State of Hawaii

MONTH: November 2008

PREPARED: December 4, 2008

State: [Text data table for rain gages]

November started out with relatively stable conditions occurring within mainly moderate trade winds across the State of Hawaii. During the third week of the month, the north Pacific weather pattern shifted to more winter-like conditions. A shear line pushed across the island chain on November 16 and 17 before stalling and dissipating near the Big Island. An upper level trough swept over the state on November 17 and 18 which helped destabilize shear line remnant and promoted the development of heavy rainfall along the windward slopes of the islands. Heavy rains over east Molokai on the morning of November 18 produced flash flooding that forced the brief closure of the Kamehameha V Highway near Mile Post 11. As the upper level trough shifted eastward, the area of heavy rainfall moved over to Maui where minor flooding occurred along the slopes of the West Maui Mountains and over the windward slopes of Haleakala.

On November 21, a kona low, or subtropical cyclone, developed northwest of the state and produced about 1 to 4 inches of widespread rainfall over Kauai, Oahu, and Molokai. Fortunately, most of the rainfall occurred at light to moderate intensities over prolonged periods which helped minimize flooding problems. In fact, the steady, lighter intensity rainfall was able to soak into the ground and helped bring meaningful drought relief to the west half of the state. Embedded heavy showers did occur in some areas, particularly north Molokai and east Oahu during the late morning of November 22. A couple of gages in the Maunawili area briefly recorded rain rates of 1 to 3 inches per hour but the rainfall eased before significant flooding occurred.

As the kona low weakened and shifted westward away from the island chain, fresh to strong trade winds moved in with showers falling mainly over windward areas. A shear line affected Kauai and Oahu on November 29, dropping as much as 1 to 2 inches on both islands before stalling and dissipating on November 30.

Despite the wet conditions in the west half of the state, the Big Island remained drier than normal overall and the area under severe drought spread eastward into the North Hilo, South Hilo, and Puna Districts.

Island of Kauai : [November 2008 map] [Year-to-date map]

Most of the Kauai gages recorded near to above normal rainfall during the month of November. The exceptions came from the northeast and north sides of the island where the Moloaa Dairy gage reported only 46 percent of normal rain and the Hanalei gage recorded a total at 70 percent of normal. Not surprisingly, the U.S. Geological Survey’s Mount Waialeale gage recorded a statewide leading monthly total of 31.10 inches (89 percent of normal). This gage also recorded the state’s highest daily total of 8.60 inches on November 17 during a shear line passage. The Kapahi total of 13.41 inches (160 percent of normal) marked the highest monthly rainfall total since March 2006 when the gage recorded 45.37 inches.

Rain totals for 2008 through the end of November remained at below normal levels at most of the gages on Kauai. The Mount Waialeale total of 292.45 inches (77 percent of normal) continued to lead all year-to-date totals statewide. The gages at Kapahi, Wailua, and Port Allen had the only totals at or above 80 percent of normal.

Island of Oahu: [November 2008 map] [Year-to-date map]

Most of the windward Oahu gages recorded near to above normal rainfall for the month of November while leeward totals were mostly below normal. The Oahu Forest National Wildlife Refuge (NWR) gage, operated by the U.S. Fish and Wildlife Service, recorded the highest island-wide monthly total of 18.91 inches (113 percent of normal) and the highest daily total of 5.60 inches on November 17. On November 22, a burst of heavy rainfall at the St. Stephen’s gage upslope from Maunawili Valley produced 0.73 inches in a 15-minute period from 11:45 AM to Noon. Leeward Oahu totals for November mostly fell within the 40 to 60 percent of normal range.

Rain totals for 2008 through the end of November remained at below normal levels at most of the gages across Oahu. The only exception was the USGS gage at the South Fork Kaukonahua Stream site which has recorded 87 percent of normal rain so far this year. The Oahu Forest NWR total of 136.80 inches (74 percent of normal) ranks third highest statewide, up one position from last month.

Maui County: [Maui November 2008 map] [Year-to-date map] [Molokai/Lanai November 2008 map] [Year-to-date map]

Maui County totals displayed its normal wide range of rainfall conditions, from 9 percent of normal at Kihei to 142 percent of normal at Molokai Airport. Most of the other gages recorded totals in the below normal range. The USGS’ Puu Kukui gage recorded the highest county-wide total of 16.35 inches but this was only 50 percent of normal. This gage also received the highest daily total of 6.42 inches on November 19.

Rain totals for 2008 through the end of November remained at below normal levels at most of the gages across Maui County. The Puu Kukui total of 178.69 inches (51 percent of normal) remained the second highest in the state. The Oheo Gulch total of 83.13 inches was the only year-to-date value above normal in the county.

Island of Hawaii: [November 2008 map] [Year-to-date map]

Most of the gages on the Big Island reported less than 50 percent of normal rainfall for the month of November. Only the Pali 2 gage, ironically located in the Kau Desert, recorded above normal rainfall with 5.72 inches. Of this total, 5.51 inches occurred in a 38-hour period from November 12 to early on November 14 within moist southeast low level flow. The Mountain View gage recorded the highest monthly total of 8.60 inches but this was only 54 percent of normal. The ongoing below normal rainfall has been spreading severe drought into the normally wet windward side of the island.

Most of the Big Island rain totals for 2008 through the end of November were in the below normal range. The Pali 2 and Hilo Airport sites had the highest percent of normal values at 112 and 84 percent of normal, respectively. Most of the remaining site totals were in the range of 50 to 80 percent of normal.

Data Sources: Data used in this report are largely from National Weather Service sources including climate network weather observation stations at Lïhue, 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 Hawai‘i Department of Land and Natural Resources, the US Geological Survey, the US Bureau of Land Management, the US National Park Service, the Department of Defense, and the US Fish and Wildlife Service. Data presented here are not certified and should be used for information purposes only.

Kevin R. Kodama
Senior Service Hydrologist
NOAA/NWS Weather Forecast Office Honolulu