Forecast Discussion

Synopsis

Discussion

20 Nov 2024 19:58:00 GMT: 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 Friday 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. Early next week, confidence in the details of the forecast is quite reduced, but light winds appear likely with no significant rainfall anticipated headed into Thanksgiving.

Aviation

20 Nov 2024 19:58:00 GMT: 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.

Marine

20 Nov 2024 19:58:00 GMT: Moderate to locally fresh trade winds will decline through tomorrow as high pressure north of the state weakens and drifts southward. For Thursday night through Saturday, a surface ridge will be stalled just north of Kauai, producing gentle to locally moderate trades, strongest around the Big Island. Winds are expected become light and variable Saturday night and Sunday as a weak and shallow front approaches. The front may reach the islands as early as Monday, though strong winds look unlikely at this time. A series of north-northeast and northwest swells are due this week. A tiny northwest swell of about 1 foot at 15 to 16 seconds is detectable on the PacIOOS Hanalei and Waimea buoys this morning. This swell will move down the island chain today and peak at around 2 feet late tonight through Friday. A more significant 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 of about 3 to 4 feet will arrive tonight and hold into Saturday. A very deep storm off the U.S. Pacific Northwest coast will send an overlapping pulse of north-northeast swell on 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. As trade winds decline, easterly wind wave energy will steadily drop through Friday and will fade out during the weekend. Surf along south facing shores will remain small through the week.

Fire weather

20 Nov 2024 19:58:00 GMT: KBDI values remain high in most leeward areas, where a dry weather pattern is anticipated the next several days. Minimum relative humidity values will likely near the critical 45% threshold from late morning through the afternoon each day through Saturday. However, weak winds will mitigate the potential for critical fire weather conditions.