textproduct: Honolulu

SYNOPSIS

Breezy and gusty northeast trade winds will prevail through Tuesday before decreasing a notch midweek, then becoming light and variable heading into next weekend. A cool and dry airmass should keep showers light and over windward and mauka areas for the next few days, except windward areas of the Big Island where lingering moisture could keep scattered showers through Monday. A cold upper trough may slightly enhance trade wind showers during the overnight and early morning hours each day this week.

DISCUSSION

A 1034 mb high to the far northwest and a 1011 mb low to the far northeast are continuing to drive breezy and gusty northeast trade winds across the state this afternoon. Current observations (as of 3 PM HST) show northeast trade winds gusting to between 30 and 40 mph across some of the windier areas statewide. Breezy and gusty trade winds are expected to remain in place for the next few days as the high to the northwest remains nearly stationary. Model guidance continues to keep wind speeds below Wind Advisory criteria (sustained speeds of 30-39 mph and gusts 50-57 mph), though a few of the typically windier spots across the state may edge up pretty close to criteria at times this afternoon through Tuesday.

With drier air filtering across the state, shower activity is limited this afternoon, with low level clouds and a few showers focusing over windward Maui and the Big Island, where the greatest amount of moisture resides. Generally, in this breezy northeasterly trade wind pattern, clouds and light showers will favor north and east facing coasts and slopes, particularly during the overnight to early morning period. These showers may become slightly enhanced (produce brief moderate rainfall) at times as an upper level trough edges over the state and brings much cooler temperatures aloft. However, limited moisture, along with the relatively strong low level temperature inversion under the surface ridge, will help to keep shower activity limited.

By midweek, the high pressure to the northwest is forecast to weaken and move east, which in turn will allow the trade winds to ease. Next weekend could see light and variable winds as the pressure gradient backs off further. With a weak upper level trough swinging quickly through Friday into Saturday, shower activity may be enhanced slightly, though moisture still looks to remain limited and low level forcing, minimal.

AVIATION

Moderate to breezy NE trade winds persist across the state today. Embedded light showers remain limited to windward and mountain areas, providing brief MVFR conditions within showers while VFR prevails elsewhere. Expect these conditions to remain steady through tomorrow.

AIRMET Tango is in effect for moderate turbulence downwind of terrain due to breezy tradewinds. AIRMET Tango is also in effect for moderate turbulence from Maui to Big Island between FL240-FL360 due to the subtropical jetstream positioned near the area. This area of mid-upper level turbulence will likely persist through tonight, and potentially strengthen tomorrow.

No other AIRMET's are in effect.

MARINE

Strong high pressure NNW of the islands and low pressure to the NE maintain fresh to strong NE trades through Monday. The gradient then relaxes as the low dissipates allowing winds to ease and veer to the E as the high settles to the N through midweek. The Small Craft Advisory for all waters due to winds and seas remains in effect through tonight.

The aforementioned low is directing a moderate to large short period NNE (020) swell that will peak tonight. Given recent observations at NDBC Buoy 51000, surf will reach the High Surf Advisory (HSA) threshold for N facing shores, select exposed E facing shorelines, and West Maui. A High Surf Advisory has therefore been issued for these zones. This swell will slowly decline through the week.

The Marine Weather Statement remains in effect beginning at 6pm today for harbor surges due to the NNE swell, particularly for Hilo and Kahului Harbors.

Surf along E shores remains short period and choppy due to steady trade winds with select shorelines also seeing exposure to the imminent NNE swell. For S shores, a small medium period swell will provide small surf for the next few days. Surf along W shores remains small.

HFO WATCHES/WARNINGS/ADVISORIES

High Surf Advisory until 6 PM HST Monday for Niihau-Oahu North Shore-Olomana-Maui Windward West-Maui Leeward West-Kauai North- Kauai East-Koolau Windward-Molokai Windward-Molokai North-Maui Central Valley North-Windward Haleakala-Big Island East-Big Island North.

Small Craft Advisory until 6 PM HST Monday for all Hawaiian waters-