Photo Credit: James Grenz

Hilo

Today: Isolated showers before noon. Mostly sunny, with a high near 82. Light and variable wind becoming northeast 5 to 9 mph in the morning. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after midnight. Partly cloudy, with a low around 68. North northeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers, mainly before noon. Partly sunny, with a high near 81. Calm wind becoming east northeast 5 to 7 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Mostly sunny, with a high near 81. Calm wind becoming west southwest around 6 mph. Chance of precipitation is 20%.

Tonight: Scattered showers before midnight. Mostly cloudy, with a low around 67. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers after noon. Mostly sunny, with a high near 80. Light and variable wind becoming west around 5 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers after noon. Mostly sunny, with a high near 76. Breezy, with a northeast wind 13 to 16 mph, with gusts as high as 22 mph. 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 58. Breezy, with a northeast wind 13 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers. Mostly sunny, with a high near 76. Breezy, with a northeast wind 10 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Kohala

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 70. East northeast wind 6 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 56. East northeast wind 6 to 11 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 70. East northeast wind 6 to 11 mph. Chance of precipitation is 30%.

South Big Island

Today: Isolated showers before noon. Mostly sunny, with a high near 83. Breezy, with an east northeast wind 14 to 21 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 73. Breezy, with an east northeast wind 16 to 21 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers. Mostly sunny, with a high near 83. Breezy, with an east northeast wind 16 to 20 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Puna

Today: Isolated showers. Partly sunny, with a high near 77. Northwest wind 7 to 13 mph becoming north northeast in the morning. Chance of precipitation is 20%.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. North wind 6 to 8 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers, mainly before noon. Partly sunny, with a high near 77. Northeast wind 6 to 9 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Sunny, with a high near 84. Light and variable wind becoming north northwest 5 to 7 mph in the morning.

Tonight: Mostly clear, with a low around 66. Calm wind becoming east around 6 mph after midnight.

Wednesday: Isolated showers after 1pm. Sunny, with a high near 84. East northeast wind around 8 mph becoming west northwest in the afternoon. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

A ridge of high pressure 520 miles north of Kauai this morning, will be moving south to about 220 miles north of Kauai Thursday. The ridge will remain there through Friday night before moving north. This action translate to trade winds continuing over the area to Thursday, then give way to lighter winds with a slight south component on Saturday night and Friday. Trade winds return and strengthens Friday night through Sunday.

Discussion

A 1028 mb surface high is centered 1350 miles far north- northeast of the islands this Tuesday morning. A ridge extends southwestward to about 520 miles north of Kauai. The high will linger where it is now to until Thursday before heading north and become stationary off the Oregon coast on Friday. The surface ridge will be moving south in the mean time, becoming nearly stationary 220 north of Kauai Thursday. This action will cause the trade winds to weaken and shift to the east and east- southeast on Saturday night and Friday. With this wind flow, Maui and Big Island will bringing on a mix of a background easterly flow over water and a daytime sea and nighttime land breeze over the remaining islands. The convergent sea breeze overland, especially the lee and interior areas, will result in some afternoon clouds and showers there.
Latest satellite and weather radar imageries shows a very slight uptick in trade showers. These showers are pretty much widely dispersed. The 2 am HST rain gage reports have windward Kauai being the wettest, and a small handful of 1 to 3 hundredths of an inch on Oahu’s Koolau Mountains. The GFS was showing a strengthening mid level ridge this morning that will limit these trade showers today. The 2 am HST soundings from Lihue and Hilo shows a strong low level inversion, sloping from 8k feet to 66 hundred feet over Hilo.
So, as for today, we are expecting a similar picture as yesterday, that is some spotty afternoon cloudiness over the lee areas of the smaller islands along with a shower or two. Otherwise, expect a dry day with plenty of sunshine. There will be a layer of cirrus clouds floating by, but not enough to block out the sunshine. The cirrus will create a nice sunrise and sunset.
The GFS and ECMWF are both indicating a little influx of low level moisture returning to the islands tonight, mainly after midnight, as the ridge aloft weakens from an approaching shortwave trough from the north. The amount of showers Friday afternoon due to the sea breeze and less stable air mass, could be on the scattered side. We will have a better assessment of these showers as we close in on Friday. On Friday night, the trade winds make a comeback as a new surface high moves in from the west. The surface ridge that is parked 200 miles or so north of Kauai Thursday through Saturday, is being held in place by a front located just to the north of the ridge. The front is expected to dissipate Saturday and Saturday night, allowing the ridge to head north, and the trades to spread across the region. Trade winds are expected to strengthen to locally strong by Sunday or Sunday night.

Aviation

Light to locally moderate trade wind flow will persist for the next few days. Scattered low clouds and showers will favor east and northeast facing slopes and coasts, especially in the late night and early morning hours. Isolated MVFR conditions are to be expected in passing showers, otherwise VFR conditions will prevail.
The lighter background flow will allow for nighttime land breezes and overnight clearing of most leeward slopes. In the afternoon and early evening, localized sea breezes will develop along leeward coasts and promote inland cloudiness.
No AIRMETs are currently in effect or anticipated at this time. However, model guidance suggests an area of moderate upper-level turbulence developing over the far western portion of the forecast area this coming afternoon. Will monitor for potential AIRMET Tango.

Marine

A ridge northwest of the area will produce moderate to locally fresh easterly trade winds across the coastal waters for the next few days. The winds will strengthen over the weekend and could reach Small Craft Advisory levels around Maui and the Big Island.
The current south swell will subside through tonight. Small to moderate south swells are expected through the weekend. A small southeast swell is expected starting Thursday. Small northwest swells will continue into the weekend. The weaker than normal trade winds will limit surf along east facing shores but stronger winds off the California coast will produce a small northeast swell.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov