Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 70 near the shore to 52 to 59 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 65 to 71 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Friday Night: Breezy. Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 51 to 58 at 4000 feet. North winds up to 20 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy. Isolated showers in the evening. Haze through the night. Lows around 73 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 85 near the shore to 65 to 70 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows around 73 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 71 near the shore to 54 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 80 near the shore to 71 to 79 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday Night: Breezy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 62 near 3000 feet. East winds up to 25 mph. Chance of rain 40 percent.

Kohala

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 71 near the shore to 54 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 80 near the shore to 71 to 79 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday Night: Breezy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 62 near 3000 feet. East winds up to 25 mph. Chance of rain 40 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows around 73 near the shore to around 52 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Friday: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 86 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday Night: Partly cloudy. Breezy and haze. Lows around 73 near the shore to around 52 near 5000 feet. East winds up to 20 mph.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 70 near the shore to 52 to 59 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 65 to 71 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Friday Night: Breezy. Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 51 to 58 at 4000 feet. North winds up to 20 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 71 to 76 near the shore to 51 to 56 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs 84 to 91 near the shore to 66 to 73 above 4000 feet. North winds up to 20 mph. Chance of rain 20 percent.

Friday Night: Mostly clear. Breezy and haze. Lows around 73 near the shore to 51 to 56 above 4000 feet. Northeast winds up to 25 mph with gusts to 45 mph.

Detailed Forecast

Synopsis

Breezy trades become strong this weekend into next week delivering limited clouds and showers mainly to windward and mauka areas.

Discussion

Closed mid-level low positioned west of the islands at press time is transitioning to a weak and sheared out low amplitude shortwave as it's partially absorbed back into mid-latitude westerlies. This low remains of little consequence other than the attendant subtropical jet which is gracing area skies with occasional cirrus. Near the surface, observed soundings indicate a very firm trade wind inversion anchored near 6kft at Lihue and Hilo, though slightly weaker in the vicinity of Kauai courtesy of closer proximity to the low. This has kept a kept a lid on overnight showers while the daytime diurnal max has maintained dry predominantly dry conditions each afternoon. Little change expected going forward as showers remain light and ridging north of the islands strengthens. This will only reinforce stable trade wind conditions as trades become strong this weekend into early next week. Given the strength of the inversion and strengthening background trades, it will be worth monitoring favored downslope areas for gusty wind potential as early as Friday, mainly in Maui County and the Big Island.
Shear-induced upper low development is anticipated over the islands this weekend which may diminish stability a bit, especially over the western end of the state, but the shallow boundary layer moisture field will likely be unable to capitalize leading to a rather uniform scattered coverage of light-intensity showers each night.

Aviation

A stable, moderate to locally breezy trade wind flow will persist through Friday, followed by an increase in winds during the weekend. Periods of MVFR ceiling and visibility in SHRA will focused along windward slopes, and during the overnight and early morning hours AIRMET Sierra for mountain obscuration may be needed. VFR will dominate over most leeward areas, but sheltered terrain will experience isolated MVFR conditions each afternoon, especially on the Kona slopes of the Big Island. The stable trade wind flow will produce light turbulence below 7,000 feet, but these conditions should not require AIRMET Tango through Friday. An upper-level low to the west may produce some light turbulence above FL300 into early Friday.

Marine

High pressure far northeast of the islands will remain nearly stationary through the remainder of this week and bring moderate to locally strong trade winds. High pressure will then re-center north of the region this weekend and help to further strengthen trades. Thus, a Small Craft Advisory for the windier waters and channels around Maui County and the Big Island remains in effect through at least Sunday.
Surf along south facing shores will be tiny to small over the next several days. A small, long period, south swell originating from a fetch near New Zealand will build late this weekend and help to boost surf heights through early next week.
Rough and choppy surf is expected for east facing shores through the forecast period due to the moderate trades. Tiny seasonal surf is expected for North facing shores.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov