Hilo

Tonight: Mostly cloudy with a 30 percent chance of showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph.

Saturday: Partly sunny with a 40 percent chance of showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon.

Saturday Night: Mostly cloudy with a 40 percent chance of showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph.

Kona

Tonight: Partly cloudy with a 20 percent chance of showers. Lows 70 to 75 near the shore to around 56 near 5000 feet. Light winds.

Saturday: Mostly sunny with slight chance of showers in the morning, then mostly cloudy with chance of showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 30 percent.

Saturday Night: Partly cloudy with a 20 percent chance of showers. Lows 70 to 75 near the shore to around 56 near 5000 feet. Light winds.

Waimea

Tonight: Partly cloudy. Slight chance of showers early in the evening, then chance of showers in the late evening and overnight. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 30 percent.

Saturday: Mostly sunny. Breezy. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy with a 20 percent chance of showers. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 15 mph.

Kohala

Tonight: Partly cloudy. Slight chance of showers early in the evening, then chance of showers in the late evening and overnight. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 30 percent.

Saturday: Mostly sunny. Breezy. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy with a 20 percent chance of showers. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 15 mph.

South Big Island

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 20 percent chance of showers early in the evening. Lows around 71 near the shore to around 54 near 5000 feet. East winds up to 15 mph.

Saturday: Breezy. Sunny early in the morning, then mostly cloudy with a 30 percent chance of showers in the late morning and afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 20 mph.

Saturday Night: Mostly cloudy early in the evening then becoming mostly clear. A 30 percent chance of showers early in the evening. Lows around 71 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy with a 30 percent chance of showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph.

Saturday: Partly sunny with a 40 percent chance of showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon.

Saturday Night: Mostly cloudy with a 40 percent chance of showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph.

Waikoloa

Tonight: Mostly clear. Lows around 73 near the shore to 52 to 59 above 4000 feet. East winds up to 15 mph.

Saturday: Mostly sunny. Breezy. A 20 percent chance of showers in the late morning and afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 20 mph.

Saturday Night: Mostly clear. A 20 percent chance of showers early in the evening. Lows around 73 near the shore to 52 to 59 above 4000 feet. Northeast winds up to 10 mph.

Detailed Forecast

Synopsis

Light to moderate trade winds will continue into Sunday, with light and variable winds for the first part of next week. Showers will be limited, and a mostly dry weather pattern will continue. Trade winds will likely strengthen after the middle of next week.

Discussion

Light winds and mostly dry weather will prevail well into next week, with seasonably warm and, at times, muggy conditions expected. The exceptions include an expected brief and modest increase in trade wind speeds tonight and Saturday, and the potential for a pair of dissipating frontal boundaries to bring increased moisture to Kauai, centered on Sunday and Tuesday.
High pressure cells centered far NE and NW of the islands are supporting a light to moderate trade wind flow, as a cutoff low about 750 miles N of the islands has weakened the ridge. The modest short-term increase in trade wind speeds (and slight backing to the NE) is expected as the high to the NW moves a little closer and the low moves NE.
A strong shortwave aloft (currently near 38N 165W) will move rapidly SE tonight and Saturday, ejecting the current cutoff low while carving out a new deep-layer cutoff low about 900 miles NNE of the area over the weekend. As this new low moves slowly W to the N of the islands from late Sunday through Wednesday, the local pressure gradient will be quite slack, and winds will be light and variable. As the low slowly dissipates, high pressure building far NE of the area will promote a strengthening trade wind flow by Thursday.
A strong mid-level ridge will become even stronger over the weekend, with 500 mb temperatures becoming anomalously warm while PWAT will be near to below normal, thus any rainfall that occurs will produce little in the way of accumulation. In the short term, best chance of showers will be windward as trades persist. As the winds become light and variable, expect mostly clear nights and mornings in response to land breezes, with warm and muggy afternoons. There's the potential for afternoon sea breezes to drive the formation of interior/mauka clouds that may be able to drop an isolated shower. There could be a bit more cloud and shower coverage across Kauai due to the decaying fronts.

Aviation

A slight strengthening of the trade winds is expected tonight and we should see moderate trade wind weather through Saturday. Overall fairly dry conditions are expected, but some scattered windward showers will be possible. Brief MVFR ceilings will be possible with any showers.
No AIRMETs in effect.

Marine

Surface high pressure centered approximately 1,300 nautical miles northeast of Oahu is exerting just enough of an influence on our local winds despite a stationary surface boundary and its associated low about 300 nautical miles north of the far offshore waters weakening the high's pressure gradient back toward the islands. This is will maintain areawide low end moderate to locally fresh (through island channels) easterly trade winds. Trades will drop off early next week as the boundary slowly drifts south into the northern offshore waters and further weakens the gradient. Variable breezes will become light to gentle over lowered seas Monday through Wednesday.
A small, medium period north swell that peaked last night will be gradually declining through the weekend. This due north swell will produce waist to chest high surf (at highest) within most sets along many north-facing shores through Saturday. A low that has formed along the aforementioned boundary may develop gale force winds along its northern periphery. As the low slowly meanders westward next week, the proximity of these stronger north winds to the islands may focus a north fetch toward the state. This increases the chances that a near 6 foot size, short-to-medium period north swell may pass through the nearshore waters next Monday night through Wednesday.
South-facing shore surf will remain small through early next week as a combination of short period southeast and background medium- to- long period south southwest swells travel by. A storm force low passing south of New Zealand this weekend may push a very small, long period swell into our southern waters the following weekend. The progressive eastward motion of this low may not allow gale/storm force winds to anchor very long along a southern great circle route aimed toward Hawaii. Thus, confidence is highest of only southern exposures experiencing a slight bump in surf late next week. East- facing shore waves will remain small and choppy through early next week due to the lack of trades over and upstream of the state.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov