Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 15 mph. Chance of rain 30 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 66 near the shore to around 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Saturday: Mostly cloudy with scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.
Kona
Today: Sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 80 to 85 near the shore to around 68 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.
Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 73 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Saturday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 80 to 85 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 20 percent.
Waimea
Today: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 66 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.
Saturday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
Kohala
Today: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 66 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.
Saturday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
South Big Island
Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.
Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 68 to 74 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.
Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 15 mph. Chance of rain 30 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 66 near the shore to around 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Saturday: Mostly cloudy with scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.
Waikoloa
Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. North winds up to 15 mph. Chance of rain 20 percent.
Tonight: Partly cloudy. Isolated showers after midnight. Lows around 74 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.
Saturday: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs around 85 near the shore to 69 to 75 above 4000 feet. North winds up to 20 mph. Chance of rain 20 percent.
Detailed Forecast
Synopsis
The high pressure ridge north of the islands will strengthen from later tonight into the weekend, trade winds will remain in the moderate to breezy range from Saturday through the end of next week. Three upper level disturbances passing from east to west over the next seven days will lift the subsidence inversion heights enough for more typical windward and mountain shower activity. These periods of showers will favor the overnight to early morning hours along the eastern slopes of each island.
Discussion
Satellite imagery this morning shows a band of moderately unstable clouds just east of the Big Island and Maui drifting westward on the trade winds. These clouds are associated upward vertical motions along the eastern side of a weak upper level low drifting westward across the state. Expect increasing windward and mountain cloud and shower trends as this low slowly drifts across the state through Saturday morning. Local radar imagery shows isolated shower coverage this morning over windward and mountain slopes with increasing shower intensity along leeward convergence bands south and west of the state.
Moderate trade winds will continue today as a high pressure ridge remains in place north of the state. This ridge will strengthen from tonight into the weekend with trade wind speeds increasing into the moderate to breezy range, lasting from Saturday through the end of next week. A combination of stronger trade winds and three passing upper level lows, drifting in from east to west across the island chain, will produce periods of more normal windward and mountain showers. These passing upper lows will weaken the subsidence inversion aloft and allow cloud heights to deepen and produce increasing shower coverage over the state. Longer range models suggest a cloud band remnant from an old front will move into the region from the northeast on Wednesday. These passing showers will tend to favor the overnight to early morning hours with the arrival timing tied to each low passing over the islands, with basically two periods of wetter trades from today through Sunday, and from Tuesday night through Thursday.
The main changes in this mornings forecast were upgrading the precipitation chances and coverage with the highest trends favoring the overnight to early morning hours each day. Wind speeds were also increased over windier eastern waters and channels, and the mountain summits of Mauna Kea and Mauna Loa.
Aviation
With a surface ridge just north of the state, trade winds will remain in the light to moderate range. VFR will prevail over most areas most of the time through tonight, though brief periods of MVFR may occur across windward slopes as moisture embedded in the trades interacts with island terrain.
No AIRMETs are currently in effect, and none anticipated through tonight.
Marine
A weak ridge north of the islands will drive light to moderate east to east-southeast winds across local waters today. Winds will increase into the moderate to strong range tonight and Saturday as the ridge strengthens. A Small Craft Advisory (SCA) will be needed for the windier zones around Maui County and the Big Island over the weekend and early next week, and the SCA may need to include additional zones Sunday or Monday.
No significant swells are expected through the forecast period. A small northwest swell is due Sunday and Monday. Expect background summertime surf for south facing shores, though a small pulse from the southwest is possible during the middle of next week. Small, short-period surf along east facing shores will build to seasonal average over the weekend as trade winds strengthen, then hold into next week.
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