East Hawaii residents should expect the wet weather that’s drenched the windward side of the island for much of the month to continue through Christmas weekend.
That’s according to the seven-day forecast from the National Weather Service in Honolulu.
A flash flood watch posted for the Big Island early Tuesday afternoon is set to expire at 6 a.m. Wednesday — although forecasters have the options of extending it or upgrading it to a flash flood warning, depending on weather conditions.
“Recent rainfall has produced nearly saturated conditions, especially over windward slopes of the Big Island,” NWS meteorologist Derek Wroe noted in the flash flood watch, and added an upper-level disturbance was “expected to produce additional heavy showers and thunderstorms” that could lead to possible flash flooding Tuesday afternoon and evening.
“The highest flood risk will be across windward slopes, though heavy rainfall could affect the entire island,” Wroe continued.
Hilo International Airport logged 5.84 inches of rain in the 72-hour period ending 8 a.m. Tuesday, and ponding was an issue on Hilo’s roadways, especially on Kamehameha Avenue near the intersection with Pauahi Street and Bayfront Highway, which is always troublesome during heavy rains.
Rain continued intermittently during the day Tuesday, and a landslide closed Highway 19 (Hawaii Belt Road) near Honomu for at least an-hour-and-a-half during the midday hours.
Police also reported a downed tree across Old Mamalahoa Highway in the area of Church Gulch, which left no other detour route except the Daniel K. Inouye Highway.
Wednesday’s forecast is for frequent showers and possibly a thunderstorm with a 90% chance of rain. NWS is forecasting new rainfall totals between three-quarters of inch and an inch today and between an inch and two inches tonight.
East Hawaii areas have daily rain in the forecast until Monday night, with daily high temperatures in the lower 70s and overnight lows near 60 degrees and possibly dipping into the upper 50s.
Leeward areas also received rainfall Tuesday, with NWS posting a flood advisory in the early afternoon.
According to Wroe, there were “spotty heavy showers continuing to fall over leeward and interior Big Island at rates of one to two inches per hour” with the heaviest rainfall between Kalaoa and Puuanahulu, but residents on North and South Kona and South Kohala were advised to expect possible flooding.
In addition, a winter weather advisory was posted for the summits of Maunakea and Mauna Loa until 6 a.m. Wednesday, also subject to renewal or upgrading.
In the forecast for the summits were snow accumulations of up to three inches with a slight chance of freezing rain, making driving to the summits hazardous.
Maunakea Access Road was closed Tuesday at the Visitor Information Station at the 9,200-foot level “due to heavy fog, icy road conditions and snow on the road,” according to the University of Hawaii’s Maunakea Weather Center.
The summit temperature on Maunakea was slightly under 28 degrees Fahrenheit at 4 p.m. Tuesday.
Email John Burnett at jburnett@hawaiitribune-herald.com.