Hilo

Today: Showers likely, mainly after noon. Partly sunny, with a high near 83. Light and variable wind becoming east 6 to 11 mph in the morning. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 66. East wind 5 to 9 mph becoming calm after midnight. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 83. Calm wind becoming east 5 to 8 mph in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Mostly sunny, with a high near 79. Calm wind becoming west 5 to 8 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. West wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers after noon. Partly sunny, with a high near 79. Calm 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.

Waimea

Today: Showers likely, mainly after 1pm. Partly sunny, with a high near 78. Breezy, with a north northeast wind 7 to 16 mph, with gusts as high as 20 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly before 7pm. Mostly cloudy, with a low around 58. Breezy, with an east northeast wind 15 to 20 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 78. Windy, with a northeast wind around 23 mph, with gusts as high as 32 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. Partly sunny, with a high near 64. Breezy, with an east southeast wind 7 to 17 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 53. Windy, with an east wind 13 to 18 mph increasing to 20 to 25 mph after midnight. Winds could gust as high as 36 mph. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 64. Windy, with an east wind 14 to 24 mph, with gusts as high as 33 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 84. Breezy, with an east northeast wind 16 to 21 mph, with gusts as high as 24 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 74. Windy, with an east wind 20 to 23 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Isolated showers after noon. Mostly sunny, with a high near 84. Windy, with an east wind 20 to 26 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly after noon. Partly sunny, with a high near 82. West northwest wind 5 to 13 mph becoming east in the afternoon. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Occasional showers. Low around 64. East wind 10 to 13 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 82. Northeast wind 10 to 13 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Scattered showers after noon. Mostly sunny, with a high near 84. East southeast wind 5 to 14 mph becoming west northwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Partly cloudy, with a low around 66. Breezy, with a northeast wind 5 to 10 mph becoming east southeast 13 to 18 mph after midnight. Winds could gust as high as 24 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Isolated showers after noon. Mostly sunny, with a high near 84. Breezy, with a northeast wind 16 to 21 mph decreasing to 7 to 12 mph in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Light to moderate trades will hold in place today, with localized sea breezes developing in the more sheltered leeward areas. Fairly dry conditions should prevail in most areas, although a slight increase in showers is expected over the eastern end of the state this afternoon as a band of moisture moves in from the east. This band of moisture will then move westward bringing an uptick in windward showers to the remaining isles tonight. Trades will get a boost back to moderate and breezy levels Wednesday through much of the holiday weekend, with the strongest winds expected Friday and Saturday. A return of more typical windward and mauka focused showers is expected as well, with a stray shower reaching leeward areas from time to time.

Discussion

Currently at the surface, a ridge of high pressure is located a couple hundred miles north of Kauai, while, a weakening trough of low pressure is nearly stationary around 350 miles northwest of Garden Isle. The resulting gradient is producing light to moderate trade winds across the island chain early this morning, with land breezes present in some of the more sheltered leeward areas. Infrared satellite imagery shows clear to partly cloudy skies in most areas, with a bit more cloud cover over leeward Big Island. Radar imagery shows a few isolated showers moving into windward areas, with very little if any shower activity in leeward areas. Main short term concerns revolve around rain chances and trade wind trends during the next few days.
The trade winds will gradually trend upward during the next couple days, as the ridge of high pressure north of the islands lifts slowly northward and the trough to the northwest dissipates. Light to moderate trades will hold in place through today, with some localized land and sea breezes developing in the most sheltered leeward areas. High pressure building northeast of the state will strengthen the trades to moderate and breezy levels Wednesday through much of the Holiday Weekend, with the strongest winds expected Friday and Saturday.
As for the remaining weather details, rather dry conditions should persist in many areas today, although a band of moisture currently around 150 miles east of the Big Island, should bring an increase in shower activity to the eastern end of the state this afternoon. The band of moisture will continue to shift westward tonight, bringing an increase in showers to windward areas of the remaining islands, with a stray shower possibly reaching leeward locales. A more typical trade wind shower pattern appears to resume Wednesday through the Holiday Weekend, with showers favoring windward and mauka areas mainly during the overnight and early morning hours, and a stray shower reaching leeward areas from time to time.

Aviation

The surface ridge north of the state is expected to gradually strengthen, leading to a modest increase in trade wind speeds over the next twenty-four to forty-eight hours. These east to northeast winds will steer scattered clouds and isolated showers towards mainly windward slopes and coasts.
Meanwhile, a weak eddy in the wake of the Big Island will keep the Kona and Kohala coasts more in than out of clouds through the morning hours. In the afternoon, daytime heating and light sea breezes will encourage cumulus build-ups over the Islands interior.
Localized MVFR CIG and VIS are to be expected in brief showers, otherwise VFR conditions will prevail all areas. No AIRMETs are currently in effect or anticipated at this time.

Marine

A surface ridge is a couple of hundred miles north of the islands this morning. The trough just to the north of the ridge is rapidly falling apart, allowing the area of high pressure to expand westward and strengthen. So the trade winds will continue to strengthen today, becoming locally strong by daybreak Wednesday. By Thursday night, the ridge will be a good 600 nm north of Kauai, where it remains nearly stationary into the upcoming weekend. So the trades are here to stay, at least through the 4th of July weekend. Due to the strong trades, a Small Craft Advisory (SCA) will be hoisted later today, covering the typical nearshore waters of Maui County and waters south of the Big Island. The trades may pick additonal speed towards Friday night, to widespread moderate to strong as the surface high strengthens northeast of the islands. There is a good possibility that the SCA will be expanded to most, if not all of the nearshore waters, and this will likely last through the 4th of July weekend.
Small pulses from the west-northwest to north are expected to reach our west and north facing shores through early next week. These small pulses will maintain some wave action along the north and west facing shores. The largest of the swells is slated for this Friday.
There will be a series of south swells coming in through early next week. One of two larger pules is due in tonight with a period of 16 seconds. The second pulse is a long 19 second period slated to arrive Sunday. This swell is likely to produce a significant increase in surf heights along south facing shores, just in time for the Forth of July celebration. Strengthening trade winds means the surf along east facing shores will be on the rise, but staying below high surf advisory. Certainly the waters will become dangerously rough and choppy, especially over the weekend.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov