Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Highs 81 to 87 near the shore to around 73 above 3000 feet. Light winds.

Tonight: Partly cloudy. Lows 66 to 71 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph.

Monday: Mostly sunny. Highs 82 to 87 near the shore to around 73 above 3000 feet. East winds up to 10 mph.

South Kaua’i

Today: Mostly sunny. Isolated showers in the morning. Highs 79 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs 78 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 79 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 60 to 68 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 72 to 80 in the valleys to around 64 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 84. Southeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 70. East winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 73 to 84. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 72 to 83. North winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 74. Northeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 71 to 83. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate easterly trades will gradually strengthen starting today with brief passing showers favoring windward and mountain areas. Fairly dry conditions continue next week as trade winds steadily strengthen into the breezy to strong range by the middle of this week. Wind speeds will then start a gradual decline into the moderate to locally breezy range from Thursday into next weekend. An upper level low passing just south of the islands by late Friday may enhance rainfall coverage over the eastern half of the state lasting into next weekend.

Discussion

The latest satellite imagery this morning continues to show a fairly stable weather pattern around the islands with limited clouds under the influence of the subtropical ridge aloft. A weakening cold front northwest of the state will stall out before reaching the island chain with no significant impacts to island weather.
The main weather story this week will be a steady strengthening of the trade winds from moderate levels today into the breezy to windy range by Tuesday, with wind speeds peaking on Wednesday across the island chain. Sea breeze wind coverage will diminish into Monday as trade winds return with a vengeance. Wind speeds will likely reach wind advisory thresholds for some of our windier zones possibly starting on Tuesday night. The highest summits of Mauna Kea and Mauna Loa we may see wind advisory highlights starting as early as Monday morning. Relative humidity levels do not appear to fall low enough in the windier leeward areas to reach fire weather concerns at this time. We will continue to closely monitor these wind and humidity levels as this weather pattern evolves through the week.
In the long range outlook, global weather models continue to show an upper level cut off low moving into the Hawaii region. Current operational runs show the center of this low passing south of the Big Island by Wednesday. This low may bring up tropical moisture and instability into the windward and southeastern slopes of the Big Island, enhancing shower activity from Friday into next weekend. The American (GFS) model also shows windward Maui picking up additional shower activity by Saturday. Rainfall impacts for the eastern islands will to a large degree depend upon the strength and final track of this upper level low. Stay tuned for more details as the forecast time period grows shorter.

Aviation

Trade winds will strengthen to moderate levels from east to west across the state today, with some localized sea breezes possible in some of the more sheltered leeward areas. The trades will become locally breezy on Monday. Low clouds and showers will favor windward and mauka areas through the period, with some isolated MVFR cigs/vsbys possible.
No AIRMETs are in effect and none are anticipated. AIRMET Tango will likely be needed for moderate upper level turbulence tonight.

Marine

Easterly trade winds will increase to light to moderate levels today, then strengthening to fresh to strong on Monday as high pressure builds to the north. This will lead to Small Craft Advisory conditions for the windier waters around Maui County and the Big Island starting Monday, with possible expansion to additional waters by Tuesday through the rest of the week due to a combination of stronger winds and building seas.
Surf along north and west-facing shores will gradually ease today before trending back up through the first half of the week as overlapping north-northwest swells arrive. Surf heights may near advisory levels on Monday through Tuesday. A gradual downward trend is anticipated by Friday and through the weekend.
Surf along south-facing shores will remain up through Monday due to an out-of-season south swell, which will gradually subside Tuesday. Seasonal conditions will return around midweek with a mix of smaller southeast and south-southwest swells.
Surf along east-facing shores will begin to increase through the week as trade winds strengthen locally and upstream across the eastern Pacific.

Fire weather

Critical fire weather conditions are not anticipated through much of the week. Even as trade winds strengthen across all islands, these stronger wind speeds do not appear to line up over leeward areas where lower relative humidity levels may briefly reach our minimum thresholds.

HFO Watches/Warnings/Advisories

None.

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