Hilo

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 60 to 68 near the shore to around 53 at 4000 feet. Light winds becoming west up to 10 mph after midnight. Chance of rain 40 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. South winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 61 to 68 near the shore to around 55 at 4000 feet. Light winds. Chance of rain 40 percent.

Kona

Tonight: Mostly clear. Isolated showers in the evening. Lows 66 to 72 near the shore to 45 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs 81 to 86 near the shore to around 67 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Mostly clear. Isolated showers in the evening. Lows 66 to 72 near the shore to 46 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 61 near the shore to 50 to 60 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 40 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 65 to 83. Northeast winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 62 near the shore to 52 to 60 near 3000 feet. Light winds. Chance of rain 40 percent.

Kohala

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 61 near the shore to 50 to 60 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 40 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 65 to 83. Northeast winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 62 near the shore to 52 to 60 near 3000 feet. Light winds. Chance of rain 40 percent.

South Big Island

Tonight: Mostly clear. Lows around 69 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph.

Monday: Sunny. Isolated showers in the afternoon. Highs around 80 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows around 69 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph in the evening becoming light.

Puna

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 60 to 68 near the shore to around 53 at 4000 feet. Light winds becoming west up to 10 mph after midnight. Chance of rain 40 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. South winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 61 to 68 near the shore to around 55 at 4000 feet. Light winds. Chance of rain 40 percent.

Waikoloa

Tonight: Mostly clear. Lows 63 to 72 near the shore to 46 to 53 above 4000 feet. Southeast winds up to 10 mph.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85 near the shore to 64 to 70 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows 63 to 72 near the shore to 46 to 53 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

A ridge north of the area will shift southward as a front approaches from the northwest. The front will pass north of the area today into Tuesday. An upper trough will pass over the area late Wednesday through Thursday night. High pressure will begin to build back in northwest of the area Friday and Saturday.

Discussion

A high far east northeast of Hawaii has an associated ridge extending across the western islands this morning, resulting in gentle east to east southeast winds across local waters. Overnight soundings show a very strong inversion at around 5500 feet along with PW just above an inch and positive lifted index values. Satellite loop shows lingering patchy broken low clouds across the smaller islands as well as across windward portions of the Big island. Radar shows isolated to scattered showers within cloud cover northeast of Oahu and Molokai, but very little elsewhere. Expect daytime sea breezes and nighttime land breezes to develop across many areas around the state through much of the forecast period. Total rainfall will be light.
A front will pass north of Hawaii tonight into Tuesday, keeping the ridge across the islands. The land and sea breeze pattern will likely continue into Thursday. An upper trough will move over the area late Wednesday through Thursday night. Increasing moisture, along with a less stable airmass, will increase chances for showers for most of the state. A drier and more stable airmass is expected to move in from the west later Friday and Saturday, with winds becoming more northerly.

Aviation

Periods with MVFR CIGS over windward and mauka areas will continue through the early morning hours today before improving. Elsewhere, VFR conditions are expected. Light northeast (western end of state) to easterly trades (elsewhere) will support land and sea breeze conditions for most areas.
AIRMET SIERRA for mountain obscuration due to clouds and showers remains in effect for Kauai and may be expanded to other areas later this morning.

Marine

The ongoing long-period west-northwest swell will gradually decline over the next several days, but a fresh pulse of shorter period northwest swell has been arriving and will stretch into Tuesday. Thus, the High Surf Advisory (HSA) for exposed north and west facing shores has been extended through this afternoon. The HSA may need to be extended further in time, depending on how large the latest pulse turns out to be. Surf heights will decrease slowly late Tuesday into Wednesday, but another batch of long- period west-northwest swell is expected to arrive Wednesday night, peak Thursday/Friday, then gradually subside. Peak surf heights will easily reach HSA levels with this swell, with more northwest swells expected into the long range.
Generally expecting light to locally moderate trade winds this week, with latest model guidance showing a little more agreement on the evolution of weather features near the islands. In the short term, a surface ridge north of the Big Island will move south and weaken as an approaching front stalls to the north of the area. A high passing north of the area will bring a brief period of moderate northeast winds to Kauai waters, with light to moderate east winds elsewhere as a trough develops northeast of the islands. The trough will linger for at least a couple of days as the surface high moves to a position far northeast of the area. This scenario will lead to more light to moderate northeast trade winds over Kauai and Oahu waters, and light east trade winds over Big Island and Maui County waters. The potential exists for increased shower coverage after midweek as a low aloft develops near the islands. Winds are expected to remain below Small Craft Advisory (SCA) levels through the period, however.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.

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Data Courtesy of NOAA.gov