UPDATE: SATURDAY, 9:45 a.m.

A high surf warning has been canceled for north and west facing shores of Niihau, Kauai, Oahu and Molokai, and for north facing shores of Maui and the Big Island.

The National Weather Service this morning replaced the warning with an advisory for all affected shores that will remain in effect until 6 a.m. Sunday.

Surf is expected to reach 18 to 24 feet along north facing shores and 12 to 18 feet along west facing shores.

Forecasters predict a north-northwest swell to deliver large surf today, though wave height is expected to gradually decrease through tonight.

In addition to the large surf, the previously forecast cold front is still predicted to sweep across the state on Monday.

Heavy rainfall is expected along the front, with thunderstorms potentially forming Sunday night and Monday.

UPDATE: 4:35 p.m.

The National Weather Service is warning Hawaii residents that a “vigorous cold front” will bring strong kona winds and thunderstorms late Sunday and Monday.

”A powerful cold front is forecast to sweep across the state on Monday,” forecasters said in a special weather statement issued just before 4 p.m. “Southwest, or kona, winds will increase ahead of the front on Sunday, with gusty conditions initially developing across windward communities, as well as any locations over and downwind of terrain. These strengthening winds may become damaging Sunday night and Monday. Impacts could include roof damage, downed trees, and power outages.”

They said thunderstorms and heavy rain may develop as early as Sunday, and some thunderstorms could be severe Sunday night and Monday.

“At this time, chances for widespread flash flooding do not appear to be high. However, leeward communities could experience a period of heavy rainfall and potential flood impacts, especially on Maui and the Big Island later Sunday into Monday,” the advisory said.

The weather system system will also generate a large northwest swell that will affect the islands, bringing high surf and possible coastal impacts along north and west shores.

PREVIOUS COVERAGE

A large northwest swell will build across the islands today, according to the National Weather Service which has issued a high surf warning.

The warning covers north and west shores of Niihau, Kauai, Oahu and Molokai, and north shores of Maui and is in effect until 6 a.m. Saturday, forecasters said.

NWS expects “dangerous waves” of 20 to 30 feet along north shores and 14 to 22 feet for west shores of Niihau, Kauai, Oahu and Molokai. “Maui will see surf heights along north-facing shores building to 20 to 25 feet by this afternoon and evening,” officials said.

The swell “is expected to peak this afternoon and evening before slowly dropping to advisory levels on Saturday,” they said this morning.

Forecasters caution beach-goers to expect strong breaking waves and powerful currents. “Waves breaking in channel entrances may make navigating the channels dangerous,” the high surf warning said.

In addition to the high surf, Hawaii can expect rainy conditions today and again on Sunday and Monday, the weather service said.

“A front moving down the island chain from the northwest will continue to bring unsettled weather to the state into Saturday,” the NWS forecast said. “Showers, along with some thunderstorms, will spread over Maui and the Big Island today, tapering off early Saturday morning. Another round of unsettled weather and increasing winds, is expected Sunday through Tuesday, as a stronger front approaches the state.”