Photo Credit: James Grenz

Hilo

Today: Partly sunny in the morning then becoming mostly sunny. A 20 percent chance of showers. Highs 77 to 82 near the shore to 66 to 71 at 4000 feet. East winds 10 to 15 mph.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. A 50 percent chance of showers. Lows 60 to 67 near the shore to 51 to 56 at 4000 feet. East winds 10 to 15 mph.

Friday: Partly sunny with chance of showers in the morning, then mostly sunny with slight chance of showers in the afternoon. Highs 76 to 82 near the shore to 65 to 71 at 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with a 20 percent chance of showers in the afternoon. Highs 80 to 85 near the shore to around 68 near 5000 feet. East winds around 10 mph shifting to the northwest in the afternoon.

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then mostly clear after midnight. Lows 66 to 71 near the shore to 44 to 53 near 5000 feet. North winds around 10 mph shifting to the east after midnight.

Friday: Sunny in the morning, then mostly cloudy with a 20 percent chance of showers in the afternoon. Highs 80 to 85 near the shore to around 68 near 5000 feet. East winds around 10 mph shifting to the northwest in the afternoon.

Waimea

Today: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 65 to 84. East winds 10 to 20 mph.

Tonight: Partly cloudy with a 20 percent chance of showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds 10 to 15 mph.

Friday: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 65 to 84. East winds 10 to 20 mph.

Kohala

Today: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 65 to 84. East winds 10 to 20 mph.

Tonight: Partly cloudy with a 20 percent chance of showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds 10 to 15 mph.

Friday: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 65 to 84. East winds 10 to 20 mph.

South Big Island

Today: Sunny in the morning then becoming mostly cloudy. Breezy. Highs around 81 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph.

Tonight: Mostly cloudy in the evening then clearing. Breezy. Lows around 68 near the shore to around 48 near 5000 feet. East winds 10 to 20 mph.

Friday: Sunny and breezy. Highs around 80 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph.

Puna

Today: Partly sunny in the morning then becoming mostly sunny. A 20 percent chance of showers. Highs 77 to 82 near the shore to 66 to 71 at 4000 feet. East winds 10 to 15 mph.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. A 50 percent chance of showers. Lows 60 to 67 near the shore to 51 to 56 at 4000 feet. East winds 10 to 15 mph.

Friday: Partly sunny with chance of showers in the morning, then mostly sunny with slight chance of showers in the afternoon. Highs 76 to 82 near the shore to 65 to 71 at 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Highs 79 to 85 near the shore to 64 to 71 above 4000 feet. East winds 10 to 15 mph shifting to the north in the afternoon.

Tonight: Mostly clear. Lows 63 to 71 near the shore to 44 to 52 above 4000 feet. North winds 10 to 15 mph shifting to the east after midnight.

Friday: Sunny. Highs 78 to 85 near the shore to 65 to 71 above 4000 feet. East winds 10 to 15 mph shifting to the north in the afternoon.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail into the weekend, then weaken Sunday into next week. A mostly dry weather pattern is expected, with passing low clouds bringing a few brief windward showers.

Discussion

Locally breezy trade winds will hold for the next couple days, while the mostly dry pattern is expected to persist well into next week. A surface ridge will meander about 300-500 miles north of the islands through Saturday, maintaining moderate to breezy trade winds. With below-normal PWAT expected to be <1″, and a strong ridge aloft supporting a low and strong subsidence inversion, any windward showers will be limited in coverage and intensity. Leeward areas will remain dry, except for a chance of a shower over leeward Big Island slopes. Most rain gages across the chain have remained dry over the past 24 hours. Note that our radars are in Volume Coverage Pattern 32, with the associated increased sensitivity meaning that not all of the detected echoes are resulting in precipitation that is reaching the ground.
Trade wind speeds will diminish Sunday, and will likely remain suppressed early next week as a passing front weakens the surface ridge. The front is expected to stall and dissipate N of the state Monday and Tuesday as an upper-level short wave trough erodes the ridge by mid-week. Moisture associated with the stalled front could fuel an increase in showers byu mid-week, with the highest rain chances expected to be over Kauai.

Aviation

Moderate to breezy easterly trades continue across the state into Friday, as a surface ridge remains anchored north of the islands. The relatively dry airmass will limit areal coverage of clouds and showers through the TAF period, while easterly trades focus any showers toward windward zones. VFR conditions are expected to continue at most TAF sites, however a few windward showers may briefly generate MVFR cigs.
Satellite based turbulence probabilities and upper lvl bulk shear trends, continue to suggest that the areal coverage and intensity of the upper lvl turb, which was evident over the eastern half of the state earlier this morning, continues to weaken and drift east/southeast away from the region.
However, AIRMET Tango will remain in effect for turbulence downwind of higher terrain below 7K ft across much of the state, as locally breezy trades continue.

Marine

High pressure located far northeast of the islands will produce a tight enough pressure gradient back across the state to maintain primarily fresh to locally strong trade winds for the remainder of the week. A Small Craft Advisory (SCA) is in effect for the typical windier waters around Maui County and Big Island. The Small Craft Advisory (SCA) has been expanded further west beginning tonight to account for increased combined seas in response to the passage of a large west northwest swell.
A very large fetch area of Northwest Pacific gale to severe gale force winds blowing parallel to the island's northwest great circle paths is pushing a significant size west northwest swell toward the state. Long period forerunners of this swell are reaching the northwest buoys this morning. This times the swell to arrive in Kauai during the early afternoon hours…Oahu and Maui during the mid to late afternoon. This swell will lift surf to High Surf Warning thresholds along north and west facing shores of those islands within the HSA from as early as tonight through Saturday afternoon. The anticipated swell, both from data within the fetch generation area and early signs of high period energy reaching the buoys this morning, maintains an ongoing forecast that reflects higher- than- model predicted values for both swell and resultant surf. There is a moderate probability that overwash will impact typically vulnerable low-lying coastal roadways. The best chance of overwash will occur around peak high tide times around midnight both tonight and Friday night. The only other mentionable surf will be along east facing shorelines as strengthened trades will bump up the small period, wind wave chop.

HFO Watches/Warnings/Advisories

High Surf Warning from 6 PM this evening to 6 PM HST Saturday for North and West facing shores of Niihau Kauai Oahu and Molokai and for North facing shores of Maui and for West facing shores of the Big Island.
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory from 6 PM this evening to 6 PM HST Saturday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov