Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs around 84 near the shore to around 72 above 3000 feet. West winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 68 near the shore to around 61 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Partly sunny with isolated showers. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs around 81. Northeast winds around 10 mph in the morning becoming light. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 65 to 70. Light winds. Chance of rain 20 percent.

Tuesday: Partly sunny with isolated showers. Highs around 81. Northwest winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 60 to 66 in the valleys to around 58 above 4000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 74 to 83. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 70. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 74 to 83. South winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 74 to 82. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 58 to 71. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 74 to 82. Southwest winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Dry and stable conditions are expected through the first half of the week, with a deep-layer ridge remaining in place over much of the region. A land and sea breeze regime will become established beginning today as the trades diminish, causing afternoon clouds and a few showers over interior and leeward areas. Increased moisture from a cold front potentially moving into the area will lead to better rain chances through the second half of the week, particularly for northern and windward slopes as northerly winds accompany it.

Discussion

Dry and stable conditions, with a deep-layer ridge in place over much of the region, are expected through the first half of the week. A weak upper low currently located over or near the Big Island will shift south of the area today, with little impact on the local conditions. The surface ridge will weaken and shift southward in response to a progressive pattern evolving over the northern Pacific, featuring a series of fronts passing nearby to the north. The low-level flow will shift from the south to southeast today, then transition to the south to west-southwest from Tuesday through Wednesday. This will lead to a land and sea breeze regime becoming established, with the best chance for cloud coverage shifting to interior and leeward locations during the afternoon hours. While a few afternoon showers can't be ruled out each day in these areas, accumulations will be minimal due to the suppressed environment.
For the second half of the week, there is an increasing likelihood of higher moisture (though shallow) and rain chances. This is due to the tail-end of one of the aforementioned cold fronts settling south into the islands from Wednesday night through Thursday. Probabilistic QPF guidance supports this, showing the best chances for accumulations along northern and windward slopes, with northerly winds filling in. The progressive pattern will persist into next weekend, with another front approaching.

Aviation

Light winds will prevail today and tonight, with land and sea breezes common across the state. Rather dry weather will prevail, with a few light showers possible near the coast at night, with a slight chance for a shower over interior and mauka areas during the afternoon hours.
AIRMET Tango remains in effect for moderate upper level turbulence for Maui County and the Big Island. Conditions may improve over Maui County later this morning, but will likely hold over the eastern end of the state through the day.

Marine

The high pressure ridge north of the state will weaken and drift south over the islands today through next weekend. This pattern shift will cause the trade winds will transition to a fairly light and variable wind pattern for most days this week. A weakening cold front will drift over the area on Thursday, bringing gentle to locally moderate northerly winds. A weak surface high passing near or just north of Kauai may generate a brief period of gentle trades on Thursday night and Friday.
Surf along north and west shores will be at a minimum during the during the next 12 hours, followed by a significant rise for much of the coming week. The current northwest swell will be reinforced by a moderate pulse of north-northwest swell that will arrive later today, peaking by Tuesday. A very intense storm developed between Japan and the Aleutian islands this past weekend, and a series of additional storms are expected to form in a similar area every two to three days this week. The first of several large long period northwest swells will build through the day on Tuesday and will produce surf well above High Surf Advisory levels by Tuesday night and Wednesday. Surf will likely exceed High Surf Warning levels Thursday into next weekend if conditions evolve as projected, this swell energy will peak on Friday. Seas should also surpass the SCA threshold of 10 feet for waters exposed to the large swells.
Small surf remains in the forecast for south and east facing shores. East shore surf will stay small through the week as trade winds decline overnight then become disrupted, aside from some swell energy wrap from larger northwest swell Wednesday into next weekend. Surf along south facing shores will remain seasonally small, mainly due to short period southeast swell.
Peak monthly high tides combined with water levels running higher than predicted could lead to minor coastal flooding issues for vulnerable low lying coastal areas this morning. Impacts will be confined to the early morning high tides and will be borderline during the high tide cycle early Tuesday morning.

Fire weather

Despite the dry and stable conditions, critical fire weather conditions are not anticipated through the week due to a combination of light winds (first half of the week) and increasing moisture as a front settles southward into the area (second half of the week).

HFO Watches/Warnings/Advisories

None.

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