Breezy trades will gradually weaken through the weekend as a stout low pressure system developing to the far north disrupts the surface ridge extending over the islands. Clouds and showers will favor windward and mauka areas today, then the focus shifts to sea breezes each afternoon over the weekend. Early next week, increasing moisture will move up the island chain from the southeast, increasing rain chances for the eastern end of the state Monday night through Tuesday night. Moderate to locally breezy trades are expected to return shortly thereafter for the remainder of the forecast period.
Trade wind pattern continues today with isolated showers in windward areas. Localized MVFR windward and mauka, but improving conditions during the day. VFR prevails.
AIRMET Sierra is in effect for mountain obscuration on Kauai Oahu and the Big Island, but will likely be cancelled by 20Z as conditions improve but may be needed again tonight.
And AIRMET Tango is in effect for moderate turbulence downwind of mountain areas which will continue today.
Fresh to strong trade winds will persist today as the subtropical ridge remains strong north of the state. As such, the Small Craft Advisory is in effect through this afternoon for the windier waters around Maui and the Big Island. Thereafter, guidance depicts the ridge beginning to weaken in response to broad low pressure developing roughly 1,500 nautical miles to the north near the Aleutian Islands this weekend through early next week. This will translate to local trades easing into the light to moderate range, likely giving way to localized land and sea breezes near the coasts late this weekend through early next week. A return of moderate to fresh easterly trades is likely by midweek as the ridge strengthens.
An active pattern is in store for surf along south-facing shores as we head into June due to a series of recent gale- to storm- force lows passing through our swell window near New Zealand over the past week. Expect surf to gradually build today as forerunners from a long-period south-southwest swell arrive while the current medium-period south swell fades out. Our buoys are already reflecting this new source with energy registering in the 20-23 second bands this morning. Surf heights will likely reach the advisory level by tonight, with the swell becoming fully established by Saturday. Heights will hover near the advisory level through the weekend. As the swell gradually begins to ease early next week, long-period forerunners from the next south- southwest swell are expected to arrive. Heights may briefly dip below the advisory level Monday night, but as the next swell fills in, surf will likely return to the advisory level Tuesday through midweek as it peaks. A gradual downward trend is then expected through the second half of next week.
A combination of advisory-level surf this weekend and water levels hovering above predicted levels could lead to some wave runup issues, with water sweeping across areas of beaches that typically remain dry. Water levels will steadily lower each day early next week as the next large south swell arrives.
The current small northwest swell will slowly lower through Saturday before fading on Sunday. A small north swell will likely produce surf near seasonal averages along north-facing shores from late Tuesday or Wednesday into Thursday.
Expect surf along east-facing shores to remain near seasonal averages today, then gradually decline through early next week as trade winds ease. A slight increase is possible Tuesday and Wednesday due to a combination of rebuilding trade winds and a wrapping north swell.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
