Hilo

Today: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 78. East wind around 11 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Occasional showers, mainly after 7pm. Low around 65. East wind 6 to 11 mph becoming light and variable in the evening. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Occasional showers, mainly before 1pm. High near 79. Light and variable wind becoming east 6 to 11 mph in the morning. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Increasing clouds, with a high near 79. West wind around 9 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Mostly cloudy, then gradually becoming mostly clear, with a low around 63. East southeast wind around 6 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Isolated showers after noon. Increasing clouds, with a high near 80. West wind 6 to 8 mph. Chance of precipitation is 20%.

Waimea

Today: Scattered showers. Partly sunny, with a high near 75. Breezy, with an east northeast wind around 17 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 54. Breezy, with an east wind around 17 mph, with gusts as high as 24 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Scattered showers before noon. Mostly sunny, with a high near 76. Breezy, with an east northeast wind around 18 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Occasional showers. High near 71. Breezy, with a northeast wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Occasional showers, mainly after midnight. Low around 47. Breezy, with an east wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Showers likely, mainly before noon. Mostly cloudy, with a high near 72. Breezy, with a northeast wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Sunny, with a high near 76. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph.

Tonight: Isolated showers after midnight. Partly cloudy, with a low around 70. Windy, with an east northeast wind around 24 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Tuesday: Sunny, with a high near 75. Windy, with an east northeast wind around 24 mph, with gusts as high as 31 mph.

Puna

Today: Showers likely. Mostly cloudy, with a high near 75. East northeast wind around 13 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Occasional showers. Low around 63. West northwest wind around 5 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Occasional showers, mainly before noon. High near 76. East northeast wind around 13 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 81. North northwest wind around 9 mph.

Tonight: Mostly clear, with a low around 63. East northeast wind around 10 mph.

Tuesday: Sunny, with a high near 82. North northwest wind around 10 mph.

Detailed Forecast

Synopsis

Breezy trade winds will persist through Tuesday as strong high pressure holds far north of the state. A band of moisture will produce active showers along mainly windward portions of Maui County and the Big Island this morning, and then drift south of the state late today, as a drier air mass moves in from the north. Trade winds will decrease on Wednesday and remain at moderate strength through Friday, leading to typical trade wind weather.

Discussion

The forecast remains on track, so little change with this morning’s package. High pressure remains far north of the islands, and a nearly stationary low remains to the northeast. Breezy trade winds are expected today with a bit of a downward trend expected tomorrow.
The remains of an old front continue to bring showers to the islands in the trade wind flow. The band had been focused over Oahu and Maui County earlier in the evening, but is drifting southward, impacting Maui County and the Big Island early this morning. Any of this moisture making it to the summits on the Big Island could fall in the form of winter weather with temperatures below freezing. An upper level trough axis is just east of the Big Island this morning and is expected to continue moving away from the islands today.
A drier airmass is sinking in over Kauai, with the overnight sounding showing precipitable water (PW) values of 0.91 inches. Satellite derived PW shows that drier air is spreading over Oahu early this morning. Anticipate the drier airmass to spread over Maui County and the Big Island tonight, and then stick around state wide through the end of the week.
Dew points are already in the low 60s in many locations, and are expected to fall into the mid to upper 50s by tonight, and then stay low through much of the week. Combined with the drier airmass, it will feel a little on the cool side, particularly at night with the breezy trades. As this pattern sets up, expect showers to be focused on the windward sides of the islands.
Trade winds will likely drop a notch on Wednesday and remain at moderate strength through Friday. Global models show a mid- to upper-level trough just east of the state and an upper ridge to the west. At this time, it looks like the islands will remain in a stable trade wind flow, with some shallow bands of moisture riding in on the trades from time to time.
Heading into next weekend, the GFS and ECMWF show the cutoff low to the northeast falling apart and drifting toward the islands. As a result, we could experience a decrease in trades with additional moisture moving in.

Aviation

Breezy northeast trade winds will continue, with clouds and showers focusing over windward and mountain locations. The greatest shower coverage will continue to be from Oahu to Big Island where a band of clouds/moisture lingers. MVFR CIGS/VSBYS can be expected in and around these passing showers.
AIRMET SIERRA for mountain obscuration remains in effect for Windward Big Island through Oahu.
AIRMET TANGO remains in effect for lee turbulence for the entire area.

Marine

High pressure far to the north will maintain fresh to strong northeast trade winds into Wednesday before gradually dropping to moderate levels Thursday as the high weakens. A small craft advisory is in effect for all coastal waters for winds and seas.
A gale low centered near 35N140W is expected to retrograde toward Hawaii over the next few days, sending NNE swell toward the islands. Current buoy observations show some small forerunners heightening surf along exposed shores but a more robust increase is expected this afternoon/evening with a peak Tuesday night, and then a gradual decline into the weekend. A high surf advisory will likely be necessary Tuesday/Wednesday for east facing shores exposed to this NNE swell. An increase in surf is also possible for the northern beaches on Lanai and along the shoreline north of Keahole Point on the Big Island. More normal trade wind swell will also increase with gusty trade winds. Background, long period southerly swells will bring small surf to south facing shores through the week. A slight increase in southerly surf is possible by the weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory from 6 AM this morning to 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

Data Courtesy of NOAA.gov