Photo Credit: Braden Jarvis

West Kaua’i

Rest Of Today: Mostly clear. Breezy. Highs around 79 near the shore to around 66 above 3000 feet. Northeast winds up to 20 mph shifting to the east in the afternoon.

Tonight: Mostly clear. Lows 58 to 63 near the shore to around 52 above 3000 feet. Light winds.

Sunday: Sunny. Highs around 79 near the shore to around 68 above 3000 feet. Northwest winds up to 10 mph.

South Kaua’i

Rest Of Today: Mostly clear. Highs 75 to 80. Light winds becoming northwest up to 10 mph in the morning, then shifting to the southwest in the afternoon.

Tonight: Mostly clear. Lows around 59. Light winds.

Sunday: Sunny. Highs 77 to 82. West winds up to 10 mph.

Kaua’i Mountains

Rest Of Today: Mostly sunny early in the morning then becoming sunny. Breezy. Highs 67 to 73 in the valleys to around 59 above 4000 feet. North winds up to 20 mph.

Tonight: Mostly clear. Lows 53 to 61 in the valleys to around 50 above 4000 feet. North winds up to 10 mph in the evening becoming light.

Sunday: Sunny. Highs 70 to 76 in the valleys to around 62 above 4000 feet. Light winds becoming west up to 10 mph in the afternoon.

North Kaua’i

Rest Of Today: Mostly clear. Breezy. Highs 68 to 78. North winds up to 20 mph.

Tonight: Mostly clear. Lows 55 to 63. Southwest winds up to 10 mph in the evening becoming light.

Sunday: Sunny. Highs 70 to 79. West winds up to 10 mph.

East Kaua’i

Rest Of Today: Mostly clear. Breezy. Highs 67 to 78. North winds up to 20 mph.

Tonight: Mostly clear. Lows 54 to 67. Northwest winds up to 10 mph in the evening becoming light.

Sunday: Sunny. Highs 71 to 80. Light winds becoming west up to 10 mph in the afternoon.

Detailed Forecast

Synopsis

A crisp and cool morning as the coolest airmass of the season remains entrenched over the area. Showers will continue to steadily diminish as winds become increasingly light during the next couple of days. Another front will approach the islands Monday night and Tuesday, with increasing south to southwest winds allowing the air mass to warm and moisten. The front may move over the islands by Wednesday, bringing additional rainfall, especially to leeward areas.

Discussion

A crisp and cool start to the day with light northerly winds, dewpoints in the 50s, and temperatures in the low to mid 60s at sea level. A few choice locations such as Poipu on Kauai have fallen into the mid-50s with other favored locales such those in central Oahu (Wahiawa and Mililani) possibly touching the upper 50s by sunrise. Twenty-four hours of airmass modification will result in high temperatures today a touch warmer than yesterday, likely in the upper 70s to 80 degrees at the area climate sites. Strong winds continue at the Big Island Summits with borderline High Wind Warning threshold conditions observed at 1329z/329am HST. The High Wind Warning will be allowed to continue in the immediate term with potential for transition to an advisory within the next few hours.
Strong dry advection has manifested within the subsidence wake trailing the departing extratropical cyclone. This has resulted in a considerable reduction in shower coverage over the state during the last 12 hours, especially over Kauai and Oahu where meaningful rainfall has ended and the trade inversion has crashed just below 5kft at press time. Signs of building low-level anticyclonic flow are evident in the low-level flow west of Kauai where low cloud cover within the remnant moisture field is eroding from west to east. With the exception of isolated light showers over north- facing slopes of Maui County and potentially the Big Island, today will be dry with little to no chance for shower activity over Kauai and Oahu. Light northerly winds will persist through today.
The gradient further diminishes tonight as a strong zonal jet works its way into the Central Pacific Basin and suppresses the trade wind belt well south of the area. The islands will be within a highly subsident environment with the surface ridge axis transecting the area tonight into Sunday. Light land breezes potentially develop tonight leading to another chilly morning on Sunday followed by rebounding high temperatures to around 80 degrees. The land and sea breeze pattern holds into Monday.
Consolidation of multiple waves of low pressure results then results expansive pressure falls across the NE and Central Pacific Basins early-mid next week. Global model consensus suggests winds become increasingly southerly by late Monday into Tuesday as the islands catch the southern periphery of pressure falls. Strengthening southwesterlies in advance of an approaching front will bring an increasing chance for rain, especially to leeward areas, Tuesday and Wednesday. Some stronger wind gusts will be possible with downsloping over eastern areas within this regime, but the overall background pattern of decreasing stability and a slowly rising inversion will prove less-than-optimal.

Aviation

Isolated showers embedded within northerly flow will continue to impact areas east of Oahu through the morning hours, with showers tapering off from west to east today as drier air settles over the islands. Expect mainly VFR conditions, with brief MVFR possible under passing showers.
Low-level winds will continue to weaken today and become more northerly as the upper low moves east. AIRMET Tango remains in effect for both low-level and mid/upper level moderate turbulence over Maui and the Big Island early this morning. However, as the upper low moves away from the state and winds across the islands weaken will likely be able to drop these AIRMETs this morning.

Marine

The cold front has moved southeast of the offshore waters this morning and continues to track east. Winds over the coastal waters have subsided slightly as moderate to locally fresh northerly winds will linger today before it trends down from the northwest Sunday. Another front will approach the islands Monday night, and Tuesday with increasing strong to near- gale south to southwest winds. A Small Craft Advisory (SCA) will likely ramp up for select zones as this front comes through.
North facing shores will continue to see surf above High Surf Advisory (HSA) criteria as the northerly swell has peaked over the western islands this early this morning well above guidance as it will peak before day break over the eastern end of the state. The north swell is expected to transition to the north- northeast as the gale- force low associated with the cold front moves northeast. A Marine Weather Statement has been issued for the potential for harbor surges impacts for both Kahului and Hilo Harbor through tonight. Despite the winds trending down, the current SCA will remain in effect through the day for all waters due to the elevated seas from the current north swell.
The HSA for west facing shores has been cancelled as surf heights have decreased with the declining northwest swell. East facing shores will remain small except for areas exposed to the north swell.
The northwest Pacific continues to remain fairly active and continue to generate additional northwest swells that are expected to reach the islands next week. A moderate medium period swell will fill in Monday which could bring surf back up to near High Surf Advisory levels. Models are showing dominant swell direction from the west- northwest with the potential for High Surf Warning level surf next week Wednesday.
Tides are currently running about 0.35 to 0.75 feet above predicted levels. With high astronomical tides near 3 feet, combined with the northwest and north swells, anticipate minor/ nuisance coastal flooding within low lying flood-prone areas during the early morning pre-dawn high tides Saturday. A Coastal Flood Statement remains in effect for all islands for this possibility.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Wind Advisory until Noon HST today for Big Island Summits.
Small Craft Advisory until 6 PM HST this evening for all Hawaiian waters except Maalaea Bay,

Data Courtesy of NOAA.gov