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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
    The trade winds will give way to a hybrid mix of light trades with daytime sea breeze and night time land breeze for the second half of the week. An upper level trough will move through the islands wednesday and help boost the afternoon and evening showers. The mugginess level will also rise under this light wind pattern.

  • Discussion
    The weather will be changing during the next 18 hours as a surface trough forms around Kauai later today. The trough will alter the wind flow that will result not only in lighter winds but winds with a slight south of east component for most of the islands. At the upper levels, a short wave trough will be approaching the islands from the northwest. The combo of this light wind and approaching trough, will lead to a spat of enhanced showers for the Koolau Mountains and windward communities of Oahu this early evening. breeze will likely take over the lee side of the smaller islands leading to some fair weather there. Over on the windward side...there is enough strength in the easterly wind flow to carry in a few showers. On Wednesday, we are anticipating maximum convergence over all the islands. The combination of the convergent sea breezes along, daytime heating, and ample low level moisture, will result in some scattered convective showers. As per GFS and ECMWF, the upper level disturbance, accompany by a pool of marginally cold air of minus 9 to 11 degree C, will help enhance a few of these showers to locally heavy. This language is not yet part of the forecast due to its marginal status but will be included if the models continues at this temperature range or colder. The air mass will regain some stability after the passage of the upper level disturbance on Thursday. The surface winds will tether between east and slightly south of east, or both, as we head into the weekend at light to moderate speeds, with the lightest winds over on kauai. At this strength, local sea breezes will result in afternoon and evening clouds and spotty showers over the interior and leeward areas. At night, the windward areas may receive a stray shower or two due to the background easterly winds. But other parts of the islands may have an off shore breeze leading to fair skies there. Depending on which model you choose, the trade winds will be disrupted once more on Sunday, as per GFS, when it gives way to light southerly winds. This is due to a front approaching the islands from the northwest. The ECMWF has a different solution by keep the front just out of reach of the islands and thus maintaining an easterly wind flow Sunday through Monday. The GFS, on the other hand, has the frontal boundary moving down the island chain Monday and Monday night. If we take a blend of these two models, which is preferred solution, the wind turns southerly Sunday, then backs to the east Monday night as light trades. There is an upper level trough accompanying the front. The dynamics, however, are not there. Instead of a pool of cold air, both the ECMWF and GFS are indicating warm temps of minus 3 to 4 degrees C at 500 MB. The GFS's RH cross section reveals moisture depth to 12 to 15k feet. All highly questionable forecast for Memorial Day at this point. Almost a sure bet, though, the winds will be light and rather humid on Monday. Currently, the central islands consisting of Maui County and Oahu... are in an area of rather dry air and minimal showers. There is a small pocket of enhance moisture about to reach Kauai that will give the island a dosage of showers for a good part of this morning. The afternoon hours may have more showers especially on the western half of Kauai as remnant moisture mixes in with day time heating. The leading edge of a low cloud field is now affecting windward Big Island. There are other shower bearing clouds advancing westward toward Maui. However, they are finding this hard as they appear to be dissipating as they near Hana. Never the less, we are maintaining scattered showers for the windward and mauka areas of the smaller islands through out the day today. The Kona slopes will have their usual afternoon and evening clouds with scattered showers.

  • Aviation
    Clouds and showers will continue to favor windward and mountain areas under a weakening and veering light to moderate trade wind regime. Some showers at times will likely carry MVFR conditions to the smaller islands. AIRMET Sierra for mountain obscuration has been posted from Laupahoehoe to Apua Point, including Hilo, on the Big Island. Showery low clouds will continue to stream over the Big Island likely into mid-morning. PHTO will see a range of conditions from VFR to IFR throughout this time. Most other terminals should remain VFR. Sea breezes along the leeward areas on the Big Island will introduce convective showers along the slopes this afternoon. Expect periods of MVFR conditions to be embedded within these showers. Showers along windward areas are forecast to increase later tonight as enhanced moisture and a surface trough move into the area, bringing more prolonged periods of lowered cigs/vis.

  • Marine
    There are currently no marine advisories or warnings in effect for the Hawaiian waters now, and none is expected through Sunday. The winds will remain below SCA level for a few days, at least through Sunday. Small surf will dominate on most shores the rest of this week. The one exception is a small to moderate southwest swell that will build on Thursday, peak Friday, then decline during the weekend. This swell will originate from the Tasman Sea, which tend to be inconsistent for the Hawaiian Islands. This is due to blockage from other Pacific islands while enroute to Hawaii. Please refer to the Collaborative Nearshore Swell and Wind Forecast (SRDHFO) for more details.

  • HFO Watches/Warnings/Advisories

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