Hilo

Today: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 66 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 61 to 69 near the shore to around 55 at 4000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Friday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 66 to 72 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Today: Partly sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 69 near 5000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 67 to 72 near the shore to 46 to 54 near 5000 feet. Northeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 81 to 86 near the shore to around 69 near 5000 feet. North winds up to 10 mph shifting to the west around 10 mph in the afternoon. Chance of rain 20 percent.

Waimea

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 66 to 85. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 62 near the shore to 51 to 59 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 66 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 66 to 85. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 62 near the shore to 51 to 59 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 66 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Breezy. Highs around 82 near the shore to around 68 near 5000 feet. East winds up to 20 mph.

Tonight: Partly cloudy. Breezy. Lows around 70 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph.

Friday: Mostly sunny. Highs around 82 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph.

Puna

Today: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 66 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 61 to 69 near the shore to around 55 at 4000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Friday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 66 to 72 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Highs 80 to 86 near the shore to 66 to 72 above 4000 feet. Northeast winds up to 10 mph shifting to the north in the afternoon. Gusts up to 30 mph.

Tonight: Partly cloudy. Lows 64 to 73 near the shore to 46 to 53 above 4000 feet. East winds around 10 mph.

Friday: Mostly sunny. Highs 80 to 86 near the shore to 66 to 72 above 4000 feet. North winds 10 to 15 mph.

Detailed Forecast

Synopsis

Expect drier weather as trade flow persists through Saturday. Trades will shift to southerlies on Sunday as a front approaches the state. The front will move down portions of the island chain Monday and Tuesday, bringing rainfall to windward and north facing slopes.

Discussion

Trade winds will strengthen as drier conditions spread from east to west tonight. Models show a front far north of the state will dissipate as high pressure builds farther north. Our airmass will remain stable as upper ridging persists. Expect showers to diminish along windward areas of the Big Island and Maui as well as leeward areas of all islands this evening, with decreasing moisture causing Kauai to clear out near sunrise.
After tonight, expect a moderate, stable, and somewhat dry trade wind flow through Saturday. PW values will fall below seasonal normal to around and inch, and upper ridging will keep stable conditions in place. Total rainfall will be light and, aside from a few afternoon showers on the South Kona slopes, leeward areas should be dry.
Winds will shift to southerlies on Sunday, followed by a frontal passage early next week. Models show that the front and its associated rainfall will reach Kauai late Monday, then move to the central portion of the island chain Tuesday. A cutoff low developing along the front far north of the state introduces forecast uncertainties regarding where the front will stall and how strong the northerly winds behind it will be.

Aviation

This evening, low clouds and showers that developed earlier in the day across windward/southeast Big Island are beginning to diminish. Meanwhile, low clouds that developed across Kauai and Oahu have lingered a bit longer than expected as an area of diffuse moisture continues to track west across the smaller islands. However, these clouds are still expected to diminish this evening as the enhanced moisture eventually moves away from the state overnight. High pressure will build northeast of the island chain into Thursday as a frontal boundary diminishes north of Kauai. Drier easterly trade winds will return state-wide, with any cloud and shower development that does occur favoring the more typical north and east facing sections of the islands.
AIRMET Sierra for tempo mountain obscuration across windward portions of the Big Island has been cancelled this evening as conditions have improved. Meanwhile, the AIRMET Sierra for tempo mountain obscuration across Kauai and Oahu that was originally set to end by 0600z has been extended for a couple more hours based on latest surface observations. However, clouds should continue to dissipate and the AIRMET is now expected to end by 0800z. Additionally, as trade winds strengthen overnight into Thursday, low-level mechanical turbulence is expected to increase downwind of the mountains. Therefore, an AIRMET Tango for tempo moderate low-level turbulence may be needed by Thursday morning.

Marine

Trade winds have been strengthening to moderate to locally breezy as a ridge of high pressure moves farther north of the state. Thus, a Small Craft Advisory for the typically windy zones around Maui County and the Big Island is in effect through Friday afternoon. Winds are forecast to weaken and veer southeast over the weekend as a front approaches from the northwest. The front will likely move through the state early next week with moderate northwest and north winds filling in behind the feature, and becoming northeast as the front advances farther down the island chain.
Surf along north and west facing shores will remain elevated, but below advisory levels, through Saturday as a series of small northwest swells move through the coastal waters. A larger northwest swell is possible early next week, with forerunners as early as Sunday night or early Monday, that could raise surf to advisory levels along north and west facing shores through mid- week.
Surf along south facing shores will remain small, with only small background swells through the rest of the week. A small south swell is possible towards the middle of next week. East facing shores will have small, choppy surf into the weekend due to the local trades, though surf will slowly subside late in the weekend into early next week as trade winds ease.

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.

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Data Courtesy of NOAA.gov