textproduct: Honolulu

SYNOPSIS

Moderate trade winds will prevail through tonight, then increase Friday through this weekend. Most shower activity will occur during the nights and early mornings and affect windward and mauka locations. From Saturday afternoon through Monday, an area of tropical moisture will move over the southern half of the state (Big Island and Maui) from east to west and bring enhanced showers. A typical stable trade wind pattern will return by Tuesday of next week.

SHORT TERM UPDATE

Water vapor imagery loop from this evening depicts the broad cyclonic spin of an upper low, centered around 450 miles northwest of Kauai. This feature continues to draw areas of mid and upper level moisture northward over the state.

Trades have remained in the light to moderate range, thanks to a trough far to the northeast acting to subdue the effect of stronger high pressure further north. The 00Z Hilo upper air sounding indicates a rather shallow marine layer, near 5000 feet. This has helped to put up a cap on any cumulus and kept shower coverage to a minimum. Expecting only isolated showers to affect windward and mauka to continue tonight. In the short term update, chances of precipitation and cloud cover were decreased across all islands through Friday morning to account for current trends. All other forecast parameters looked on track.

AVIATION

Trade winds are forecast to ramp up into the weekend as the driving high strengthens and pushes slightly closer to Hawaii. Stability will also be increasing on Friday as an upper low to the west lifts away. Leeward turbulence will likely increase around Friday night or Saturday, but no AIRMET will be needed for now.

A band of low clouds and showers will move onto windward Big Island tonight, then become more diffuse as it spreads westward. Mountain obscurations/AIRMET Sierra will be possible for this area overnight as this moisture tracks in, but nothing will be needed through the evening.

MARINE

Issued at 308 PM HST Thu Aug 6 2026 Moderate trades persist as surface troughing to the northeast maintains a rather weak pressure gradient over the state. Dissipation of the trough to the northeast combined with renewed trough development south of the islands and strengthening high pressure to the northeast will favor fresh to locally strong trades by week's end.

Background medium and long period energy will produce small surf for south facing shores through Friday. A series of larger, medium to long period south swells arrive beginning on Saturday, causing surf to trend up for south and west facing shores this weekend into early next week. A moderate, long period south swell will peak near the High Surf Advisory threshold by the middle of next week.

Along east facing shores, trade wind swell and moderate trades will support surf slightly below seasonal averages. Surf will build this weekend in response to strengthening trade winds. Surf along north shores remains flat to tiny through the period.

HFO WATCHES/WARNINGS/ADVISORIES

None.