Today: Mostly sunny with showers likely in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 83 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.
Tonight: Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Friday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 84 near the shore to 66 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.
Kona
Today: Sunny in the morning, then mostly cloudy with scattered showers and isolated thunderstorms in the afternoon. Highs 81 to 87 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 70 to 75 near the shore to 49 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 40 percent.
Waimea
Today: Sunny in the morning then becoming partly sunny. Isolated showers. Highs 66 to 84. East winds up to 15 mph. Chance of rain 20 percent.
Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 68 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.
Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 67 to 84. East winds up to 15 mph. Chance of rain 40 percent.
Kohala
Today: Sunny in the morning then becoming partly sunny. Isolated showers. Highs 66 to 84. East winds up to 15 mph. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 68 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.
Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 67 to 84. East winds up to 15 mph. Chance of rain 40 percent.
South Big Island
Today: Breezy. Mostly sunny with showers likely in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 82 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 30 percent.
Tonight: Partly cloudy. Lows around 71 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph.
Friday: Breezy. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 83 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly sunny with showers likely in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 83 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.
Tonight: Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Friday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 84 near the shore to 66 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.
Waikoloa
Today: Sunny in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs around 85 near the shore to 67 to 73 above 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.
Tonight: Partly cloudy. Lows 69 to 75 near the shore to 49 to 57 above 4000 feet. Southeast winds up to 15 mph.
Friday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 30 percent.
Detailed Forecast
Synopsis
Light winds will favor afternoon clouds and a few showers over leeward and sheltered areas while isolated thunderstorms will be possible over Leeward Big Island. Moderate trades will return by Friday and will strengthen to breezy by Sunday. During this time, a return to typical trade wind weather can be expected with clouds and showers focused over windward and mauka areas.
Discussion
A SW-NE oriented surface trough remains established over the central portion of the state. Light northeast flow to its west has been largely dry this morning with very isolated shower activity focused over the windward slopes of Oahu and Kauai. To its east, ESE flow supported moderate showers over the lower slopes of the Kau district through the first half of the night, but those have since dissipated as well. As a result, tranquil weather and mostly clear skies exist across the islands this morning with just a few passing high clouds noted on IR imagery.
A much drier airmass is seen upstream of the Big Island on the CIMMS MIMIC PWAT product. This airmass will reach Windward Big Island during mid-to-late morning and will limit the potential for another day of heavy afternoon rain and thunderstorms over that area. The hi-res guidance is also relatively muted over Leeward Big Island this afternoon, but this seems at least somewhat suspect given that the upper level environment will not be terribly different than yesterday and the incoming dry airmass is unlikely to have fully made inroads to the leeward side by this afternoon. The forecast will therefore be updated to add mention of isolated thunderstorms over Leeward Big Island during the peak heating period today.
Finally, the potential for afternoon rainfall in this pattern has not completely ended over the smaller islands, especially Oahu. The latest observations and modeling suggest the gradient may remain just elevated enough to prevent a pure sea breeze pattern from emerging, instead favoring something more hybrid in nature. This would in turn shift the favored region for convergence toward the most sheltered leeward areas of Kauai and Oahu. Locally heavy afternoon rainfall cannot be ruled out given the moisture availability and the proximity of the surface trough as it drifts westward, but confidence is somewhat diminished owing to the borderline nature of the wind field. Slightly stronger winds will limit the potential for heavier rain while slightly weaker winds would allow for stronger low-level convergence in support of deeper afternoon convection.
Moderate trades will return on Friday, gradually strengthening to breezy by Sunday. During this time, a typical trade wind weather pattern will return to the area with showers mainly focused over windward and mauka areas, especially at night and in the early morning.
Aviation
Light winds will continue today due to a diminishing surface trough over the eastern end of the state, which will give way to localized land and sea breezes. This trough combined with plenty of moisture in the area will support another round of locally heavy showers this afternoon. Additionally, a thunderstorm or two can’t be ruled out over the Big Island slopes through this time. Trades are expected to return tonight through Friday as the ridge builds to the north and the trough diminishes.
AIRMET Sierra remains in effect for mountain obscuration over windward sections and slopes of the Big Island (MVFR CIGS). Although some improvement will be possible through the morning hours, the onset of afternoon clouds/showers will keep the potential for these conditions in place today.
Marine
A low-level trough near Maui and the Big Island will gradually weaken as it moves W over the next day or so. This will allow a surface ridge to strengthen N of the islands, leading to strengthening trade winds, especially over eastern waters. As this occurs, a Small Craft Advisory (SCA) may be required for windier zones around Maui and the Big Island on Friday. An approaching front (currently near Midway) will stall NW of Kauai Friday night into Saturday, briefly weakening the ridge (and the trade winds) for a day or so. After the front dissipates later this weekend, high pressure building N of the area will support stronger trade winds, with the SCA likely going back into effect for the same areas.
Surf will remain well below High Surf Advisory levels along all shores into next week. Small swells from the N and NW are expected for the next several days, biggest on Monday and Tuesday, with swell heights near 4 feet expected. A larger NW swell is possible around the middle of next week. Increasing trade winds will bring a slight increase in wind waves along E facing shores late this weekend.
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