Photo Credit: James Grenz

Hilo

Today: Scattered showers. Partly sunny, with a high near 82. Calm wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 65. Light and variable wind. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Showers likely, mainly before noon. Partly sunny, with a high near 84. East wind 5 to 8 mph becoming calm in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Mostly sunny, with a high near 79. Light and variable wind becoming west 5 to 7 mph in the morning. 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 64. North wind 3 to 7 mph. Chance of precipitation is 20%.

Tuesday: Scattered showers after noon. Partly sunny, with a high near 80. West southwest wind 3 to 6 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Partly sunny, with a high near 78. Breezy, with a northeast wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 57. Breezy, with a northeast wind 11 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 79. Breezy, with a northeast wind 10 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a high near 64. Breezy, with an east wind 16 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Partly cloudy, with a low around 52. Breezy, with an east wind 17 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Showers likely, mainly before noon. Partly sunny, with a high near 65. Breezy, with an east wind 14 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Sunny, with a high near 85. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph.

Tonight: Isolated showers after 7pm. Partly cloudy, with a low around 73. Windy, with an east wind 23 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers. Partly sunny, with a high near 85. Windy, with an east wind 21 to 25 mph, with gusts as high as 33 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before 8am. Partly sunny, with a high near 81. North wind 6 to 9 mph becoming east northeast in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 63. Northeast wind 5 to 7 mph becoming calm. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Showers likely, mainly before noon. Partly sunny, with a high near 83. Northeast wind 6 to 11 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after noon. Mostly sunny, with a high near 84. Northeast wind 6 to 13 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 65. East northeast wind 8 to 11 mph. Chance of precipitation is 20%.

Tuesday: Scattered showers after noon. Mostly sunny, with a high near 85. East northeast wind 5 to 11 mph becoming northwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

Trade winds will persist through the rest of the week, although the trades will trend down from locally strong to moderate speed around mid week. This is the result of the weakening of the surface high centered far north of Kauai. Locally breezy trades will return over the weekend as the high strengthens north and northeast of the islands. Showers will continue to favor the windward and mauka areas, with higher frequency of these showers coming during the nights and mornings.

Discussion

The moderate to locally breezy trades are currently being sustained by a weakening 1032 mb surface high located 1130 miles north- northwest of Kauai. This high will dissipate in the next 24 and be replaced by a new 1037 mb high located further north and west from the current high. In response, the locally strong trades will trend down to moderate speed by Thursday. It will hold at this strength to until Friday night or Saturday where trades will get a fresh boost to locally strong as the high drops south and closer to the islands.
The slightly weaker trade winds in the coming days may favor some locally daytime sea breeze over the west end of the smaller islands, leading to some spotty afternoon showers. Otherwise, the moderate trades will continue to usher some scattered showers into the windward and mountain areas. The frequency of these trade showers will be highest during the overnight and early morning hours. Mid level ridging over the islands is strong and will persist through the week, thus maintaining ordinary trade showers.
Current satellite imagery shows the pool of moisture that moved into Kauai late yesterday afternoon continuing to exit Kauai County. We anticipate the bulk of these clouds and showers to be west of Kauai shortly after sunrise. During the evening hours, ending at 2 am HST, rain gages across the lower elevations of windward Kauai pickup an average of a quarter inch. The highest amount recored was at North Wailua with 1.35 inches.
On Oahu, the showers eased up after 10 pm HST, joining the rest of the islands with limited trade showers. Satellite imagery shows an area of potential scattered showers, however, just upwind of windward Big Island. Models suggest scattered showers for windward Big Island and Maui later this morning, continuing into this afternoon. There should be more sunshine for Kauai and Oahu today, especially over on the south and lee side of the islands.

Aviation

High pressure north of the state will keep moderate to locally breezy trade winds in place through today and tonight. A band of enhanced moisture is moving through Kauai early this morning, bringing more frequent showers along with some reduced cigs/vsbys to windward slopes and coasts. Low clouds and showers are more sparse over windward sections from Oahu eastward to the Big Island. Drier conditions should develop over windward areas of Kauai later this morning, with VFR conditions then prevailing through the remainder of the day. Elsewhere, predominantly VFR conditions should prevail during the next 24 hours.
AIRMET Sierra remains in effect for windward sections of Kauai. Conditions should improve here later this morning.
AIRMET Tango remains in effect for low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through the day.

Marine

A strong surface high pressure system centered far north- northwest of the islands will maintain locally strong trade winds across the state into the middle of this week. As a result, a Small Craft Advisory (SCA) remains in effect for the typically windier waters adjacent to the islands of Maui County and the Big Island through Wednesday afternoon. The surface high will drift slowly northwest during the next few days, so the latest forecast indicates the trade winds will weaken slightly by Thursday.
A long-period south-southwest swell continues to spread up across the area early this morning. Recent observations from the nearshore buoys along the south shores show the swell height is around 4 feet with a wave period of approximately 18 seconds. This swell will continue to build through tonight, and then will likely peak on Tuesday, followed by a slow downward trend from Tuesday night through Wednesday. As a result of the elevated surf produced by this swell, a High Surf Advisory (HSA) is in effect for the south facing shores of all Hawaiian Islands through Wednesday afternoon. The south-southwest swell will continue to gradually lower from Thursday into next weekend.
Small northwest swells are expected early this week, which will likely keep surf just above typical summertime flat conditions along most north facing shores into Wednesday. Strong easterly trades in the vicinity of, as well as upstream of, the islands will continue to produce slightly elevated choppy surf along east facing shores through this evening. As the trades weaken, expect surf along east facing shores to gradually trend downward from Tuesday through late in the week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Wednesday for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov