Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny early in the morning, then isolated showers in the late morning and afternoon. Highs around 82 near the shore to around 69 above 3000 feet. North winds 10 to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers early in the evening. Lows around 66 near the shore to around 55 above 3000 feet. North winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 82 near the shore to around 68 above 3000 feet. West winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 81. North winds 10 to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers early in the evening. Lows around 63. Northwest winds 10 to 15 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Sunny and breezy. Highs around 81. West winds 15 to 20 mph.

Kaua’i Mountains

Today: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 56 to 64 in the valleys to around 52 above 4000 feet. West winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the late morning and afternoon. Highs 73 to 79 in the valleys to around 63 above 4000 feet. Northwest winds around 10 mph. Chance of rain 30 percent.

North Kaua’i

Today: Mostly sunny early in the morning, then isolated showers in the late morning and afternoon. Highs 71 to 81. South winds around 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 58 to 66. Southwest winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 70 to 81. Northwest winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny early in the morning, then isolated showers in the late morning and afternoon. Highs 72 to 82. Northwest winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 57 to 68. Northwest winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Sunny. Highs 73 to 82. Northeast winds around 10 mph.

Detailed Forecast

Synopsis

Light winds and mostly dry weather will prevail until Wednesday, but a weak front may bring a few windward showers Monday night and Tuesday. Southwest winds will increase on Wednesday as a stronger front approaches. This front will bring a period of widespread clouds and showers as it moves down the island chain from Wednesday night through Friday. Breezy and cool northeasterly trade winds on Friday will gradually veer to the east this coming weekend, bringing passing windward showers.

Discussion

A surface ridge just NE of the islands will move SE today, with associated light and variable winds allowing land breezes to drive mostly clear skies over the islands this morning. The exceptions are windward and SE Big Island, and windward Haleakala, where light E-SE winds are pushing some low clouds and showers ashore. A few showers are noted over near shore waters of the smaller islands, where the land breezes are converging with the light and variable flow over the water.
Afternoon sea breezes later today will lead to partly to mostly cloudy skies over interior and upslope areas, with the potential for a few showers, but the limited PWAT and strong stability seen in morning soundings will limit their coverage and intensity. The gradient between a mid-level trough passing N of the islands and a strong mid-level high to the W will bring increasingly strong W winds to the Big Island Summits tonight and Monday, with gusts potentially reaching High Wind Warning level speeds. A High Wind Watch has been issued in anticipation.
Otherwise, little significant change to the land/sea breeze pattern is expected tonight and Monday, but the light low-level winds will shift to the W and NW as a fast-moving and weak bubble high passes N of the area. This high will push a weak front toward the islands from the N, with associated increased low-level moisture bringing an increase in mainly windward showers Monday night into Tuesday. Winds will become light and variable and showers will diminish as a surface ridge develops over the islands once again later Tuesday and Tuesday night.
The ridge will move SE of the islands on Wednesday, and locally breezy SW winds will develop (especially over Kauai and Oahu) as a stronger front approaches from the NW. This front is expected to sweep SE down the island chain from Wednesday night through Friday, bringing widespread clouds and showers. Upper-level support will be lacking, and moisture will be capped below 10 kft, thus significant rainfall accumulations are not expected with the frontal passage.
Breezy and cool NW to N winds will steadily veer to a NE trade wind flow after the front, with the trades bringing clouds and showers to windward areas as they become increasingly easterly this coming weekend.

Aviation

Weak ridging north of the state will maintain light flow with a land and sea breeze pattern for the islands. Thus, expect mainly dry conditions over land this morning with little cloud cover, then a transition to increasing clouds and isolated showers over the islands interior by this afternoon.
No AIRMETs are currently in effect.

Marine

Light and variable winds will prevail through early Monday as a surface ridge over the area moves slowly SE. Light to locally moderate winds out of the W to NW will accompany a passing weak front Monday and Monday night. This will be followed by another brief interval of light to variable winds later Tuesday before moderate to fresh SW winds develop late Wednesday as a stronger front approaches. Locally fresh winds then turn from NW to N to NE as the cold front advances through the area and high pressure builds to the NW from Wednesday night through Friday.
The current medium-period NW swell remains slightly higher than expected, but surf has fallen below High Surf Advisory (HSA) levels, and the HSA has been cancelled. This swell will subside through tomorrow as it gradually becomes more northerly. Small, short-period NW swell will support small surf Tuesday and Wednesday.
A powerful, extra-large, long-period northwest (320 deg) swell is expected to arrive Thursday, very likely producing surf well above warning levels along exposed N and W facing shores through Friday. Lack of significant high tides may limit coastal impacts. This swell will gradually diminish Saturday and Sunday. The increased winds and seas from Wednesday onward will lead to the issuance of a Small Craft Advisory (SCA) for most coastal zones, but until then, no SCA conditions are expected.
A couple of small, long-period SSW swells with Tasman Sea origins will provide small surf to S facing shores for the next couple of days.

HFO Watches/Warnings/Advisories

High Wind Watch from this evening through Monday afternoon for Big Island Summits.

Data Courtesy of NOAA.gov