textproduct: Honolulu

SYNOPSIS

Light to moderate background trade winds will prevail, allowing sea breezes to develop in sheltered leeward areas today. A brief increase in windward showers is expected Monday night into Tuesday, especially for the easternmost islands. Moderate trade winds will begin building back into the region during the second half of the week, becoming locally breezy again by the weekend.

DISCUSSION

Currently as of 3AM HST, radar and satellite shows a mostly to partly cloudy sky with a few isolated light showers going on across the state. A weak low in the mid and upper levels is located just east of the Big Island. Over the next few days, this feature will linger and then move off to the northeast, with little effect on island weather. However, an area of enhanced moisture associated with a trough east of the islands will make its way westward, reaching the eastern end of the state later today. As this feature quickly moves through, windward showers are anticipated to increase, especially for the Big Island and Maui. The remaining islands may see a slight increase in windward and mauka showers as well.

By Wednesday, moderate trades will build back into the region, strengthening to become locally breezy by the end of the week. Showers will generally favor windward and mauka areas throughout the rest of the week, especially during the overnight and morning hours. An additional band of moisture approaching from the east could bring another uptick in showers late this week into next weekend.

AVIATION

Light to moderate trade flow will to continue today. Isolated afternoon clouds and showers should once again develop over terrain sheltered/leeward areas due to the light winds. However, shower activity across windward and mountain areas will be limited. A surface trough is forecast to approach from the east tonight and provide an increase in shower coverage along windward areas of Big Island. Brief periods of MVFR ceilings and visibility may occur with this activity. VFR conditions elsewhere.

No AIRMETs are currently in effect.

MARINE

Moderate to locally fresh trade winds continue through Tuesday before decreasing by mid-week into the light to moderate range. Slight day to day fluctuations are expected, then trades are expected to strengthen towards the end of the week as high pressure builds north of the area.

A long-period south swell will hold through Monday, producing elevated surf along south and west-facing shores, but it will remain below advisory levels. South shore surf will decline gradually Tuesday into Wednesday, but a new long-period south swell arriving late Wednesday will provide another bump in surf for Thursday and Friday.

A small small, long-period northwest swell will arrive this afternoon and peak Tuesday into Wednesday. This swell is expected to boost north shore surf to moderate levels. A moderate mid period north- northwest swell is possible by the end of the week into the weekend, depending on the evolution of a projected low in the north Pacific. However, confidence is low given differences in model solutions with this feature.

Surf along east-facing shores will remain small as local winds remain fairly weak with only slight variations each day. Small, moderate-period west and east swells generated by multiple Pacific tropical cyclones continue to move through the islands through Monday.

FIRE WEATHER

Light to moderate trade winds will continue for the first half of the week. Dry air will bring RH levels down to near- critical values for parts of the state through this afternoon but winds will be light. Inversion heights range from 4000-11000 feet.

HFO WATCHES/WARNINGS/ADVISORIES

None.