Photo Credit: Tyler Rooke

West Side

Today: Showers likely and possibly a thunderstorm before 8am, then isolated showers. Mostly sunny, with a high near 78. Breezy, with a north northeast wind 14 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Partly cloudy, with a low around 62. Breezy, with a northeast wind 15 to 20 mph, with gusts as high as 28 mph.

Wednesday: Sunny, with a high near 78. East northeast wind 10 to 13 mph.

South Side

Today: Showers likely and possibly a thunderstorm before 8am, then isolated showers. Mostly sunny, with a high near 78. Windy, with a north wind 10 to 15 mph increasing to 23 to 28 mph in the morning. Winds could gust as high as 40 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Partly cloudy, with a low around 62. Northeast wind 10 to 14 mph, with gusts as high as 18 mph.

Wednesday: Sunny, with a high near 78. East northeast wind around 10 mph.

North Shore

Today: Occasional showers and possibly a thunderstorm before 8am, then scattered showers. High near 76. Breezy, with a north northeast wind 5 to 10 mph increasing to 13 to 18 mph in the morning. Winds could gust as high as 25 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Isolated showers. Partly cloudy, with a low around 60. Breezy, with a northeast wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Wednesday: Sunny, with a high near 76. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph.

Central Maui

Today: Showers likely and possibly a thunderstorm before 9am, then scattered showers. Partly sunny, with a high near 76. Breezy, with a north wind 5 to 10 mph increasing to 11 to 16 mph in the afternoon. Winds could gust as high as 22 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers, mainly before 7pm. Partly cloudy, with a low around 58. Breezy, with a northeast wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Sunny, with a high near 76. East northeast wind 11 to 14 mph, with gusts as high as 18 mph.

Upcountry

Today: Occasional showers and possibly a thunderstorm before 8am, then isolated showers. High near 62. Breezy, with a northeast wind 10 to 15 mph increasing to 16 to 21 mph in the morning. Winds could gust as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Partly cloudy, with a low around 49. Northeast wind around 14 mph, with gusts as high as 18 mph.

Wednesday: Sunny, with a high near 65. Breezy, with an east northeast wind 10 to 15 mph, with gusts as high as 21 mph.

East Maui

Today: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 74. Breezy, with a west northwest wind 13 to 16 mph becoming north in the afternoon. Winds could gust as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Isolated showers. Mostly cloudy, with a low around 57. Breezy, with a north northeast wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers. Mostly sunny, with a high near 74. East northeast wind around 14 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.

Lanai City

Today: Showers likely and possibly a thunderstorm before 8am. Mostly cloudy through mid morning, then becoming sunny, with a high near 71. Windy, with a northeast wind 14 to 19 mph increasing to 24 to 29 mph in the morning. Winds could gust as high as 41 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Mostly clear, with a low around 57. Windy, with a northeast wind 20 to 23 mph, with gusts as high as 32 mph.

Wednesday: Sunny, with a high near 71. Breezy, with an east northeast wind 11 to 16 mph, with gusts as high as 22 mph.

Kaunakakai

Today: Occasional showers and possibly a thunderstorm before 8am. High near 76. Breezy, with a northeast wind 15 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Partly cloudy, with a low around 62. Breezy, with a northeast wind around 17 mph, with gusts as high as 24 mph.

Wednesday: Sunny, with a high near 76. Breezy, with an east northeast wind 18 to 20 mph, with gusts as high as 28 mph.

Detailed Forecast

Synopsis

A fast-moving cold front is expected to move over the Big Island today. Some clouds, showers and the change for thunderstorms will accompany the front. Cool, breezy northerly winds will spread across the islands behind the front. Winds will become moderate trade winds Wednesday through Friday, bringing gradually increasing windward showers. Southeast winds may bring a further increase in moisture starting next weekend.

