Dry conditions persist through November in some parts of Big Island; others saw near or above average rainfall
After two months of the 2022-23 wet season, some portions of the state remain under significant drought, with Maui County and the Big Island having the worst conditions, according to the monthly rainfall summary for November from the National Weather Service in Honolulu.
Big Island rainfall totals for the year through the end of last month were near or below average at most rain gauges, said the report prepared by Senior Service Hydrologist Kevin Kodama. The U.S. Geological Survey gauge at Honoli‘i Stream in East Hawai‘i had the highest year-to-date rainfall total for the island with 155.47 inches, or 73% of its average.
An October outlook by the National Oceanic and Atmospheric Administration Climate Prediction Center, however, favored above normal temperatures and rainfall into spring next year. Based on that outlook, drought conditions are expected to ease throughout the state, with rainfall increasing toward the end of this year.
To see the year-to-date totals from rain gauges around the island, click here.
Very dry conditions persisted in several places last month on the Big Island.
The rain gauge at Kohala Ranch saw just 10% of its 1.16-inch November average, receiving just 0.12 of an inch of rain. The Puhe CS gauge in North Kohala, which normally receives just 0.95 of an inch of rain in November, recorded no rainfall last month. The rain gauge in Waikōloa also was more than parched, getting a measly 0.04 of an inch of rain, just 4% of its average for November.
The gauge at Kaʻūpūlehu received just 0.07 of an inch of rain last month, or 5% of its average of 1.31 inches. The Kona International Airport gauge saw only 0.09 of an inch in November, or 11% of its average 0.83 of an inch for the month.
Fortunately, along the Big Island’s windward slopes, wet trade wind conditions in late October and early November helped remove severe drought, according to the November drought information statement. Kodama’s rainfall summary said the state also saw a higher than normal frequency of trade wind days in November.
Rain gauges on the windward slopes saw mostly near average rainfall last month.
Among automated rain gauges in East Hawai‘i, Pāpa‘ikou Well had the highest monthly total of 16.52 inches, or 77% of average. However, the highest overall total came from the Wainaku Community Collaborative Rain, Hail and Snow Network, or CoCoRahs, site with a manually recorded November total of 17.75 inches. The highest daily rainfall total for the month was 4.30 inches reported Nov. 3 by the Hilo Airport gauge.
The gauges on the east side that saw more rain than usual were the Hilo Airport, which recorded a total of 16.36 inches of rain in November, or 114% of its average, and the Kawainui Stream gauge ended the month at 113% of its average 8.05 inches, recording 9.08 inches for the month.
A low pressure system aloft just north of the main Hawaiian Islands destabilized airmass from Nov. 2-4, resulting in enhanced rainfall within the low level easterly flow. Periods of heavy rainfall along the windward slopes of the Big Island, Maui, and O‘ahu produced minor flooding but no reports of significant damage.
Atmospheric conditions stabilized Nov. 5, with moderate to fresh trade winds persisting through Nov. 15, then weakening to light to moderate speeds Nov. 16. A weak surface low pressure trough over the state induced by a low pressure system aloft became the focus for heavy rainfall Nov. 17 and 18 on Maui and Moloka‘i, but fortunately there were no reports of damage.
Then, on Thanksgiving Day, Nov. 24, a cold front swept across the islands, bringing strong northeasterly winds but not enough rainfall to produce flooding. The winds weakened rapidly, becoming light within two days. A slow-moving surface trough moved over the state from the south on Nov. 27 and 28 accompanied by a deep tropical airmass that helped fuel heavy rainfall over portions of Kaua‘i and east Maui, but there were no reports of significant flooding.
While gauges on the Big Island’s windward slopes had mostly near average rainfall totals last month, those in South and North Kona south of Hualālai mostly had above average totals.
The gauge at Kanaliu received 6.84 inches of rain in November, a whopping 220% of its average of 3.11 inches. The Puho CS gauge recorded 4.04 inches last month, 200% of its 2.02-inch average. The Kealakekua gauge saw 6.17 inches of rain, or 190% of its average of 3.25 inches, and the Honaunau rain gauge recorded 152% of its average of 3.12 inches, or 4.73 inches total.
Most of the remaining sites on the Big Island recorded below average totals. To see all of the November totals from around the island, click here.
To see Kodama’s entire rainfall summary for November, which includes information for Kaua‘i, Maui and O‘ahu, click here.