Photo Credit: Jason Weingardt

West Kaua’i

Rest Of Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 85 near the shore to around 71 above 3000 feet. Southwest winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy. Lows 66 to 72 near the shore to around 60 above 3000 feet. Southwest winds up to 10 mph.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 77 to 85 near the shore to around 72 above 3000 feet. Southwest winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 77 to 84. West winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 70. West winds 10 to 15 mph.

Monday: Mostly sunny. Highs 78 to 85. Southwest winds 10 to 15 mph.

Kaua’i Mountains

Rest Of Today: Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 80 in the valleys to around 64 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 60 to 68 in the valleys to around 57 above 4000 feet. Southwest winds up to 15 mph.

Monday: Sunny. Isolated showers in the afternoon. Highs 74 to 80 in the valleys to around 65 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 20 percent.

North Kaua’i

Rest Of Today: Mostly sunny. Isolated showers in the afternoon. Highs 74 to 82. South winds up to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 62 to 69. South winds up to 15 mph.

Monday: Sunny. Highs 75 to 82. South winds up to 15 mph shifting to the west in the afternoon.

East Kaua’i

Rest Of Today: Mostly sunny with isolated showers. Highs 72 to 84. Southwest winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 62 to 72. Southwest winds up to 15 mph.

Monday: Sunny. Highs 73 to 84. Southwest winds up to 15 mph.

Detailed Forecast

Synopsis

Today will be another fairly dry day as a stalling cold front northwest of the state will result in light to gentle southerlies. This relatively light wind pattern will favor the development of daytime sea breezes and overnight land breezes. Southwesterly winds will strengthen over the western third of the state in the coming days as energy diving down in a Central Pacific trough pushes the front in proximity of Hawaii. The mid week passage of this boundary across the northern waters will likely be the impetus to statewide beneficial rain and strengthened breezy winds.

Discussion

Overnight satellite imagery depicts convergent bands of warmer clouds streaming up across the state ahead of an approaching front. Light streamer showers within these lower clouds are mainly moving north across the Kauai Channel and east of Big Island. Haze across the eastern half of the state from Kileau's emissions and periods of cirrus are drifting across from the north as cooler mid to upper level air overrides a couple of Central Pacific frontal boundaries. Despite decreased eruption activity over Halemaumau Crater's hot spot on Big Island, a weak veering wind regime around the southern half of the dial will transport SO2 emissions and resultant vog across Maui County and Oahu through tonight. A fairly dry resident atmosphere all the way up with regional 1″ to 1.25″ precipitable waters (climatological lower quartile for early January) translating to low to mid 60 dew point air at the surface will guarantee many communities will experience mostly sunny skies today. Interior clouds will build in by the afternoon as the mid day sea breezes become better established. A near stationary front encountering island ridging will begin to slowly advance eastward tonight before stalling again today. This scenario will maintain a weak southerly wind regime of due south winds around Maui County and Big Island, veering more southwesterly over Oahu and Kauai through Monday. Due to the weak background wind flow brought on by the vicinity front, localized land and sea breeze activity will remain the dominant wind pattern. This will favor very limited daytime leeward cloud and shower development with clearing star-gazing night skies.
Hawaii and its surrounding waters will remain on the northeastern nose of upper ridging centered far off to the southwest. Energy moving into and deepening a Central Pacific upper level trough will have this trough diving down into the area mid next week, sweeping across the region and driving the aforementioned stalled front through (at least) the western third of the island chain. Southwesterly flow will strengthen across the western half of the state Monday afternoon through Tuesday evening ahead of this deepening upper trough as it rotates through the far northern waters. This will initiate a transition from light diurnally- driven breezes to more widespread strengthened southerly-becoming- northeasterly flow. This flow will tap into a more moist southern air mass and generate pre-frontal leeward area clouds and showers Tuesday into Wednesday. The latest numerical weather prediction (NWP) guidance times the front to reach Kauai Tuesday evening, then slowly move it into the central islands Wednesday evening before stalling and dissipating. This frontal passage is expected to offer beneficial rain and breezy statewide northeasterlies for the majority of the island archipelago.
Mid to lower level streamline convergence along the dissipating boundary, along with an abundance of higher upstream moisture, will keep rain chances in the picture through the latter part of next week. Primarily eastern island precipitation caught within returning trades will focus over windward and mauka areas as high pressure builds in the front's wake. Long-term NWP model guidance is hinting at the aforementioned upper trough evolving into a closed-off low over the eastern end of the state next weekend. This scenario would enhance statewide rainfall and slightly increase storm chances. No need to put the cart ahead of the horse as the development and progression of the upper trough will determine the long term solution of this low.

Aviation

Light southerly background winds will prevail across the islands through the weekend with ridging in place over the state. This will allow for the development of overnight land breezes and daytime sea breezes. Aside from a few passing high clouds, expect mainly clear skies overnight with clouds and a few showers over the interior tomorrow afternoon.
No AIRMETs are currently in effect.

Marine

Expect several days of warning level surf along exposed north and west facing shores may last through Wednesday night, as overlapping significant swell energy moves into the Hawaii region. The current west-northwest (290-310 degree) swell is peaking this morning. Reported swell heights at the buoys continue to run slightly above wave model guidance. Surf along exposed north and west facing shores of all islands are peaking well above warning thresholds this morning, and will only slightly decline later today, holding above warning levels into Monday.
The next round of significant northwest swell will arrive late Monday. Surf heights may briefly drop below warning thresholds by Monday morning, however this next round of significant swell energy will will swiftly build surf heights back above warning levels from Monday night through Wednesday.
The High Surf Warning (HSW) was extended in time through Monday afternoon for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, as well as north facing shores of Maui, and west facing shores of the Big Island. A Small Craft Advisory (SCA) was also extended through Monday afternoon for all waters except Maalea Bay as 10 ft or higher seas are expected for all waters exposed to the northwest swell. This HSW and SCA will likely be extended in time to cover the multiple rounds of significant swell energy moving though Hawaiian Island waters.
Surf heights along east and south facing shores will remain small through the forecast period.
The surface ridge over the state will shift southeastward in response to an approaching cold front. Light and variable winds over the western half of the state will give way to moderate to fresh southwesterlies today, then moderate to strong northwest winds from Tuesday night to Wednesday. Across the eastern end of the state, gentle to locally fresh east to southeast winds will hold through Monday then become light and variable by Tuesday. The front may reach Kauai as early as Tuesday night with moderate northerly winds filling in behind it.

Fire weather

No critical fire weather conditions are expected for the next week. Light southerly flow with local land/sea breezes will continue into early next week, with relative humidities staying above critical levels through the forecast period. A front is expected to move through part of the state during the middle to late part of next week, initiating breezy northeasterlies and much needed rain.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Monday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala, Big Island South.
Small Craft Advisory until 6 PM HST Monday for all Hawaiian waters except Maalaea Bay,

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