Marine Weather and Tide Forecast for Naalehu, HI

DISCUSSION

Light winds continue across the state this evening as a weak surface trough extends northward from Oahu and high pressure remains far northeast of the islands. Radar and satellite imagery show the numerous moderate to locally heavy showers that have developed over island interiors this afternoon as sea breezes matured are trending down and pushing offshore as land breezes begin to develop. A deep upper level low just east of the state will begin to shift eastward and open up into a trough overnight through Wednesday. The proximity of the low this evening will keep thunderstorms in the forecast but will taper off by Wednesday. Volcanic emissions and light background east southeast flow will keep vog in place over portions of the state through tonight.

Wednesday will serve as a transition day where gentle to moderate trades will gradually build back as the surface trough dissipates west of the state. This will allow drier air to slowly filter in from the east. The airmass will also gradually become more stable as the upper level low shifts eastward and weakens, allowing a mid level ridge to build over the state. Vog will also shift away from the smaller islands and blow mostly offshore by Wednesday night.

Moderate to locally breezy trades are expected to return Friday then hold through early next week as a pair of strong high pressure systems move north of the state. Expect showers to favor windward and mauka areas, particularly during the overnight and early morning hours.



AVIATION

A few heavy SHRA and isol TSRA is possible the rest of this evening. Trades return tomorrow with SHRA along windward and mauka locations. Brief periods of MVFR/IFR conds may occur with the more robust showers and storms, otherwise VFR should prevail.

AIRMET Sierra for mtn obsc is currently in effect for Maui, Lanai, and the Big Island. Conds are expected to improve later this evening.



MARINE
A trough of low pressure north of the island chain will linger through the night and continue to weaken the high pressure ridge over the state, keeping light and variable winds across the region. Trades with more stable weather conditions will build back in from tomorrow onward, strengthening to Small Craft Advisory levels for the typical windier coastal waters around Maui and the Big Island by Thursday.

A small northwest swell will continue to slowly fade, allowing surf along north and west facing shores to remain near or below average levels for this time of year. By Thursday, a moderate to long period north-northwest swell is expected to arrive, producing surf above the seasonal average. This north-northwest swell will slowly decline over the weekend.

Multiple small south swells will keep elevated south shore surf heights into the weekend. Trade winds should strengthen through Friday with rough and choppy surf rising along east facing shores by this weekend.



HFO WATCHES/WARNINGS/ADVISORIES
None.