March 2017 Precipitation Summary

State of Hawaii

MONTH: March 2017

PREPARED: April 5, 2017

Note:  This summary uses the arithmetic mean, or average, for “normal” rainfall values.

State: [Text data table for rain gages]

The month of March started with the Hawaiian Islands under a continuation of a wet weather pattern that started in February. Unstable conditions from a nearby low pressure system resulted in flash flooding on Oahu and Kauai on February 28 and into the early morning hours of March 1. The flooding caused significant damage to Waimea Valley Park in north Oahu and closed Kuhio Highway near the Hanalei Bridge on Kauai for several hours. Please see last month’s summary at http://www.prh.noaa.gov/hnl/hydro/pages/feb17sum.php for additional details.

Although local weather conditions stabilized by March 2, the overall weather pattern in the central North Pacific remained unsettled. A weak cold front reached Kauai on March 4 then stalled and dissipated near Maui County and the Big Island on March 5, depositing roughly an inch of rainfall in isolated locations along the way. The enhanced moisture within the remnant frontal band served as a focal point for heavy rain development when a strong upper level trough of low pressure moved into the area on March 7. That afternoon, thunderstorms developed over the leeward areas of Haleakala on Maui. Intense rainfall caused flash flooding in Kulanihakoi Gulch which closed South Kihei Road. The flooding damaged several condominiums and vehicles, and fire crews rescued 7 people who were trapped by the fast flowing waters. Conditions on March 9 supported another round of strong thunderstorm development. Initially, these thunderstorms were mainly in the coastal waters north of Maui County. One of these thunderstorms exhibited radar signatures suggesting the presence of large hail and a significant waterspout. Strong afternoon thunderstorms also developed over the Big Island and Oahu. The Big Island thunderstorms dropped heavy rain and small hail over portions of the Saddle Road, Hilo, and the Hawaiian Paradise Park area in the Puna District, but there were no reports of significant flood damage. The Oahu thunderstorms mainly affected the Mililani and Wahiawa areas but also did not result in any notable damage. Interestingly, the last time radar signatures this strong were seen in the Hawaiian Islands was five years ago to the day. The March 9, 2012 severe thunderstorm generated intense rainfall, the state record hail stone (4.25 inches wide), and a tornado in Kailua on the island of Oahu.

The atmosphere stabilized somewhat after March 9 but remained sufficiently unsettled to produce briefly heavy rainfall and minor flooding over portions of the Big Island, Oahu, and Kauai from March 10 through March 12. Drier conditions finally arrived on March 13 as a ridge of high pressure moved over the island chain and remained in the area through March 15. A weak cold front reached Kauai on the afternoon of March 16 then crawled eastward, reaching the Big Island on March 18. Rainfall amounts from this front were less than an inch at all gage locations. Following the dissipation of the cold front east of the Big Island the following day, light to moderate trade winds returned to the state. However, very stable middle and upper level conditions restricted significant rainfall production for most of the rest of March.

Island of Kauai : [March 2017 map] [year-to-date map]

Early March rainfall put monthly totals in the near to above average range at most of the gages in the southern half of Kauai. March totals from the rest of the island were mostly in the below average range. The U.S. Geological Survey’s (USGS) Mount Waialeale gage had the highest monthly total of 10.21 inches but this was just 27 percent of average and registered as the lowest March total at this site since 1993 (6.09 inches). The gages at Kokee and the Wailua Experiment Station had their lowest March totals since 2001. The highest daily total was 4.35 inches at the Kapahi gage as part of the flash flood event on March 1.

Most of the rain gages in the southern half of Kauai have recorded near average rainfall totals for 2017 through the end of March. Totals from gages in the northern half were mostly in the below average range. The highest year-to-date total was from the Mount Waialeale gage which has recorded 45.70 inches (53 percent of average) thus far in 2017.

Island of Oahu: [March 2017 map] [year-to-date map]

Rainfall totals for the month of March were in the near to below average range at most of the rain gages on Oahu. Many of the totals from locations on the Koolau Range were less than 50 percent of average. Honolulu Airport stands out as a March rainfall anomaly with its 2.75 inches coming in at 136 percent of average. The USGS’ Poamoho No. 1 gage had the highest monthly total of 9.39 inches (44 percent of average), but this was its lowest March total since 2000. The Ahuimanu gage logged the highest daily total of 5.74 inches on March 1.

Rainfall totals remain in the near to below average range at most of the rain gages for 2017 through the end of March. The USGS’ Poamoho No. 1 Gage had the highest year-to-date total of 37.83 inches (69 percent of average). Honolulu Airport’s 10.08 inches for 2017 is 159 percent of average. Since this location is one of the main climate monitoring sites on the island, it is currently painting an unrepresentative wet picture for the island as a whole.

Maui County: [Maui March 2017 map] [year-to-date map] [Molokai/Lanai March 2017 map] [year-to-date map]

Many of the leeward gages on the island of Maui recorded near to above average rainfall while most of the windward totals were in the below average range for the month of March. Most of the March totals from Molokai and Lanai were in the below average range. The USGS’ gage at West Wailuaiki Stream had the highest monthly total of 8.63 inches (30 percent of average) and the highest daily total of 3.04 inches on March 8. The USGS’ gage at Puu Kukui (5.09 inches, 13 percent of average) posted its lowest March total on record. The previous record was 6.74 inches set just last year. Contrasting the Puu Kukui dryness, March totals from Kahului Airport and Ulupalakua Ranch were the highest since 2006.

Nearly all of the rainfall totals for 2017 through the end of March were in the near to below average range across Maui County. Ulupalakua Ranch is the sole exception where its year-to-date total of 12.57 inches checks in at 127 percent of average. The USGS’ West Wailuaiki gage had the highest 2017 total of 40.73 inches (64 percent of average) and remained third highest in the state.

Island of Hawaii: [March 2017 map] [year-to-date map]

Most of the gages on the Big Island recorded less than 50 percent of average rainfall during the month of March. The USGS’ Saddle Road Quarry rain gage had the highest monthly total of 13.83 inches (88 percent of average) while the Pahala rain gage had the highest daily total of 3.13 inches on March 25. The Kamuela Upper gage (0.53 inches, 8 percent of average) had its driest March in a data record going back to 1993. Gages at Glenwood, Hilo Airport, Laupahoehoe, Mountain View, and Pahoa had their lowest March totals since 2003.

Several significant weather systems that affected the state in February and early March for the most part dissipated before reaching the Big Island. This has resulted in below average rainfall totals from most of the Big Island rain gages for 2017 through the end of March. The USGS’ Saddle Road Quarry rain gage had the highest year-to-date total of 56.89 inches (155 percent of average). This total is highly anomalous compared to totals from the rest of the island. Most year-to-date amounts on the west side of the Big Island were less than 40 percent of average while most of the windward totals were less than 60 percent of average.

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