Hilo

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 69 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy with showers likely. Lows 66 to 73 near the shore to around 55 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 70 to 75 near the shore to around 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 75 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 55 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 74 to 81 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Kohala

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 75 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 55 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 74 to 81 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to around 74 near 5000 feet. East winds up to 25 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 71 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 74 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 69 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy with showers likely. Lows 66 to 73 near the shore to around 55 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Highs 84 to 89 near the shore to 70 to 77 above 4000 feet. Northeast winds up to 15 mph.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to 53 to 61 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Sunny in the morning then becoming partly sunny. Highs 83 to 89 near the shore to 70 to 77 above 4000 feet. East winds up to 10 mph in the morning becoming light.

Detailed Forecast

Synopsis

The high pressure ridge strengthening north of the state will maintain a typical trade wind weather pattern into Thursday, with clouds and limited showers favoring windward and mauka areas. Winds will weaken by early Friday before trending southeast on Saturday, as an area of low pressure passes well west of the state. Trade winds will redevelop Sunday and Monday as the ridge restrengthens north of the state.

Discussion

Radar trends this morning show scattered to isolated showers drifting across the islands, focused mainly along windward areas in strengthening trade wind flow. The band of enhanced moisture that has been drifting across the region since Sunday, continues to exit westward of the state. The latest satellite trends continue to show a much drier airmass streaming into the region from the east (PW values falling below 1.35 inches). Both satellite and model data support even drier air moving into the region today through Wednesday.
The surface ridge becoming reestablished north of the state will maintain moderate trade wind flow across the islands to begin the work week. Shallow layered moisture will limit the areal coverage of showers to mainly windward locations into Thursday, with the greatest areal coverage of showers expected during overnight and early morning hours. Leeward areas are expected to remain mainly dry through the period, however increasing trades could potentially push brief showers leeward.
Thursday night through Saturday, another area of low pressure organizing well northwest of the state on Thursday, will quickly drop southward while maintaining a track over 800 miles west of Kauai. This pattern will weaken winds and promote a more southeast wind direction Friday night and Saturday. The weaker background winds Thursday into Friday, will help support sea breeze clouds and showers across leeward areas, while southeast trades organize showers across the windward zones. Recent model runs have trended toward an increase of mid level moisture across the islands Friday into the weekend, as the surface low drops southward. The increased moisture could potentially enhance shower activity by the end of the week, especially over southeast facing slopes as well as where low level winds are able to converge along terrain features.
Sunday and Monday, the high pressure ridge will rebuild north of the state as the area of low pressure exits southwest of Kauai. This pattern will support the return of more typical trade wind weather, as drier easterly trades redirect showers to favored windward mauka areas.

Aviation

With high pressure strengthening north of the islands, trade winds will become moderate to breezy as the day progresses. Any showers, with accompanying MVFR conditions, will mainly affect windward and mauka sections statewide. VFR will prevail overall, however.
No AIRMETs are in effect.

Marine

Upper ridging will take hold the next couple of days and provide stable conditions over the state though mid week. Surface high pressure centered over the Gulf of Alaska will produce a tight enough pressure gradient down across the islands to maintain moderate to fresh trades, locally strong, the next couple of days. A Small Craft Advisory is in effect within the notoriously windier bays and channels around Maui County and Big Island, as well as south of Big Island, through Tuesday afternoon. As the driving high weakens Wednesday, mid to late week winds will fall back to more gentle and moderate speeds. A developing trough of low pressure northwest of the islands may veer winds more south late in the week.
Small, short period south and southeast swells will continue to decline into Tuesday. A reinforcing small, long period south swell arrives late Tuesday and will pass around the islands through the end of the week. A moderate size, slightly longer period northwest swell arrives late today and fills in through Tuesday. Strengthened trade winds support more elevated wind wave, choppy surf along east-facing shores the next couple of days.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov