West Side

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 83. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 65 to 72. Light winds. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 82. Southwest winds up to 10 mph. Chance of rain 30 percent.

South Side

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 63 to 74. Light winds becoming south up to 10 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85. Southwest winds up to 10 mph. Chance of rain 20 percent.

North Shore

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 78 to 83 near the shore to around 67 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 69 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 82 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Central Maui

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 82 to 87. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 69. Light winds becoming south around 10 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 81 to 86. South winds around 10 mph shifting to the southeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Isolated showers late in the morning. Highs around 64 at the visitor center to around 71 at the summit. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 46 at the visitor center to around 48 at the summit. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 64 at the visitor center to around 67 at the summit. Light winds. Chance of rain 20 percent.

East Maui

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 78 to 83 near the shore to around 67 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 69 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 82 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Lanai City

Today: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 72 to 78. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 61 to 66. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 70 to 78. Light winds. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 69 to 86. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 56 to 72. Light winds becoming south up to 10 mph after midnight. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 69 to 87. Southwest winds up to 10 mph. Chance of rain 30 percent.

Detailed Forecast

Synopsis

Increasing southerly winds and moisture ahead of an approaching cold front and upper disturbance will lead to better rainfall chances for portions of the state later today through the second half of the week. The front will reach Kauai on Thursday, then stall and begin to diminish over or around Oahu Thursday night into Friday. Breezy north-northeast winds will fill in behind it Thursday and Thursday night over the western end of the state, with a brief return of trades Friday. A second front passing north of the area over the weekend could lead to the trades weakening again.

Discussion

A transition period is anticipated today through tonight as upper heights begin to lower in response to a shortwave trough digging southward into the area. Increasing southerly winds and lift ahead of the attendant cold front could lead to a few pre-frontal showers today, especially through the late morning and afternoon hours for the western end of the state. Early morning radar and satellite data reflect this potential with a few light showers developing over the waters south of Oahu and Kauai, and along the southeast Big Island coast. The better dynamics (35 to 45 kt 0-6 km shear) and upper height falls are expected tonight over and around Kauai as the front draws closer. Although the chances are low, a thunderstorm or two can't be completely ruled out, especially over the adjacent waters north of Kauai tonight and into Thursday.
The front will stall and slowly diminish around Oahu Thursday night through Friday as the shortwave trough begins to lift northeastward and away from the area. Breezy north to north- northeast winds trailing the front Thursday and Thursday night over the western end of the state will veer out of the east on Friday, with the residual moisture associated with the front retreating westward. A brief return of light trade winds is possible over the weekend as another front passes to the north.

Aviation

Stable conds expected through the first half of today. The second half of today through Friday a front approaches the islands. Winds should become light to moderate with frontal approach. This should also increase the chances for some SHRA and low cigs. MVFR conds can be expected in any SHRA, however VFR should prevail.
No AIRMETs in effect.
AMD NOT SKED in at PHJR and PHMK for equipment issues, with no estimated time for repair.

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 today. A low passing N of the islands late tonight and Thursday will force the ridge eastward, with a tightening low-level gradient supporting fresh to locally strong S to SW winds near Kauai and Oahu as a front approaches from the NW. Fairly high confidence in the front moving over Kauai on Thursday, then stalling near Oahu from late Thursday into Friday. Winds and/or seas will likely reach Small Craft Advisory (SCA) criteria in at least some of the waters Thursday and Friday, and the front will bring a slight chance of thunderstorms.
As the front stalls and dissipates, locally fresh to strong post- frontal N winds over Kauai and Oahu will gradually ease and veer to the NE Thursday night into Friday, while light to moderate E winds will prevail over Maui and Big Island waters. Wind speeds will quickly diminish statewide on Saturday, then light to moderate ENE trade winds on Sunday are expected to strengthen next week as high pressure builds to the distant NE.
Long fetches of near-gale to gale-force winds associated with low pressure systems passing well N of the area will send NW swell of varying sizes and periods toward the islands the next several days. Most of the swell energy will be in the shorter- period 12-14 second bands, with resultant surf expected to be near or above High Surf Advisory (HSA) levels along exposed N and W facing shores into the weekend.
In the short term, swell heights at NDBC buoys 51001/51101 NW of Kauai have diminished slightly overnight, with a primary period ~12 seconds. The High Surf Advisory (HSA) for exposed N and W facing shores has been cancelled. Another NW swell late Thursday into Friday will likely produce HSA-level surf, with a smaller NNW pulse possible next weekend.
A long-period S swell is will gradually decline through Thursday. Another long-period S swell is expected by this weekend, but it will likely be a little smaller than this swell at its peak.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov