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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 weak front currently near the Big Island will focus showers across windward Big Island before pushing south of the state on Sunday. Cool and rather dry northeasterly winds in place over the western half of the state will gradually fill in over the entire island chain on Sunday and persist through the holiday weekend, confining light showers to northeast facing slopes. Lighter winds are expected during the new work week.

  • Discussion
    A rare late may front near the Big Island will move south tonight, with an atypical late may weather pattern expected through much of the upcoming week. The front is currently located over the Big Island and continues to drift southward at less than 10 mph. Rainfall has been unimpressive across windward Big Island so far, generally less than one half of an inch, while the Kona slopes have not received much enhancement from the frontal moisture. Expect continued modest showers across windward slopes tonight with the dissipating front stalling just south of the Big Island on Sunday. A cool and rather dry northeasterly in place across the western half of the state will fill in across all of the smaller islands tonight. Dew points from Kauai to Molokai are hovering in the upper 50's to low 60/s, quite dry by late may standards. Models are hinting at a slight increase in low level moisture within the northeast flow late tonight and early Sunday morning, but we expect mainly an increase in low clouds and only meager rainfall along windward and northern slopes, while leeward areas remain dry. Expect somewhat cool conditions tonight with overnight low temps running around 3 to 5 deg f below normal. The large scale pattern responsible for this unusual late may set up consists of a deep trough to the northeast of the islands along 150°W and surface high pressure displaced southwest of its typical late may position to near 30°N 175°W. The islands lie between these features within a rather dry and stable northeast flow behind the above mentioned front. Once the front pushes south of the Big Island, the entire island chain will experience moderate and rather dry northeast flow through the remainder of the holiday weekend. Rainfall will remain modest and confined to northeast slopes as well as the Kona slopes each afternoon. Models hint at the trough shifting westward toward the state late Tuesday or Wednesday. This should lead to a decrease in winds along with a convective land and sea breeze pattern. The forecast currently calls for a light trade wind pattern during the second half of the work week, but recent runs of the GFS and ECMWF suggest trade winds could become disrupted as a trough forms to the northeast of the islands.

  • Aviation
    The dissipating front is now just NE of the Big Island. Expect N thru E slopes of the Big Island to see enhancement in clouds and showers as the front, or what is left of the front, pushes S into Sunday. Periods of MVFR and possible isol IFR will likely be along these slopes overnight, including PHTO. Airmets for mountain obsc will be issued as needed. The broken to overcast clouds along leeward areas of the Big Island should scatter out with sunset and VFR will prevail. Over the smaller islands, moderate N to NE winds will continue through the period, and clouds and minimal showers will favor the N thru E sections. Vfr will prevail.

  • Marine
    Moderate to fresh northeasterly winds will persist behind a slowly southward moving front currently near the Big Island. A small craft advisory /sca/ is currently posted for Kauai leeward waters, mainly due to acceleration of northeast winds within the channel between Kauai and Niihau. The Barking Sands observation and a recent ascat pass suggest border line conditions are in place, so we will let the SCA continue through the afternoon. Border line conditions may also be experienced around Maui county and the Big Island as the front continues its push to the south tonight. Expect all waters to be below SCA criteria tonight through much of the upcoming week. An extended run of south swell, generated by several lows in the deep south Pacific over the last week, will bring somewhat elevated surf to south facing shores through the week and beyond. Surf heights are expected to remain below advisory levels for the bulk of the time, but overlapping swells from Sunday into Tuesday could bring surf to near advisory-levels along exposed south facing shores. A small NNE swell is expected to arrive on Sunday and linger through Monday. Otherwise, a couple of small swells from the NNW and WNW are expected over the weekend and early next week, with resultant surf well below advisory levels. See the latest Oahu surf discussion /srdhfo/ for more details.

  • HFO Watches/Warnings/Advisories
    Small craft advisory until 6 pm HST this evening for Kauai leeward waters.

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