textproduct: Honolulu

SYNOPSIS

Moderate easterly trade winds will ease Tuesday as the surface ridge weakens, bringing a transition to light winds, increasing humidity, and land and sea breeze conditions through Thursday. Showers will remain brief and mainly over interior and leeward areas during the afternoons. Rainfall chances may increase by next weekend as an upper disturbance and a weak front approach the islands.

DISCUSSION

Moderate easterly trades will remain in place through much of the overnight hours, with low clouds and a few light showers focused over windward and mauka areas. Leeward areas will remain mostly dry, with only isolated passing showers possible.

Beginning late tonight or early Tuesday, the ridge north of the islands will weaken in response to a series of cold fronts passing well north of the state. This will lead to a gradual easing of the trade winds, with local land and sea breeze circulations becoming more dominant through midweek. From Tuesday through midweek, a more humid air mass will settle over the islands, with dewpoints potentially climbing into the mid- to upper-60s. These dewpoints combined with the afternoon sea breezes will support localized afternoon cloud buildups and a few brief showers over interior and leeward areas, followed by clearing at night as land breezes develop.

By the latter part of the week into the weekend, moisture and rainfall chances may trend up. Global guidance indicates upper heights lowering as an upper-level disturbance approaches the region. In addition, a weak attendant frontal boundary may move into the area. However, there remains considerable spread among the model solutions regarding the timing and strength of these features, so confidence in the details remains limited at this time.

AVIATION

Moderate trade winds will deliver showers over windward and mountain areas through this evening before weakening overnight. Light winds tomorrow will allow a land and sea breeze pattern to take place with possible afternoon showers over island interiors. Periods of MVFR ceilings and visibility are possible in showers, otherwise VFR is expected.

AIRMET Sierra is currently in effect for mountain obscuration over windward areas of Maui, but expect conditions to improve overnight. No other AIRMET's are in effect.

MARINE

High pressure northeast of the state will drive moderate to fresh trades tonight. The trades will ease and shift southeasterly at light to moderate levels Tuesday and Tuesday night as an approaching front merges with a trough north of the island chain. the trough will weakening front will pass north of the area on Wednesday, bringing light and variable winds, with sea and land breezes present near the immediate coasts. A new high building northwest of the state will bring a return of light to moderate trades Thursday and Friday, with the trades strengthening to moderate and fresh levels over the weekend. Winds and seas are expected to remain below Small Craft Advisory thresholds through at least Friday.

A moderate medium-period northwest swell will gradually lower during the next couple of days. A new long period swell will build Wednesday night and give a nice boost to north and west shore surf Thursday and Friday, followed by a gradual decline over the weekend into early next week.

A series of overlapping south swells will keep steady small surf rolling into south facing shores during the next week.

Surf along east facing shores will remain below normal during the next 7 days due to the lack of strong trades over and upstream of the islands.

HFO WATCHES/WARNINGS/ADVISORIES

None.