Photo Credit: James Grenz

Hilo

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 69 near the shore to around 53 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kona

Today: Sunny in the morning then becoming partly sunny. Isolated showers. Highs around 82 near the shore to around 66 near 5000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70 near the shore to around 53 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Thursday: Sunny in the morning then becoming partly sunny. Isolated showers. Highs around 82 near the shore to around 66 near 5000 feet. Northeast winds up to 10 mph in the morning becoming light. Chance of rain 20 percent.

Waimea

Today: Partly sunny in the morning then becoming mostly sunny. Windy. Scattered showers. Highs around 78 near the shore to 64 to 75 near 3000 feet. East winds up to 25 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 40 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows 61 to 67 near the shore to 54 to 63 near 3000 feet. East winds 10 to 30 mph decreasing to up to 25 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 78 near the shore to 64 to 75 near 3000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

Kohala

Today: Partly sunny in the morning then becoming mostly sunny. Windy. Scattered showers. Highs around 78 near the shore to 64 to 75 near 3000 feet. East winds up to 25 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 40 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows 61 to 67 near the shore to 54 to 63 near 3000 feet. East winds 10 to 30 mph decreasing to up to 25 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 78 near the shore to 64 to 75 near 3000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

South Big Island

Today: Mostly sunny. Breezy. Highs around 82 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph.

Tonight: Partly cloudy. Windy. Lows around 70 near the shore to around 51 near 5000 feet. East winds 10 to 30 mph.

Thursday: Mostly sunny. Breezy. Highs around 82 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph.

Puna

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 69 near the shore to around 53 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny and breezy. Highs 78 to 85 near the shore to 65 to 71 above 4000 feet. North winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 71 near the shore to 49 to 58 above 4000 feet. Southeast winds up to 20 mph decreasing to up to 10 mph after midnight.

Thursday: Sunny and breezy. Highs 78 to 86 near the shore to 65 to 71 above 4000 feet. North winds up to 25 mph.

Detailed Forecast

Synopsis

Stable and relatively dry atmospheric conditions persist across the Hawaiian Islands. Breezy trades will continue to transport some low clouds and brief, isolated showers mainly over windward and mauka sections this week. The winds are forecast to weaken and shift out of the southeast later this weekend. This may allow a weather pattern with local afternoon sea breezes and nighttime land breezes to develop from Sunday into early next week.

Discussion

A 1032 mb surface high is centered near 36N 139W, or more than 1400 miles northeast of Hilo. The tight pressure gradient southwest of this feature is maintaining breezy trade winds across the Aloha State early this morning. Aloft, a mid-level ridge is keeping the atmosphere relatively stable over the region. In addition, the lowest levels of the atmosphere have near. to slightly below normal moisture values. The latest satellite imagery and radar reflectivity data show a narrow band of low clouds and showers along some windward areas. This band will continue moving westward, with drier conditions likely developing once it passes west of the islands later this morning. Conditions appear to be generally dry over most leeward areas of the state,
The forecast guidance shows the surface high northeast of the state will continue to maintain locally breezy trade winds through late Friday. The mid-level ridge is also expected to remain established over the area, along with near, to slightly below normal low-level moisture. Therefore, the forecast looks relatively unchanged from later today and tonight into the start of the weekend. Windward and mauka areas will continue to have some low clouds and brief, isolated showers. The upslope sections of the leeward Big Island will have clouds and a chance of showers each afternoon and evening, while most leeward areas on the smaller islands will be mostly clear and dry.
By Saturday, the forecast guidance continues to show a weak cold front moving down toward the islands from the north-northwest, while the surface high that is now far northeast of here moves south and weakens. This will cause the trade winds to ease and shift out of the east-southeast or southeast from late Saturday through Sunday. This lighter wind regime will likely persist into early next week once it becomes established. As a result, an alternating local afternoon sea breeze / nighttime land breeze weather pattern is expected to develop. This weaker wind regime will result in noticeably warmer afternoon temperatures. At the same time, the mid-level ridge in the vicinity of the islands will likely flatten as a mid-level trough propagates toward the area from the west-northwest. This will cause the atmosphere to become somewhat less stable. However, low- and mid-level moisture is not expected to increase substantially. Therefore, cloud cover and only isolated showers are expected to develop over leeward and interior sections of the islands during the afternoon hours due to the sea breezes. Expect clearing skies over most areas each night as the land breezes become established.

Aviation

High pressure far northeast of the state is expected to track slowly southward over the next few days. This will serve to keep increasingly breezy, mostly dry, trade wind conditions in place through the remainder of the work week. Occasional bands of weak showers off the Pacific will impact mainly east and northeast facing slopes and coasts. A well defined trade wind inversion around 06 kft will inhibit most local shower development. Brief MVFR CIG or VIS are to be expected in passing showers; otherwise VFR conditions will prevail all areas.
AIRMET Tango for moderate low level mechanical turbulence to the lee of higher terrain remains in effect. Conditions are expected to persist for the next several days.

Marine

Surface high pressure far northeast of the area will continue to produce moderate to locally strong trade winds over the next several days. A Small Craft Advisory (SCA) is in effect for the typically windy waters around Maui County and the Big Island, as well as the Windward and Leeward Maui County waters and the Kaiwi Channel through tonight. Starting Thursday morning, the SCA has been scaled back to only include the typical windy waters around Maui County and the Big Island through Thursday night. This SCA will likely need to be extended through Friday. Trades are expected to weaken slightly over the weekend as the high weakens.
Choppy surf will dominate east facing shores this week with seasonally normal heights, followed by a slight downward trend over the weekend as trade winds weaken. A couple of small medium period northwest swells will move through the island chain today through the rest of the week, keeping below seasonally normal heights along north and west facing shores. Surf along south facing shores will remain small today and into tomorrow. A couple of small, long-period south swells may give south facing shores a small boost late Thursday and into the weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST Thursday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

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Data Courtesy of NOAA.gov