A flood watch remains in effect for all Hawaiian islands through Saturday afternoon.

A kona low will move west and away from Hawaii over the next day or so as an area of high pressure north of the islands shifts to the east, according to the National Weather Service. The convergence will bring a “plume of deep tropical moisture” to the islands over the next few days.

“Widespread heavy rainfall and even a few thunderstorms will be possible, with the heavy rain beginning over the Big Island later today, then spreading to the smaller islands tonight,” the NWS said in a bulletin. “High rainfall rates for an extended period of time could result in flash flooding, particularly in areas which are already saturated from recent rainfall.”

Periods of heavy rain with the possibility of thunder are possible through the weekend, forecasters said.

A winter storm warning is also in place for Big Island summits through 6 p.m. Saturday due to temperatures hovering near or below freezing over the highest elevations.

Heavy snow is expected, along with winds gusting up to 60 mph. Forecasters are expecting total snow accumulations of 2 to 4 feet.

Travel to the summits will be extremely dangerous, with snow-covered, slippery roads, along with gusty winds, creating near-zero visibility conditions at times. Any travel plans to the summits should be postponed until the threat diminishes, officials said.

At the same time, a high surf advisory is in place for the north shores of Niihau, Kauai, and for the east shores of Kauai and Oahu, through 6 p.m. today due to a northeast swell generated by the kona low.

Surf of 12 to 16 feet is expected along north shores, and surf of 10 to 14 feet is expected along east shores, with strong, breaking waves and currents, which will make swimming dangerous in these areas.

The swell is expected to diminish rapidly this afternoon as the low moves away.

Forecasters say periods of heavy rain and thunder will be possible through the weekend, and that this weather pattern may continue into next week.

Kauai County officials urged the public to be vigilant and prepared because a flood watch means that conditions are favorable for flash flooding, which is life-threatening.

“In the event of a Flash Flood Warning, heavy rain, and other inclement weather, officials advise caution and avoiding all non-essential travel, especially to or through areas prone to flooding or flash flooding, such as roadways, rivers/streams and low-lying areas,” said Kauai Emergency Management Agency Administrator Elton Ushio in a news release. “Kuhio Highway, in the vicinity of the Hanalei Bridge, may need to be closed with short to no-advanced notice.”

Residents and visitors should monitor the weather and be prepared to take action if a flash flood warning is issued. They should also check conditions before venturing out for any hike or beach excursions.