Hilo

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then partly cloudy after midnight. Lows 60 to 67 near the shore to 51 to 57 at 4000 feet. Southwest winds up to 10 mph.

Wednesday: Mostly sunny. Highs 78 to 83 near the shore to 66 to 71 at 4000 feet. South winds up to 15 mph.

Wednesday Night: Mostly clear. Lows 61 to 68 near the shore to 51 to 56 at 4000 feet. Light winds.

Kona

Tonight: Partly cloudy. A 20 percent chance of showers in the evening. Lows around 70 near the shore to 46 to 52 near 5000 feet. Light winds.

Wednesday: Mostly sunny. Highs around 84 near the shore to around 68 near 5000 feet. Light winds.

Wednesday Night: Mostly clear. Lows around 71 near the shore to 45 to 51 near 5000 feet. Light winds.

Waimea

Tonight: Partly cloudy. Lows 61 to 70 near the shore to 54 to 61 near 3000 feet. Light winds.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs around 78 near the shore to 69 to 77 near 3000 feet. Northwest winds up to 10 mph.

Wednesday Night: Partly cloudy. A 20 percent chance of showers in the evening. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. Light winds.

Kohala

Tonight: Partly cloudy. Lows 61 to 70 near the shore to 54 to 61 near 3000 feet. Light winds.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs around 78 near the shore to 69 to 77 near 3000 feet. Northwest winds up to 10 mph.

Wednesday Night: Partly cloudy. A 20 percent chance of showers in the evening. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. Light winds.

South Big Island

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then partly cloudy after midnight. Lows around 71 near the shore to around 51 near 5000 feet. Northeast winds up to 15 mph.

Wednesday: Mostly sunny. Breezy. Highs around 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

Wednesday Night: Mostly clear. Lows around 71 near the shore to around 50 near 5000 feet. East winds around 10 mph.

Puna

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then partly cloudy after midnight. Lows 60 to 67 near the shore to 51 to 57 at 4000 feet. Southwest winds up to 10 mph.

Wednesday: Mostly sunny. Highs 78 to 83 near the shore to 66 to 71 at 4000 feet. South winds up to 15 mph.

Wednesday Night: Mostly clear. Lows 61 to 68 near the shore to 51 to 56 at 4000 feet. Light winds.

Waikoloa

Tonight: Partly cloudy. Lows 69 to 74 near the shore to 49 to 54 above 4000 feet. Light winds.

Wednesday: Mostly sunny. Highs 81 to 86 near the shore to 65 to 71 above 4000 feet. West winds up to 10 mph.

Wednesday Night: Partly cloudy. Lows around 71 near the shore to 49 to 54 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Relatively dry and stable conditions will persist through Wednesday, with nighttime land breezes developing tonight. A front will move across Kauai on Thursday, then dissipate over the central portion of the state on Friday. Chances of rain will increase ahead of and along the frontal boundary, with moderate to locally breezy northeast winds filling in behind it.

Discussion

A dry and stable air mass will remain in place due to a ridge of high pressure over the state. Winds this afternoon remained light and variable with a background southerly flow. This allowed for the development of weak afternoon sea breezes which brought a few clouds and light showers to interior portions. Expect nighttime land breezes to develop shortly after sunset which will allow for some clearing tonight.
Starting Wednesday, a front will begin to approach the state from the northwest. Southerly wind flow will strengthen around the western end of the state, increasing chances of showers. By Thursday, the front is expected to be over or through Kauai with some prefrontal showers increasing over Oahu and possibly parts of Maui County. The front is expected to eventually stall out and dissipate near the central portion of the state Friday. Overall the front does not look very impressive, but it could bring some light to moderate rainfall to some much needed locations on the leeward side. Some locally heavy rainfall will be possible late Thursday into Friday, in the area where the frontal boundary stalls.
Moderate to locally breezy trades should briefly return over the western half of the state on Friday as a weak high develops northwest of the state. Trades will be short-lived as the high quickly shifts east as another front passes north of the state. This will put the western end of the state in a light wind flow patter while gentle easterly winds linger over the eastern end. Confidence in the weather forecast over the weekend remains low with most of the ensemble members showing some type of upper level trough pushing through the state. Stay tuned for more details.

Aviation

Light to occasionally variable winds out of the southerly quadrant persist. Sea breezes brought a few afternoon clouds which will be followed by offshore land breezes and clearing tonight. VFR prevails through the forecast period. Any showers will be light and transient in nature.
No AIRMETs in effect.

Marine

An E-W oriented surface ridge extending over the islands from the E is supporting gentle winds statewide that are out of the E-SE over Big Island waters, and from the S-SW over Kauai and Oahu waters. Little overall change in the ridge's position is expected through Wednesday. A low passing N of the islands late Wednesday and Thursday will force the ridge eastward, with a tightening low-level gradient supporting fresh to locally strong S to SW winds statewide as an associated front approaches from the NW. Fairly high confidence in the front moving over Kauai and Oahu from late Thursday into Friday, likely stalling on Friday over the central portion of the island chain. Winds and/or seas will likely reach Small Craft Advisory (SCA) criteria in at least some of the waters Thursday and Friday.
As the front dissipates, locally fresh post-frontal N winds will gradually ease and veer to the NE Thursday night into Friday. Wind speeds will quickly diminish into Saturday, when a period of light and variable winds is expected. Light NE winds on Sunday are expected to give way to increasing trade wind flow into next week.
Fetches of near-gale to gale-force winds associated with fast- moving low pressure systems passing well N of the area will send NW swell of varying sizes and periods toward the islands this week. Although most of the swell energy will be in the shorter- period 12-14 second bands, resultant surf is expected to be near or above High Surf Advisory (HSA) levels along exposed N and W facing shores at times.
Wave/swell heights at NDBC buoys 51001/51101 NW of Kauai have peaked this morning, which should translate to surf peaking this evening into tonight at HSA thresholds along north and west facing shores. This current northwest swell should gradually decline over the next few days and likely drop below HSA thresholds on Wednesday. Another NW swell Thursday into Friday will likely produce HSA-level surf before a general diminishing trend in NW swell develops by next weekend.
An out of season long-period S swell is currently producing surf near summertime averages along S facing shores. This current south swell should gradually decline through Thursday. Another long-period S swell is expected by this weekend, but it will likely be a little smaller than the current swell.

Fire weather

Critical fire weather conditions not expected through the weekend. Daytime relative humidity will trend above critical levels through the weekend due to increasing moisture and showers associated with a dissipating front.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Wednesday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.

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Data Courtesy of NOAA.gov