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Home News Hawaii Area Forecast Hawaii Area Forecast
Hawaii Area Forecast
Area Forecast Discussion for Hawaii
Area Forecast Discussion for Hawaii

Area Forecast Discussion for Hawaii
  • Synopsis
    Spotty heavy showers driven by a humid sea breeze regime will diminish rapidly on the smaller islands late this afternoon but will linger into early evening on leeward Big Island. Some relief from the humidity is on the way, as trades will gradually strengthen Monday and Tuesday. Showers become focused across windward slopes, though clouds and a few showers will continue to develop over leeward terrain each afternoon. A wetter trade wind pattern is expected during the second half of the week.

  • Discussion
    This afternoon features a continued and uncomfortable humid sea breeze regime. Afternoon temperatures are running in the high 80's to around 90, but with dew points running in the low to mid 70/s, the temperature feels more like the mid 90's. Look for one more warm and humid night. The sea breezes are triggering spotty heavy showers on the islands this afternoon along with some thunderstorms on the Big Island. Enhanced low level moisture along the flank of a weak surface trough passing several hundred miles southwest of the sate is helping to fuel the convection. This moisture is focused more the Big Island, where showers are more active, and an overlying upper level trough is triggering thunderstorms, mainly in the Kau district. Central Oahu is also experiencing spotty heavy showers due to sea breeze convergence from the north and south shores. Shower activity will taper off on the smaller islands late this afternoon but will likely linger into early evening across leeward Big Island. The background trade wind flow will remain weak tonight, leading to one last night of widespread land breezes. A nearly stationary remnant front 400 miles north of Kauai and a weak surface trough about 275 miles north of Maui will weaken overnight as high pressure builds to the northwest, but the trades should remain light enough for dominant land breezes, especially leeward. Some clouds and a few evening showers are possible over leeward areas, especially on the Big Island, but expect clearing skies as the enhanced moisture moves off to the west. Windward slopes could see a few showers on the building trade wind flow, but aside from windward Big Island, not much rainfall is expected. Trade winds will build on Monday and Tuesday, bringing some relief. Low level moisture will initially decrease as slightly drier air moves in behind the departing surface trough to the southwest. Even though the dew point temps will only be dropping a couple of degrees, the combination slightly drier conditions and building gentle trade winds will be noticeable. Leeward areas will remain hot, with sheltered areas near terrain experiencing some afternoon clouds and a slight chance of showers on Monday. Trades will strengthen to moderate levels on Tuesday, and a typical, windward-focused shower regime will prevail. A wet trade wind rainfall pattern is due during the second part of the week. Forecast models are showing a band of remnant frontal moisture sagging southward over the smaller islands Wednesday and stalling Thursday. Initial indications are that this band could stick around into next weekend, keeping mainly windward areas wet. For now, the forecast broad brushes wet conditions, but look for fine tuning as we get a handle on which islands will be most affected by the moisture band.

  • Aviation
    Convection has flared up over interior and leeward Oahu and the Big Island this afternoon. Tcu tops on Oahu are reaching around 23 kft. On the Big Island, thunderstorms have formed over the southern half, including Kau and south Kona districts, with CB tops between 30 and 35 kft and some reaching above 40 kft. Expect MVFR with periods of IFR cigs/vis to be embedded within these showers. However, main island terminals have remained predominately VFR and should continue to do so. On all islands, convective activity should begin to diminish with sunset. Overnight, only brief MVFR conditions in passing showers will remain, mainly for windward and mauka areas. Trade winds are expected to gradually return tomorrow, and shower activity will mainly focus along windward and mauka areas with a few clouds developing over leeward areas.

  • Marine
    No issues in the short term. Increasing trade winds will bring border line small craft advisory winds to the typically windy waters around the Big Island and Maui county starting Tuesday. Surf will remain around background levels through much of the week. A slightly higher swell of around 4 feet is expected from the NNE Thursday through Saturday. A moderate SSW is due next weekend.

  • HFO Watches/Warnings/Advisories
    None.

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    DISCUSSION/MARINE...WROE AVIATION...EATON