textproduct: Honolulu

SYNOPSIS

An unstable and somewhat wet trade wind pattern will continue through mid-week, with brief downpours possible. During the second half of the week, a strengthening area of high pressure north of the islands will increase stability across the region, producing drier, but windier conditions.

DISCUSSION

This morning, local satellite and radar imagery shows just a few light scattered showers moving into the islands on moderate easterly trade wind flow. While some areas of the state received significant rainfall totals yesterday, shower intensity and coverage eased area-wide after sunset. With that said, the early morning sounding from Hilo continues to show over two inches of precipitable water, compared to the much drier Lihue sounding. Broad troughing aloft persists over the islands, and with this amount of ample moisture available, expect that a generally wet trade wind pattern will continue for the next couple of days with frequent showers over windward areas, especially for the Big Island. Some showers could produce brief downpours, similar to those that were observed this past weekend at times. Showers will generally favor windward areas during the overnight and morning hours, with scattered leeward showers developing during the afternoons. Additionally, dewpoints will continue to linger in the upper 60s to low 70s, which should make temperatures feel warmer than normal.

Increased stability and stronger trade winds are expected by Thursday. Latest global guidance remains in good agreement with a strong high developing far north of the state during the second half of the week, which should result in windy conditions. Winds could potentially reach Wind Advisory levels Thursday into Friday for select areas downstream of terrain. Drier conditions are also expected during this time, but scattered showers embedded within the windy trade wind flow will continue, especially during the night and early morning hours.

AVIATION

Moderate to locally breezy trades expected for the next couple days. Low cigs and SHRA should primarily impact windward and mauka locations with some limited spillover to leeward areas. MVFR conds possible in heavier SHRA, otherwise VFR prevails.

AIRMET Sierra is in effect for mtn obsc for Kauai, Oahu, Maui and windward sections of the Big Island.

MARINE

The pressure gradient back from a surface high centered about 1,400 nautical miles northeast of the islands remains tight enough to support moderate to locally fresh trades the next few days. This anchored high will strengthen and expand past mid week. The resultant tightening gradient will produce fresh to locally strong trades during the later half of the week.

A small size, short to medium period north northwest (320-330 degree) bump tonight into early Tuesday will provide an additional foot or two upon north-facing shore surf Tuesday.

The arrival of a couple of medium to long period south southwest (200 degree) swells the next few days will maintain seasonable surf along southern facing shores. Strengthening trades later this week will keep short period, elevated wind wave chop alive going into the weekend.

Water levels peaking between 2.5 to 3.0 ft MLLW during today's high tides may result in some minor overwash within low lying coastal areas.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.