Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 90 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 71 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny. Highs around 89 near the shore to around 75 above 3000 feet. East winds up to 15 mph.

South Kaua’i

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 88. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 71. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Friday: Mostly sunny. Breezy. Highs 81 to 88. East winds 10 to 20 mph.

Kaua’i Mountains

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 in the valleys to 63 to 69 above 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 71 in the valleys to around 58 above 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Friday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 86 in the valleys to 64 to 69 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 90. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Mostly sunny with isolated showers. Highs 78 to 89. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 76. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Mostly sunny with isolated showers. Highs 75 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A broad high pressure ridge north of the Hawaiian Islands will keep moderate trade winds in the forecast through the first half of next week. Satellite imagery this morning shows an unsettled patch of clouds moving through the western islands with more stable clouds east of the state drifting into the Big Island and Maui on the trade winds. Only brief periods of showers are forecast over windward and mountain areas from this afternoon into early next week as an upper level ridge settles in over the region.

Discussion

Satellite imagery this morning shows an unsettled patch of clouds moving through the western islands with more stable clouds east of the state drifting into the Big Island and Maui on the trade winds. This weakly unstable patch of clouds will keep passing showers in the forecast for windward and mountain areas of Oahu and Kauai through the early morning hours. Drier conditions will spread to all islands starting later this morning and last into early next week.
A broad subtropical ridge will remain in place north of the Hawaiian Islands into next week. An upper level ridge will then settle in over the islands producing strong and stable subsidence today through Monday. Increasing downward vertical motions (subsidence) under this upper ridge will lower the trade wind thermal inversion heights, limiting vertical cloud development and thereby decreasing shower coverage. This upper level ridge will lift north on Monday and Tuesday, opening the door for a slight increase in windward and mountain shower coverage trends.
Long range global weather models continue to suggest that another low level wave in the easterlies may transit through the Hawaii Region by the middle of next week, potentially increasing our shower trends as this trough passes from east to west down the island chain. This next weak system may be our next best chance for decent rainfall amounts over windward and mountain areas. More numerous showers are possible over windward and mountain areas from Tuesday night through Wednesday night as this system slowly passes through each island. Rainfall amounts will also increase in this pattern during the typical overnight to early morning diurnal rainfall maximum with some windward and mountain areas possibly seeing 0.10 to 0.25 inch amounts. Forecast rainfall coverage and amounts were increased for the middle of next week to cover for this passing trough scenario.

Aviation

Moderate to locally breezy trades will continue for the next few days. SHRA and brief MVFR conds should be confined to windward and mauka locations. Otherwise VFR should prevail.
No AIRMETs currently in effect.

Marine

The upstream pressure gradient from surface high pressure far northeast of the islands will weaken the next couple of days as troughing develops over the eastern Pacific. Trades may occasionally become locally fresh, especially in the Alenuihaha Channel, through Friday morning. Sea heights will remain in the 4 to 6 foot range the next several days.
No significant swells are expected from any direction for the remainder of the week. A series of small, medium period south southeast swells will keep south-facing shores from going completely flat through the weekend. A small fetch of strong northeast winds off the U.S. Pacific Northwest coast will generate a very small, medium period northeast swell that is scheduled to arrive this holiday weekend.
Higher than normal water levels, in tandem with new moon tides, has produced higher than normal water levels around Big Island. Water levels have exceeded 3 feet above Mean Lower Low Water (MLLW) during the past few afternoon's high tides. This will continue to create minor coastal flooding issues through the weekend. Peak water levels of around 3.5 feet are expected during periods of high tides. Therefore, a Coastal Flood Statement highlighting this flooding will remain in effect for Big Island's coastal zones for the remainder of the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel.

Data Courtesy of NOAA.gov