textproduct: Honolulu

SYNOPSIS

Light winds, increasing humidity, and land and sea breeze conditions will persist through midweek as a series of fronts pass north of the state. Showers will remain brief and primarily over interior and leeward areas during the afternoons. Rainfall chances may increase by the weekend as an upper disturbance approaches the region.

DISCUSSION

The subtropical ridge will remain weak through midweek as a series of cold fronts pass well north of the state. This pattern has disrupted the typical trade wind flow, allowing land breezes to develop overnight into this morning. A more humid air mass will settle over the islands, with dewpoints climbing into the upper 60s.

These elevated dewpoints, combined with a weak front in the vicinity and afternoon sea breeze development, will support localized cloud buildups and scattered showers over interior and leeward areas each afternoon. Clearing is expected overnight as land breezes reestablish.

By the latter part of the week into the weekend, moisture and rainfall chances may increase. Global guidance indicates lowering heights aloft as an upper-level disturbance and its attendant cold front approach and move into the area. Uncertainty, however, remains high due to differences in model solutions regarding the timing and strength of these features, resulting in low confidence in the details.

AVIATION

Trades will continue to weaken over the coming days, resulting in sites seeing more of a land/sea breeze pattern, especially by the evening. In the meantime, windward showers are expected to persist, with MVFR conditions possible at times due to low clouds and degraded visibilities.

AIRMET Sierra remains in effect for windward Maui and the Big Island due to mountain obscuration. Conditions may improve by daybreak, but satellite imagery suggests that low-level moisture and clouds may persist into the afternoon hours.

MARINE

The trades will ease and shift southeasterly at light to moderate levels today and tonight as an approaching front merges with a trough north of the island chain. The 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.