The Big Island could experience thunderstorms this week due to an unsettled weather system expected to stall over the state.
Meteorologist Tom Birchard of the National Weather Service in Honolulu said Friday that the weather system is one that’s particularly difficult to make predictions about.
But, he said, “the potential for unsettled weather is increasing.”
A winter storm watch was issued for Big Island summits starting this morning.
The Weather Service believes the system will stall over Maui County and have its most-severe effects there.
However, it’s a large enough system and there’s enough uncertainty about where it will track that a flash flood watch was issued for most of the state, including the Big Island, through Sunday afternoon.
“Heavy showers and thunderstorms may cause flooding,” an alert from Hawaii County Civil Defense said Friday afternoon. “Be aware of debris, runoff, and ponding of water. If lightning threatens your area, power outages may occur, and, the safest place to be is indoors.”
There was also a high surf advisory already on Friday for south-facing shores on the Big Island.
The Mauna Kea weather line advised Friday morning that there was no snow on the summit, where it was “clear and cold with a moderate breeze.”
Birchard said there’s a “pretty good chance” snow could start on the summit as early as Friday and could also be possible today. But the best chance for snow on summits, he said, will be Sunday.
“It’s kind of a dynamic situation,” he said.
What makes the weather unstable, Birchard said, is a significant amount of cold air.
That air could fight with warmer, humid air below and trigger the storms.
Birchard said it’s likely small hail will be created during the weekend, “especially up-slope on the Big Island.”