West Kaua’i

Rest Of Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72 near the shore to around 63 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 84 to 92 near the shore to around 77 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 74 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Rest Of Tonight: Breezy. Mostly cloudy with scattered showers. Lows 70 to 75. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Monday: Mostly cloudy in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 78 to 89. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 69 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then showers after midnight. Lows around 68 in the valleys to around 60 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 80 percent.

Monday: Mostly cloudy. Showers in the morning, then scattered showers in the afternoon. Highs 73 to 81 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows around 67 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

North Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 64 to 74. East winds 10 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 71 to 86. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 73. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 70 percent.

East Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 67 to 75. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 66 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will persist through Monday as high pressure remains north of the state, with weaker trades Tuesday through at least Friday. Windward and mauka showers will continue, with a slight uptick in moisture likely Tuesday into Tuesday night, and possibly from Friday into next weekend.

Discussion

Radar showed numerous showers across the islands today, mainly windward and mauka, but not leaving the lee side out completely. Rainfall amounts in the past 6 hours ranged up to a half inch on windward and mauka areas on most islands, and up to three-quarters of an inch on the Big Island. Skies were partly to mostly cloudy in most areas. Winds were a little stronger than Saturday, averaging 12 to 25 mph, with gusts over 40 mph in the windier locations.
As a strong surface high pressure system remains nearly stationary to our north, we will be kept in east to northeast trade winds through the coming week. Winds will weaken slightly Monday, and then a little more Tuesday, then remain around that level for several days. An area of increased moisture, and therefore showers, is still on schedule to arrive Tuesday through Tuesday night, with drier air moving in for Wednesday and Thursday. Details remain to be worked out beyond Thursday, but there are indications of additional moisture moving back in Friday and potentially lasting into next Sunday.

Aviation

The slug of moisture that brought widespread MVFR to windward Big Island through early this afternoon has finally mixed upslope allowing conditions to improve there. Low clouds and showers stacked along the Ko'olau range of Oahu have likely demonstrated improvement during the last couple of hours. AIRMET Sierra has therefore been dropped for both locations. Elsewhere and otherwise, breezy trades will deliver clouds and showers with transient pockets of MVFR to windward and mauka locations through the period.
AIRMET Tango is in effect for lee turb.

Marine

A strong 1035 mb high remains north of the state, bringing fresh to strong trade winds to the area. Daytime ASCAT pass showed widespread fresh to strong winds with near Gales in the Alenuihaha Channel. The trades are expected to weaken by late Monday into Tuesday as the high north of us lifts further northeast. This should allow the Small Craft Advisory (SCA) to be scaled back sometime on Monday and is expected to drop below SCA thresholds by Tuesday.
A small, long-period southwest swell (220 degrees) will continue to fill in tonight and peak on Monday then gradually decline through the middle of the week. Surf along east-facing shores will remain rough and choppy through Monday, then steadily decline through the middle of the week. A series of small, moderate period west to west-northwest (260 to 300 degrees) swells are possible throughout this week from former Super Typhoon Bavi in the far western Pacific. As with any tropical cyclone swell, there is a higher margin of error due to the compact nature of tropical cyclones. Otherwise, no significant north or northwest swells are expected, so surf along north-facing shores is expected to remain flat to tiny.
Peak monthly high tides combined with water levels that are running slightly higher than predicted will lead to minor flooding along the shoreline and in low-lying coastal areas. Coastal flooding is possible around the daily peak tide, which will be during the afternoon hours. A Coastal Flood Statement has been issued through Tuesday afternoon.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Big Island Windward Waters, Kaiwi Channel, Kauai Channel, Kauai Leeward Waters, Kauai Northwest Waters, Kauai Windward Waters, Maalaea Bay, Maui County Leeward Waters, Maui County Windward Waters, Oahu Leeward Waters, Oahu Windward Waters, Pailolo Channel.

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Data Courtesy of NOAA.gov