Photo Credit: James Grenz

Hilo

Today: Scattered showers. Partly sunny, with a high near 83. Calm wind becoming northeast 5 to 9 mph in the afternoon. 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 66. East northeast wind around 6 mph becoming calm. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely, mainly before noon. Partly sunny, with a high near 81. Light north northeast wind becoming northeast 5 to 10 mph 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. East wind 5 to 8 mph becoming west southwest 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 65. East wind 6 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Scattered showers, mainly after noon. Mostly sunny, with a high near 78. East wind 7 to 13 mph becoming west southwest in the morning. 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 73. Windy, with a northeast wind 20 to 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.

Tonight: Scattered showers. Mostly cloudy, with a low around 56. Breezy, with a northeast wind 18 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Scattered showers. Partly sunny, with a high near 71. Windy, with a northeast wind 21 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Showers likely. Mostly cloudy, with a high near 62. Windy, with an east wind 21 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 55. Windy, with an east wind 23 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely, mainly before noon. Mostly cloudy, with a high near 66. Windy, with an east wind 22 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers after noon. Mostly sunny, with a high near 80. Windy, with an east wind around 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly before midnight. Partly cloudy, with a low around 73. Windy, with an east northeast wind 21 to 23 mph, with gusts as high as 30 mph. Chance of precipitation is 30%.

Friday: Isolated showers. Mostly sunny, with a high near 79. Windy, with an east wind 22 to 24 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Puna

Today: Scattered showers. Partly sunny, with a high near 80. North northwest wind 7 to 14 mph becoming northeast in the morning. Winds could gust as high as 18 mph. Chance of precipitation is 50%. 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 8 to 10 mph becoming northwest after midnight. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Showers likely, mainly before noon. Partly sunny, with a high near 78. Breezy, with a north northeast wind 9 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Sunny, with a high near 82. Windy, with an east southeast wind 16 to 24 mph becoming northeast in the morning. Winds could gust as high as 34 mph.

Tonight: Mostly clear, with a low around 66. Breezy, with an east wind around 18 mph, with gusts as high as 25 mph.

Friday: Isolated showers after noon. Mostly sunny, with a high near 81. Windy, with a northeast wind 17 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Surface high pressure far north of the island chain will maintain moderate to locally breezy trade winds through this weekend. Low clouds and passing trade showers will continue to favor windward and mauka areas, while brief showers are possible over some leeward sections.

Discussion

A 1031 mb surface high is centered near 39N 150W, or slightly more than 1300 miles north-northeast of Honolulu, early this morning. A surface ridge extends southwest from this high through a point about 830 miles north of Kauai. The tight pressure gradient south of these features is maintaining moderate to locally breezy trade winds in the vicinity of the island chain.
Aloft, an upper-level low trough is evident in water vapor imagery northeast of the islands. At the same time, a weak short wave trough is moving down across the islands. The low-level trade wind flow is currently transporting scattered to broken low clouds with embedded scattered showers into windward sides of the islands based on satellite imagery and radar reflectivity data. In addition, the trades are strong enough to transport a few brief showers over to the leeward sections of some of the smaller islands.
The forecast models indicate surface high pressure will remain in place far north of the state through this weekend. As a result, expect the moderate to locally breezy trade winds to persist. The forecast models also indicate the upper-level low and trough will stall later today, and remain northeast of the islands into Sunday. By early next week, the upper-level low will likely lift out to the northeast away from the region.
The relatively close proximity of the upper low and trough to the state may provide some enhancement to low clouds and trade showers into this weekend. However, the models are showing a decrease in the low-level moisture sources upstream of the state later this week. If so, this would potentially limit the actual cloud cover and precipitation as we head into the weekend. Another short wave swinging down across the area late this weekend. This could help to enhance shower activity if there is sufficient moisture coinciding with the arrival of this feature. The current forecast depicts a typical trade wind weather pattern this weekend unless we see evidence that there will actually be increased shower activity.

Aviation

High pressure north of the state will keep moderate to breezy trades in place through tonight. Passing showers may bring brief MVFR cigs/vsbys to windward areas, primarily during the early morning and overnight hours. Otherwise VFR conditions should prevail statewide.
AIRMET Sierra remains in effect for mountain obscuration over windward sections of the Big Island. Conditions should improve later this morning.

Marine

A Small Craft Advisory remains in effect for the windier waters around Maui and the Big Island through Friday afternoon, thanks to persistent high pressure north of the main Hawaiian Islands. Surf will remain up along south facing shores as a series of overlapping small, long period swells originating from the southern hemisphere pass by. Eastern shores will experience small swell and choppy wind wave conditions due to persistent moderate to fresh trades. Surf along north facing shores will remain low as a northwest swell fades.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov