Photo Credit: Braden Jarvis

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 87 near the shore to around 73 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 65 to 70 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Monday: Mostly sunny with isolated showers. Highs 80 to 86 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 85. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 68. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 86. Light winds. Chance of rain 30 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with scattered showers. Highs 72 to 80 in the valleys to around 63 above 4000 feet. East winds up to 20 mph becoming 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 67 in the valleys to around 56 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 73 to 80 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 84. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 69. Southeast winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning. Highs 74 to 83. Light winds. Chance of rain 30 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 71 to 83. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 72. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 84. Light winds. Chance of rain 40 percent.

Detailed Forecast

Synopsis

High pressure far north and northeast of Hawaii will drive breezy trade winds, with a slight increase in windward showers, through rest of the weekend. Expect light winds through the first half of next week as a front approaches from the northwest. This front will bring additional showers through the island chain Thursday, with mainly light to moderate northeast to east winds behind it and scattered windward showers into next weekend.

Discussion

IR satellite imagery continues to reveal widespread high cirrus clouds drifting over the islands this morning, associated with an upper-level trough grazing the northern edge of Hawaii through the day. This trough is also providing enough instability to enhance shower coverage throughout the night, especially over the western half of the state, with rainfall totals up to a quarter of an inch for several windward sites on Kauai and Oahu. A few showers have also been able to make it over to leeward areas on the trades, but with little to show for it in the gages. The early morning (12Z) soundings from Hilo and Lihue still show pronounced stability in the lower levels, though inversion heights have risen by around 500 to 1000 feet, respectively, due to the proximity of the trough. Plenty of dry air aloft persists, though, keeping rainfall totals from being too significant. Surface high pressure far north and northeast of Hawaii will continue to drive moderate to locally breezy trade winds and enhanced, windward-focused showers through the remainder of the weekend.
Trade winds will weaken to a light and variable pattern from Monday through Wednesday as a cold front approaches the state from the northwest. This lighter flow will allow for the development of sea breezes and limited shower activity over interior and leeward areas each afternoon and land breezes helping to clear out cloud cover overnight. Current model guidance suggests that the cold front will move into Hawaii during the second half of next week as it weakens. Shower activity associated with the front is expected to be brief as the front quickly moves through the island chain Thursday into Friday. At this time, rainfall amounts do not appear to be very significant. Winds will strengthen a bit out of the north behind the front Thursday and eventually veer to the northeast by Friday, with mainly light to moderate northeast to east winds and scattered windward showers are expected into next weekend.

Aviation

Moderate to breezy trade winds continue through this afternoon. A passing upper level disturbance will produce a few more clouds and showers over the islands this morning, favoring the windward and mountain areas of each island. Mostly VFR conditions are expected for the next 24 hours with brief periods of MVFR conditions in any developing shower bands.
An AIRMET for upper level moderate turbulence was issued for the entire state between FL300-400 due to a passing upper level trough.

Marine

Fresh to strong easterly trade winds will prevail today, then lower tonight through the first half of the week as a surface ridge weakens and shifts south due to a series of cold fronts passing to the north. A Small Craft Advisory remains in place through this afternoon over the windier channels and waters around Maui County and the Big Island. Starting late tonight, the trades will quickly ease, likely enough for overnight and early morning land breezes and daytime sea breezes to form. This pattern will persist through the first half of the week as the background flow shifts southeast on late tonight and into Monday, then south to southwest Tuesday through midweek as a cold front approaches. If the front moves through, moderate northerly winds trailing it would become a possibility later in the week.
Surf along exposed north and west-facing shores will gradually ease into Monday as the current northwest swell fades. By Tuesday, surf will begin to rise, with a significant upward trend anticipated through the second half of the week. This increase will be driven by a decent-sized fetch developing over the far northwest Pacific, near the Aleutians from the Date Line to the Kuril Islands. Heights could exceed warning-levels late in the week if conditions evolve as projected. Seas should also exceed the Small Craft Advisory threshold of 10 feet for coastal zones exposed to the northwest swells.
Surf along east-facing shores will remain rough today, but will gradually ease late tonight through much of next week as the trade winds diminish.
Surf along south-facing shores will remain near seasonal averages, influenced by a mix of short-period southeast swells and occasional longer-period background south-southwest swells.
Peak monthly tides combined with water levels running higher than predicted could lead to minor coastal flooding issues for vulnerable low-lying coastal areas. The best chance for these impacts will occur during the early morning high tides between midnight and daybreak through the early Monday.

Fire weather

Critical fire weather conditions are not expected for the next seven days. Relatively dry conditions will persist statewide through Wednesday, aside from some enhancement to trade wind showers through today. A weakening cold front will drift into the western islands Thursday into Friday. This will briefly increase shower activity again, especially over the western half of the state.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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