Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Isolated showers in the morning. Highs around 80 near the shore to around 67 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 65 near the shore to around 55 above 3000 feet. East winds around 15 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with scattered showers. Highs around 80 near the shore to around 66 above 3000 feet. East winds 15 to 20 mph. Chance of rain 50 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 80. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 65. East winds 20 to 25 mph. Chance of rain 50 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80. East winds 20 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 69 to 75 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 57 to 63 in the valleys to around 53 above 4000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

Monday: Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 69 to 75 in the valleys to around 58 above 4000 feet. East winds 15 to 25 mph. Chance of rain near 100 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 70 to 81. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 58 to 66. East winds 15 to 20 mph. Chance of rain 50 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 70 to 81. East winds 15 to 20 mph. Chance of rain 70 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 68 to 78. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 58 to 70. East winds 15 to 20 mph. Chance of rain 50 percent.

Monday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 68 to 78. East winds 15 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

High pressure to the north of the main Hawaiian Islands will continue to drive locally windy trade winds through much of the week. Clouds and showers will favor windward and mauka areas, with stronger winds helping to carry some showers to leeward areas.

Discussion

Strong high pressure far north of the main Hawaiian Islands continues to drive breezy to windy conditions across local waters this morning. Windy trades are expected for the next several days and a Wind Advisory remains in effect for portions of Maui County and the Big Island. The areas most likely to see advisory level winds include the Kohala Mountains on the Big Island, the central valley of Maui and over ridges and through gaps on Molokai, Lanai and Kahoolawe. Models suggest that advisory level winds could occur on Oahu, but confidence is too low to include that island in the Wind Advisory at this time. Nevertheless, winds will be quite breezy there.
Satellite loop shows bands of broken low clouds riding in on the trades, with radar confirming isolated to scattered moderate showers beneath this cloud cover. These bands continue at intervals far to the east of the islands, so expect increased windward showers over the next day or so as each band passes by. Stronger trade winds will push some of these showers across leeward areas from time to time. A subtropical jetstream, marked by the persistent pall of middle and high clouds, remains over the islands and may enhance showers due to improved venting aloft.
By late next week, models show an upper trough moving over the islands from the northwest, introducing a pool of destabilizing cold air aloft. At the surface, high pressure will remain north of the state and trade winds will persist at the surface. However, associated trade showers may be heavier and more widespread as the upper trough moves in.

Aviation

Breezy to locally windy easterly trade winds will remain in place over the next several days and will focus showers primarily over windward and mountain areas. Latest satellite imagery early this morning shows bands of broken low clouds upstream of the islands that are moving westward towards the state. These bands will maintain increased windward showers over the next 24 hours or so. While VFR flight conditions will prevail for the most part, occasional MVFR is expected as these bands move through.
AIRMET Tango remains in effect for moderate low-level turbulence, and this AIRMET will likely be needed throughout the next several days. AIRMET Sierra may be needed later this morning for mountain obscuration across north through east facing slopes and coasts as low clouds move through.

Marine

An area of large high pressure centered approximately 1,100 nautical miles north of the islands is producing a tight enough pressure gradient back toward the state to sustain fresh to locally strong trade winds. Little overall change in the Central Pacific weather pattern will occur in the coming days as the high remains anchored north of the area and maintains these winds for several days. A Small Craft Advisory (SCA) remains in effect for all Hawaiian nearshore waters primarily due to these winds but also for relatively higher seas produced by the passage of both a northwest and northeast swell. Little change in the overall nature of these stronger trades and agitated seas with passing swells has the all-water SCA now in effect through (at least) Tuesday night. Winds may trend down a touch going into the middle of next week as the high gets replaced by another slightly weaker high to the northwest and moves closer to the islands.
The moderate size, long period northwest (320 degree) swell that peaked yesterday will continue to gradually fall off through early Monday. This swell decline has allowed the High Surf Advisory (HSA) to expire along north and west-facing shores. North shore surf will remain elevated the next few days with eastern exposure surf on the rise as a fairly large, medium period east northeast (40-60 degree) swell from a close proximity gale low arrives Monday. East-facing shore surf heights will likely achieve HSA levels, with surf potentially reaching warning levels, as this ENE swell peaks Monday night into Tuesday. Days of fresh to locally strong trades has produced a rough, short period wind wave, and these rough conditions are expected to continue along eastern shores with no substantial break in the trades. Eastern passing southern hemispheric gale lows will produce swell energy that may eventually make it into our local waters late this week. South-facing shore surf will probably increase by another foot or two with the arrival of these small, long period south swells.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Kahoolawe, Maui Windward West, Kohala, Molokai, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Kipahulu, Big Island North.
Small Craft Advisory until 6 AM HST Wednesday for all Hawaiian waters,

Data Courtesy of NOAA.gov