West Kaua’i

Tonight: Partly cloudy. Haze. Lows 70 to 75 near the shore to around 63 above 3000 feet. East winds 10 to 15 mph.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 86 to 92 near the shore to around 79 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Isolated showers after midnight. Lows 69 to 74 near the shore to around 62 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Haze. Lows around 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Breezy. Partly sunny with isolated showers. Highs 81 to 89. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers. Haze. Lows 65 to 70 in the valleys to around 61 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 76 to 85 in the valleys to around 69 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 65 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Haze. Lows 66 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88. East winds 10 to 20 mph. Chance of rain 30 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Haze. Lows 66 to 77. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 74 to 87. East winds 10 to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will gradually strengthen through Sunday with mostly dry conditions expected through the weekend. A weak upper level trough approaching the area will likely bring an increase of showers starting Monday and will likely persist through at least the middle of next week. Bands of moisture could produce some showery weather at times especially across windward and mountain locations.

Discussion

This afternoon's radar and satellite imagery shows stable stratocumulus clouds across many windward and mountain areas with very little rainfall across the state. Soundings from Lihue and Hilo show a strong inversion near 5000 feet, which is limiting any vertical development this afternoon.
Going into Sunday, dry and stable conditions should continue with trade winds strengthening across the state. Due to the winds strengthening and the relatively dry conditions in place, elevated fire weather concerns are expected for Sunday, especially over Maui County and parts of the Big Island, where fuels are drier and the winds are stronger than the western half of the state. It is urged that everyone remains mindful of activities that could produce a spark when working or recreating outdoors.
Starting next week Monday, an increase of showers is expected as an upper level trough approaches the state. Enhanced trade wind showers with periods of showery weather will be possible starting Monday and likely persisting through at least the middle of the week. No significant rainfall is expected, but it just might be enough rainfall to alter your outdoor plans if caught in these bands of moisture that will be moving through the island chain at times. Showers will likely be most active over windward and mountain areas on Tuesday or Wednesday of next week.
In the long range, the upper level trough should move westward and away from the state during the second half of next week with a ridge building in from east. Passing showers will likely still persist, but the showers should be less frequent and less intense than the showers during the first half of the week. Trades will also gradually decrease Tuesday into Wednesday as the high weakens to our north. Moderate to locally breezy trades are expected by Wednesday.

Aviation

High pressure situated well northeast of the islands will build through tomorrow, resulting in breezy trades this afternoon that will strengthen into Sunday. Expect limited shower activity across the islands under a drier, more stable airmass. However, clouds and a few showers will still favor windward and mountain areas and may cause brief periods of MVFR conditions. Otherwise, VFR conditions are expected to prevail.
AIRMET Sierra for tempo mountain obscuration is in effect for windward portions of Oahu and Kauai as MVFR ceilings persist this afternoon.
AIRMET Tango will likely be needed this evening or overnight as the low level winds increase under the strengthening inversion.

Marine

High pressure anchored northeast of the islands will drive fresh to strong trades tonight through Sunday before easing slightly early next week. The Small Craft Advisory has been expanded accordingly.
Small, medium period S swell maintains below average surf until Monday when a moderate, long period S swell fills in. This swell peaks Tuesday near the High Surf Advisory threshold. At the same time, king tides will be reaching their peak leading to potential for coastal flooding of susceptible areas. The threat for coastal flooding will be exacerbated by the ongoing S swell.
Strong trades maintain short period fresh swell and plenty of chop along E facing shores. Surf remains very small N and W through the period.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 PM this evening to 6 PM HST Sunday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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