Hilo

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 83. East wind 6 to 11 mph becoming light and variable. 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 63. West northwest wind around 6 mph becoming light and variable in the evening. Chance of precipitation is 20%.

Wednesday: Scattered showers, mainly after 10am. Partly sunny, with a high near 84. Light north wind becoming northeast 5 to 9 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after 1pm. Partly sunny, with a high near 83. Light and variable wind becoming west southwest 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: Scattered showers before 7pm. Partly cloudy, with a low around 63. North northwest wind around 5 mph becoming light and variable in the evening. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers after 11am. Partly sunny, with a high near 84. West wind 3 to 7 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 75. Light and variable wind becoming west 5 to 7 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 52. Light and variable wind. Chance of precipitation is 20%.

Wednesday: Scattered showers, mainly after 10am. Mostly cloudy, with a high near 76. North northeast wind 3 to 7 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Showers likely, mainly after noon. Mostly cloudy, with a high near 67. West wind 3 to 5 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 44. Light and variable wind. Chance of precipitation is 20%.

Wednesday: Scattered showers, mainly after 10am. Increasing clouds, with a high near 68. Light east northeast wind. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 83. East northeast wind 5 to 8 mph becoming light and variable in the afternoon.

Tonight: Partly cloudy, with a low around 69. Light and variable wind becoming east around 5 mph after midnight.

Wednesday: Mostly sunny, with a high near 84. Southeast wind 5 to 7 mph.

Puna

:

Waikoloa

Today: Scattered showers after noon. Partly sunny, with a high near 81. Light and variable wind becoming west northwest 6 to 11 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Partly cloudy, with a low around 62. South southeast wind 3 to 7 mph.

Wednesday: Scattered showers after 10am. Partly sunny, with a high near 82. Light and variable wind becoming west northwest 5 to 9 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

A light and variable wind regime with land and sea breezes will continue through Wednesday as a weakening cold front approaches the islands from the northwest. An upper low near Maui and the Big Island will continue drifting northeast away from the state and the approaching cold front will combine forces producing enhanced shower activity over the next few days. A migratory high passing from west to east across the basin will allow trade winds to return to the region from Thursday onward. A wet trade wind weather pattern remains in the forecast through the weekend.

Discussion

A slow moving shower band formed over Western and Southern Oahu on radar this morning producing light rainfall amounts over leeward areas. These enhanced showers were caused by an upper level low near Maui and the Big Island will continue to drift northeast away from the islands today. This passing upper low and a weakening cold front approaching the islands from the northwest will help enhance shower activity over the islands through Wednesday. A light wind pattern will keep land and sea breezes over each island through Wednesday evening. Converging sea breezes and island heating during the day time hours will build clouds over island mountain and interior sections. Additional showers will drift in from pre- frontal cloud bands developing ahead of the approaching front.
The weak cold front roughly 200 miles northwest of Kauai, now appears to drift into the western islands of Niihau, Kauai and Oahu on Wednesday. This slow moving front will enhance cloud and shower coverage a bit for these western islands, favoring Kauai. However, rainfall amounts continue to appear modest at this time. A high pressure system will then build in behind the front by Wednesday night allowing trade winds to return.
Trade winds return on Thursday as a high pressure system migrates from west to east across the Central Pacific. Trade wind subsidence inversion heights,as suggested in model cross sections, will range from around 8000 to 10000 feet into the weekend. A wet trade wind pattern will result as northeast winds push clouds and showers up the slopes of windward and mountain areas. A few of the stronger showers will also drift into leeward areas. Remnant cloud bands from the dissipating front will also drift westward back over the islands into the weekend keeping continued unsettled weather conditions in the forecast.

Aviation

A weakening/dissipating front about 200 nm NW of Kauai as of 2 am HST, is slated to reach Kauai around sunset today. Mainly light southwest and west winds will run out ahead of the front. Expect some random showers to come and go throughout today into tonight. Remnants of the front is expected to get hung up over the central islands Wednesday into Thursday. Expect brief MVFR ceiling/vis with these showers, with tops no higher than 15k feet. No AIRMET Sierra for mountain obscuration expected at this time.
As the mid/upper level low/trough moves east of the Big island shortly, so will the turb. A new area of high level turb will move in later today that will warrant another AIRMET TANGO.

Marine

A high is centered northeast of the area while a front is located several hundred miles northwest of the state. This has caused winds to become lighter and favor a more east to southeast direction, especially over the west end of the island chain. Winds will become more southerly today as the front nears the state. By Wednesday, the front will linger and dissipate across the area while a new high builds in north northwest of the state. This will allow for a return of northeast trade winds across the area. Winds will become more easterly later in the week as the high moves eastward north of the state. Winds and seas are expected to remain below Small Craft Advisory (SCA) levels through Friday but may become stronger on Saturday, resulting in SCA conditions over the typically windy waters around Maui County and the Big Island.
A small long period west northwest swell will continue to fill in today. The westerly direction of this swell will allow Kauai to block some of it from reaching the central islands. Meanwhile, a small short period northwest swell will fill in tonight, then linger through Wednesday and Thursday.
A longer period west northwest swell is expected to fill in late Thursday and Thursday night, peak late Friday and Friday night, then lower gradually over the weekend. The initial pulse from this swell may be somewhat blocked for the central islands by Kauai but should see less blockage as the swell swings around to a more northwest direction.
Models indicate there will be a series of small southerly swells throughout the forecast period. Some of these swells will have rather long periods so surf may be inconsistent at times. Do to the lack of trade winds, surf along east facing shores will remain rather small over the next several days, with an uptick expected later in the week and into the weekend as the trade winds strengthen.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov