Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 64 to 74 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Wednesday: Mostly sunny with isolated showers. Highs 80 to 86 near the shore to 64 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.
Kona
Today: Mostly sunny. Isolated showers in the afternoon. Highs 84 to 90 near the shore to around 70 near 5000 feet. Light winds becoming west around 10 mph in the afternoon. Chance of rain 20 percent.
Tonight: Partly cloudy. Lows around 73 near the shore to 49 to 56 near 5000 feet. Light winds.
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ARTICLE CONTINUES BELOW AD
Wednesday: Mostly sunny with isolated showers. Highs 84 to 89 near the shore to around 70 near 5000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.
Waimea
Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 70 to 79 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.
Wednesday: Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 79 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
Kohala
Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 70 to 79 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.
Wednesday: Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 79 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
South Big Island
Today: Mostly sunny. Highs around 86 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph.
Tonight: Partly cloudy. Lows around 74 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph.
Wednesday: Mostly sunny. Highs around 85 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph shifting to the southeast in the afternoon.
Puna
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Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 64 to 74 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Wednesday: Mostly sunny with isolated showers. Highs 80 to 86 near the shore to 64 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.
Waikoloa
Today: Sunny. Highs 84 to 89 near the shore to 67 to 72 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon.
Tonight: Mostly clear. Lows around 74 near the shore to 52 to 57 above 4000 feet. East winds around 10 mph.
Wednesday: Sunny. Highs 84 to 89 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 10 mph.
Detailed Forecast
Synopsis
The high pressure ridge north of the islands will weaken over the next few days as a cold frontal system passes from west to east across the Central Pacific basin. Trade winds will weaken into the light to moderate range through Thursday. Lighter trade winds are in the forecast from Friday through the first half of next week, allowing afternoon sea breezes to expand in coverage. Brief passing trade wind showers are forecast from the overnight through the early morning hours through Friday morning, mainly over windward and mountain areas. Cloud bands associated with a cold front that dissipated far north to northeast of the state will drift into the Hawaiian weather picture from Thursday through Friday, briefly increasing shower activity over the island chain.
Discussion
Regional satellite imagery this morning continues to show a subtropical jet stream over the islands producing a large band of high level cirrus clouds spreading from southwest to northeast across the state. A few low level cumulus cloud bands are just upstream of the state riding in on the trade winds. Expect brief showers through the early morning hours mainly over windward and mountain areas. Upper air balloon soundings from 2 AM HST (12Z) this morning continue to show a stable environment with trade wind temperature inversion heights at Lihue and Hilo remaining around 5,000 and 6,000 feet above the surface respectively. At these levels upper level large scale subsidence is strong enough to limit shower coverage within the isolated to scattered range, favoring windward and mountain areas.
The subtropical ridge far north of the Hawaiian Islands will weaken over the next few days as a high center within the ridge drifts farther eastward and a cold frontal system moves from west to east across the northern Central Pacific basin. Cold air advection with the cold front will weaken the ridge, decrease local area pressure gradients, and decrease trade winds speeds across the region. Moderate trade winds are forecast from Wednesday through Thursday, then becoming lighter trades from Friday through the first half of next week. Cloud bands associated with a different cold front that dissipated far north to northeast of the state will drift into the Hawaiian weather picture from Thursday through Friday, briefly increasing shower activity across the island chain.
Lighter large scale trade winds will allow afternoon sea breezes to expand in coverage over all islands, especially from Friday onward. This means less windward and mountain overnight shower activity with a transition to a few interior sea breeze showers during the late afternoon to early evening hours. Land/mountain breezes each night with a high pressure ridge aloft will trend the weather pattern towards less overnight shower activity.
Little changes are expected in the long range forecast and only slight decreasing precipitation trends were added to the morning forecast grids. No significant changes in weather impacts are expected over the next seven days.
Aviation
Trade winds will relax slightly into the moderate range today as high pressure over the area moves to the east and the local pressure gradient weakens. Some shallow moisture in the relatively stable trade wind flow will bring isolated to scattered showers and brief MVFR conditions to mainly the windward side of the islands today and tonight. Otherwise, besides any showers that may develop in sheltered areas over some leeward areas this afternoon, VFR conditions will prevail.
A weak subtropical jet stream will continue to drift northward this morning and bring TEMPO moderate turbulence aloft. AIRMET Tango is currently in place over the state between FL300 and FL400 and model guidance suggests that it will likely be able to be dropped later this morning.
Marine
No significant changes to the forecast this morning. High pressure to the north will continue to maintain a moderate to locally fresh trades over the coastal waters. Winds are expected to remain below Small Craft Advisory levels. The high will continue to move to the east tonight, and a series of fronts will pass to the north over the next several days. This will keep winds on the weaker side into the weekend.
A series of overlapping small, medium to long period northwest swells will fill in through Friday, keeping surf heights steady. Forecast guidance Friday into early next week shows a moderate, long period northwest swell, from a still yet to develop system, to impact north and west facing shores. Surf heights may reach just below High Surf Advisory criteria. More details can be expected as the low develops in the far northwest pacific over the next few days.
Small surf along south facing shores is expected through the week as a series of medium to long period background southerly swells move through. Long range models suggest the potential for surf to pick up over the weekend and persist through much of next week as a series of small long period south swells move through, boosting surf near to above average. Surf along east facing shores look to remain small and choppy due to weaker than normal local trade winds and will gradually ease to tiny to nearly flat during the second half of the week into early next week as winds weaken.
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