textproduct: Honolulu

SYNOPSIS

Breezy to locally windy trades will weaken slightly through Monday, then hold at moderate strength through the remainder of the week. Showers will favor windward and mauka areas, with little rainfall over most leeward sections.

DISCUSSION

Locally windy trades remain in place this afternoon, though down slightly from yesterday's peak. A 1032 mb surface high centered about 950 miles north of the islands is driving the strong trade wind flow, and mid level ridging northwest of the state is creating very stable conditions with an inversion ranging between 5,000 to 7,000 feet. Under this environment, winds continue to be accelerated over and downwind of terrain, and the Wind Advisory has been extended through tonight for portions of Big Island and Maui, mainly to account for the evening hours that tend to experience stronger gusts. Even though the atmosphere is stable and precipitable water is near to below seasonal average, trades will continue to focus showers over windward and mauka areas, where generally less than a quarter of an inch of rainfall is expected tonight. Aside from a few lingering showers over the Kona slopes of the Big Island this evening, little leeward rainfall is expected.

Trades will drop a notch during the weekend but will still remain breezy through the Memorial Day holiday. The surface high driving the winds will weaken slightly but remain at around 1029 mb, strong enough to produce breezy trades. Stable conditions will continue, and modest windward rainfall and a few afternoon showers over the Kona slopes are expected. Moderate trade winds will prevail Tuesday through the middle of next week.

AVIATION

While trades will subtly weaken through the period, most sites will still experience moderate to occasionally strong gusty winds. A relatively dry air mass moving across the island chain will hold shower activity to a minimum. Quick passing areas of deeper moisture will increase shower frequency and be focused on either windward sites or within higher terrain. MVFR conditions may occur within heavier showers.

AIRMET Tango remains in effect for all islands due to the low level turbulence created over and downwind of terrain in response to amplified winds.

MARINE

A strong high pressure ridge will remain north of the Hawaiian Islands maintaining strong to near gale force trade winds into Saturday. The high will begin a weakening trend Saturday then shift northeast of the state during the first half of next week. Strong trade winds will gradually trend down to moderate to locally strong speeds by Tuesday and then hold through the end of next week.

A Small Craft Advisory (SCA) for all Hawaiian Coastal Waters remains in effect through early Sunday morning. The SCA conditions will likely continue for locally windier waters through the first half of next week.

A High Surf Advisory (HSA) for east facing shores has been cancelled. Near shore observations show surf heights have dropped below advisory levels thresholds thus have went ahead and cancelled the HSA. Surf heights are expected to remain just below advisory thresholds through the weekend and trend down next week as trade wind speeds ease locally and upstream.

Surf along north facing shores will remain tiny today. A small, moderate period north-northwest (330 degree) swell will trickle in early Saturday and peak Saturday night, bringing a small boost in surf heights along north and west facing shores through the weekend. A slightly larger northwest swell will fill in Tuesday and peak Wednesday of next week that could bring near to slightly above average summertime surf for north and west facing shores.

A small, long period south swell will continue to fill in tonight, peak Saturday, boosting surf to near to slightly above average. This swell will begin to fade out Sunday. Another similar south swell will slowly fill in Tuesday, peak Wednesday then slowly fade into the second half of next week.

HFO WATCHES/WARNINGS/ADVISORIES

Wind Advisory until 6 AM HST Saturday for Maui Windward West- Maui Leeward West-Kohala-Maui Central Valley North-Maui Central Valley South-South Haleakala-Big Island South-Big Island Southeast-Big Island North.

Small Craft Advisory until 6 AM HST Sunday for all Hawaiian waters-