Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 85 near the shore to around 71 above 3000 feet. East winds 10 to 20 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 67 near the shore to around 56 above 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 84 near the shore to around 69 above 3000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 84. East winds 20 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 66. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 75 to 82. East winds 20 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Cloudy and windy. Showers in the morning, then numerous showers in the afternoon. Highs 70 to 78 in the valleys to around 62 above 4000 feet. East winds 15 to 30 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Windy. Numerous showers in the evening, then showers after midnight. Lows 61 to 66 in the valleys to around 53 above 4000 feet. East winds 15 to 30 mph. Chance of rain 90 percent.

Saturday: Breezy. Mostly cloudy with numerous showers. Highs 70 to 79 in the valleys to around 60 above 4000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly cloudy. Breezy. Showers in the morning, then numerous showers in the afternoon. Highs 73 to 85. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 60 to 69. East winds 10 to 25 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 72 to 84. East winds 15 to 20 mph. Chance of rain 70 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Showers in the morning, then numerous showers in the afternoon. Highs 69 to 81. East winds 15 to 20 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 70. East winds 15 to 20 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 69 to 80. East winds 15 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

A very strong high pressure system north of the state will maintain strong and gusty trade winds today. Periods of showers will favor typical windward and mountain areas, with a few showers drifting into leeward areas at times. Trade wind speeds will decrease into the moderate to breezy range by Sunday. A slight drying trend remains in the forecast through the first half of next week.

Discussion

The strong high pressure system north of the state will slowly weaken as the center drifts south towards the island chain. The latest forecast guidance shows breezy to windy conditions continuing at least through this afternoon and possibly into Saturday. Most areas will see wind speeds blowing at advisory levels with Leeward Kohala on the Big Island observing periods of High Wind Warning level wind speeds and higher gusts. The strongest wind gusts last night were observed at Kohala Ranch and Waikoloa Village in the 60 to 65 mph range. Wind speeds across the state will begin to slowly weaken starting on Saturday with wind speeds decreasing into the moderate to breezy range by Sunday.
Periods of showers will continue to blow into windward and mountain areas on these strong trade winds, favoring the overnight to early morning hours. A few of the stronger showers will reach the typically drier leeward zones. Subsidence temperature inversion heights will remain around 8,000 feet through the weekend, keeping all windward areas in a fairly wet rainfall pattern. Shower activity will begin to trend drier early next week as a ridge aloft increases regional stability ahead of an approaching cold front.
Long range model solutions continue to show a weakening cold frontal cloud band sweeping into the islands from the northwest by the middle of next week. This passing front should bring another round of enhanced showers to all islands by the middle to end of next week. Northerly trade winds will blow much cooler temperatures into the Hawaiian Islands from Thursday onward after the frontal band passes through each island.

Aviation

Strong high pressure north of the state will continue to drive breezy to windy trades during the next couple days. MVFR cigs/vsbys will affect windward slopes and coasts at times, with a few decaying showers reaching leeward areas where predominantly VFR conditions should prevail.
AIRMET Sierra remains in effect for mountain obscuration over windward Kauai, Oahu, Molokai, Maui and Big Island. Improving conditions are expected later this morning, with conditions potentially deteriorating again this afternoon.
AIRMET Tango remains in effect for low level turbulence over and downwind of the terrain of all islands. Little change is expected during the next couple days.
AIRMET Tango is also in effect for strong surface winds over the Kohala region of the Big Island.

Marine

A 1045 mb strong high pressure north of the islands continues to support strong to gale-force easterly trade winds across the coastal waters. The high is expected to weaken as it drifts south then east over the next few days. Despite the weakening high pressure, the gradient will still remain fairly tight over the island chain as the high inches closer to the state. This will continue to support strong to gale- force easterly trade winds through tonight. The Gale Warning for windier waters around Maui and the Big Island has been extended through tonight. Similarly the Small Craft Advisory (SCA) for all other waters has been extended through Saturday for the combination of strong winds and high seas. Trades are expected to ease Saturday as the high weakens and tracks east, however lingering strong winds and high seas may still support SCA conditions for all or most zones Saturday night into Sunday. Winds will continue to decline early next week as the weakening high tracks farther east. The SCA may be dropped altogether by late Monday.
Large, trade wind generated seas will continue to prevail into this weekend. The High Surf Advisory for all exposed east facing shores has been extended through Saturday. As trade winds gradually ease near and upstream of the state, the rough east shore surf will gradually decline. The trade wind swell is expected to fall to around April average Monday or Tuesday. Additionally, a small medium- period north- northeast swell mixed in with the trade wind swell will continue to fade early this morning. Thus, surf heights along north- facing shores drop a notch by this afternoon. For southern shores, small pulses of medium period south- southeast swell and long period southwest swell may arrive this weekend, though surf along south- facing shores will remain small throughout the next several days.

Fire weather

Long-term conditions over leeward areas are drier than normal for this time of year. Though the Keetch-Byram Drought Index, measured in Honolulu, will remain well below the critical 600 mark this week, the strong and gusty trade winds will elevate the fire danger over the drier leeward areas through this afternoon.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for windier areas of each island.
High Surf Advisory until 6 PM HST Saturday for exposed east facing shores.
High Wind Warning until 6 PM HST this evening for Leeward Kohala.
Small Craft Advisory until 6 PM HST Saturday for all Hawaiian Coastal Waters outside of the Gale Warning areas.
Gale Warning until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov