Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny. Highs around 89 near the shore to around 77 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Partly cloudy. Lows around 71 near the shore to around 61 above 3000 feet. Northeast winds 10 to 15 mph.

Tuesday: Mostly sunny. Highs around 90 near the shore to around 78 above 3000 feet. East winds up to 15 mph shifting to the northeast in the afternoon.

South Kaua’i

Today: Mostly sunny. Highs 82 to 89. Northeast winds around 15 mph.

Tonight: Partly cloudy. Lows around 72. Northeast winds around 15 mph.

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

Kaua’i Mountains

Today: Mostly sunny. Breezy. Highs 74 to 85 in the valleys to around 66 above 4000 feet. East winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 65 to 71 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph.

Tuesday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 85 in the valleys to around 68 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny. Highs 76 to 90. East winds 10 to 15 mph.

Tonight: Partly cloudy. Lows 65 to 74. East winds 10 to 15 mph.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 77 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny. Highs 74 to 85. Northeast winds 10 to 15 mph.

Tonight: Partly cloudy. Lows 65 to 76. Northeast winds 10 to 15 mph.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 75 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure north of the Hawaiian Islands will continue, maintaining a dry trade wind pattern through much of the week. Light windward and mauka showers will primarily occur during overnight through early morning hours each day. A mid to upper level disturbance developing northeast of the state this week will weaken trades from Tuesday onward.

Discussion

No significant changes to the forecast this evening, and no change in the overall forecast philosophy. Broad high pressure remains about 800 miles north of the state, continuing to funnel moderate to locally breezy trades to the region. An upper level ridge over the islands is helping to maintain a dry and stable airmass which is limiting rainfall. Satellite continues to show stable stratocumulus clouds riding in on the trades. Expect this pattern to hold into early Tuesday.
A trough developing into a front to the far northeast of the islands will help to disrupt the broad ridge over the next 24 hours. During this time, an upper level trough is expected to develop to the northeast, with a possible mid to upper level low developing along the trough a day midweek. These features will help to weaken the trade wind flow over the islands Tuesday onwards. The mid to upper level low looks to remain well enough east of the area that the upper level ridge remains anchored over the islands. This should continue the stable and mostly dry airmass through much of the week.
Towards the end of the week, the upper level trough may approach the islands, which could provide a little more instability leading to a modest increase in showers, particularly over the eastern end of the state which would be closest to the upper level trough.

Aviation

Breezy to locally windy trades will continue today before gradually easing into mid week. Showers and periodic low ceilings will favor windward and mauka locations with a few showers occasionally making it to leeward locations. Brief MVFR conditions are possible in passing showers, otherwise VFR conditions will prevail.
AIRMET Sierra for mountain obscuration is in effect this morning for windward portions of the island chain due to an uptick in low ceilings and showers. Conditions should improve later this morning.
AIRMET Tango for moderate low-level turbulence lee of island terrain is in effect and will likely be needed through at least tomorrow due to the strong trades under a strong inversion.

Marine

Surface high pressure north of the islands between 30N and 40N will maintain fresh to locally strong trade winds the next couple of days. A Small Craft Advisory (SCA) remains in effect for the typically windier waters surrounding Big Island and Maui County through Tuesday afternoon. Trades will drop off to more moderate speeds, or fall below SCA criteria, Wednesday through Friday in response to lower pressure northeast of the state.
A long period south swell will be moving around the island chain through the day. This 4 to 5 foot swell is peaking within the 16 to 18 second spectral bands early this morning. As a result, greater than 10 foot surf (face value) sets will occur along better exposed southern coasts today. The large south swell is expected to slowly decline through the afternoon. The High Surf Advisory has been extended and is now in effect for all southern shores until 6 AM HST Tuesday. South-facing shore surf will fall below advisory levels Tuesday morning, then gradually decline through Friday.
Rough east-facing shore surf will remain slightly above July averages today. This short period wind wave energy will slowly decline as mid week trades upstream of, and eventually over, the islands weaken. East surf will fall below seasonal averages by Wednesday and will fade further into Friday. No significant source for northerly swell is expected for the remainder of the week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Tuesday 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 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov