Hilo

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to 67 to 72 at 4000 feet. North winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 64 near the shore to 44 to 53 at 4000 feet. Light winds becoming west up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs around 78 near the shore to around 69 at 4000 feet. Northwest winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 20 percent.

Kona

Today: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs around 83 near the shore to 64 to 71 near 5000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy early in the evening then becoming mostly clear. Isolated showers in the evening. Lows around 69 near the shore to 47 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83 near the shore to 65 to 72 near 5000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to around 71 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows around 64 near the shore to around 51 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs around 79 near the shore to around 72 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to around 71 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows around 64 near the shore to around 51 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs around 79 near the shore to around 72 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 81 near the shore to around 64 near 5000 feet. Northeast winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 67 near the shore to around 46 near 5000 feet. Light winds becoming north up to 10 mph after midnight.

Friday: Sunny in the morning then becoming partly sunny. Highs around 81 near the shore to around 65 near 5000 feet. Northeast winds up to 15 mph shifting to the southeast in the afternoon.

Puna

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to 67 to 72 at 4000 feet. North winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 64 near the shore to 44 to 53 at 4000 feet. Light winds becoming west up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs around 78 near the shore to around 69 at 4000 feet. Northwest winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 20 percent.

Waikoloa

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 80 near the shore to 65 to 73 above 4000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers early in the evening. Lows 64 to 69 near the shore to 46 to 53 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs 78 to 83 near the shore to 65 to 74 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A somewhat dry and stable land and sea breeze pattern will prevail through Friday. Trade winds will rebuild during the weekend as high pressure strengthens north of the state. Periods of enhanced windward rainfall will be possible as the trade winds push increased moisture over the state and a nearby upper level low produces some instability.

Discussion

The weather pattern remains benign and forecast philosophy has not changed since last evening. A surface ridge near the islands has weakened winds significantly and caused them to veer to southeasterlies across most waters. Ridging aloft maintains stable conditions, with a strong subsidence inversion and PW of less than an inch. Not surprisingly, rainfall has been scant recently.
Expect a land and sea breeze pattern through Friday. The ridge will stall just north of Kauai today and, as a front passes by farther north and dissipates on Friday, a high will move in from the northwest. Light to moderate trades will hang on across the Big Island and east Maui, but the rest of the island chain will be under light southeasterly flow through at least Friday morning. Expect a land and sea breeze regime to produce clearing at night and interior clouds and isolated showers each afternoon. A ridge aloft will maintain stable conditions, even though this feature will weaken on Friday.
Trade winds will rebuild during the weekend, and periods of increased, mainly windward, showers are possible. High pressure will pass far north of the state on Saturday, boosting trade winds and likely carrying pockets of increased moisture. An upper trough will dig southeastward just northeast of the islands Saturday, then carve out a cutoff upper low northeast of the Big Island on Sunday. This feature could enhance the pockets of rainfall moving along the trade winds and produce increased rainfall over windward areas. Trade winds will persist and showers could remain slightly active. Models show the nearby upper low weakening as broad upper troughing settles over the region, which could keep windward showers enhanced.

Aviation

A weakening surface ridge over the state will produce a light and variable wind pattern with land and sea breezes over each island. Clouds will build over island mountain and interior sections each afternoon with clouds clearing out each night. No AIRMETs in effect and none expected.

Marine

A surface ridge axis lies across the northwest and north offshore Hawaiian waters. This is the impetus to this weak regional trade wind regime. A slow eastern-advancing cold front approximately 450 nm northwest of Kauai will reach the northwest offshore waters today and slowly veer winds around to the north northeast Friday. Trades will strengthen over the weekend as high pressure passes off north of the area. Gentle to moderate early week trades will occur from a relatively tight pressure gradient created by this high as it moves further off to the northeast.
The west northwest swell that peaked yesterday will continue to slowly lower and flatten out through the day. Due to the slow decline, this swell will remain slightly elevated through Friday night. The next moderate size west northwest swell will arrive and fill in next Tuesday. This swell may push north and west facing shore surf back up to High Surf Advisory levels by Tuesday night or Wednesday. Small, mainly background south swell energy will move through the next several days. A slightly larger south swell is scheduled to arrive late Monday into Tuesday. East facing shore wind wave chop will remain small as trade wind magnitudes fall off through Friday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov