Photo Credit: Brittney Cruz

West Side

Today: Isolated showers before 1pm. Sunny, with a high near 84. East wind around 6 mph becoming calm. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 65. Light and variable wind.

Tuesday: Sunny, with a high near 83. Calm wind becoming west southwest around 6 mph in the afternoon.

South Side

Today: Isolated showers after noon. Mostly sunny, with a high near 84. Northeast wind around 6 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 63. Light and variable wind becoming northeast around 5 mph after midnight.

Tuesday: Isolated showers after noon. Mostly sunny, with a high near 83. Calm wind becoming west southwest 5 to 7 mph in the afternoon. Chance of precipitation is 20%.

North Shore

Today: Isolated showers. Mostly sunny, with a high near 82. Breezy, with an east wind 9 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 64. East wind 5 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers. Mostly sunny, with a high near 81. South southeast wind 5 to 9 mph becoming north in the afternoon. Chance of precipitation is 20%.

Central Maui

Today: Mostly sunny, with a high near 82. Breezy, with a northeast wind 5 to 15 mph, with gusts as high as 21 mph.

Tonight: Partly cloudy, with a low around 62. Northeast wind 5 to 8 mph becoming calm in the evening.

Tuesday: Mostly sunny, with a high near 81. Light and variable wind becoming north northeast 6 to 11 mph in the afternoon.

Upcountry

Today: Mostly sunny, with a high near 70. Calm wind becoming west northwest around 6 mph.

Tonight: Partly cloudy, with a low around 53. Light and variable wind.

Tuesday: Mostly sunny, with a high near 69. Calm wind becoming west 5 to 7 mph in the afternoon.

East Maui

Today: Scattered showers. Partly sunny, with a high near 80. Southeast wind 10 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 60. Southeast wind 6 to 10 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 79. Southeast wind 7 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Scattered showers after noon. Mostly sunny, with a high near 76. Calm wind becoming north northeast 5 to 7 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 62. North wind 3 to 7 mph. Chance of precipitation is 20%.

Tuesday: Scattered showers, mainly after noon. Mostly sunny, with a high near 75. Light and variable wind becoming south southwest 5 to 10 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kaunakakai

Today: Sunny, with a high near 82. East wind 5 to 9 mph.

Tonight: Mostly clear, with a low around 66. East wind around 5 mph becoming calm in the evening.

Tuesday: Sunny, with a high near 81. Light and variable wind becoming south southwest 5 to 9 mph in the afternoon.

Detailed Forecast

Synopsis

Light to moderate trade winds will hold in place today, with passing showers favoring windward and mauka areas, and a stray shower reaching leeward areas from time to time. A sea breeze and land breeze pattern should take hold on Tuesday as the trades become disrupted due to an approaching cold front. This cold front is forecast to bring an increase in showers Wednesday through Thursday as it moves into and gradually dissipated across the islands. A cold front will approach from the northwest Friday and Saturday, bringing a land and sea breeze pattern back to the state, with some beneficial rains possible late in the weekend as the front moves into the island chain.

Discussion

Currently at the surface, a west-east oriented ridge of high pressure is located around 200 miles north of the Kauai, and is driving light to moderate trade winds across the island chain early this morning. Infrared satellite imagery shows clear to partly cloudy skies across Kauai, with a mix of high and low clouds resulting in partly to mostly cloudy conditions from Oahu eastward to the Big Island. Radar imagery shows scattered showers moving into most windward areas from Oahu eastward to the Big Island, with a few showers reaching leeward locales. Meanwhile, rain free conditions prevail over Kauai at the moment. Main short term focus revolves around trade wind trends and rain chances during the next couple days.
The ridge of high pressure north of the islands will keep light to moderate trades in place today. The trades won’t last long, as an approaching cold front will bring light and variable winds back to the island chain late tonight through Tuesday, with land breezes and sea breezes common. As the front draws closer Tuesday night, light south to southwest winds will develop, with moderate westerly winds expected on Wednesday. Winds should shift around to the north and northeast at moderate levels Wednesday night, then become more easterly on Thursday as the front stalls out and dissipates around the central or eastern end of the state. A cold front is then forecast to approach from the west Friday and Saturday and possibly move into the islands late in the weekend. This should bring another period of light and variable winds to the state with sea breezes and land breezes developing in many areas.
As for the remaining weather details, quite the progressive pattern is in store for the islands through the week, with a series of fronts approaching and/or moving into the state. In the near term, high pressure building north of the islands will keep a stable and relatively dry trade wind pattern in place today, with brief passing showers over windward and mauka areas, along with the occasional leeward spillover. A sea breeze/land breeze pattern should set up on Tuesday in advance of the next cold front, with a few showers possible near the coast in the morning and mainly over the island interiors in the afternoon. Rain chances should increase from west to east as a cold front slides into the western islands Wednesday, then stalls out and slowly dissipates over the central or eastern end of the state Wednesday night and Thursday. A sea breeze and land breeze appears to set up Friday and Saturday featuring a few showers near the coast at night and during the morning hours, and over the island interiors during the afternoon and early evening. Model solutions appear to be latching onto a higher potential for some unsettled weather moving into the islands late in the weekend, potentially bringing some beneficial rainfall.

Aviation

Surface high pressure will build northeast of the state today and help to generate light to moderate easterly trades. Thus, expect isolated showers to mainly affect areas along the windward coasts and slopes. Brief MVFR ceilings and visibility may accompany this activity. Elsewhere, expect partly cloudy skies and VFR conditions.
AIRMET TANGO remains in effect for the entire island chain between 25000 and 40000 feet due to tempo moderate turbulence. This should begin to ease after around 15 UTC.

Marine

The progressive winter-time pattern is expected to continue through the week across the northern Pacific with a cold front approaching and moving into the area Tuesday through midweek. Guidance shows the local winds easing across the state beginning late tonight ahead of this front, which will lead to a land and sea breeze regime setting up around the coasts for most areas. West winds will precede the front Tuesday night into Wednesday with a shift out of the north over the western end of the state following the front Wednesday into Wednesday night. Long-term guidance shows the trades briefly returning Thursday, then diminishing again as another front approaches Friday into the weekend.
The large north swell that peaked Sunday is slowly lowering. Nearshore PacIOOS buoy observations at Hilo are holding around the Small Craft Advisory level of 10 ft this morning, which may continue through the day. Although the seas over the western end of the state have dipped just below the advisory level, a new, long-period northwest swell will begin to build down the island chain by tonight and drive seas back to advisory levels for most waters exposed to northwest swells. Expect this trend to persist through the week with overlapping large northwest swells arriving and moving through.
Surf along north and west facing shores will remain at or above advisory levels much of the week. As the north swell that peaked Sunday slowly moves out by tonight, the next long-period swell in the series will arrive out of the north-northwest (330 deg) later today into tonight, then ease by midweek. Surf could briefly dip below advisory levels by Wednesday before the next large north- northwest swell (330-340 deg) arrives Wednesday night. Guidance shows this source peaking late Thursday/Thursday night around warning levels, then lowering Friday. Although confidence remains low being this far out, a more significant northwest swell could arrive over the weekend, driving surf along exposed north and west facing shores well above warning levels.
A combination of large surf this week coinciding with peak monthly water levels will worsen beach erosion issues for shores exposed to north and northwest swells. Additionally, low-lying vulnerable coastal locations not exposed to the large swells may experience nuisance flooding at and around the peak daily tide cycles this week (between midnight and daybreak).
Surf along east facing shores will remain small each day due to the previously discussed pattern with trades being disrupted frequently and the lack of fetch upstream across the eastern Pacific.
Surf along south facing shores will trend up slightly by midweek from recent activity down south in the Tasman Sea.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Molokai, Maui Windward West, Maui Central Valley, Windward Haleakala, Big Island North and East.
Small Craft Advisory until 6 PM HST Tuesday for Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

Data Courtesy of NOAA.gov