Hilo

Today: Mostly cloudy with scattered showers. Highs around 82 near the shore to around 66 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 52 at 4000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers early in the morning, then showers likely and chance of thunderstorms in the late morning and afternoon. Highs around 83 near the shore to around 66 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs around 84 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers early in the evening, then mostly cloudy with isolated showers late in the evening. Mostly clear after midnight. Lows 66 to 72 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 40 percent.

Friday: Sunny early in the morning, then mostly cloudy with scattered showers and chance of thunderstorms in the late morning and afternoon. Highs around 84 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Partly sunny with scattered showers. Highs around 81 near the shore to 70 to 76 near 3000 feet. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65 near the shore to 50 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers early in the morning, then showers likely and chance of thunderstorms in the late morning and afternoon. Highs around 82 near the shore to 70 to 76 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kohala

Today: Partly sunny with scattered showers. Highs around 81 near the shore to 70 to 76 near 3000 feet. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65 near the shore to 50 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers early in the morning, then showers likely and chance of thunderstorms in the late morning and afternoon. Highs around 82 near the shore to 70 to 76 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

South Big Island

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers early in the morning, then mostly cloudy with scattered showers and chance of thunderstorms in the late morning and afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Puna

Today: Mostly cloudy with scattered showers. Highs around 82 near the shore to around 66 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 52 at 4000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers early in the morning, then showers likely and chance of thunderstorms in the late morning and afternoon. Highs around 83 near the shore to around 66 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs around 84 near the shore to 65 to 72 above 4000 feet. Northwest winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers early in the evening, then partly cloudy with isolated showers late in the evening. Mostly clear after midnight. Lows 67 to 72 near the shore to 47 to 55 above 4000 feet. Light winds. Chance of rain 50 percent.

Friday: Sunny early in the morning, then mostly cloudy with scattered showers and chance of thunderstorms in the late morning and afternoon. Highs around 84 near the shore to 65 to 72 above 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will diminish today through tonight as a broad surface trough and upper disturbance move in. Added instability associated with these features will lead to an increasing threat for strong to severe thunderstorms and heavy rainfall late tonight through Saturday. Although the thunderstorm potential will lower Sunday into early next week, plenty of moisture lingering combined afternoon sea breezes and a broad surface trough nearby will support afternoon showers over our interior and leeward areas each day. The wet pattern could continue through the latter half of next week as another upper disturbance approaches.

Discussion

The morning water vapor imagery showed broad upper troughing over the region with a strong shortwave digging southeastward toward the area. The local winds will respond and diminish over the next 24-Hrs as the attendant cold front passes to the north and broad surface troughing evolves over the islands. The short-term guidance has initialized well with this pattern and depicts strong upper height falls later today into tonight as the shortwave trough closes off into an upper low and settles southward into the area. MUCAPES of 1000 to 2000 J/Kg combined with effective deep layer shear values of 35 to 45 knots will support a few strong to severe thunderstorms and locally heavy rainfall that could lead to flash flooding through this period. Impacts could begin over the western end of the state as early as tonight, with a transition to more of a widespread/statewide potential Friday through Saturday.
Guidance shows the upper low beginning to weaken as it lifts off to the northeast later this weekend, which will support a diminishing threat of thunderstorms. The rainfall chances, however, will likely linger as the aforementioned broad surface trough remains over or nearby to the west Sunday through next week. Expect the light to moderate east to southeast low-level flow to persist, which will allow the land and sea breeze regime to hold for most areas. This combined with a sufficient amount of moisture will keep the rainfall chances up each day, especially through the afternoon and early evening periods over interior/leeward areas with the sea breezes. The wet pattern could persist through the second half of the week as another upper low drops southward into the area drawing up deep tropical moisture over the state.

Aviation

Light to moderate trades will persist today and gradually weaken heading into Friday. Daytime sea breezes and nighttime land breezes are expected over wind-protected leeward areas.
Showers will continue to favor windward and mauka areas with the greatest coverage and intensity during the late night and early morning time period. MVFR conditions will accompany any of these heavier showers. As sea breeze activity resumes by this afternoon, clouds and showers will begin to develop across some leeward/interior locations. In addition, a disturbance aloft will approach the area later today, helping to enhance shower activity across the state and bringing instability that may help to spark a few thunderstorms near Kauai sometime tonight into tomorrow morning.
AIRMET Sierra is in effect through this morning for tempo mountain obscuration across windward areas as a band of moisture moves in from the east. This AIRMET may be needed periodically throughout the next 24 to 36 hour period due to enhanced shower activity.

Marine

A trough developing north of Kauai today will strengthen and expand southward over the island chain tonight into Friday, then linger through the weekend. As a result, winds will remain rather light and below Small Craft Advisory thresholds. A strong disturbance aloft moving overhead will bring a threat for strong to severe thunderstorms late tonight through Saturday. These thunderstorms will have the potential to produce dangerous wind gusts, hail, and frequent lightning. Moderate east to southeast trade winds will gradually rebuild Sunday through early next week.
A long-lived south swell will affect the islands during the next several days, keeping south shore surf above the summertime average. The surf is expected to peak below the High Surf Advisory threshold of 10 feet today through Friday, then gradually decline Saturday through Tuesday. A series of overlapping long-period south swells will give another sizable boost to south shore surf Wednesday through late next week.
North shore surf will remain tiny today and tonight, followed by a small reinforcing short-period north-northwest swell late Friday through the weekend. A small long period northwest swell will build Sunday night, giving north shore surf a boost early next week. Surf along east facing shores will be well below normal levels through the middle of next week.

HFO Watches/Warnings/Advisories

None.

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