Moderate to locally breezy trade winds will persist through the week and into the upcoming weekend. Bands of low clouds and showers will periodically push across the islands, focusing primarily over windward and mauka areas during the overnight and early morning hours. A couple bands of enhanced moisture will move through the islands today through Thursday morning, bringing an increase in shower coverage and intensity, with some locally heavy rainfall possible. In addition, humidity levels will rise, bringing muggier conditions across the island chain through the middle of this week.
Currently at the surface, a 1037 mb high is centered around 1650 miles north-northeast of Honolulu, driving moderate trade winds across the island chain this evening. Infrared satellite imagery shows mostly cloudy to overcast conditions across much of the state, with a few leeward areas experiencing less cloud coverage. Radar imagery shows numerous showers moving into windward slopes and coasts, with some showers spilling over into leeward communities at times. Main short term focus revolves around rain chances.
High pressure will meander well to the north of state during the next 7 days, keeping moderate, to at times locally breezy, trade winds solidly in place. Somewhat wetter than normal, 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 will affect the state this week, bringing an increase in shower coverage and intensity as they move through. The first batch of enhanced moisture is already affecting the island chain, and will continue to do so through the day today, before exiting to the west of the state tonight. The next area of enhanced moisture is located around 550 miles east-northeast of the state in the vicinity of 147W. Portions of this area of enhanced moisture will begin to affect the islands beginning Tuesday night, and lingering into 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 affecting the islands during the middle of the 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 over windward and mauka areas during this time. Additionally, dewpoints are forecast to increase to around 70 or the lower 70s today through the middle of the week, making it feel more muggy across the island chain.
An easterly wave moving through the islands will produce MVFR conditions and showers across the state through the morning hours. MVFR conditions could decrease in coverage and frequency through the afternoon. Another low level disturbance will move through the islands bringing another round of MVFR conditions and showers from Tuesday night into Thursday.
AIRMET Sierra remains in effect for mountain obscuration above 020 along northern and eastern mountain slopes of most islands. These conditions will persist through the morning hours, then decrease in coverage later this afternoon.
An area of surface high pressure will remain centered well north of the Hawaiian Islands this week and help drive moderate to fresh trades trades across the region. The Small Craft Advisory (SCA) will continue through this afternoon for much of the waters around Maui County and Big Island, as well as the Kaiwi Channel. The SCA will then be trimmed back to the typical windy waters around Maui County and the Big Island by this evening as trades ease slightly into Tuesday.
The current long period south swell will maintain today, then gradually decline through midweek. Another larger south swell energy pulse will arrive by late Saturday.
Surf along east facing shores will remain rough and choppy through the week with moderate to fresh trades in place. Surf heights along north facing shores will remain nearly flat.
Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel-Maui County Windward Waters-Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
