textproduct: Honolulu

SYNOPSIS

Breezy trade winds will persist into Thursday, with showers favoring windward and mauka areas. Friday into the weekend, trades will ease slightly and a passing upper-level disturbance, along with increasing moisture, should bring an uptick in trade wind shower activity, with pockets of heavy rain possible. Then a more stable, breezy trade wind pattern should redevelop by midweek next week.

SHORT TERM UPDATE

Latest satellite imagery is showing a band of cumulus clouds 100 to 150 miles east of the Big Island. This band of moisture should arrive late tonight into Thursday morning across windward areas of the eastern half of the state. With the increase of showers expected, I did increase the POP's for windward areas during this time especially over the Big Island. Otherwise, no major changes this evening.

PREV DISCUSSION

Issued at 339 PM HST Wed May 13 2026 Broad high pressure to the far north of the state (centered around 40 N) will maintain breezy trade winds across the region into Thursday, delivering clouds and isolated to scattered showers to windward and mauka areas, particularly during the overnight to early morning hours.

During this time, a weakness will develop in the ridge aloft and a mid- to upper-level low will break away from the base of a longwave trough and move directly over the main Hawaiian Islands by Friday evening. This upper level disturbance will induce a broad surface trough over the region, weakening the local pressure gradient and allowing the trade winds to ease and veer slightly. Cooler temperatures aloft and the potential weakening of the low- level inversion will help to create a more unstable environment over the state, likely enhancing trade wind showers. In addition, deep tropical moisture will move up from the south, with models showing precipitable water values climbing into the 1.5 to almost 2 inch range over the eastern end of the state. This setup will likely bring enhanced showers to the western end of the state beginning on Friday where the greatest instability will be, then transition over the eastern end by Sunday into Monday, where the deepest moisture will be. The main limiting factor to a more organized enhanced shower setup is the lack of any strong lifting mechanism at the surface. As such, the most likely locations to experience heavy rain are the windward and mauka areas that are impacted by orographic lift in a trade wind pattern, though the hi-res guidance is just now reaching Friday afternoon where they also highlight interior and leeward Oahu as the upper-level low moves overhead and the background winds become light enough to support sea breeze development. In addition to the the potential for pockets of heavy rain this weekend, dew points are expected to rise into the lower 70s, leaving this weekend feeling muggier with lighter winds.

Beyond Monday, differences between the global models become more apparent, but for now, expecting a more stable, breezy trade wind pattern to redevelop by midweek next week.

AVIATION

Breezy trades expected for next few days. Low cigs and SHRA expected along windward and mauka locations. MVFR conds possible but VFR should prevail.

AIRMET Tango is in effect for turb lee of terrain due to the breezy trade winds.

MARINE

High pressure established north of the islands maintains locally strong trades until an upper disturbance causes winds to weaken by this weekend. Our current fresh to locally strong trades should hold through the day Thursday then gradually weaken and veer towards the east-southeast Thursday night into Friday. Moderate to fresh east to east-southeast winds are expected Friday into the weekend. The SCA remains in effect for the windier zones of Maui County and the Big Island through Thursday afternoon.

Small, short period NW swell fades tonight and will be replaced by a small to moderate, long period NW swell that will peak on Thursday bringing small to moderate surf to favored exposures. Latest readings on buoy 51001 is showing long-period forerunners in the 15 to 17 second energy bands, which should steadily fill in tonight.

Small, medium to long period S swell maintains small surf along S shores. A series of gales initially passing south of New Zealand a few days ago and now setting up E of New Zealand should send a series of small south swells all of next week. Surf should rise to near the summer average around Sunday and hold near the summer average throughout next week. Meanwhile along east facing shores, locally strong trades will maintain rough and choppy surf along E facing shores. A slight decrease of wind swell is expected Thursday into Friday as the trades weaken to moderate to locally fresh speeds.

Tides peak around 2.5 ft MLLW this weekend. Combined with ongoing trades and a modest boost in S swell, water levels will peak around 3.0 ft late this weekend into early next week. Minor overwash of low lying coastal areas will be possible during the afternoon high tides at this time.

HFO WATCHES/WARNINGS/ADVISORIES

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