Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with a 20 percent chance of showers in the morning, then partly sunny in the afternoon. Highs around 84 near the shore to around 73 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 66 to 71 near the shore to around 58 above 3000 feet. Light winds becoming northeast up to 10 mph after midnight.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs around 84 near the shore to around 73 above 3000 feet. East winds up to 10 mph shifting to the south around 10 mph in the afternoon.

South Kaua’i

Today: Mostly sunny with a 20 percent chance of showers in the morning, then partly sunny in the afternoon. Highs 79 to 86. Southwest winds 10 to 15 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows around 69. Light winds.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs 79 to 86. Southwest winds up to 10 mph.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Highs 74 to 82 in the valleys to around 66 above 4000 feet. Light winds.

Tonight: Partly cloudy with a 20 percent chance of showers. Lows 59 to 67 in the valleys to around 56 above 4000 feet. Light winds.

Wednesday: Mostly sunny with a 20 percent chance of showers. Highs 74 to 82 in the valleys to around 65 above 4000 feet. Southwest winds up to 15 mph.

North Kaua’i

Today: Mostly sunny. Highs 75 to 85. Northeast winds up to 10 mph.

Tonight: Partly cloudy. Lows 62 to 69. Light winds becoming south up to 10 mph after midnight.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs 75 to 85. Southeast winds up to 10 mph shifting to the west in the afternoon.

East Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Highs 75 to 86. Southwest winds up to 15 mph.

Tonight: Partly cloudy. Lows 61 to 71. Southwest winds up to 10 mph.

Wednesday: Mostly sunny. A 20 percent chance of showers in the afternoon. Highs 74 to 85. Southwest winds up to 15 mph shifting to the south in the afternoon.

Detailed Forecast

Synopsis

Relatively dry and stable conditions will persist through Wednesday with light winds that will allow for sea breezes each day and land breezes overnight. A front will move through 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 through today due to a ridge of high pressure over the state. Winds will be light and variable with a background southerly flow. Winds should be light enough for day time sea breezes and night time land breezes. Day time sea breezes will lead to afternoon clouds over interior and mountain areas with a few light showers possible. A slightly stronger southeast flow is expected to fill in from the south today into Wednesday, ahead of the front that should gradually increase moisture in the area tonight into Wednesday.
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

A ridge of high pressure sitting over the state will allow for light and variable winds causing sea/land breezes every day/night through at least midweek. SHRA and isol low cigs will be possible but VFR conds should prevail.
No AIRMETs currently in effect and none are anticipated.

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 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 in the longer term.
Fetches of near-gale to gale-force winds associated with fast- moving low pressure systems passing well N of the area will send NW swells 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 increased overnight, where significant wave heights have reached as high as 11 feet. Although primarily associated with relatively short- period (12 seconds) NW swell, longer period (14-17 second) bands are seeing increased NW swell energy over the last several hours. Resultant surf is expected to peak near High Surf Advisory (HSA) levels later today, and a HSA is in effect for exposed shores. Another NW swell Thursday into Friday will likely produce HSA- level surf before a general diminishing trend in NW swell develops by next weekend.
A long-period S swell will peak today, producing surf near summertime averages along S facing shores, before gradually diminishing through Thursday. Another similarly-sized long-period S swell is expected by next weekend.

Fire weather

Critical fire weather conditions are not expected through the rest of the week and into the weekend. Daytime relative humidity values may briefly approach critical levels this afternoon but winds will remain light and preclude any fire weather concerns. From Wednesday into the weekend, minimum relative humidity values are expected to trend above critical levels due to increasing moisture and showers as a front approaches and dissipates near the central portion of the state.

HFO Watches/Warnings/Advisories

High Surf Advisory from noon today to 6 AM HST Wednesday for north and west facing shores of Niihau Kauai Oahu Molokai and north facing shores of Maui.

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