Hilo

Tonight: Partly cloudy. Isolated showers in the evening. Lows 58 to 66 near the shore to 47 to 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 76 to 82 near the shore to 63 to 69 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Haze. Lows 59 to 67 near the shore to 48 to 54 at 4000 feet. Light winds.

Kona

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows around 69 near the shore to 42 to 48 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 80 to 86 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday Night: Mostly clear. Haze. Lows around 69 near the shore to 42 to 49 near 5000 feet. Light winds.

Waimea

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 59 to 67 near the shore to 50 to 58 near 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 77 near the shore to 68 to 75 near 3000 feet. Light winds. Chance of rain 20 percent.

Sunday Night: Mostly clear. Haze. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. Light winds.

Kohala

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 59 to 67 near the shore to 50 to 58 near 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 77 near the shore to 68 to 75 near 3000 feet. Light winds. Chance of rain 20 percent.

Sunday Night: Mostly clear. Haze. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. Light winds.

South Big Island

Tonight: Partly cloudy. Haze. Lows around 69 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph in the evening becoming light.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Haze. Lows around 70 near the shore to around 49 near 5000 feet. Light winds.

Puna

Tonight: Partly cloudy. Isolated showers in the evening. Lows 58 to 66 near the shore to 47 to 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 76 to 82 near the shore to 63 to 69 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Haze. Lows 59 to 67 near the shore to 48 to 54 at 4000 feet. Light winds.

Waikoloa

Tonight: Partly cloudy. Haze through the night. Lows 67 to 72 near the shore to 45 to 51 above 4000 feet. Southeast winds up to 10 mph in the evening becoming light.

Sunday: Mostly sunny. Haze. Highs around 83 near the shore to 63 to 69 above 4000 feet. Light winds.

Sunday Night: Mostly clear. Haze. Lows 67 to 72 near the shore to 46 to 51 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Light to moderate winds will veer out of the south this weekend as a front approaches and stalls to the northwest. With the lighter flow, overnight land breezes and afternoon sea breezes will prevail before southwesterly winds strengthen for the western end of the state early next week. A cold front will move over portions of the state by mid-week, bringing beneficial rain and breezy winds.

Discussion

Current visible satellite imagery shows scattered low-topped cumulus clouds moving up from the south over the western half of the state, with some inland cloud build-ups over island interiors with the afternoon sea breeze development. Radar imagery is very quiet this afternoon, with little to no echoes to report and nearly all zeroes in the rain gages today. These conditions are confirmed by the afternoon balloon soundings from Hilo and Lihue, which still depict a strong temperature inversion around 5500 ft, below normal precipitable water and extensive dry air aloft. As a weak cold front inches closer and stalls north of the state this weekend, local winds will continue to weaken and veer out of the south, then eventually southwest across the western end of the island chain. During this period, land and sea breeze activity will become more widespread, allowing for limited cloud and shower development over leeward and interior areas during the day and clearing at night.
An upper-level trough will dive down and sweep across the central Pacific and help drive the stalled front through at least the western portion of the island chain by the middle of next week. Late this weekend into early next week, southwesterly flow will strengthen across the western half of the state ahead of the front. This may be enough to overcome the land and sea breeze pattern for Kauai and Oahu and focus clouds and showers over leeward areas, especially with any prefrontal convergence bands. The latest global model runs continue to bring the front to Kauai Tuesday evening, then slowly move it through the middle of the island chain by Wednesday evening before it stalls again and dissipates. This frontal passage looks to bring some beneficial rain to the islands, along with breezy north-northeasterly winds for the western half of the state.
Convergence along the dissipating front, an abundance of upstream moisture, and a new plume of moisture associated with a low-level disturbance moving towards the eastern end of the state will keep rain chances in the picture through the latter part of the week. Rainfall will mainly be focused over windward and mauka areas for this period as high pressure builds behind the front and trades return. Long-term model guidance is hinting at the aforementioned upper trough becoming a closed low over the eastern end of the state next weekend, which could enhance the remaining shower activity and bring a slight chance of thunderstorms. Confidence is low regarding timing and location of any thunder, so have left it out of the forecast for now.
Finally, a hot spot over Halemaumau Crater on the Big Island continues to be seen on infrared satellite imagery despite decreased eruption activity. As winds weaken and shift out of the southeast, then south and southwest this weekend through early next week, SO2 emissions and vog are expected to to increase across some of the smaller islands.

Aviation

Light background winds will prevail across the island chain through the rest of the weekend with ridging in place over the state. While background flow will generally be southerly to southwesterly, winds will be light enough for daytime sea breezes and overnight land breezes to develop. Aside from a few passing high cirrus clouds, lower clouds and showers will form over the interior of the islands from late morning through the early evening, followed by clearing at night.
There are currently no AIRMETs in effect and none are anticipated through the rest of the weekend.

Marine

Extra large surf has arrived. Near shore buoys at Hanalei, Waimea, and Kalaeloa are now showing sharp increases in northwest swell height as expected. Reported swell heights are at or slightly above guidance. Surf along exposed north and west facing shores of all islands is expected to rise steadily this evening, peak overnight, then gradually decline. A High Surf Warning is in effect for north and west facing shores of Niihau, Kauai, Oahu, and Molokai as well as north facing shores of Maui and west facing shores of the Big Island. Warning level surf is expected to persist through Sunday afternoon and possibly into the evening hours. A Small Craft Advisory (SCA) is also in effect through Sunday afternoon for all waters except Maalea Bay, as 10 ft or higher seas are expected for all waters exposed to the northwest swell.
The next round of large to extra large northwest swells are expected to arrive Monday night. A strong low just south of the Aleutians is expected to maintain a sizable and strong fetch aimed at Hawaii as it presses eastward. Surf heights may briefly drop below HSW criteria HSW Sunday Night or Monday, but should rebuild to extra large levels Tuesday through Thursday.
Meanwhile, surf along east and south facing shores will remain small through the forecast period.
The surface ridge over the state will shift southeastward in response to an approaching cold front. Light and variable winds over the western half of the state will give way to moderate to fresh southwesterlies on Sunday, then moderate to strong northwest winds on Tuesday. Across the eastern end of the state, gentle to locally fresh east to southeast winds will hold through Monday then become light and variable.
The front may reach Kauai as early as Tuesday night with moderate northerly winds filling in behind it. The front is expected to stall and dissipate over the central islands during the second half of next week. Moderate to fresh trades may return to the eastern end of the state later in the week. Bands of scattered thunderstorms in advance the front could impact the far northwest offshore waters.

Fire weather

No critical fire weather conditions are expected for the next week. Light southerly flow with local land/sea breezes will continue into early next week, with relative humidities staying above critical levels through the forecast period. A front is expected to move through part of the state during the middle to late part of next week, bringing breezy northeasterly winds and much needed rainfall.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Sunday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala, Big Island South.
Small Craft Advisory until 6 PM HST Sunday for all Hawaiian waters except Maalaea Bay,

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Data Courtesy of NOAA.gov