Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny. Highs around 90 near the shore to around 78 above 3000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon.

Tonight: Partly cloudy. Lows around 72 near the shore to around 62 above 3000 feet. Northeast winds 10 to 15 mph.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs around 89 near the shore to around 76 above 3000 feet. North winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 82 to 90. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 82 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 85 in the valleys to around 68 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 71 in the valleys to around 58 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 74 to 84 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 77 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 89. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 75 to 86. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 65 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Broad high pressure north of the state will weaken, resulting in the breezy trade winds to ease to moderate strength Wednesday through Friday. Stable and somewhat dry conditions will prevail through at least Friday, with light showers favoring windward slopes.

Discussion

No changes to the forecast this morning. A broad high pressure system remains between 30 and 35N, driving locally breezy trade winds to the region. An upper level ridge over the islands is helping to maintain a very stable and mostly dry airmass over the area. Some moisture areas remain within the shallow boundary layer. The night started off with very few light showers riding in on the trades, but a few more spotty showers have been seen on radar over the last couple of hours. Anticipate a few more over the next several hours, mainly over windward and mauka areas, with showers diminishing again this afternoon.
The ridge to the north is expected to weaken, which will allow trades to ease some tonight and Wednesday. Stable conditions will persist with limited moisture in the trade wind flow. As a result, expect modest windward rainfall, and aside from a few afternoon showers on Kona slopes of the Big Island, leeward areas should be dry.
In the long range, trades may strengthen during the weekend, and the GFS and ECMWF suggest that an increase in showers will be possible.

Aviation

Breezy trade winds will persist today, then gradually ease through the end of the week. Light showers and low clouds will favor windward and mauka areas and bring the potential for brief periods of MVFR. Otherwise, VFR will prevail.
AIRMET Tango for moderate low-level turbulence lee of island terrain is in effect and will continue through the day due to strong trades.

Marine

A broad surface high pressure over the central and eastern Pacific will remain stationary through today maintaining fresh to locally strong trade winds. A Small Craft Advisory (SCA) for the typical windier waters around Maui County and the Big Island through has been extended through Wednesday morning. A disturbance will develop far northeast of the state late tonight into Wednesday, weakening the ridge. SCA conditions may drop off as early as Wednesday as winds ease to moderate to fresh then persist through Friday. A high will strengthen north of the state over the weekend as the disturbance weakens and dissipates. Trades may strengthen back to moderate to locally strong over and upstream of the state this weekend into early next week.
The current long period south swell continues to hold in the 16 second range based on near shore and offshore buoy data. Thus have extended the High Surf Advisory (HSA) through today as surf height slowly trend down around or slightly above HSA criteria. This swell will continue to slowly decline through Thursday before dropping to background levels Friday through the weekend.
Rough, choppy surf along east facing shores will remain slightly elevated through today before slowly declining as trades upstream of, and eventually over, the islands weaken. In addition a small pulse of northeast swell energy appears to have arrived at near shore buoys and will continue to fill in today. This small swell could provide a tiny boost along north and east facing exposures. East shore surf will fall below average by Wednesday and will decline further Thursday through Friday as the northeast swell quickly fades and trades over and upstream ease.
North facing shores may see a tiny bump from the combination of a small, medium period northwest swell and the northeast swell mentioned above today into Wednesday but will quickly fade Wednesday night.

Fire weather

The ongoing breezy and dry weather will produce elevated fire weather concerns today, though critical conditions are not forecast. Improvement is expected as winds decline Wednesday into Friday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov