Today: Occasional showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain near 100 percent.
Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to around 54 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.
Monday: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.
Kona
Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 83 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 30 percent.
Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 70 near the shore to around 54 near 5000 feet. West winds up to 10 mph shifting to the northwest after midnight. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Monday: Sunny in the morning, then cloudy with isolated showers in the afternoon. Highs around 83 near the shore to around 70 near 5000 feet. Southwest winds around 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.
Waimea
Today: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to 70 to 78 near 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.
Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 52 to 60 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.
Monday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 81 near the shore to 70 to 78 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
Kohala
Today: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to 70 to 78 near 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 52 to 60 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.
Monday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 81 near the shore to 70 to 78 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
South Big Island
Today: Breezy. Mostly cloudy with scattered showers. Highs around 83 near the shore to around 71 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.
Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 69 near the shore to around 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.
Monday: Breezy. Sunny in the morning, then cloudy with isolated showers in the afternoon. Highs around 83 near the shore to around 71 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Occasional showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain near 100 percent.
Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to around 54 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.
Monday: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.
Waikoloa
Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 83 near the shore to 66 to 72 above 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.
Tonight: Partly cloudy. Isolated showers in the evening. Lows around 71 near the shore to 50 to 56 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.
Monday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 82 near the shore to 66 to 72 above 4000 feet. North winds 10 to 15 mph. Chance of rain 20 percent.
Detailed Forecast
Synopsis
Trade winds will gradually strengthen the next couple of days, delivering a few windward showers. Trade wind speeds will likely peak on Tuesday, becoming locally strong and gusty. Winds will diminish and become light Thursday and Friday as a front approaches, with continued limited rainfall. The front will likely dissipate near the islands over the weekend, with light to moderate trade winds returning.
Discussion
After a recent period of beneficial rainfall, island weather will be on the drier side over the next week, especially over leeward areas.
Light (to locally moderate) trade winds are delivering a cluster of low clouds and showers to windward portions of the Big Island and Maui this morning, while the remainder of the state is under mostly clear skies. Wettest locations in windward Big Island received about .5″-.75″ of rain overnight. The clouds appear rather innocuous in infrared imagery, but surface observations indicate low cloud bases with embedded areas of light to moderate rain and low visibility. This area of clouds is expected to weaken as it moves W today, but will bring a chance for windward showers, especially to Maui and Hawaii counties.
The trade winds are being supported by surface highs to the distant NW and NE, while a weakening and lingering trough NW of Kauai is keeping the local pressure gradient on the looser side. As the trough weakens and the high to the NW moves E through Monday, trade winds will gradually strengthen, favoring a NE direction over Kauai and Oahu. Trades will likely be strongest on Tuesday as the high passes N of the islands, with the potential for a Wind Advisory where winds are most accelerated by terrain. The high will push a frontal band toward the islands from the N, but guidance indicates it will stall N of Kauai. A trough aloft is currently over the E end of the island chain, but will soon be replaced by a ridge aloft building in from the W. Thus the strengthening trade winds are not expected to bring much more than a few brief windward showers that favor nights and mornings.
Late Wednesday and Thursday, developing strong low pressure to the N will force the high eastward, with the associated ridge extending over the islands from the NE. Winds will weaken and become light and variable through Friday as a front associated with the low approaches from the NW, with continued mostly dry weather expected. The front may bring a brief period of increased showers to Kauai and Oahu early next weekend before dissipating, with light to moderate trade winds and limited showers returning thereafter.
Aviation
Light to moderate trades will persist through today, then strengthen tonight into Monday as high pressure builds north of the state. Land breezes have developed overnight, and sea breezes can be expected to develop in sheltered leeward areas during the day today. Any showers that develop will be isolated to scattered in nature, and VFR flight conditions are expected to prevail for most locations throughout the forecast period. However, MVFR conditions have been prevailing at PHTO all night and will likely persist into the morning hours as trades continue to bring in some lower clouds and showers to mainly the eastern end of the state.
AIRMET Sierra for mountain obscuration is in effect for the eastern slopes of the Big Island through this morning, and is expected to improve by this afternoon. Eastern slopes of Maui may also need an AIRMET Sierra for mountain obscuration this morning if lower clouds and showers persist.
Marine
Weak ridging north of the state has maintained a lax pressure gradient over the local waters. This synoptic scenario has resulted in light to gentle trade winds. Weak high pressure to the north will allow this lighter trade pattern to remain unchanged through Monday. A better established area of high pressure northwest of the islands builds in behind a hurricane force low that will be tracking due east across the North Pacific and into the Gulf of Alaska through early Monday. This set up will tighten the pressure gradient down across the region and ultimately restrengthen trades from fresh to locally strong magnitudes by Tuesday afternoon. These speeds will hang on through Wednesday before backing off again in response to the high north of the islands moving east and being replaced by an area of low pressure. This low may be far enough south to drag a very weak, diffuse boundary into the waters by next weekend. A potentially large swell created by the hurricane force low positioned near 44N164W this morning will send a large enough swell down our northwest great circle route and into our offshore waters Monday to prompt Small Craft Advisories (for seas) by as early as tonight. This will occur just before the period of strong winds commences Monday night into early Tuesday across the typical windier waters surrounding Maui County and Big Island.
The High Surf Advisory (HSA) has been extended in time for the north and west-facing shores of the smaller islands and is now in effect through Monday afternoon. This is a result of this morning's passing northwest (320 degree) long period swell. Recent nearshore buoy observations indicate that this long period (15-17 second) 7 to 8 foot swell is already a couple of feet above guidance. This swell will peak today and result in solid HSA level surf through Monday as it forecast to be slow to subside. The next north northwest (330-350 degree) swell will be on the heels of today's swell, generated from the hurricane force low mentioned above, and is scheduled to arrive late Monday and peak Tuesday. This large, long period swell will likely drive surf heights to above High Surf Warning thresholds Tuesday. This large swell should slowly decline from Tuesday night through the remainder of the week as it veers more northerly. Strengthening trades should increase eastern exposure chop and lead to rough surf from Tuesday into the middle of the week. Small background swell leading to very small surf will continue along south-facing shores throughout the week.
HFO Watches/Warnings/Advisories
High Surf Advisory until 6 PM HST Monday for north and west facing shores of Niihau, Kauai, Oahu, Molokai and for north facing shores of Maui.
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