textproduct: Honolulu

SYNOPSIS

High pressure will build in from the north today and allow the trade winds to strengthen into the moderate to locally breezy range through Wednesday. Brief passing showers will favor windward and mountain areas in the overnight to early morning hours through Wednesday and then over southeastern slopes of the Big Island and Maui, including all island interior sections from Thursday onward. Winds will weaken and veer slightly from a more east- southeast direction from Thursday on into the weekend. Shower activity will remain limited during this time period.

DISCUSSION

The large band of high level cirrus clouds and mid level alto stratus clouds currently over the islands will continue to slowly diminish through the day. Trade winds will blow into the region and strengthen into the moderate to locally breezy range through Wednesday.

A slight decrease in wind speeds and a shift from a more east- southeast direction remains in the forecast from Thursday onward as another cold front approaches Hawaii from the northwest, weakening and lifting the ridge near the islands northward. Local scale sea breeze winds will develop along terrain sheltered slopes of each island as the large scale winds weaken. Limited shower activity will prevail into next weekend with only brief showers possible.

Looking out into the long range forecast outlook. Our next best chance for unstable statewide rainfall may develop by early next week in southerly wind flow as another cold front moves into the Hawaiian Islands from the west. Stay tuned.

AVIATION

A weakening trough will keep mid and high level clouds in place today with some disorganized showers in the morning before trade winds build in during the afternoon. Once trade winds return, drier and more stable air will fill in and showers will focus back over typical windward and mountain areas. Brief MVFR conditions may occur with showers, otherwise VFR is expected.

AIRMET Tango remains in effect across the islands due to upper- level turbulence from FL200-400, with conditions expected to gradually move down to the lower flight levels through the day. Light icing is also possible in cloud layer 120-180 and will likely decrease later today.

MARINE

A cold front dissipated into a trough and will linger just northwest of the area today. Fresh to locally strong easterly trades will build in tonight as surface ridge strengthens to the north, and a Small Craft Advisory will likely be needed for the typically windy channels and waters of Maui County and the Big Island by that time. Winds will maintain strength but veer east southeast towards the end of the week as another weather system approaches from the west.

Surf along north- and west-facing shores will remain slightly elevated, but still well below advisory levels, today as a moderate, medium period northwest swell (310 degrees) continues to impact the islands. Surf along north- and west-facing shores will then gradually decrease on Tuesday and remain small though the rest of the week, with another small northwest bump expected this weekend.

Surf along exposed east-facing shores will be a bit elevated due to a short period northeast (40 degrees) swell that will maintain today, then decline Tuesday. However, as this northeast swell declines, short period choppy conditions are expected to return as fresh trade winds redevelop and expand upstream of the state.

Surf along south-facing shores will remain small to tiny, with no significant swells forecast for at least the next several days.

HFO WATCHES/WARNINGS/ADVISORIES

None.