Moderate to locally breezy trades will persist tonight, slightly decrease on Sunday, then remain at mostly moderate speeds through late next week. Bands of low clouds and showers will periodically push across the islands, focusing primarily over windward and mountain areas during the overnight and early morning hours. A couple bands of enhanced moisture will move through the islands Sunday night through Thursday morning, bringing an increase in shower coverage and intensity, with some locally heavy rainfall possible. In addition, humidity levels will rise, making the first half of the upcoming work week fell rather muggy across the island chain.
Currently at the surface, a 1035 mb high is centered around 1700 miles north-northeast of Honolulu, driving moderate to locally breezy trade winds across the island chain this evening. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud coverage the highest in windward and mauka areas as well as leeward sections of the Big Island. Radar imagery shows scattered 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 locally breezy trades 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 next week. The first batch of enhanced moisture is evident in satellite imagery approaching 150W or about 300 miles east of the Big Island. This band of moisture is expected to ramp up shower coverage and intensity as it moves from east to west across the islands Sunday night through Monday evening. The next area of enhanced moisture currently near 140W or about 1000 miles east of the state, is forecast to move through the islands Tuesday night through early Thursday, increasing shower coverage and intensity once again.
Both these bands will raise precipitable water values into the 1.5 to 2.0 inch range and elevate inversion heights to between 10 and 12 kft. Some locally heavy rainfall can't be ruled out as these bands of moisture move through, particularly the second batch of moisture moving through during the middle of next week. That said, with the trades in place, a widespread flash flood threat is not expected, but some minor flooding could very well necessitate flood advisories during this time. Additionally, 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.
Moderate to breezy trades are expected through the forecast period. Low clouds and scattered showers may occur at times over primarily windward sites, making for intermittent MVFR conditions. Otherwise VFR conditions are expected.
AIRMET Tango is in effect for moderate turbulence downwind of terrain due to breezy trade winds and will continue through the forecast period.
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 through tonight for Oahu Leeward Waters, all coastal waters and channels around Maui, and windier waters near the Big Island. 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 through this period.
The current small, long period south swell will peak on Sunday, before gradually declining through the first half of next week.
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.
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.
