Hilo

Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 65 to 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to around 49 at 4000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Sunday: Mostly sunny with scattered showers. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Kona

Today: Mostly sunny. Isolated showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 63 to 70 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to 71 to 78 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 62 near the shore to 48 to 56 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to 71 to 78 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 62 near the shore to 48 to 56 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 83 near the shore to around 72 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 65 near the shore to around 49 near 5000 feet. Northeast winds up to 15 mph.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 83 near the shore to around 72 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 65 to 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to around 49 at 4000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Sunday: Mostly sunny with scattered showers. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Today: Sunny. Isolated showers in the afternoon. Highs around 82 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 65 to 70 near the shore to 45 to 53 above 4000 feet. Southeast winds up to 10 mph.

Sunday: Sunny. Isolated showers in the afternoon. Highs around 82 near the shore to 66 to 73 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light northeast to east trade winds will return today through Sunday as a surface high passes by to the north of the state. Rather dry conditions are expected through the weekend, with limited rainfall favoring windward terrain. An upper level disturbance will pass over the state Monday and Tuesday and will likely bring a slight increase in rainfall, particularly across Oahu and Kauai, and potentially pop a thunderstorm or two each afternoon over the Big Island. Light and variable winds Monday will be replaced by moderate north to northeast winds Monday night and Tuesday as a new high builds north of the state. Drier more stable conditions are expected along with light to moderate trade winds Wednesday through the end of the work week, as a surface ridge parks itself north of the island chain.

Discussion

Currently at the surface, a 1018 mb high is centered around 600 miles west-northwest of Kauai. Meanwhile a 1003 mb low is located around 1000 miles north-northeast of Honolulu, with a trough extending southward from the low to a location around 600 miles east of Hilo. These features are producing a light northerly flow across the island chain early this morning, with land breezes present in many areas. Infrared satellite imagery shows clear to partly cloudy skies across the state, with radar imagery showing a few showers attempting to push onshore along north facing slopes of east Maui and the Big Island, while rain free conditions persist over the remaining isles. Main focus during the next few days revolves around rain chances, wind trends and the potential for thunder early next week.
High pressure will build eastward a few hundred miles north of the islands this weekend, while a cold front approaches from the northwest. The front will be losing steam as it nears Kauai late Monday, and may move into the northwestern islands Monday night and Tuesday before washing out. A new high will build in behind the front Tuesday and Wednesday, with ridging holding in place a few hundred miles north of the islands through the end of the upcoming work week.
A light wind regime is expected across the state through Monday, with light background northerly flow early this morning, switching around to a light northeast and eventually easterly flow this afternoon through Sunday. Winds will become light and variable Sunday night and Monday as the approaching front nears the state, allowing for overnight land breezes and daytime sea breezes in many areas. Moderate north to northeast winds will build from northwest to southeast down the island chain Monday night and Tuesday, then ease slightly into the light to moderate range and shift around to more of a typical easterly trade wind direction Wednesday through Friday.
As for the remaining details, rather dry weather is expected to persist through the weekend with precipitable water values holding around an inch or less. Limited shower activity will be confined primarily to windward slopes and coasts with most leeward areas not seeing any rain at all. An energetic upper level trough will move over the islands early next week, with 500 mb temps dropping down to around -14 to -16C as a couple shortwave impulses dive southeastward through the islands. There will be a subtle increase in moisture associated with the front approaching and moving southward into the islands, but precipitable water values remain unimpressive holding around or slightly above 1 inch. All these elements point to a slight increase in rain chances Monday and Tuesday, with perhaps a few heavier showers in the afternoon hours each day. Given the instability aloft however, a thunderstorm or two is not out of the question even with very low PW values, and have added in a mention of thunder over the Big Island during the afternoon hours Monday and Tuesday. If some more moisture works its way into the area early next week, thunder chances may need to be expanded to include additional portions of the state. Drier and more stable conditions will build back over the islands Wednesday through late next week, with showers favoring windward and mauka areas, and a shower or two developing each afternoon over interior and leeward areas with the assistance of localized sea breezes.

Aviation

An upper level ridge over the Hawaiian Islands will keep fairly stable conditions in the forecast today and tonight limiting rain shower activity across the region. A low pressure system remains far north of the state keeping light background trade winds. Expect more variability in the wind directions as land and sea breezes develop over each island through the weekend. VFR conditions will prevail with isolated MVFR conditions possible with showers.
No AIRMETs in effect and none are expected.

Marine

Winds will be below Small Craft Advisory strength through the middle of next week. Winds will shift out of the northeast and east today through Sunday as high pressure passes by several hundred miles north of the islands and a front approaches. The weak front will stall out and dissipate near or over the Monday night and Tuesday as trade winds return to moderate strength.
The current northwest swell will slowly decline through the weekend, while a moderate, short-period north-northeast swell holds steady today, then declines tonight and Sunday. Another northwest swell will arrive late Monday and peak on Tuesday, likely producing north shore surf just below the High Surf Advisory level. Mainly background south swells are expected through Tuesday, with a slightly larger and longer period south swell possible Thursday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov