Photo Credit: Brendan Stephen

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to around 72 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 65 to 70 near the shore to around 58 above 3000 feet. Light winds. Chance of rain 20 percent.

Saturday: Sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 76 to 84. Northeast winds 20 to 25 mph decreasing to 10 to 25 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 69. Northeast winds around 10 mph in the evening becoming light. Chance of rain 30 percent.

Saturday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 77 to 85. Light winds. Chance of rain 40 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 70 to 79 in the valleys to around 62 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 60 to 67 in the valleys to around 56 above 4000 feet. East winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 71 to 79 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 72 to 84. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 62 to 70. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Saturday: Mostly sunny. Scattered showers in the afternoon. Highs 73 to 83. Light winds. Chance of rain 40 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 69 to 81. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 61 to 73. East winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 71 to 83. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A slow-moving front over Oahu will provide continued shower activity across the western portion of the state as it stalls and weakens today. Breezy north-northeast winds will fill in behind the front this morning, then weaken and shift out of the east- northeast state-wide this afternoon and evening. Winds will briefly become light and variable over the weekend before strong and gusty trades return for much of next week.

Discussion

A ragged 120 mile band of broken to overcast layered clouds marks a front straddling Oahu and surrounding waters. An upper trough is noted across the western islands, supporting the front and triggering deep convection far north of local waters. Radar and satellite loops show the front has slowed almost to a halt over Oahu, with the exact location of the front within the cloud band becoming quite uncertain. Models continue to show the front will stall and weaken near Oahu through today. The moisture associated with this front will hang around, resulting in widespread showers over and around Oahu, with scattered showers expected over Kauai, which lies behind the front. The upper trough will wash out and lift northeastward through the day today, taking the best dynamics and thunderstorm chances with it.
Gusty north to north-northeast winds behind the front will spread eastward over Oahu this morning. Winds will gradually weaken and veer out of the east statewide through the day today as residual frontal moisture retreats westward. A brief return of light trade winds is possible over the weekend as another front passes to the north. Models show an increasing likelihood of strong easterly trades building in early next week as high pressure builds to the north in the wake of this passing front. These strong trades could last through much of next week.

Aviation

A dissipating front just northwest of Oahu will continue to slowly move eastward this morning before eventually dissipating later today. As the front dissipates expect any residual moisture to retreat westward towards Kauai. Low clouds and showers generally remain offshore over the Kauai Channel this morning, with isolated showers moving across Oahu bringing brief periods of MVFR. AIRMET Sierra for tempo mountain obscuration remains in effect with conditions expected to improve this afternoon.
Conditions across Kauai remain VFR this morning. However, guidance continues to show an uptick in clouds and showers later today. AIRMET Sierra for tempo mountain obscuration may become necessary across Kauai as residual moisture moves across the island.
Otherwise, expect predominately VFR conditions across Maui County and the Big Island under mostly dry conditions. Light to moderate winds will allow local sea breezes to develop across some of the smaller islands this afternoon.

Marine

A weakening cold front advancing into the central waters is stalling and will dissipate near Oahu this morning. Overnight fresh to locally strong post-frontal northeast winds are occurring over the western third of the state while, downstream of the boundary, easterly to variable breezes prevail. A Small Craft Advisory (SCA) for strong winds west of the front along with high seas as a result of both wind and a passing northwest swell. The SCA will be in effect from the windward Oahu waters westward through the day. A passing front far north of the waters this weekend will keep the regional pressure gradient weak and maintain either variable or gentle trades. High pressure begins to reestablish itself northeast of the state early next week. This will allow the upstream gradient to tighten up enough to generate water-wide fresh to strong trades by late Monday. Strong trades may likely persist through the majority of next week.
A moderate size, shorter period northwest swell will peak through the early morning hours. This swell has elevated surf along better focused north and west facing points to its 320 degree direction. The swell hit the Waimea nearshore buoy and peaked late last night at 10 feet, 12 seconds. The swell is likely producing advisory level surf along Kauai and Oahu's north shores early this morning. A High Surf Advisory (HSA) is in effect for the north and west-facing shores of Kauai and Niihau and the north-facing shores of Oahu through the day. This relatively shorter period swell will slowly level out as it moves through the island waters the next couple of days, holding elevated surf along many exposed north and west-facing spots through the weekend. A reinforcing moderate size, medium period north northwest swell will arrive Saturday, with another pulse expected to arrive Monday. Resultant surf from these series of passing swells are expected to keep north and west-facing shore surf near or slightly above HSA heights into early next week.
Elsewhere, a small south swell will continue to diminish through the day. The next small, long period south southwest swell is expected to come through this weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Oahu North Shore, Kauai North.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

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