Hilo

Tonight: Mostly cloudy with numerous showers. Lows 62 to 69 near the shore to 53 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 63 to 68 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 52 to 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 74 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 30 percent.

Saturday: Mostly sunny. Scattered showers in the afternoon. Highs 83 to 88 near the shore to around 67 near 5000 feet. Light winds. Chance of rain 30 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 73 near the shore to 47 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 65 to 83. East winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Kohala

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 65 to 83. East winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

South Big Island

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 74 near the shore to around 52 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Saturday: Sunny and breezy. Isolated showers in the afternoon. Highs around 84 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Saturday Night: Mostly clear. Isolated showers in the evening. Lows around 73 near the shore to around 51 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with numerous showers. Lows 62 to 69 near the shore to 53 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 63 to 68 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 52 to 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Partly cloudy with isolated showers. Lows around 74 near the shore to 52 to 57 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Sunny. Isolated showers in the afternoon. Highs 83 to 89 near the shore to 65 to 72 above 4000 feet. Northeast winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Saturday Night: Mostly clear. Isolated showers in the evening. Lows around 73 near the shore to 50 to 55 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure far north northeast of the islands will maintain breezy trade winds through the rest of today. A front approaching from the northwest will weaken the high and thus the trades tonight through the weekend. Bands of showers will remain focused primary along windward and mauka areas. Tropical moisture and a low level trough approaching from the east will increase chances of precipitation and thunderstorms early next week ahead of another approaching front. The front will move over the state around mid week next week.

Discussion

A 1030 mb surface high centered around 800 miles north northeast of the state remains the main driver of breezy conditions rest of today. Radar and satellite imagery show showers have tapered off slightly since earlier this morning. However showers have picked up along Kona slopes of the Big Island due to seabreezes. Expect showers to increase along windward and mauka areas tonight with some showers spilling over to leeward locations, especially during the overnight and early morning hours. Showers should taper off along the Kona slopes tonight as land breezes develop.
Starting tonight through the weekend a front passing far north of the state will weaken the high to our northeast, easing trade wind speeds through the weekend to more gentle to locally breezy speeds. Expect bands of showers embedded in the tradewind flow to maintain scattered showers along windward and mauka areas with some showers spilling over to leeward areas, especially overnight and during the early morning hours through the weekend.
The weather pattern will shift early next week as a low level trough and tropical moisture moves from east to west across the state. This will bring an up tick in showers to the Big Island as early as Monday morning then spreading to the rest of the state Tuesday ahead of the approaching front from the northwest. This surface level trough will coincide with an upper level trough digging down from the northwest which could also produce thunderstorms and locally heavy rainfall particularly for the Big Island Monday night and possibly windward Maui. Global models are in general agreement that a strong front will move over the state by midweek bringing with it another potential for showers ahead of the front and strong northerly winds following behind with a significantly drier airmass. There are some differences between the GFS and EC models by midweek regarding the timing and vertical features which will impact the fine details, however overall both models show a wetter pattern starting next week with a drier and cooler airmass filtering in during the second half of the week.

Aviation

Breezy trades weaken to moderate and veer to ESE tonight into Saturday. Low clouds and showers will be rather limited over the smaller islands but activity will still show a preference for the usual windward and mauka areas. A batch of moisture upstream of the Big Island will bring periods of MVFR late this evening into tonight before drier air becomes established over the area for Saturday.
AIRMET Sierra for mountain obscuration remains in effect for the Big Island.
AIRMET Tango for lee turb remains in effect.

Marine

Fresh to locally strong easterly trade winds continue through tonight, and a Small Craft Advisory remains in effect for the typical windy waters around Maui and the Big Island. Winds then ease into the moderate to locally fresh range out of the east- southeast this weekend and into early next week. An uptick in winds is expected late Tuesday through the end of next week as a front moves across the waters.
A small north-northeast swell will continue to decrease through the weekend as a building north-northwest swell moves into the coastal waters. The latest buoy observations northwest of the Hawaiian Islands have started to pickup on the long period forerunners and are approximately 1-2 ft higher than guidance. Expect this swell to continue building through the weekend with peak swell heights expected by Sunday morning. Surf along exposed north and west facing shores will likely reach advisory levels on Sunday. The northwest swell will gradually decrease on Monday, then hold through early next week. Another building northwest swell is expected to move into the coastal waters for the latter half of next week.
Surf along east facing shores will remain rough through tonight due to the strong trades locally and upstream across the eastern Pacific. A slight downward trend is expected this weekend.
Surf along south-facing shores will remain small, with mainly a mix of short period southeast and background long period south swell energy.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov