Hilo

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 78 near the shore to 63 to 68 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 63 to 68 near the shore to around 56 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Friday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 78 near the shore to around 64 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Today: Mostly sunny. Scattered showers in the afternoon. Highs 76 to 81 near the shore to around 63 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 69 near the shore to 49 to 54 near 5000 feet. North winds up to 10 mph shifting to the east after midnight. Gusts up to 30 mph. Chance of rain 50 percent.

Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 76 to 82 near the shore to around 63 near 5000 feet. East winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Waimea

Today: Partly sunny. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 76 near the shore to 63 to 73 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Windy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 69 near the shore to 53 to 61 near 3000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Windy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 76 near the shore to 65 to 72 near 3000 feet. East winds 15 to 30 mph. Chance of rain 70 percent.

Kohala

Today: Partly sunny. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 76 near the shore to 63 to 73 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Windy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 69 near the shore to 53 to 61 near 3000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Windy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 76 near the shore to 65 to 72 near 3000 feet. East winds 15 to 30 mph. Chance of rain 70 percent.

South Big Island

Today: Mostly sunny. Windy. Isolated showers in the afternoon. Highs around 80 near the shore to around 67 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 69 near the shore to around 51 near 5000 feet. Northeast winds 20 to 25 mph decreasing to 10 to 25 mph after midnight. Chance of rain 20 percent.

Friday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 80 near the shore to around 66 near 5000 feet. East winds 15 to 25 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 78 near the shore to 63 to 68 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 63 to 68 near the shore to around 56 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Friday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 78 near the shore to around 64 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny and windy. Isolated showers in the afternoon. Highs around 80 near the shore to 64 to 70 above 4000 feet. Northeast winds up to 35 mph. Chance of rain 20 percent.

Tonight: Windy. Partly cloudy with isolated showers. Lows around 70 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 30 mph. Chance of rain 20 percent.

Friday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 80 near the shore to 63 to 69 above 4000 feet. Northeast winds up to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Drier air and strong trade winds are expected through Friday. An upper level system moving towards the eastern end of the state this weekend could bring a wetter trade winds.

Discussion

Have made some tweaks to the winds through the forecast period. Wind Advisory level winds remain in the forecast for the north portion and Kohala areas of the Big Island today. Winds will remain on the breezy to locally windy side over the coming days. However, have lowered the winds to just below advisory levels beyond today. Otherwise the forecast, and the forecast philosophy, remains largely the same as last evening.
The upper level low and surface trough continue to move west away from the main Hawaiian Islands this morning, but continues to be playing a role in the local weather. Thunderstorm activity associated with this system continues to be found west of the coastal waters this morning, and it is expected that these thunderstorms will also continue to move west with the trough.
High pressure to the far northeast, combined with the exiting trough to the west is helping to keep a tight pressure gradient over the islands. As the trough moves to the west, the high is expected to sink southward, maintaining the pressure gradient over the islands which will provide a boost to the winds. Combined with a drier airmass moving in, we can expect an uptick in the returning trade wind flow today. At this time, the highest confidence for advisory level winds is over and downslope of the Kohala Mountains on the Big Island today. Other downslope areas will also likely see some strong gusts at times over the next couple of days. Will monitor the situation before determining if the Wind Advisory needs to be extended or expanded.
Winds are expected to shift to a more easterly direction on Friday, as the high sinks slightly south, and the trough continues to move to the west. This will likely allow winds to decrease just a bit on Friday. Low clouds and light showers will focus over windward areas, with isolated showers passing to leeward sides of the smaller islands. Overall rainfall accumulation will be light.
The GFS and ECMWF global models show an upper level trough moving in from the northeast this weekend. The GFS hints at an upper level low forming along this trough Saturday afternoon for a brief time. Regardless of whether the upper low forms, the lowering upper level heights and increased stability could support an enhancement to the trade winds showers. Although the bulk of the showers will favor windward areas in the low level trade wind flow, the continued breezy trade winds will carry some of them onto leeward areas, especially through the overnight and early morning periods.
Although this upper level trough axis swings through late Sunday, the global models show another one swinging through a little further east early next week. High pressure remaining to the north of the islands will maintain breezy trades well into next week, but the upper level trough will likely enhance some of the showers upstream of the islands. These will be carried in on the trade winds during the first half of next week, focusing over windward areas and occasionally blowing over the leeward areas.

Aviation

Breezy to strong easterly trade winds are expected through the 24-hr forecast period and beyond, with clouds and mostly light showers favoring windward and mauka locations. Upper-level debris clouds associated with convection and the upper low several hundred miles to the west-southwest will continue to stream over the state. MVFR CIGS/VSBYS remain likely for some windward areas as pockets of moisture move through delivering light to moderate showers.
AIRMET Sierra for mountain obscuration remains in effect for all windward zones.
AIRMET Tango for lee turbulence below 080 will continue.
AIRMET Tango for moderate mid- to upper-level turbulence in the FL250/400 layer remains in effect.
Light icing potential is noted in the Zulu section of the AIRMET due to a band of mid/upper clouds moving through in the 140/FL250 layer. The best chance for icing will remain over the western end of the state.

Marine

Strong high pressure will hold in place northeast of the state through the end of the work week, then merge with a new strong high building north of the islands over the weekend into early next week. Strong to near-gale force trade winds will continue through the period. A Small Craft Advisory (SCA) is now in effect for all waters due to a combination of winds and rough seas through 6 PM Monday. The SCA will likely need to be extended at least through the middle of next week.
Surf along east facing shores will remain large and rough through the middle of next week due to persistent strong trade winds over and upstream of the islands. A High Surf Advisory (HSA) is now in effect for east facing shores through 6 AM Saturday. The HSA could briefly lower below advisory levels this weekend, then ramp back up to advisory levels Monday through Wednesday.
A series of small northwest swells (310-320 degrees) will move through the islands today through Monday, keeping some small surf in place along north and west facing shores. Northwest swell energy appears to fade entirely by the middle of next week. South shore surf will remain small through the middle of next week, with nothing more than background south swell energy moving through.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Saturday for east facing shores of Kauai, Oahu, Molokai, Maui and the Big Island.
Wind Advisory from 6 AM this morning to 6 PM HST this evening for Kohala, Big Island North.
Small Craft Advisory until 6 PM HST Monday for all Hawaiian waters,

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Data Courtesy of NOAA.gov