textproduct: Honolulu

SYNOPSIS

A powerful kona storm will remain anchored northwest of the state producing periods of hazardous weather impacts across the Hawaiian Islands through the weekend. Expect a combination of threats ranging from significant flash flooding, damaging winds, strong to severe thunderstorms, and snow and ice over the highest Big Island summits. Strong southerly to southwesterly will hold through Saturday and producing damaging wind gusts. The highest threats for damaging winds remain along north and east of the island mountains. Unsettled wet weather conditions with decreasing southwesterly wind trends will continue into early next week. This kona storm begins to lift northward on Monday, and unsettled weather will start to ease across the Hawaii region. High pressure will build back in north of the state during the second half of next week allowing trade winds to gradually return from north to south.

SHORT TERM UPDATE

Looking into the satellite picture this evening we see the powerful kona storm northwest of the state with rotating upper level troughs enhancing showers and thunderstorms across the Hawaiian Islands. Large bands of heavy showers and thunderstorms will develop rapidly in this unstable weather pattern and may anchor or train over island mountains. Rainfall rates based on available radar and weather observation sites indicate these heavy rain bands are capable of producing 1 to 3 inches per hour. Flash Flood Warnings remain active for most islands this evening with numerous reports of flooding statewide.

Strong southerly to southwesterly winds above High Wind Warning thresholds have been reported this evening across the state. These damaging winds will likely continue through early Sunday morning across the state, and linger into Sunday evening for the Big Island.

Please postpone travel if possible at least through Saturday as weather conditions will remain a threat to life and property due to the ongoing strong winds, heavy rain, thunderstorm, and flooding impacts from this strong kona storm.

MARINE

ASCAT passes this morning showed gale-force winds in the waters near Oahu and Maui County this morning, and radar signatures supported gale-force winds with some of the strongest bands of showers moving through the area in association with the strong kona storm impacting the area. Gusty winds, steep and fast building seas, and low visibility in heavy showers will continue across the entire marine waters through the weekend.

The Gale Warning near Kauai and Oahu was expanded to include Maui County following the morning ASCAT pass. The Gale Warning was expanded to include waters near the Big Island starting tonight. The winds are expected to weaken near Kauai and Oahu tomorrow, but continue near Maui County and the Big Island through tomorrow night. These gale force southerly winds will create large and rough surf along south facing shores through Saturday afternoon and as such a High Surf Advisory is in effect for south facing shores. The winds by early next week will shift westerly and diminish as the storm gains increasing distance far to the north of the islands.

A small, short to medium period west to west-northwest swell will bring small to moderate surf to north and west facing shores through the weekend. Kauai will block some of this swell energy from reaching Oahu and Maui, but it will make it into the west facing shores of the Big Island. Additionally, a small, medium period north swell will peak Saturday before gradually declining.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday afternoon for Kauai County.

Flood Watch through late Saturday night for Oahu.

Flood Watch through late Sunday night for Maui County and the Big Island.

High Wind Warning until 6 AM HST Sunday for all Hawaiian Islands.

High Wind Warning until 6 PM HST Sunday for Big Island Summits- Haleakala Summit.

Winter Storm Warning until 6 PM HST Saturday for Big Island Summits.

Gale Warning until 6 AM HST Saturday for Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Oahu Leeward Waters.

Gale Warning until 6 AM HST Sunday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters-Big Island Windward Waters-Kaiwi Channel-Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Windward Waters-Pailolo Channel.

High Surf Advisory until 6 PM HST Saturday for south facing shores of all islands.