Hilo

Tonight: Cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 69 near the shore to 49 to 57 at 4000 feet. Northeast winds up to 10 mph shifting to the northwest after midnight. Chance of rain 70 percent.

Thursday: Mostly cloudy with scattered showers. Highs 78 to 83 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 69 near the shore to 49 to 56 at 4000 feet. North winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 72 near the shore to 46 to 52 near 5000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly cloudy with scattered showers. Haze. Highs 83 to 88 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Haze through the night. Lows around 72 near the shore to 45 to 51 near 5000 feet. East winds up to 10 mph shifting to the north after midnight. Chance of rain 40 percent.

Waimea

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 62 to 71 near the shore to 53 to 61 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Thursday: Mostly cloudy. Breezy. Isolated showers in the afternoon. Highs around 80 near the shore to 71 to 79 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 62 to 71 near the shore to 53 to 61 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Thursday: Mostly cloudy. Breezy. Isolated showers in the afternoon. Highs around 80 near the shore to 71 to 79 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Haze through the night. Lows around 73 near the shore to around 50 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Thursday: Mostly cloudy. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 86 near the shore to around 65 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Breezy and haze. Lows around 72 near the shore to around 49 near 5000 feet. East winds 10 to 20 mph.

Puna

Tonight: Cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 69 near the shore to 49 to 57 at 4000 feet. Northeast winds up to 10 mph shifting to the northwest after midnight. Chance of rain 70 percent.

Thursday: Mostly cloudy with scattered showers. Highs 78 to 83 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 69 near the shore to 49 to 56 at 4000 feet. North winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Haze after midnight. Lows 70 to 75 near the shore to 49 to 54 above 4000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Thursday: Mostly cloudy. Breezy. Haze through the day. Scattered showers in the afternoon. Highs 82 to 90 near the shore to 64 to 73 above 4000 feet. Northeast winds up to 20 mph shifting to the north in the afternoon. Chance of rain 50 percent.

Thursday Night: Mostly cloudy in the evening then becoming mostly clear. Haze in the evening. Lows 70 to 75 near the shore to 48 to 53 above 4000 feet. Northeast winds up to 10 mph.

Detailed Forecast

Synopsis

Moderate to breezy trades will continue to focus showers over windward and mauka areas through next week. A developing low aloft could increase trade wind showers this weekend into early next week.

Discussion

Current radar and satellite imagery show isolated to scattered showers moving into windward areas on the breezy trades this afternoon, along with some high clouds streaming over the area from the west. These high clouds are associated with the subtropical jet to our south and are expected to stream across portions of the island chain through tomorrow before gradually clearing out this weekend as the subtropical jet shifts eastward.
High pressure currently centered about 1500 miles northeast of the state will gradually sag a bit south this weekend as a series of lows traverse across the northern Pacific. The movement of this feature will have little affect on the local weather as moderate to breezy trade winds are expected to persist across the area. However, one of those northern Pacific lows will drag a front that will stall well to the northwest of Kauai and turn into a trough early next week. Model guidance suggests that the interaction of this distant front/trough with the surface high to our northeast will weaken the local pressure gradient and reduce trade wind speeds slightly on Sunday into early next week.
Pockets of moisture caught up in the trades will bring periodic clouds and showers into windward and mauka areas throughout the forecast period. As a developing lower latitude upper level trough/low develops and moves over the state tomorrow into early next week, it will lower temperatures aloft slightly and increase the temperature inversion heights. While the overall instability isn't expected to be impressive, the raised inversions will likely allow for some enhancement of trade wind showers over the weekend and into early next week as those pockets of moisture roll through.

Aviation

Moderate to breezy trade winds continue to prevail across the island chain through at least Thursday afternoon, steered by high pressure centered far northeast of the main Hawaiian Islands. Showers and occasional low clouds embedded within the trades will favor north through east sections of the islands throughout this period, especially during the overnight to early morning hours. While VFR flight conditions will prevail at most locations, periods of MVFR conditions will be possible within any showers that occur.
AIRMET Tango remains in effect for moderate low-level turbulence downwind of island terrain. This AIRMET will likely be needed through at least Thursday. Additionally, mountain obscuration could become an issue across windward sides of the islands again later this evening and tonight.

Marine

A strong high will remain far northeast of the state through the week and continue to bring fresh to locally strong trade winds to all local waters. A Small Craft Advisory (SCA) for the windier waters around Maui County and the Big Island remains in effect through Thursday. Winds may ease slightly and veer toward the east-southeast over the weekend due to a weak front far northwest of the state.
The current moderate period south-southwest swell will continue to decline through tonight. Expect mainly background energy along south-facing shores on Thursday. A tiny long-period south- southwest swell is possible this weekend. Otherwise, expect mainly background energy through the middle of next week.
Surf along east-facing shores will remain rough and choppy the next several days due to the fresh to locally strong trades. Surf along north-facing shores will remain small with some background northwest energy moving through throughout the week and into the weekend.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov