Photo Credit: James Grenz

Hilo

Today: Partly sunny with scattered showers. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 52 at 4000 feet. North winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 82 near the shore to 67 to 72 at 4000 feet. Southeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 73 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to 54 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 80 near the shore to 67 to 77 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to 54 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 80 near the shore to 67 to 77 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 15 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy. Scattered showers in the evening. Lows around 68 near the shore to around 51 near 5000 feet. East winds up to 15 mph. Chance of rain 30 percent.

Saturday: Breezy. Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 71 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Puna

Today: Partly sunny with scattered showers. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 52 at 4000 feet. North winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 82 near the shore to 67 to 72 at 4000 feet. Southeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 73 near the shore to 49 to 56 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 74 above 4000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will prevail through the forecast period, but will be on the lighter side today through the weekend. The trade winds will periodically deliver clouds and showers to windward areas, with the potential for increased showers at times over the weekend. The shower activity will decrease and the trades will strengthen on Monday, with breezy trades and typical windward focused showers expected Tuesday through Thursday.

Discussion

Currently at the surface, high pressure systems are centered to the distant north and northeast of the islands, with a weak front in between these two features, located around 700 miles north of Kauai. Infrared satellite imagery shows partly cloudy skies across most of the state, with a bit more cloud coverage over some windward areas as well as leeward Big Island. Radar imagery shows scattered showers moving into windward areas, with a shower or two making the trip over the mountains and into leeward communities at times. Main short term focus revolves around trade wind trends and rain chances.
Trade winds will continue to ease today as a front far north of the state makes southward progress, but are expected to hold at moderate levels. The trades will ease further over the weekend as the front continues its slow southward push. Light to moderate trades will prevail, with daytime sea breezes and overnight land breezes developing in some leeward areas. The front is expected to dissipate several hundred miles north of the islands Sunday night, with high pressure then becoming more dominant to the distant north. This should allow the trade winds to strengthen back to moderate levels statewide on Monday, then ramp up to breezy levels Tuesday through Thursday as the high strengthens to the north-northeast of the island chain.
As for the remaining weather details, some deeper moisture will work southwestward into the islands today, while an upper level trough shifts southward and closer to the island chain. This should bring a slight increase in windward showers today, and possibly allow for a few leeward showers to develop in the afternoon. The upper trough will remain nearly stationary just north of Kauai tonight, then close off into an upper level low near or over the western islands this weekend. This should keep showers a bit more active over windward areas, and allow for some leeward shower development each afternoon in the weakened trade wind regime. A plume of deeper moisture should result in an increase in shower coverage as it moves into the eastern end of the state on Saturday, then spreads to the rest of the state by Sunday, before slowly exiting from east to west across the island chain Sunday night and Monday. A more typical less showery trade wind pattern will resume late Monday through Thursday.

Aviation

With high pressure weakening far north of the islands, northeast to east trade winds will ease into the light to moderate range over the next few days. Areas of showers, with accompanying MVFR conditions in lower ceilings and visibilities, will mainly affect windward and mauka sections from time to time, especially in the late night and early morning hours. And with winds decreasing, cloud buildups are also likely in leeward sections during the afternoon and early evening, most particularly on the Kona side of the Big Island. Overall, however, VFR will prevail.
No AIRMETs are in effect, though one or more may be needed later this morning for mountain obscurations affecting the isles.

Marine

Trade winds will remain gentle to moderate the next few days as low pressure along with a front passes far northeast of the islands. These features will weaken the pressure gradient enough to generally maintain weakened breezes through the weekend. Trades are expected to restrengthen early next week. Winds will likely achieve Small Craft Advisory magnitudes over the more windier eastern island bays and channels by Monday.
Surf along all shores will remain below surf advisory thresholds through the forecast period. South facing shore surf will stay steady through Saturday with a new long period south swell forecast to arrive Sunday. This swell will peak early work week south shore surf to or above head high through the middle of the week. This recent weakness in the trades will keep eastern facing shore wind wave winds and chop down. A small, low period northeast swell will pass through the islands from late Saturday into Monday and provide a small boost to early week north and east facing shore surf.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov