January 2017 Precipitation Summary

State of Hawaii

MONTH: January 2017

PREPARED: February 3, 2017

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

State: [Text data table for rain gages]

Wet conditions during December switched off abruptly shortly after the new year began as changes in the North Pacific weather pattern pushed a high pressure ridge over the state. The ridge remained near or over the main Hawaiian Islands for a couple of weeks resulting in light large scale winds. This allowed local conditions to be dominated by land and sea breezes with very little rainfall through January 16. Trade winds resumed on January 17 and persisted until dropping off on January 20 in response to an approaching cold front. The front moved across the island chain on January 21 and produced less than an inch of rain at most locations from Kauai to Maui. Rainfall accumulations were higher, 2 to 7 inches on the windward Kohala and Hamakua slopes of the Big Island, when the movement of the front slowed. The higher rainfall accumulations did not produce significant property damage. However, a woman died in the Ahumoa area when she was swept away while crossing knee-deep but fast flowing water in a driveway on the night of January 21. After the frontal passage, very strong northeasterly winds filled in across the state resulting in numerous power outages, downed trees and power lines, and roof damage in several areas across the state through January 22.

Unstable conditions aloft combined with remnant frontal moisture in the lower levels produced abundant rainfall over the windward slopes of the Big Island from January 22 through 24. Peak rainfall occurred on January 23 with 24-hour totals of about 4 to 8 inches producing minor flooding problems mainly in the Hilo area. Trade winds persisted through the rest of the month at mainly moderate to fresh intensity levels. A weak cold front moved across the state on January 28 but most rainfall totals were around an inch or less and did not produce any notable flooding issues.

Island of Kauai : [January 2017 map]

All of the gages on the island of Kauai recorded below average rainfall totals for the month of January. Lihue Airport’s 0.20 inches (5 percent of average) broke the record for the driest January which was last set in 1986 (0.30 inches). The Hanapepe gage (0.33 inches, 8 percent of average) posted its second lowest January total with the record being last year’s 0.20 inches. The U.S. Geological Survey’s (USGS) Mount Waialeale gage had the highest monthly total of 13.65 inches (55 percent of average) and the highest daily total of 4.27 inches on January 23.

Island of Oahu: [January 2017 map]

Below average rainfall totals were posted by all of the gages on Oahu for the month of January with most of the totals at less than 30 percent of the long term average. A record low January total was recorded by the gage at Ahuimanu. Gages at Kunia, Kamehame, Hakipuu Mauka, Waihee Pump, and Waiawa Correctional Facility logged their second lowest January totals on record. The USGS’ Poamoho No. 1 Gage had the highest monthly total of 9.75 inches (54 percent of average) and the highest daily total of 3.32 inches on January 24.

Maui County: [Maui 2017 map] [Molokai/Lanai January 2017 map]

Most of the gages in Maui County recorded below average monthly rainfall totals. A majority of the totals came in below 50 percent of average. The USGS’ West Wailuaiki gage had the highest monthly total of 17.74 inches (89 percent of average) and the highest daily total of 4.75 inches on January 1. Molokai Airport had its second driest January on record.

Island of Hawaii: [January 2017 map]

There were substantial differences in rainfall conditions across the Big Island in January. Most of the windward gages posted near to above average monthly totals. Meanwhile, most of the leeward sites recorded totals at less than 10 percent of the January average, which is a dramatic change from December where most totals were 2 to 3 times greater than the monthly average. The USGS’ Saddle Road Quarry rain gage had the highest monthly total of 31.80 inches (304 percent of average) and the highest daily total of 8.27 inches on January 23. Hilo Airport and Waiakea Uka had their wettest January since 2008, and Kamuela had its wettest January since 1993. In contrast, the 0.26 inches (7 percent of average) logged at the Honaunau gage marked the second lowest January total on record.

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