Discussion

The front has continued to progress down the island chain overnight and is edging closer to the Big Island. The cloud band associated with the front has started to fall apart overnight, with fewer showers evident on radar over the central islands. That being said, some thunderstorms have still developed to the southwest of the islands over the last couple of hours, speaking to the instability introduced to the region by the front and the upper trough on the heels of the front.
Temperatures at the higher elevations of Haleakala are dropping closer to freezing, so any precipitation falling there is likely in the form of freezing rain and/or snow. With the front near Maui, the threat for winter weather continues, so the Winter Weather Advisory for Haleakala will continue for now, but may be able to be dropped later today, depending on how quickly the drier air moves over Maui.
Relatively clear and dry conditions were seen on the Big Island overnight, but as the front approaches over the next few hours, clouds and showers are expected. Temperatures atop Mauna Kea and Mauna Loa are at or below freezing, so the winter weather advisory continues there as well, however it looks like it could still be a few hours before any precipitation reaches the summits. As such, they will likely remain under the advisory through much of the day.
Northerly winds are filling in over Kauai, Oahu and parts of Maui County behind the front, and dewpoints have dropped into the mid 50s along the coast, and lower inland. However wind speeds have not been too strong. Suspect we will see an uptick after daybreak, so have left winds as they were, with a few areas approaching advisory levels.
There is good model agreement in the short term with the front moving over the Big Island today, and then moving to southeast/east tonight. Leftover moisture from the front will linger off to the east for a few days. Meanwhile, winds are expected to become moderate trades Wednesday, and then hold on into the weekend. As the trades become established, some of that leftover moisture will ride in on the trades, which could boost some of the trade wind shower activity.
The models remain in good agreement into the weekend, but start to diverge Sunday. Both the GFS and ECMWF show a front or boundary to the northwest of the islands, which will bring southeast winds to the islands again for start of the new week. Beyond that confidence is low. The PoPs and associated grids are weighted towards the GFS solution in the extended at this time.

Aviation

The quick moving cold front passing over the state has begun to deteriorate, but is still expected to bring low clouds, rain, and possible thunder and lightning to Maui County and portions of the Big Island this morning. Kauai and Oahu which now lie in the wake of the front are experiencing scattered light showers and locally breezy north to northwest winds.
AIRMET Sierra remains in effect for current or expected mountain obscuration across Maui County. Conditions could spread to Windward Big Island early this afternoon, but should end across Molokai and Lanai by late morning.
Winds will veer from north northwest to east northeast Tuesday evening as the front exits the area. Expect winds to be breezy to locally strong immediately along and behind the front. A return to dry light to moderate trade wind flow is expected Tuesday night.
AIRMET Tango remains in effect for low level mechanical turbulence to the lee of higher terrain. Tango currently includes Kauai and Oahu but will likely need to be expanded to include Maui County by late morning.
The front is being strengthened by a digging upper level trough that trails the surface feature. An AIRMET for moderate upper level turbulence has been issued for Maui County and adjacent waters. Conditions are not expected to persist past 1600Z as the trough is expected to weaken as it moves eastward.

Marine

A cold front will continue moving southeastward through the Big Island waters this morning. The front will move into the far eastern waters tonight. Periods of showers are forecast along the front with isolated thunderstorms. Breezy to locally strong northerly winds this morning will shift to northeasterly trade winds this afternoon.
A Small Craft Advisory (SCA) remains in effect for all coastal waters due to increasing winds and elevated seas with a rising northwest swell. This SCA will decrease in coverage over the western waters on Wednesday as trade winds decrease and seas lower from west to east. The SCA will likely be cancelled for all waters by Thursday morning. Another large northwest swell will arrive on Friday with a SCA likely going up again for Hawaiian waters exposed to this swell.
The northwest swell arriving this morning will continue to build today, peaking from this afternoon through tonight. Surf heights are expected to rise into advisory levels along most north and west facing shores of the smaller islands from this afternoon through Wednesday morning. This swell will lower from Wednesday into Thursday as the forerunners of a new large northwest swell arrives by early Friday morning.
A new long period northwest swell will rise quickly on Friday. Surf heights will likely reach High Surf Warning levels late Friday through Sunday. The swell and surf heights will then slowly lower through the first half of next week.
Surf along east and south facing shores will remain on the small side through the next seven day forecast period.

HFO Watches/Warnings/Advisories

High Surf Advisory from noon today to 6 AM HST Wednesday for Niihau, Kauai Windward, Kauai Leeward, Waianae Coast, Oahu North Shore, Oahu Koolau, Olomana, Molokai, Maui Windward West, Windward Haleakala.
Winter Weather Advisory until 6 PM HST this evening for Haleakala Summit, Big Island Summits.
Small Craft Advisory until 6 PM HST this evening for all Hawaiian waters,

Data Courtesy of NOAA.gov