Photo Credit: James Grenz

Hilo

Today: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 68 to 73 at 4000 feet. North winds 10 to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 69 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph shifting to the west after midnight. Chance of rain 60 percent.

Tuesday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 68 to 73 at 4000 feet. Northwest winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 79 to 84 near the shore to around 68 near 5000 feet. East winds up to 10 mph shifting to the south 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 73 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 80 to 85 near the shore to around 68 near 5000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 69 near the shore to 57 to 62 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with isolated showers. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 69 near the shore to 57 to 62 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with isolated showers. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 84 near the shore to around 72 near 5000 feet. East winds up to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 66 to 71 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph.

Puna

Today: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 68 to 73 at 4000 feet. North winds 10 to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 69 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph shifting to the west after midnight. Chance of rain 60 percent.

Tuesday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 68 to 73 at 4000 feet. Northwest winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Breezy. Highs around 84 near the shore to 69 to 75 above 4000 feet. Southeast winds up to 20 mph shifting to the northeast in the afternoon.

Tonight: Partly cloudy. Breezy. Lows 68 to 73 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 20 mph.

Tuesday: Sunny in the morning then becoming partly sunny. Highs around 85 near the shore to 69 to 75 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest in the afternoon.

Detailed Forecast

Synopsis

Moderate to breezy easterly trade winds will continue into tonight, with clouds and showers favoring windward and mauka locations overnight through the morning periods. Trade winds will trend down early Tuesday through midweek, potentially enough for a localized land and sea breeze regime to become established. Expect the light winds to stick around through the weekend, which will shift the cloud and shower coverage from the typical windward areas to leeward and interior locations through the afternoon hours. Mostly dry conditions, however, should limit rainfall accumulations through most of the period.

Discussion

Guidance remains in good agreement through the start of the week and depicts the breezy trades holding into tonight before trending down early Tuesday as a weak upper low and its attendant surface reflection (weak trough) drift into the area from the east. Showers will favor windward and mauka locations through tonight as pockets of moisture move through, then transition to leeward areas through the afternoon periods Tuesday through midweek where localized sea breezes form. Rainfall accumulations are expected to remain light due to the mostly dry air/subsidence inversion in place. A band of moisture associated with the tail- end of a front will drift southward toward the state today, but should stall and diminish just north of Kauai Tuesday through Wednesday.
For the second half of the week and upcoming weekend, a progressive pattern evolving over the northern Pacific featuring a series of fronts passing to the north will keep the subtropical ridge over the region weak. This will translate to the trades completely shutting down by or come Friday, with a land and sea breeze regime prevailing statewide going into the weekend. Plenty of dry air sticking around should continue to limit rainfall chances/accumulations through Friday. Thereafter, there is a chance for increasing moisture as the tail-end of another front approaches and moves into the area by the end of the weekend. If this evolves, better interior/leeward shower coverage could materialize through the afternoon periods.

Aviation

High pressure north of the state will keep breezy trade winds in place today, before easing off slightly tonight. Low clouds and showers will favor windward and mauka areas, mainly through mid morning, with rather dry conditions expected statewide this afternoon and tonight. AIRMET Sierra remains in effect for windward sections of Kauai, Oahu and Big Island. Conditions are expected to improve here later this morning.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through the day.

Marine

High pressure far north of Hawaii has been the main driver to these recent moderate to locally strong trade winds. A Small Craft Advisory (SCA) remains in effect through this afternoon for the typically windier waters around Maui County and south of Big Island. The SCA may need a short extension in time into this evening to account for a slower wind down of local eastern island channel and bay winds. High pressure north of the islands will progressively advance east the next couple of days as a series of North Pacific storms clip the northern Central Pacific waters. These systems will weaken the pressure gradient over and upstream of the islands. This will produce weakened trades from Tuesday through the remainder of the week.
As this past weekend’s north swell fades, a moderate size, medium period north swell is arriving this morning. This swell will push today and tomorrow’s north facing shore surf heights back up to slightly over head high to double head high. This swell is not expected to produce advisory level surf and will peak Tuesday with a Tuesday night into Wednesday decline. East facing shores with northern exposures will also be affected by this latest swell energy. A series of North Pacific gale to severe gale storms will initiate a couple of new north swells that will be focused along northwest to north great circle paths aimed at Hawaii. These swells should reach the local waters late Thursday into Friday and late Saturday into Sunday. East facing shore surf will remain small and choppy through Monday. Weakening trades will lower these wind waves from Tuesday through the middle of the week. As previously mentioned, the lone exception will be along east facing shores that will be more exposed to the incoming north swell energy. South surf will be maintained by very low background south swell and short period, southeast trade wind wave energy. Surf along south facing shores will trend up by mid week with the arrival of a late season south to southwest swell Wednesday.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov