Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny with isolated showers. Highs 87 to 93 near the shore to around 79 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 73 near the shore to around 64 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 88 to 93 near the shore to around 79 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 86 to 92. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 86 to 92. East winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 76 to 86 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 72 in the valleys to around 62 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 86 in the valleys to around 69 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 79 to 90. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 68 to 75. Southeast winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 79 to 90. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 77 to 90. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 80. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 77 to 89. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Expect increasing showers state-wide today, mainly across windward areas, with the greatest shower coverage expected over windward Big Island and east Maui. Leeward areas, including the Lahaina and Kula areas of Maui, will remain mostly dry with a few light showers possible. Breezy and increasingly dry trade wind weather will return Tuesday through the rest of this week.

Discussion

Recent satellite and radar imagery show increasing clouds and showers moving into windward areas of most islands early this morning, associated with the remnant moisture from former Tropical Cyclone Fernanda. The greatest shower activity is occurring over the windward coasts and slopes of the Big Island, where 0.01 to 0.25 inches of rain has already fallen in some locations over the last 6 hours.
As we head through the rest of this morning, windward areas of the Big Island and Maui will continue to see the bulk of the rainfall. Despite decreasing trends in model rainfall amounts, we could still see event totals around 2 to 4 inches of rain over windward Big Island through tonight. Brief periods of heavy rain are possible during this time, which could lead to some nuisance- level flooding. On Maui, 1 to 2 inches of rain will be possible, primarily focused over the east Maui windward slopes and coastal areas. Leeward areas of Maui (including Lahaina and Kula) will remain mostly dry, with a few light showers possible through the evening hours. For rest of the state, mainly light to moderate showers are expected to move into windward and mountain areas through Tuesday morning. Humidity levels will be higher than normal during this time, which will make daytime temperatures feel hotter than usual.
Trade winds will also trend up over the next couple of days as surface high pressure far north of the state strengthens and drifts slightly farther south. Moderate wind speeds this morning will steadily rise to breezy levels through tonight. Tuesday afternoon through Wednesday, the atmosphere will dry out, as a mid-level ridge develops over the area. A mostly dry and breezy trade wind regime will likely hold through the rest of this week.

Aviation

Moderate to breezy easterly trade winds will continue, with clouds and showers favoring windward and mountain areas. Shower coverage has been steadily increasing overnight, which will continue today as an area of deep tropical moisture moves in. Expect periods of MVFR CIGs/VSBYs for windward and mauka areas, especially for the eastern end of the state. Elsewhere, VFR conditions will prevail.
AIRMET Sierra for mountain obscuration is now in effect for the windward areas from Oahu to the Big Island, which may continue through a good portion of the day today.

Marine

Trade winds will gradually increase today as a surface high centered about 1600 nm NNE of the islands strengthens, and the remnant of Fernanda passes well S of the islands. Fresh to locally strong trade winds are then expected to continue through the week, and a Small Craft Advisory will remain in effect for the windier zones around Maui and the Big Island.
Surf along all shores will remain relatively small today. A long- period E swell generated by former major Hurricane Hilary in the distant E Pacific is expected to arrive by tonight, peak near 4 feet Tuesday and Wednesday, then lower Wednesday night and Thursday. Confidence remains low in the details, but E shore surf will likely remain below advisory-levels, with the largest surf focused on the Big Island and Maui. As the longer-period E swell diminishes, short-period trade wind swell will build to near seasonal norms. A small, medium-period SSE swell (with a pinch of SW swell energy as well) will bring small surf to S facing shores the next couple of days.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov