Photo Credit: Brendan Stephen

West Kaua’i

Today: Breezy. Partly sunny with isolated showers. Highs around 79 near the shore to around 67 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to around 57 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with isolated showers. Highs around 79 near the shore to around 67 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 78. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 69. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 78. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 57 to 62 in the valleys to around 51 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 90 percent.

Thursday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

North Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 71 to 78. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 69. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 71 to 78. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 78. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 58 to 70. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 78. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy easterly trade winds will continue through the weekend, with clouds and showers favoring windward and mauka locations as pockets of moisture move through. Expect some showers to carry over into leeward areas periodically with the strong winds in place. An upper disturbance moving through may lead to a brief period with mostly cloudy skies and an increase in shower coverage tonight through Thursday night.

Discussion

Guidance remains in good agreement and shows breezy easterly trades persisting through the second half of the week as surface high pressure remains anchored north of the state. Plenty of mid- level dry air along with a strong subsidence inversion positioned between 7000 and 9000 ft and PWs hovering around an inch will limit rainfall accumulations today. Upper heights will lower tonight through Thursday night as an upper trough lurking to the west advances eastward through the area. Added instability associated with this upper feature moving through combined with a slight increase in moisture will support a brief period with mostly cloudy skies (mostly in the form of high clouds) and increasing shower coverage. The statistical QPF guidance supports this upward trend in shower coverage through this period, then depicts a more stable/dry pattern returning Friday.
Trades should persist this weekend through early next week, but some notable differences shown between the various sources of guidance, regarding the strength and direction, lowers the forecast confidence. Additionally, increasing moisture along with another upper level trough moving in from the west could translate to a period with cloudy skies and increasing shower coverage Sunday through the first half of next week.

Aviation

Moderate to locally breezy trade winds will continue through the remainder of the week. Clouds and showers will favor windward coasts and slopes, and be most active in the late night and early morning hours. In the afternoon and early evenings, leeward sea breezes and daytime heating will encourage cumulus build-ups along south and west facing slopes of the Big Island, but a strong inversion will limit their growth and rainfall potential.
AIRMET Sierra for mountain obscuration is now in effect for north through east sections sections of all islands. Conditions are expected to persist through mid-morning, possibly longer on Kauai.
AIRMET Tango remains in effect for moderate low-level turbulence to the lee of higher terrain, and will likely be needed through the remainder of the week.

Marine

Strong surface high pressure will continue to provide fresh to strong easterly trades making for rough conditions across the Hawaiian waters through the week. A Small Craft Advisory (SCA) has been issued for all exposed waters through Thursday due to a combination of a declining medium- period northeast swell and locally generated wind waves. Seas will drop slightly through Thursday as the northeast swell moves out. Most zones may remain in the SCA due to consistent fresh to strong trades through the end of the week.
Surf along exposed east facing shores will remain rough through the week, although the High Surf Advisory (HSA) has been cancelled as the northeast swell continues to move out.
Surf along north facing shores will remain small into Friday, except for shores exposed to northeast swells today as the swell continues to decline. An upward trend is expected late Friday through the weekend due to a combination of expected north- northeast and west- northwest swells. The north- northeast swell should steadily fill in late Friday, then peak over the weekend. The west- northwest swell is forecast to build down the island chain through the day Saturday, producing surf which will peak near HSA threshold across exposed north and west facing shores late Sunday.
Surf along south facing shores will remain small through midweek, with mainly background energy moving through. An upward trend is expected Thursday afternoon as a long-period south-southwest swell arrives. This swell will peak late Friday into Saturday, then ease Sunday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for all Hawaiian waters,

Data Courtesy of NOAA.gov