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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
    A rather dry trade wind pattern will prevail across most of the state through the next couple of days, but lingering low level moisture will continue to generate scattered shower activity across windward portions of the Big Island and Maui. Surface high pressure north of the islands will drive strong trade winds across the state through the end of this week and into the weekend. Trades should slacken a bit early next week, with showers remaining focused mainly across windward areas.

  • Discussion
    Breezy and rather dry conditions have continued across most of the state this morning. Some areas on the windward Big Island and on the windward slopes of Haleakala continue to receive small rainfall amounts. Surface analysis depicts a 1029 mb high centered 1050 miles north of Kauai, with fresh to locally strong trade wind flow prevailing over the main Hawaiian islands. The 12Z Lihue sounding found a dry and very stable profile, with a strong inversion based near 5000 feet and precipitable water /pw/ of only 0.76 inches. The 12Z Hilo sounding reflected the slightly deeper moisture lingering near the Big Island, with an inversion based around 6500 feet and 1.10 inches of PW. Mimic-total PW satellite imagery depicts a dry atmosphere around and north of the islands, with deeper tropical moisture confined well to the south of the Big Island. A breezy, stable and mainly dry trade wind pattern will prevail through the next several days. The surface high initially to our north is forecast to build slowly eastward to the north of the state between 30°N and 40°N through the rest of this week and into the weekend. Breezy conditions will be widespread over land areas during this time as fresh to strong trade winds prevail. The high resolution uh-wrf model is depicting sustained winds of 25 knots or greater across parts of the Big Island today, and recent observations show winds already near advisory criteria in exposed locations in Maui county and the Big Island. A wind advisory is in effect for parts of Maui county and the Big Island through 6 pm today. If winds verify today as models indicate, this advisory would likely need to be extended through at least Friday. Otherwise, sparse shower coverage will be mainly confined to windward and mauka areas through the weekend, with the best rain chances remaining across the windward Big Island. Blended model data keeps PW near or below one inch (below the 25th percentile for this time of year). Therefore would expect rainfall amounts to remain mostly on the light side. Trade winds should slacken a bit early next week, as the surface high to our north weakens. A modest increase in low level moisture may take place, and a very weak front or shear line may pass through the state around next Wednesday. With the added moisture windward/mauka showers could increase somewhat, but overall do not expect any major changes to the weather pattern.

  • Aviation
    Fresh and gusty trade winds beneath a well defined inversion aloft are expected to persist through 24 hours and beyond. Wind speeds in excess of 25 kt are expected along norhtheastern exposures and over mountain ridges. Channeled areas may experience stronger winds. Airmet tango for moderate low level turb lee side of all mountains is likely to remain necessary through 24 hours and possibly beyond. Precipitation is expected to remain light and mainly confined to windward portions of Maui Molokai and the Big Island. Isol MVFR possible in passing showers otherwise VFR conds expected to prevail all areas through at least Friday morning.

  • Marine
    North-northeast swell appears to have peaked at the Waimea bay and Pauwela cdip buoys, but continues to run above wavewatch guidance. This swell is forecast to gradually subside through today, but given observation trends will maintain the existing high surf advisory for north and east facing shores through 6 pm. The large NNE swell may also cause harbor surges within Kahului and Hilo harbors through today, and a marine weather statement has been issued. A combination of lingering moderate NNE swell and short period wind waves driven by strong trades will maintain elevated surf across north and east facing shores from through the weekend. The high surf advisory will likely be extended for east facing shores beyond today, and possibly for some north facing shores. The overnight ascat pass missed the Hawaiian coastal waters, but did find large areas of 25 knot winds well west and southwest of Kauai. The Wednesday morning ascat pass found 25 knot winds in the Alenuihaha channel and south of the Big Island, with winds near 20 knots in the kaiwi and Kauai channels. Trades have increased further since then with high pressure building north of the state, and the combination of wind waves and large NNE swell is still generating combined seas of 10 feet or higher across many areas. A small craft advisory /sca/ remains posted for all of the Hawaiian coastal waters. Sca conditions will likely continue for most of the waters through the rest of this week.

  • HFO Watches/Warnings/Advisories
    High surf advisory until 6 pm HST this evening for all north and east facing shores except for Lanai and Kahoolawe. Wind advisory until 6 pm HST this evening for Lanai, Kahoolawe, Maui central valley, south Big Island, Big Island north and east, Kohala. Small craft advisory until 6 am HST Saturday for Kauai northwest waters, Oahu leeward waters, Kaiwi Channel, Maalaea Bay, Pailolo channel, Alenuihaha channel, Big Island leeward waters, Big Island southeast waters. Small craft advisory until 6 pm HST this evening for Kauai windward waters, Kauai leeward waters, Kauai channel, Oahu windward waters, Maui county windward waters, Maui county leeward waters, Big Island windward waters.

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