Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Windy. Partly sunny with scattered showers. Highs around 78 near the shore to around 66 above 3000 feet. Northeast winds up to 30 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Windy. Scattered showers in the evening, then isolated showers after midnight. Lows around 65 near the shore to around 54 above 3000 feet. Northeast winds 15 to 30 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs around 76 near the shore to around 64 above 3000 feet. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Windy. Frequent showers in the morning, then numerous showers in the afternoon. Highs around 77. Northeast winds 20 to 30 mph. Chance of rain 80 percent.

Tonight: Partly cloudy. Windy. Scattered showers in the evening, then isolated showers after midnight. Lows 61 to 66. Northeast winds 20 to 30 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Windy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 75. Northeast winds 15 to 30 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Breezy. Frequent showers. Highs 65 to 73 in the valleys to around 60 above 4000 feet. Northeast winds 10 to 25 mph with gusts to 45 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Windy. Numerous showers in the evening, then scattered showers after midnight. Lows 54 to 59 in the valleys to around 48 above 4000 feet. Northeast winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 63 to 71 in the valleys to around 58 above 4000 feet. Northeast winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

North Kaua’i

Today: Windy. Frequent showers. Highs 70 to 77. Northeast winds 15 to 30 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Windy. Numerous showers in the evening, then scattered showers after midnight. Lows 57 to 66. Northeast winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 68 to 75. Northeast winds 10 to 25 mph with gusts to 45 mph. Chance of rain 40 percent.

East Kaua’i

Today: Breezy. Frequent showers. Highs 70 to 77. Northeast winds 15 to 25 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows 55 to 67. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 68 to 75. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A cold front over Kauai will push southeast through the remainder of the state late today through early Thursday. Rather wet conditions can be expected along and immediately behind the front as it moves through particularly along windward slopes and coasts. Windy conditions, along with much drier and cooler weather will develop behind the front, and continue through Friday. The air mass will moisten up slightly over the weekend into early next week, bringing an increase in trade wind showers, with breezy conditions and pleasant weather continuing.

Discussion

Currently at the surface, a cold front over Kauai remains nearly stationary early this morning, while a strong 1035 mb surface high 1200 miles northwest of the island chain is moving southeast at around 15 mph. Moderate to breezy trade winds prevail across most of the state early this morning, while over Kauai windy northeasterly trades remain in place behind the front. Infrared satellite imagery shows mostly cloudy conditions over Kauai, with variably cloudy skies across the rest of the state. Radar imagery shows widespread showers moving into Kauai, with numerous showers moving into windward slopes and coasts of the remaining isles producing rather wet conditions as well. Main short term concern revolves around the strengthening trades as the front pushes down the island chain.
The front is expected to remain nearly stationary over the Kauai Channel this morning. A shortwave trough aloft along with the building robust high to the northwest will then drive the front southeastward through the remainder of the island chain late today and tonight, with the front pushing south of the Big Island Thursday morning. Breezy to windy northeast trades will develop behind the front, and Wind Advisories have been issued for much of the state, with the strongest winds expected where the winds are best funneled through the terrain and channels. Windy conditions will continue through Friday as the strong high north of the islands settles southward and closer to the state, with the direction shifting more east- northeast along with a slight decrease in speeds expected for Friday. The trades will ease a bit more over the weekend, but remaining generally in the breezy range as the high north of the state weakens slightly. The high is then forecast to strengthen again early next week, bringing a boost in the trade winds to breezy and locally windy levels.
As for the remaining weather details, showery rather wet conditions will continue along and within 100 miles behind the front as it moves southeastward through the island chain today and tonight, with the showery conditions lingering into Thursday morning on the Big Island. The wettest conditions associated with the front will be over windward slopes and coasts, but with the front moving through some wet weather will reach leeward communities as well. A much drier and cooler airmass will settle into the state with dewpoints dropping into the 50s for Thursday and Friday along with high temperatures struggling to reach 80 degrees. The airmass will moisten up some over the weekend into early next week, bringing an increase in trade wind showers, but the pleasant weather is expected to continue.

Aviation

A cold front near Kauai will gradually move down the island chain later today into tonight and bring increased showers, low clouds and gusty winds across portions of the state as it passes through. In addition, satellite imagery and radar have been showing low clouds and showers embedded in the moderate trades ahead of the front streaming across the rest of the island chain overnight. This activity will bring periods of MVFR conditions or lower for portions of the state today and tonight.
AIRMET Sierra remains in effect for mountain obscuration across Kauai and windward portions of Oahu, Molokai and Maui this morning. This AIRMET will likely remain in effect through mid to late morning, but may need to be extended beyond that. Additionally, AIRMET Tango is in effect across the state for low- level turbulence downwind of island terrain as surface winds increase.

Marine

Strong building high pressure far northwest of the state will push a cold front located near Kauai southeast through the island chain this week. Increasing strong to locally gale force winds will fill in behind the front, along with increasing seas and swells generated from the front's parent low. The cold front will bring a period of showers as it continues to move through Oahu today, Maui County tonight and the Big Island on Thursday, with the strongest winds immediately following its passage.
Frequent gusts to gale force winds are expected over waters west of Kauai through tonight, and a Gale Warning is in effect. As the front continues to move southeast, a Gale Warning has been posted for select waters around Maui County and the Big Island starting this evening through Thursday. Also, the increasing seas and swells have prompted the issuance of a Small Craft Advisory (SCA) for all other waters, as well as a High Surf Advisory (HSA) for most north and west facing shores. Large mixed seas associated with the front has begun to fill in across Kauai and Oahu that will continue to build and fill in across the eastern waters tonight. These headlines will likely be required into the weekend, although surf along west facing shores will likely drop below HSA- level heights by Thursday. Into the weekend, the high will pass north of the islands as the near- gale winds are expected to veer to the east and potentially ease slightly.
A long-period northwest swell has begun to fill in with long period forerunners impacting the nearshore PacIOOS Buoys, producing high surf along exposed north and west facing shores through today. Mixed swell with increasing shorter- period north to northeast wind waves, will lead to choppy surf along most windward shores. East facing shores look to stay just below HSA criteria due to the predominant northerly direction, although northerly exposed shorelines may still see some wrap. The northwest swell will become increasingly northerly this evening, with another pulse of mixed- period north to northeast swell arriving Thursday night and Friday leading to another round of high surf along north facing shores. This swell will gradually lower over the weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Thursday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Wind Advisory until 6 AM HST Thursday for Niihau, Kauai,
Wind Advisory from noon today to 6 AM HST Thursday for Oahu,
Wind Advisory from 6 PM this evening to 6 AM HST Thursday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, Kipahulu, South Maui/Upcountry, South Haleakala.
Gale Warning until 6 AM HST Thursday for Kauai Northwest Waters, Kauai Leeward Waters.
Small Craft Advisory until 6 PM HST Friday for Kauai Windward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters.
Gale Warning from 6 PM this evening to 6 PM HST Thursday for Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters.

Data Courtesy of NOAA.gov