textproduct: Honolulu

SYNOPSIS

Moderate to breezy trades are expected to prevail today, slightly decrease on Sunday, then remain at mostly moderate speeds through late next week. Bands of low clouds and showers will periodically push through the islands, focusing primarily over windward and mauka areas during the overnight and early morning hours.

DISCUSSION

Currently at the surface, a 1031 mb high is centered around 1400 miles north of Honolulu, driving moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows mostly cloudy conditions across much of the state with cloud coverage the highest in windward and mauka areas. Radar imagery shows scattered to numerous showers moving into windward slopes and coasts, with a few showers spilling over to leeward communities at times. Main short term focus revolves around trade wind trends and rain chances.

High pressure will meander north and northeast of state during the next 7 days, keeping trade winds solidly in place through the period. Moderate to breezy trades today and tonight, will ease slightly on Sunday, then remain at mostly moderate speeds Monday through late next week.

As for the remaining weather details, fairly typical summertime trade wind weather is expected through the period, with showers favoring windward and mauka areas, particularly during the night and early morning hours. A couple bands of enhanced moisture appear to target the state late Sunday night and Monday, and again Tuesday night through Wednesday night. These bands will raise precipitable water values above 1.5 inches in most areas and elevate inversion heights to between 10 and 12 kft, increasing coverage and intensity of showers along with the amount of leeward spillover. In addition, dewpoints are forecast to increase to around 70 or the lower 70s beginning Monday and continuing through the middle of next week, making it feel more muggy across the island chain.

AVIATION

Moderate to breezy trades will continue today. Low clouds and scattered showers may occur at times across windward and mauka areas as moisture moves toward the islands, making for intermittent MVFR conditions. Otherwise VFR conditions are expected.

AIRMET Sierra is in effect for mountain obscuration for windward sections of Kauai, Oahu, Molokai, Maui, and the Big Island. Conditions may continue through the morning due to ongoing showers.

AIRMET Tango is in effect for moderate turbulence downwind of terrain due to the breezy trade winds and will continue through the forecast period.

MARINE

A high pressure ridge far north of the Hawaiian Islands will remain anchored in place, keeping trade winds blowing across the region through much of next week. The Small Craft Advisory (SCA) continues for Oahu Leeward Waters, all coastal waters and channels around Maui, and windier waters near the Big Island. This SCA will continue through tonight. Winds may slightly decrease from Sunday into Monday, but will likely remain at SCA levels for our typical windier waters near Maui and the Big Island.

A small, long period south swell will arrive and fill in today, peak on Sunday, then gradually decline through the first half of next week. This south swell energy will boost surf heights back up to near normal for this time of year.

Surf along east facing shores will remain rough and choppy with a slight decline possible early next week due to minor fluctuations of our trades. Surf heights along north facing shores will remain small to tiny through the first half of next week.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Sunday for Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel- Big Island Leeward Waters-Big Island Southeast Waters.