Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Highs around 89 near the shore to around 79 above 3000 feet. East winds up to 25 mph. Gusts up to 45 mph in the afternoon.

Tonight: Partly cloudy. Windy. Lows 71 to 76 near the shore to around 62 above 3000 feet. East winds up to 35 mph with gusts to 60 mph.

Tuesday: Mostly sunny. Windy. Highs around 89 near the shore to around 79 above 3000 feet. East winds up to 35 mph increasing to 10 to 35 mph in the afternoon. Gusts up to 60 mph.

South Kaua’i

Today: Partly sunny. Windy. Isolated showers in the morning. Highs around 88. Northeast winds 15 to 20 mph increasing to 20 to 30 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Windy. Isolated showers. Lows 69 to 75. Northeast winds 20 to 35 mph with gusts to 55 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Very windy. Isolated showers in the morning. Highs around 88. Northeast winds 25 to 40 mph with gusts to 60 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny. Windy. Scattered showers in the morning. Highs 75 to 83 in the valleys to around 72 above 4000 feet. East winds 10 to 20 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 30 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Very windy. Isolated showers. Lows 62 to 67 in the valleys to around 57 above 4000 feet. East winds 10 to 40 mph with gusts to 60 mph. Chance of rain 20 percent.

Tuesday: Very windy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 75 to 83 in the valleys to around 72 above 4000 feet. East winds 10 to 40 mph with gusts to 60 mph. Chance of rain 20 percent.

North Kaua’i

Today: Partly sunny. Breezy. Scattered showers in the morning. Highs 78 to 88. East winds up to 20 mph. Chance of rain 30 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 75. East winds up to 20 mph. Gusts up to 40 mph increasing to 50 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 78 to 88. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Gusts up to 50 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny. Breezy. Scattered showers in the morning. Highs 77 to 88. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 63 to 76. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Breezy. Isolated showers in the morning. Highs 77 to 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy easterly trade winds are forecast to become strong and gusty later today through midweek as Hurricane Dora passes far to the south. Outside of a few windward showers this morning, very dry air arriving from the east will limit rainfall chances through Wednesday. A return of a more typical trade wind pattern is anticipated later in the week through the weekend.

Discussion

An upper low nearby to the northwest combined with a mid-level trough and a sufficient amount of low-level moisture will support a few light showers favoring windward and mountain locations this morning. Satellite imagery showed the leading edge of a very suppressed and dry air mass approaching from the east, which also marks the leading edge of the easterly wind surge. This drier air (PWs dipping well below normal) combined with a strong pressure gradient between Dora passing to the south and high pressure to the north will support strong and gusty winds later today through midweek. The subsidence inversion is forecast to dip to around 3000 ft, which is well below normal. This stable/dry air and low inversion combined with the strong pressure gradient (50 kt winds shown around the inversion to 850 mb) will generate advisory to warning-level wind speeds this afternoon through Wednesday.
For the second half of the week through the weekend, expect a return of a more typical trade wind pattern, with windward and mountain shower coverage increasing.

Aviation

Surface high pressure north of the state will bring moderate trades across to the islands through the remainder of this morning. Some low level moisture caught up in the flow will bring scattered showers to areas along the windward coasts and slopes with accompaning brief periods of MVFR ceilings and visibility. Elsewhere, expect isolated showers. By this afternoon, drier air filtering in from the east will act to limit shower chances and cloud coverage.
A tight surface pressure gradient will develop across the region this afternoon through Wednesday, due to the combination of strong surface high pressure north of Hawaii and Hurricane Dora passing well south of Hawaii. This scenario will generate strong and gusty trades across all islands for the duration of the aforementioned period.
There are currently no AIRMETs in effect. However, AIRMET Tango for moderate turbulence downstream of terrain will likely be issued later this morning due to the strengthening trade winds.

Marine

Trade winds will strengthen through Tuesday as the ridge builds north of the islands and Hurricane Dora passes south of the Hawaiian Islands from later this afternoon through Wednesday morning on its westward track. Wind speeds will peak on Tuesday with a Gale Warning in effect through Tuesday night over the windier channels and waters around Maui County and the Big Island. Strong wind speeds and rapidly building rough seas will occur over the rest of the coastal waters through Tuesday night as well. A Small Craft Advisory remains in effect for the remaining coastal waters.
Surf along east facing shores will quickly ramp up and become rough today through Wednesday due to a combination of very strong trades, large seas and a moderately sized, moderate period easterly swell generated from Dora. The largest surf is expected over the eastern end of the state, where surf heights will reach warning levels from tonight through Tuesday afternoon. A downward trend is expected from Tuesday night through Thursday as trade winds and seas diminish to more typical conditions. A High Surf Warning was issued for all exposed east facing shores of the Big Island, Maui and Molokai. A High Surf Advisory may be needed starting tonight along exposed east facing shores of Oahu and Kauai.
Surf along south facing shores will remain small today and tonight with background south and southwest swell energy rolling through. A short to medium period southeast swell will fill in on Tuesday from Dora as it passes by far to the south. This will be a short lived event with a peak occurring late Tuesday into early Wednesday. A long period south-southwest swell from the South Pacific will arrive by Wednesday, south shore surf heights approaching advisory thresholds from Wednesday into Thursday, before diminishing through the end of the week.

Fire weather

Very dry fuels (KDBI around 600) combined with strong and gusty easterly winds and low humidities below 45 percent will produce critical fire weather conditions this afternoon through Tuesday night. See the Red Flag Warning for more information.

HFO Watches/Warnings/Advisories

Wind Advisory from 6 AM this morning to 6 AM HST Wednesday for Niihau, Olomana, Kauai East, Koolau Windward, Windward Haleakala, Kipahulu, Big Island East.
Red Flag Warning from 6 AM this morning to 6 AM HST Wednesday for Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Molokai Leeward, Lanai Makai, Lanai Mauka, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala, Big Island Interior.
High Wind Warning from 6 AM this morning to 6 AM HST Wednesday for Kauai Leeward, Kauai Mountains, Waianae Coast, Oahu North Shore, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Haleakala Summit, Kohala, Big Island Interior, Big Island Summits, Kauai North, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Koolau Leeward, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
High Surf Warning from 6 PM this evening to 6 PM HST Tuesday for Maui Windward West, Molokai Windward, Molokai Southeast, Windward Haleakala, Kipahulu, Big Island Southeast, Big Island East, Big Island North.
Small Craft Advisory from 6 AM this morning to 6 AM HST Wednesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Gale Warning from 6 AM this morning to 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov