November 2015 Precipitation Summary

State of Hawaii

MONTH: November 2015

PREPARED: December 3, 2015

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

State: [Text data table for rain gages]

The first half of November mainly involved persistent trade winds which brought daily rainfall to the east-facing slopes of the island chain. The trades reached fresh to strong intensity levels during the second week of the month which helped carry rainfall into the leeward areas of the smaller islands in the state and enhanced showers over the windward slopes of the Big Island. Several sites in the South Hilo and Puna Districts registered over 10 inches of rain during the period from November 9 through November 13 but no significant flooding problems were reported.

A disruption to the trade winds started on November 16 with the veering of low level winds to a southeasterly direction. This shift in the wind current helped transport deep tropical moisture over the main Hawaiian Islands. The boost in moisture helped enhance rainfall over the east and southeast slopes of the Big Island on November 18 and 19 with 2-day totals in the range of 4 to 9 inches. Shower bands did not focus on any specific areas which helped minimize flooding issues. As the area of deep tropical moisture shifted west, heavy rainfall occurred over portions of Molokai, Oahu, and Kauai on November 20 with flash flooding in Waikane Stream briefly closing Kamehameha Highway shortly before sunrise. Rainfall totals in the range of 4 to 7 inches on Kauai resulted in minor flooding problems in the northern and eastern sections of the island. On November 21, an approaching weak cold front further veered low level winds to the south and southwest across Kauai and Oahu. The convergence of these winds produced a shower band that stalled over Oahu for 2 days and dropped 1 to 4 inches of rain. Despite the saturated conditions, this additional rainfall did not produce significant flooding. The cold front finally reached Kauai on November 22, slowly moved eastward, then dissipated near Maui and the Big Island on November 24.

Following the dissipation of the front, a strong high pressure system moved north of the Hawaiian Islands resulting in fresh to strong trade winds over the State of Hawaii for the remainder of the month. As was the case in early November, the strong low level winds brought frequent showers to the windward slopes. While several locations recorded daily totals over an inch, the rainfall was distributed enough over time to prevent the occurrence of any notable flooding problems.

Island of Kauai : [November 2015 map] [year-to-date map]

Most of the gages on Kauai recorded near to above average rainfall totals for the month of November. The U.S. Geological Survey’s (USGS) Mount Waialeale gage had the highest monthly total of 36.35 inches (97 percent of average). The highest daily total was 6.32 inches on November 20 from the Lihue Variety Station site. Those locations with above average monthly totals were mainly from the eastern and southern sections of the island from Kalaheo to the town of Kapaa.

Rainfall totals for 2015 through the end of November were in the near to above average range at most of the gages on Kauai. Mount Waialeale had the state’s highest rainfall total of 316.23 inches (87 percent of average).

Island of Oahu: [November 2015 map][year-to-date map]

Most of the gages on Oahu logged above average rainfall for the month of November. The U.S. Fish and Wildlife Service’s Oahu Forest National Wildlife Refuge (NWR) gage had the highest monthly total of 36.16 inches (167 percent of average) and the highest daily total of 7.76 inches on November 26. Several sites reported their highest November rainfall on record. These include Moanalua Stream, Manoa Lyon Arboretum, and Nuuanu Upper. Additionally, the gages at Mililani, Palisades, Waipio, Kunia, Palolo Fire Station, and Kahuku had their highest November totals since 1996.

Nearly all of the gages on Oahu had near to above average rainfall totals for 2015 through the end of November. The Oahu Forest NWR gage had the highest year-to-date total of 249.65 inches (123 percent of average).

Maui County: [Maui November 2015 map] [year-to-date map] [Molokai/Lanai November 2015 map] [year-to-date map]

Rainfall totals for November were in the near to above average range at most of the gages in Maui County. The National Park Service’s Puu Alii gage on Molokai had the highest monthly total of 18.44 inches (200 percent of average) and the highest daily total of 7.74 inches during wet trade wind conditions on November 25. Record November rainfall occurred at the Pukalani and Haiku gages, and the gage at Ulupalakua Ranch posted its highest November total since 2001.

Nearly all of the gages in Maui County had near to above average rainfall for 2015 through the end of November. The highest available year-to-date total was from the Puu Alii gage with 183.87 inches (204 percent of average).

Island of Hawaii: [November 2015 map] [year-to-date map]

Above average rainfall totals were recorded by most of the gages on the windward side of the Big Island for the month of November. In contrast, many of the leeward sites posted below average totals. Several of the rain gages in the interior section of the Big Island near Pohakuloa and in the South Kohala District indicated rather dry conditions with monthly totals below 10 percent of average. The Waiakea Uka gage had the highest monthly total of 36.24 inches (178 percent of average) while the gage at Glenwood had the highest daily total of 6.61 inches on November 19. Most of the sites in the South Hilo, Puna, and Kau Districts had their wettest November since 2000.

Rainfall totals for 2015 through the end of November were in the near to above average range at most of the gages on the Big Island. The USGS’ gage at Kawainui Stream had the highest available year-to-date total of 203.50 inches (167 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