Photo Credit: Braden Jarvis

West Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows around 72 near the shore to around 62 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs around 88 near the shore to around 76 above 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 86. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 70 to 75. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny in the afternoon. Highs around 85. East winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 84 in the valleys to around 66 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 79 to 88. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs 78 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 77 to 87. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 77. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue through the rest of the work week as high pressure remains far to the northeast of the islands. Trades will gradually weaken as the high drifts away. An upper trough developing over the islands will enhance trade showers by Thursday night near the Big Island before enhancing showers farther up the chain. Expect increased shower coverage and intensity across the state by the weekend. Drier and more stable air will return early next week.

Discussion

There is little to no change in forecast philosophy from last evening. A high far northeast of the main Hawaiian Islands is driving breezy trade winds across local waters this morning. Overnight soundings showed a stable and rather dry airmass, with PW from 1.1 to 1.2 inches and positive lifted index values. A subsidence inversion near 7000 feet kept a cap on cloud development and limited rainfall amounts. However, the breezy trades were able to push some showers to some interior and leeward locales.
Models show the high will remain nearly stationary for another day or so before beginning to move slowly away to the northeast. Over the weekend, a low far to the northwest will start to push the trailing ridge southward toward us. This ridge will reach the islands by next Tuesday. Trade winds will gradually decrease until becoming light and variable early next week, allowing development of daytime sea breezes and nighttime land breezes.
Expect a continuation of typical trade wind showers for the next few days, favoring nights and mornings, across windward and mauka sections. A shower or two could make it to leeward sections on the smaller islands. Starting Thursday night, moisture associated with the remnants of TD14E will begin spreading up the chain. Upper troughing will move in at about the same time, resulting in increased shower coverage and intensity Thursday night through Saturday night. Isolated thunderstorms are possible over waters west of Kauai and Niihau Saturday night. Models show upper troughing will weaken and shift north of the islands Sunday and afterwards. Expect drier and more stable air to return. With continued light wind flow, also expect a hybrid or convective shower pattern, featuring localized afternoon interior showers along with a few across windward and mauka areas.

Aviation

Breezy easterly trades will continue through the 24-h forecast period and beyond, with clouds and showers favoring windward and mountain locations. Some showers will make it to leeward areas, mainly overnight through the morning hours. Periods with MVFR CIGs/VSBYs will continue for some windward areas through the morning hours, especially in passing showers.
AIRMET Tango remains in effect for tempo moderate turbulence below 9000 feet for areas downwind (south through west) of island terrain. This AIRMET will likely remain in effect through the next few days.
AIRMET Sierra for mountain obscuration will likely continue through the early morning hours before conditions improve.

Marine

A high pressure ridge far north of Hawaii will keep fresh to locally strong trade winds in the forecast through Saturday. The ridge and wind speeds will weaken on Sunday in response to a deepening low pressure system northwest of the islands. Wind directions will shift from a more southeasterly direction from Monday onward. A Small Craft Advisory (SCA) was extended in time for windier waters around Maui and the Big Island through Friday. The SCA may be extended through Saturday for these windier waters.
Surf along south facing shores will continue to slowly decline as the current small south-southwest swell eases. Mainly background swells are expected during the second half of the week. Otherwise, a small southeast swell is possible this weekend into early next week.
Surf along north facing shores will hold today and slowly decline tonight through Thursday. A similar size north-northeast swell is expected to arrive Thursday through Friday, which should keep the surf from going flat along north facing exposures. For the extended forecast, guidance is hinting at a slightly larger north- northwest swell from a low pressure system that is expected to deepen far northwest of the state later this week. This swell energy will arrive along exposed north facing shores next week from Sunday into Tuesday.
Surf along east facing shores will continue to remain rough and choppy, with a small increase today as the trades strengthen.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov