Trade winds will be on the increase tonight, with strong and gusty winds expected Wednesday through Thursday as a new high builds north of the state. Relatively dry conditions are expected through Wednesday with additional windward showers moving in Wednesday night into Thursday as a band of moisture moves from north to south across the state. Moderate to locally breezy trades will briefly return around Friday or Saturday, but trade winds will strengthen once again Saturday night into Sunday.
A 1030 mb high building far north of the state tonight into Wednesday will strengthen the trade winds and will bring windy conditions across the state. A Wind Advisory has been issued for the typical windy areas around Maui County and the Big Island starting at midnight tonight and continuing through Wednesday night. Winds will be strongest through gaps, and over and downslope of ridges Wednesday through Wednesday evening. Wind gusts of 50 mph is expected during this time. For Oahu and Kauai, strong trade winds are expected during this time, but confidence was not quite high enough to see advisory level winds. Gusty conditions should still be expected with wind gusts of 40 to 45 mph for areas downwind of terrain on Wednesday. The combination of strong trade winds and mostly dry conditions will elevate fire weather concerns on Wednesday. Please see Fire Weather section for more details.
An old frontal boundary is expected to move north through south of the island chain Wednesday night into Thursday, which should bring a brief increase of scattered showers, especially over windward and mauka areas. The strong trade winds should begin to ease some by Friday afternoon down to breezy to locally strong speeds. From Friday through the weekend, we should see our typical trade wind shower coverage with showers most frequent during the overnight and early morning hours over windward and mauka areas. Trade winds should restrengthen back to strong levels Saturday night into Sunday as another high passes far north of the state.
Trade winds are expected to strengthen tonight to locally strong wind speeds. Showers embedded within the trade winds will continue to primarily impact windward and mountain areas. Brief MVFR conditions are expected within showers while VFR prevails elsewhere.
AIRMET Tango will remain in effect for moderate turbulence downwind of terrain due to the breezy trade winds. Upper level turbulence is also expected to be present over the state through tonight, roughly between FL300 and FL370.
AIRMET Sierra is in effect for mountain obscurations for windward areas of Molokai, Maui, and the Big Island. Overnight showers could warrant this AIRMET being expanded to include other windward and mountain areas.
High pressure will build north of Hawaii resulting in trade winds will becoming strong tonight and continuing through Thursday. A Gale Warning has been issued for the typical windy waters around Maui County and Big Island, and a Small Craft Advisory (SCA) for all other coastal waters through Wednesday night, with likely SCA continuing for most areas Thursday.
Seas are also forecast to exceed 10 feet beginning Wednesday with the arrival of a large north northwest swell. Meanwhile, a front will drop south into the northern offshore waters tonight and weaken to a trough. The trough reaches the central waters by Wednesday night and will lead to increased shower activity into Thursday. Winds will slightly taper off this weekend as a front approaches from the north.
The large north northwest swell (340 degree) swell will arrive on Wednesday and will bring advisory to near-warning level surf to exposed north and west facing shores through Thursday. The High Surf Advisory has been issued for north and west facing shores of Niihau, Kauai, Oahu, Molokai and for north facing shores of Maui from Wednesday morning through Thursday afternoon. Surf will decrease Friday followed by a reinforcement this weekend which could push surf back to advisory levels.
Surf along east facing shores will increase for Wednesday as trade winds strengthen. East shore surf will remain elevated and choppy through Friday, then may diminish slightly this weekend. A small, long-period south swell may bring a small bump to south shore surf on Wednesday.
High Surf Advisory from 6 AM Wednesday to 6 PM HST Thursday for Kauai North-Maui Central Valley North-Maui Windward West-Molokai North-Molokai West-Molokai Windward-Niihau-Oahu North Shore- Waianae Coast-Windward Haleakala.
Wind Advisory from midnight tonight to 6 AM HST Thursday for Big Island North-Big Island South-Big Island Southeast-Kahoolawe- Kohala-Lanai Leeward-Lanai Mauka-Lanai Windward-Maui Central Valley North-Maui Central Valley South-Maui Leeward West-Molokai Leeward South-Molokai North-Molokai Southeast-Molokai West- Molokai Windward-South Haleakala.
Small Craft Advisory until 6 AM HST Thursday for Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters- Kauai Northwest Waters-Kauai Windward Waters-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.
Small Craft Advisory until midnight HST tonight for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
Gale Warning from midnight tonight to 6 AM HST Thursday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters-Maalaea Bay-Pailolo Channel.
