Moderate to locally breezy trades will keep showers focused mainly over windward slopes as high clouds decrease later today. A dissipating front will move across the islands Thursday night into Friday, leading to an increase in rainfall and stronger trade winds. Drier trade wind weather is favored on Saturday, followed by a potential increase in showers Sunday through Tuesday.
Updated Marine Section to include an extension in time for the Small Craft Advisory.
Showers across the state had almost completed moved away or dissipated as of 2 AM HST this morning. High clouds continued to move from southwest to northeast over the region, leading to mostly cloudy skies. Winds were east to northeast at 5 to 15 mph in most areas.
Models have changed very little for the short term forecast overnight. We expect the high clouds to decrease during the day today and that should extend into Thursday night. Clouds and showers will increase again Thursday night and Friday as a band of moisture moves in from the northeast. This moisture is associated with the leading edge of stronger trade winds, and these trades will last into Saturday before turning a little south of due east. This veering of the low level wind will occur as a surface high initially to our northeast extends southward.
Winds will become even a little more southeasterly Sunday through Tuesday as an upper level trough moves in from the northwest. This trough will help form a surface low also to our northwest, and is now agreed upon by both the GFS and ECMWF. Even though both deterministic runs agree fairly well this morning, there is always considerable uncertainty looking 6 to 7 days out, and this general solution is far from set in stone. With that said, increasing moisture drawn northward in advance of this trough could lead to heavier precipitation in the early to middle part of next week.
Breezy easterly trade winds will hold through today. Expect mostly VFR condition today with brief MVFR due to quickly passing clouds and showers mainly along windward and mauka regions. Passing high clouds over the Big Island could produce some light icing through this afternoon. Trade wind speeds are expected to increase slightly across the state Thursday afternoon and evening, pushing a band of low level clouds and showers across the state.
AIRMET Sierra has been canceled for Kauai as a band of showers moved west of the area. No AIRMETs are in effect.
Moderate to locally strong easterly trade winds will continue through the week as high pressure builds north of the islands. A Small Craft Advisory was extended through Thursday for the typically windy waters around Maui County and the Big Island. Combined seas for coastal waters will peak just under the 10 foot Small Craft Advisory threshold.
Overlapping moderate, medium period northwest (310-320 degree) and north-northwest (340-350 degree) swells will keep surf heights along north and west facing shores at advisory thresholds into the evening hours, then decline just under advisory levels later tonight. Recent buoy obs this morning continue to show the primary north-northwest swell running around 1 to 2 feet above the global wave models. Therefore the High Surf Advisory for north and west facing shores of Niihau, Kauai, Oahu, and Molokai and north facing shores of Maui and the Big Island will continue through the day. A moderate, medium period north (360-020 degree) swell will then move into Hawaiian waters by Friday, possibly producing moderate surges in north facing harbors.
Choppy east shore surf will continue into the weekend as locally breezy trade winds continue. Surf along south facing shores will remain tiny to small through the forecast period.
Peak astronomical monthly tides may result in minor coastal flooding are possible from Thursday through early next week, and may be enhanced along north facing shores later this week due to the next north swell.
High Surf Advisory until 6 PM HST this evening for Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai North-Molokai Windward-Molokai North-Molokai West-Maui Central Valley North-Windward Haleakala-Big Island East-Big Island North.
Small Craft Advisory until 6 PM HST Thursday for Pailolo Channel- Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
