Hilo

Tonight: Mostly clear. Haze. Lows 60 to 67 near the shore to 48 to 54 at 4000 feet. Southwest winds around 10 mph.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 81 near the shore to 65 to 71 at 4000 feet. Southeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 61 to 68 near the shore to 48 to 54 at 4000 feet. South winds around 10 mph in the evening becoming light.

Kona

Tonight: Mostly clear. Haze. Lows around 70 near the shore to 43 to 50 near 5000 feet. Light winds.

Friday: Mostly sunny. Haze. Highs around 84 near the shore to around 67 near 5000 feet. South winds around 10 mph shifting to the west in the afternoon.

Friday Night: Partly cloudy. Haze. Lows 67 to 72 near the shore to 44 to 50 near 5000 feet. Light winds.

Waimea

Tonight: Mostly clear. Haze. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 60 to 69 near the shore to 52 to 60 near 3000 feet. Light winds.

Kohala

Tonight: Mostly clear. Haze. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 60 to 69 near the shore to 52 to 60 near 3000 feet. Light winds.

South Big Island

Tonight: Mostly clear. Haze. Lows around 71 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph.

Friday: Mostly sunny. Haze. Highs around 83 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph.

Friday Night: Mostly clear. Haze. Lows around 71 near the shore to around 49 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly clear. Haze. Lows 60 to 67 near the shore to 48 to 54 at 4000 feet. Southwest winds around 10 mph.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 81 near the shore to 65 to 71 at 4000 feet. Southeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 61 to 68 near the shore to 48 to 54 at 4000 feet. South winds around 10 mph in the evening becoming light.

Waikoloa

Tonight: Partly cloudy. Haze. Lows around 70 near the shore to 47 to 53 above 4000 feet. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 81 to 86 near the shore to 64 to 71 above 4000 feet. South winds around 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 68 to 73 near the shore to 47 to 53 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Southerly winds across the western half of the state and southeasterly across the eastern half will persist through the weekend as a couple of fronts stall northwest of Kauai. Limited rainfall is expected, with the best chance for a few showers over leeward portions of Kauai and Oahu. Trade winds will return early next week, likely bringing an increase in showers to mainly windward areas.

Discussion

As a cold front slowly approaches Kauai from the northwest this afternoon, the surface ridge centered to the northeast will continue to be shoved south of its usual position, with its horizontal axis extending over the southern end of the state. With the surface ridge in this position, it will maintain a southeasterly flow across the eastern half of the state and a southerly flow across the western half.
This afternoon's radar and satellite imagery show a few showers moving into leeward areas on the southerly winds along with sea breeze activity increasing cloud cover and bringing a few light showers to island interiors across Maui County. The front to the northwest of Kauai will stall north of the area this evening keeping its attendant moisture out of the forecast area. Clouds and light showers over the western end of the state will favor leeward areas in this southerly flow regime, with windward sides expected to be slightly clearer. Over the eastern end of the state, the southeasterly flow will allow clouds and a few showers to favor southeast coasts and lower slopes of the Big Island and Maui overnight, and then afternoon sea breezes in the lighter wind flow (blocked from the Big Island) will bring clouds and showers over leeward areas and island interiors during the afternoon.
The surface ridge will remain positioned over the islands into the weekend and mid-level ridging will build overhead. The persistent southerly flow will maintain elevated dewpoints (near 70F) that will make it feel somewhat muggy, especially in the afternoon hours. While there will be some minor fluctuations in wind speed and direction as a few fronts pass to the north of the state, the general pattern will remain the same through the weekend with this southeasterly wind regime across the eastern end of the state and southerly wind regime across the western end. Overall, rainfall accumulations will be minimal through the weekend with subsidence from the mid-level ridge and drier air filtering across the area helping to put a damper on shower activity.
A pattern change looks to occur early next week. Another front will approach from the northwest and may move across a portion of the island chain or dissipate just before it arrives. Regardless, the driving high pressure that builds to the north of the state in its wake will bring a return to trades that are expected to build into mid week. Moisture being carried in on the newly established trades along with increased instability due to height falls and cooler temperatures aloft may lead to a “wetter” trade wind pattern Tuesday into Wednesday.
GOES GeoColor imagery, webcams, and air quality observations show vog continuing to impact the Big Island through Oahu as SO2 emissions from Kilauea are transported in the south-southeasterly low-level flow. Episode 11 of the Kilauea summit eruption paused this morning, which may lead to a reduction in emissions and vog coverage as the week progresses. As the trades build back into the islands next week, any lingering vog upstream of the islands could be carried back across the islands.

Aviation

A front to the north and a surface ridge to the south of the Hawaiian islands will maintain light to moderate southeasterly to southwesterly winds (southeasterly for the eastern end of the state becoming south-southwesterly for the western end of the state). These southerly winds are expected through at least tomorrow. Dry and stable conditions will keep clouds and showers light and isolated. Overall VFR conditions should prevail with a few brief MVFR showers moving through from south to north.
Hazy conditions should continue through at least tomorrow due to a combination of Kilauea volcanic activity and southerly winds. This could lead to pockets of reduced visibilities.
No AIRMETs in effect.

Marine

A large to extra large NW (310-320) swell is building this evening and will reach High Surf Warning (HSW) thresholds late tonight before peaking early Friday. Long period forerunners have registered on NDBC buoy 51001 roughly on schedule and an HSW remains in effect for select north and west facing shores. A High Surf Advisory may eventually be needed for west facing shores of the Big Island. Additionally, peak extra large surf is forecast to coincide with high tide early Friday which will lead to overwash of low lying coastal zones. Another moderate large WNW swell is expected on Monday.
Surf along S facing shores remains tiny and dominated by background energy through the week. Surf likewise remains tiny along E facing shores due to light background winds, but will receive an appreciable boost with the return of strong trades next week.
Light to moderate southerlies prevail over the next several days as fronts periodically advance north of the islands. Strong high pressure then builds north of the area early next week bringing a return to moderate trades during Sunday. Trades further strengthen through mid-week.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Friday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.
Small Craft Advisory until 6 PM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

Data Courtesy of NOAA.gov