Gradually diminishing trade winds will deliver just a few showers to windward areas of the smaller islands the next day or so, while windward Big Island will continue to receive passing showers. Light and variable winds and mostly dry weather are expected statewide from Thursday night into Sunday. A weak front may move over the islands from the northwest late this weekend, bringing little in the way of rainfall, with winds remaining on the lighter side.
Gradually diminishing trade winds will deliver little in the way of rainfall to windward areas of the smaller islands the next day or so, while windward Big Island will continue to receive passing showers. Light and variable winds and mostly dry weather are expected statewide Thursday night into Sunday. Late Sunday into Monday, a weak front is expected to approach from the NW, and deterministic model guidance continues to offer inconsistent solutions for the prognosis of this feature, and the evolution of the weather pattern early next week. Ensemble consensus guidance indicates that we can be confident that winds remain light, and precipitation totals associated with the potential frontal passage will remain on the lower side. While confidence in the details of the forecast is quite reduced for next week, light winds appear likely and significant rainfall unlikely headed into Thanksgiving.
A 1019 mb surface high centered about 400 miles is supporting moderate trade winds this afternoon, with a stable and dry atmosphere resulting in very little rainfall. Afternoon soundings show the inversion has lowered to near 5000' on Kauai, with a low PWAT of .8", while a deeper mixed-layer on the Big Island has pushed the inversion base to near 9000', with a PWAT of 1.3". This has allowed windward Big Island to be the exception to the mostly dry regime, at least through mid-day, where persistent showery low clouds brought about .5" to .75" of rainfall. The short term should feature little change as moderate trade winds slowly diminish, with just a few (or less) windward showers on the smaller islands, and greater coverage of showers over windward Big Island. Shower coverage and frequency over windward Big Island should taper off by tomorrow night as a land and sea breeze wind pattern develops statewide. This will occur as the high moves S and dissipates, leaving a surface ridge near/over the islands. This pattern will persist into at least Sunday, after which forecast details become increasingly uncertain.
Trades will decrease gradually through Friday. Showery weather is expected for windward Big Island through tonight with periods of MVFR conditions expected. Some of the heavier showers may produce brief IFR conditions. Elsewhere, fair trade wind weather is expected with a few light showers possible over windward and mauka areas.
AIRMET SIERRA is in effect for windward Big Island due to mountain obscuration. Conditions may briefly improve during the day, but ceilings will likely lower again during the evening and overnight tonight.
Moderate to locally fresh trade winds will decline tomorrow as high pressure north of the state weakens and drifts southward. For Thursday night through Saturday, a surface ridge will be stalled roughly 100 nm north of Kauai, producing gentle to locally moderate trades, strongest around the Big Island. Winds are expected become light and variable on Sunday as a weak and shallow front approaches. The weak front may reach the islands as early as Sunday night. Strong winds look unlikely at this time, and disrupted trade winds are expected into early next week.
A series of north-northeast and northwest swells are due this week. A tiny northwest swell of about 1 to 1.5 feet at 15 to 16 seconds is detectable on the PacIOOS Hanalei and Waimea buoys this afternoon, with hints of the swell showing on the Pauwela buoy. This swell will peak at around 2 feet late tonight through Friday. A larger northwest swell of 3 to 6 feet will build late Saturday, peak Sunday, and decline Monday, followed by a smaller pulse on Tuesday. A medium period north swell will slowly build tonight and Thursday, and hold at 4 to 5 feet Friday and Saturday. A very deep storm off the U.S. Pacific Northwest coast will send an overlapping pulse of north-northeast swell late Saturday. This swell will peak Sunday into Monday, then drop off on Tuesday. None of these swells is expected to produce advisory level surf, but we will monitor buoys for the potential of high surf on north and east shores, mainly from the pulse of north-northeast swell.
As trade winds decline, easterly wind wave energy will steadily drop through Friday, then fade out during the weekend. Surf along south facing shores will remain small through the week.
None.
