Flood watch issued for Hawaii, blizzard and high wind warnings for Big Island summits

UPDATE: 8:30 a.m.

The flood advisory for Molokai has expired.

Friday, 7 a.m.

A flood advisory is in effect for Molokai through 8:15 a.m. today.

Radar this morning showed heavy rain falling at a rate of up to 1 to 2 inches per hour, according to the National Weather Service.

Some locations that will experience flooding include Kaunakakai, Kawela, Kalaupapa National Park, Kualapuu,

Hoolehua, Kamalo, Ualapue, Pukoo, Maunaloa, Halawa Valley and Molokai Airport.

10:00 p.m.

“Unsettled weather” in the state will persist through the weekend and into early next week, resulting in consistent wet weather, the National Weather Service said in a report.

A cold front, likely over Kauai right now, will move down the island chain tonight and Friday before stalling near Hawaii island on Saturday. It will reach Oahu around midnight and move toward Maui County afterward, the NWS said. The front can result in a band of showers, including heavy ones, and thunderstorms.

A strong upper level disturbance moving into the islands on Friday will “accentuate the moisture,” particularly on Maui County and Hawaii island. By Saturday night, a stronger upper level disturbance will bring “moist southerly wind flow for all islands,” according to forecasters.

An approaching upper level disturbance will bring “very strong winds” to the summits on Hawaii island on Friday night, which will continue until early next week. Snow is expected over the summits as the front stalls near the island Friday night into Saturday.

A kona low is expected to linger near the islands starting Saturday night, with a strong potential for wet and unsettled weather.

As the low develops, near gale force northwest and north winds on Friday will shift to the west and weaken Saturday, shift again to the south and southwest and strengthen on Sunday. An unstable southerly flow could linger west of Kauai through the middle of next week.

As the front moves down the island chain, strong and gusty winds are expected, especially in and near any heavy showers or thunderstorms that develop. Although winds will east on Saturday, combined seas will be above the 10-foot threshold for a small craft advisory throughout the weekend.

Locally generated wind waves and a building north-northwest swell are expected on Saturday, the NWS said. The swell will shift to the north and continue to build through the weekend. The long-lived large north swell will likely generate surf heights close to 30 feet along north-facing shores on Saturday and Sunday. High tide early during those days can lead to wave “runup” on some coastal areas.

The swell will also lead to significant harbor surges at the Kahului and Hilo harbors, likely bringing Advisory-level surf to west shores.

Minimal surf is expected along east-facing shores through Friday, with some increase during the weekend as the north-northwest swell turns north, allowing some swell to wrap around the islands. Surf along south shores will rise slightly over the weekend and into next week due to locally generated wind waves.

Through Monday afternoon there is a flood watch throughout the state.

From 6 a.m. to 6 p.m. on Friday, there will be a wind advisory for Niihau and Kauai.

From 6 p.m. Friday to 6 a.m. on Monday there will be a high wind warning for the summits of Hawaii island and a wind advisory for the summit of Haleakala.

From 6 a.m. Friday to 6 p.m. Sunday there will be a small craft advisory for Kauai northwest and windward waters; Kauai channel; Oahu windward and leeward waters; the Kaiwi channel; Maui County windward waters; the Pailolo channel; the Alenuihaha Channel; and Hawaii island windward waters.

From 6 p.m. Friday to 6 p.m. Sunday there will be a small craft advisory for Kauai Leeward waters.

From 6 a.m. to 6 p.m. there will be a gale warning for Kauai leeward waters.

UPDATE: 6:35 p.m.

The entire state is under a flash flood watch through Monday afternoon, and the Big Island summits will be under blizzard and high wind warnings over the weekend with winds gusting over 100 mph, and a possible foot of snow, forecasters said.

The flood watch is due to a cold front that will move over the islands and then stall as a kona low develops west of Kauai, bringing the threat of an extended period of flooding rain, the National Weather Service said.

The weather service issued both high wind and blizzard warnings for the Big Island summits from 6 p.m. Friday until 6 a.m. Sunday.

“Travel could be very difficult to impossible. Blowing snow will significantly reduce visibility at times, with periods of zero visibility,” forecasters said.

They predict southwest winds from 50 to 80 mph with localized gusts over 100 mph.

“Winds this strong will make driving and walking extremely dangerous,” forecasters said, “The winds can cause significant damage or injuries.”

For the statewide flood watch, the weather service said, “A cold front will move over the islands from the northwest tonight and Friday, initially bringing a relatively short period of heavy rainfall to Kauai and Oahu.

“The front is expected to stall near Maui County and the Big Island late Friday, bringing the potential for an extended period of heavy rainfall as a slow-moving kona low forms west of Kauai on Saturday. As the low develops, moisture associated with the front will spread back toward the west, bringing the threat of heavy rainfall to all islands, with this threat likely persisting well into next week.”

Forecasters said roads in several areas may be closed, and that isolated highways, such as the Big Island’s Belt Highway, and Piilani Highway on Maui, “may be closed in one or more locations, resulting in long detours or even the isolation of communities. Landslides may also occur in areas with steep terrain.”

3:45 p.m.

The National Weather Service in Honolulu has issued a flash flood watch for the island of Oahu through Monday.

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Heavy rains and possible thunderstorms are on the way as a cold front hits Kauai tonight, according to forecasters. The front is expected to travel down the island chain and stall near Hawaii island Saturday.

The National Weather Service has issued a winter storm watch for Hawaii island summits, warning of heavy snow and high wind from Friday evening to Saturday night.

Up to 4 inches of snow is possible at the summits, along with southwest winds of 50 to 80 mph, with gusts higher than 100 mph at the summits.

A high wind watch is also in effect for the summits, but from Friday evening through late Sunday night.

Travel to the summits should be postponed until the weather improves due to reduced visibility — or periods of zero visibility — and serious injury that could result from slamming doors and flying objects.

Forecasters expect a band of showers and possible thunderstorms as the front moves down the chain, with a cool, northerly flow behind it, prompting a possible wind advisory for Kauai.

Due to the potential of very heavy rainfall, NWS has also issued a “hydrologic outlook,” warning that there will likely be numerous flooding impacts as early as Saturday or Sunday.

“It is too soon to know exactly where the main rain bands will set up, but the areas with the greatest current potential for flooding include the Big Island and Maui County,” said NWS in the outlooks. “Additional rain bands may also develop and affect Oahu and Kauai County as the event progresses into next week.”

A gale watch also remains in effect for the waters surrounding Kauai, from Friday morning through Friday afternoon.