rainfall, in the range of 1 to 2 inches, also affected Oahu on March 27 but did not cause significant flooding problems.
Other cold fronts that reached the state occurred on March 9-10, March 15-16, and March 30. None of these fronts produced significant flooding problems. Since these fronts were generally weak, leeward areas of the Big Island plagued by persistent drought conditions received only modest amounts of rainfall and limited relief.
Island of Kauai : [March 2013 map] [year-to-date map]
The late March heavy rain event helped push monthly totals on the northeast half of Kauai into the near to above average range. Totals from the southwest half were mostly below 60 percent of average. The highest monthly total of 38.27 inches (206 percent of average) was from the U.S. Geological Survey’s (USGS) Kilohana gage. Of this total, 21.88 inches occurred during the 24-hour period from 2 PM HST, March 26 to 2 PM HST, March 27 during the above mentioned flash flood event. Interestingly, while all this heavy rain occurred on the north side of island, the Kalaheo gage on the south slope posted its driest March since 2003 (0.98 inches, 18 percent of average).
Rainfall totals for most of the gages on Kauai have pushed up into the near average range for 2013 through the end of March. The USGS’ Mount Waialeale gage had the highest year-to-date total on Kauai at 82.07 inches (94 percent of average) but remained second highest in the state behind Puu Kukui on Maui. The below average totals were mainly from gages on the southwest side of the island.
Island of Oahu: [March 2013 map] [year-to-date map]
Most of the gages on Oahu recorded near to below average rainfall for the month of March. The U.S. Fish and Wildlife Service’s (USFWS) Oahu Forest National Wildlife Refuge (NWR) gage had the island’s highest monthly total of 11.54 inches (61 percent of average). The highest daily total was from the USGS’ Moanalua rain gage with 3.00 inches on March 24. Kalaeloa Airport’s 4.12 inches (224 percent of average) had its wettest month in the past year, which marked the second consecutive year where March was the wettest month at this location. This point bears mentioning because December is normally the wettest month on average at this site so it’s a bit unusual.
Most of the gages on Oahu had near average rainfall totals for 2013 through the end of March. The Oahu Forest NWR gage had the highest year-to-date total of 60.11 inches (116 percent of average) which was fourth highest in the state.
Maui County: [Maui March 2013 map] [year-to-date map] [Molokai/Lanai March 2013 map] [year-to-date map]
This was one of the rare occasions where Molokai saw most of the significant rainfall action in the county. The highest monthly total occurred at the National Park Service’s Puu Alii gage in north central Molokai which recorded 12.54 inches (101 percent of average). The highest daily total, also from Molokai, was 3.77 inches at the Kaunakakai gage on March 10. After having its wettest February in over a decade, the USGS’ Puu Kukui gage recorded only 9.44 inches (25 percent of average) making it the driest March since 1940. The island of Maui had spotty and inconsistent rainfall with most of the gages showing below average monthly totals.
Most of the Maui County gages had near average rainfall totals for 2013 through the end of March. Most of the below average totals came from leeward Maui locations. Despite having a near-record dry month, Puu Kukui’s year-to-date total of 93.48 inches (98 percent of average) remained the highest statewide.
Island of Hawaii: [March 2013 map] [year-to-date map]
Most of the gages on the Big Island recorded below average totals for the month of March. Nearly all of the windward totals were below 50 percent of average, mainly due to the lack of consistent trade winds and the weakness of the cold fronts that were able to reach the island. The highest monthly total was from the Piihonua gage (9.75 inches, 49 percent of average) while the highest daily total was from the Waiakea Uka gage nearby which recorded 3.16 inches on March 29. Hilo Airport posted its lowest March total (4.14 inches, 31 percent of average) since 2003. Just a month ago Hilo Airport had its wettest February since 2008.
Despite the dryness of the past month, most of the windward gages continued to show near to above average totals for 2013 through the end of March. Leeward totals remained below average. The Waiakea Uka total of 47.33 inches (99 percent of average) continued as the Big Island’s highest but dropped to sixth 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 Lihue, 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 Hawaii Department of Land and Natural Resources, the U.S. Geological Survey, the U.S. Bureau of Land Management, the U.S. National Park Service, the Department of Defense, the U.S. Fish and Wildlife Service, and the U.S. Department of Agriculture. Averages come from the National Climatic Data Center (1981-2010 series) and the Rainfall Atlas of Hawaii (http://rainfall.geography.hawaii.edu/). Data presented here are not certified and should be used for informational purposes only.
Kevin R. Kodama
Senior Service Hydrologist
NOAA/NWS Weather Forecast Office Honolulu