November 2016 Precipitation Summary

State of Hawaii

MONTH: November 2016

PREPARED: December 6, 2016

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

State: [Text data table for rain gages]

There were no heavy rain events that caused significant flooding during the entire month. This is significant considering that historically November has the highest frequency of flash flood events during the year. Since there was only one flash flood event in October it has been a slow start for the Hawaiian Islands wet season thus far.

Trade winds occurred on about 80 percent of the days in November, which was well above the average of 60 to 65 percent. A breakdown in the trades came with the arrival of a weak cold front which pushed the high pressure ridge southward close to the island chain from its normal position well north of the state. The front reached Kauai on November 7 but was not much of a rainfall producer as most totals were less than one inch. With the position of the ridge so close to the state, large scale winds around the islands remained light through November 13 allowing land and sea breezes to dominate local conditions. Trade winds of significance resumed on November 14 at fresh to strong intensity levels, followed by another cold front passage on November 19. This second cold front produced more rainfall across the state than the previous front with several gages recording event totals of more than one inch. After the front dissipated east of the state, remnant moisture from the frontal band remained embedded within the returning fresh to strong trade wind flow and produced numerous showers along the windward slopes. Fortunately these showers were not sufficiently intense or prolonged enough to produce significant flooding problems.

Persistent trade winds and the slow start to the wet season has resulted in a worsening of existing drought conditions over the leeward areas of the state. By the end of November, drought had re-emerged in all four counties across the state and even reached extreme levels in small sections of leeward Kauai and Maui.  Additional details on drought conditions can be found on the U.S. Drought Monitor website at http://droughtmonitor.unl.edu and in the Drought Information Statement issued by the Weather Forecast Office Honolulu at http://www.weather.gov/data/HFO/DGTHFO.

Island of Kauai : [November 2016 map] [year-to-date map]

While a few windward sites managed to turn in near average rainfall totals for the month of November, most of the gages reported below average monthly rainfall values. Several locations had monthly totals at less than 10 percent of average. The U.S. Geological Survey’s (USGS) Mount Waialeale gage had the highest monthly total of 30.65 inches (82 percent of average) and the highest daily total of 5.02 inches during the cold front passage on November 19. Meanwhile, just 12 miles away, the gage at Lihue Airport recorded just 0.40 inches (9 percent of average) setting a new record for the lowest November rainfall total. Such is the nature of rainfall in the Hawaiian Islands.

Rainfall totals for 2016 through the end of November remained in the near to above average range for many of the windward gages but leeward totals dropped further into the below average range. Mount Waialeale had the highest year-to-date total in the state with 336.85 inches (93 percent of average).

Island of Oahu: [November 2016 map] [year-to-date map]

Wet trade wind conditions during the latter half of the month helped produce near to above average monthly rainfall totals at gages along the interior slopes of the Koolau Range. The remaining gages across Oahu had below average totals, many of which were below 50 percent of average. The Manoa Lyon Arboretum gage posted the highest monthly total of 18.10 inches (119 percent of average) and the highest daily total of 5.41 inches on November 21.

Outside of the interior Koolau sites, dry fall conditions have dropped rainfall totals for 2016 through the end of November into the near to below average range. The USGS’ Poamoho No. 1 Gage had the highest year-to-date total of 169.95 inches (82 percent of average), though not far behind was the Manoa Lyon Arboretum total of 168.81 inches (122 percent of average).

Maui County: [Maui November 2016 map] [year-to-date map] [Molokai/Lanai November 2016 map] [year-to-date map]

Most of the rain gages in Maui County recorded below average monthly totals for November. Some of the windward locations received near to above average totals due to wetter trade wind conditions later in the month. The USGS’ West Wailuaiki gage had the highest monthly total of 22.58 inches (114 percent of average) but the highest daily total was from their rain gage on Puu Kukui which posted 4.16 inches on November 20. On Molokai, the gage in Kaunakakai, which is a leeward site, received only 0.02 inches (1 percent of average) and broke the record for the driest November at this location. The previous record was 0.05 inches in 2012.

Across Maui County, many of the gages had near to above average rainfall for 2016 through the end of November. Several of the leeward sites had below average totals. The West Wailuaiki gage had the highest year-to-date total of 325.85 inches (156 percent of average) which was only slightly less than Mount Waialeale’s statewide-leading total on Kauai.

Island of Hawaii: [November 2016 map] [year-to-date map]

Most of the gages on the Big Island recorded below average monthly rainfall totals with many amounts at less than 10 percent of average. The gages at Kealakekua and Honaunau along the Kona slopes broke records for the lowest November rainfall total. In the Kau District, Kapapala Ranch had its lowest November total since 2002. The highest monthly total was from the USGS’ Saddle Road Quarry rain gage with 32.62 inches (251 percent of average) and the highest daily total was 4.04 inches at Mountain View on November 21.

Near to above average rainfall for 2016 through the end of November has been logged by most of the windward Big Island gages. A majority of the leeward sites had below average totals. Leading all Big Island year-to-date totals was the 293.28 inches (229 percent of average) recorded by the USGS’ Saddle Road Quarry gage. This total was third 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