textproduct: Honolulu

SYNOPSIS

Moderate to locally breezy trades will prevail for the next several days, resulting in periods of shower activity across primarily windward and mauka locations. A nearly stationary upper- level low northeast of the islands will enhance clouds showers through Friday. By the weekend, the disturbance aloft is forecast to finally meander farther northeast away from the state. However, periods of windward and mauka showers will continue.

SHORT TERM UPDATE

Minor updates to PoP to account for some scattered showers moving across the chain. Otheriwse previous forecast remains on track.

PREV DISCUSSION

Issued at 358 PM HST Wed Apr 29 2026

This afternoon, moderate to locally breezy trade winds continue to prevail across the island chain, steered by two areas of high pressure centered north and northeast of the islands that are separated by a front that extends from southern Alaska to near 30N. Meanwhile, water vapor imagery shows a distinct low aloft northeast of the main Hawaiian Islands. This upper-level disturbance has introduced some instability in the vicinity of the state, as seen on the afternoon upper air soundings from Lihue and Hilo. This instability is resulting in deeper clouds and some enhanced shower activity this afternoon, particularly across windward sections of Maui and the Big Island. A few showers have drifted into leeward areas as well, and afternoon sea breeze convergence has also increased clouds and showers along sheltered leeward locations, such as the Kona slopes of the Big Island.

Forecast guidance is in good agreement that the upper-level low northeast of the island chain will remain nearly stationary through Friday, which will continue a similar wet trade wind pattern into the next couple of days. Showers will favor windward slopes of all islands, with some possible shower activity drifting into leeward areas briefly. However, by this weekend, the upper- level low will finally exit the region, though periods of showers will continue to favor windward areas. Only slight variations in day-to-day trade winds are expected over the next several days, with slight stenghtening followed by slight weakening this weekend. By early next week, model guidance shows a shallow cold front and another upper-level trough approaching the islands from the northwest early next week, though it remains to be seen how much moisture can be expected with this system.

AVIATION

Issued at 358 PM HST Wed Apr 29 2026

Moderate to fresh trades will strengthen slightly tonight. No AIRMETs in effect this afternoon, with light leeward turbulence expected and brief mountain obscurations due to the presence of an upper low just northeast of Hawaii. A band of showers will move in with the trades tonight, along with the boost in wind speeds, will likely result in both AIRMET Sierra for windward tempo mountain obscurations and AIRMET Tango for leeward tempo moderate turbulence overnight.

MARINE

High pressure strengthening to our north will strengthen the trade winds Thursday into Friday with widespread fresh to locally strong trade winds expected by Thursday afternoon. Currently a Small Craft Advisory (SCA) is in effect for the typical windy areas of Maui County and the Big Island. The SCA may need to be extended to other area waters as the trade winds strengthen over the next 24 to 36 hours. Over the weekend, a front passing far north of the state will shift the high further east and will allow the trade winds to decrease below SCA thresholds by Sunday.

A northwest to north-northwest (320-330 degree) will likely peak tonight into Thursday morning then slowly decline into Friday. Looking further ahead, a storm-force low currently in the North Pacific will send a moderate, longer-period northwest swell toward the islands for late Friday into Saturday, with above average surf expected along north and west facing shores. Average H1/10 heights for north facing shores is 6 feet for the month of May (Goddard- Caldwell Database).

Surf along south-facing shores will remain small through the rest of this work week, with mainly background south to southwest swell expected. A small south-southwest pulse should arrive this weekend from recent activity east of New Zealand, providing an increase in surf especially by Sunday.

Surf along east-facing shores will rise slightly Thursday and Friday as trades strengthen.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Friday for Kahoolawe.

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