Hilo

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 78 to 83 near the shore to 62 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Wednesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 72 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly clear with isolated showers. Lows around 72 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Breezy. Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 54 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 30 percent.

Wednesday: Partly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 67 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Breezy. Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 54 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 30 percent.

Wednesday: Partly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 67 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows around 72 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph.

Wednesday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 78 to 83 near the shore to 62 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Wednesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 72 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 82 to 90 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows around 72 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 20 mph.

Wednesday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 81 to 88 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally strong trades will remain wetter than normal through tonight, particularly for the windward slopes of Maui County and Oahu. Trades and shower coverage then trend downward during the latter half of the week.

Discussion

Locally strong trades around the southern periphery of surface high pressure is directing a remnant band of frontal moisture over the central portions of the state this morning. Local radar imagery reveals frequent showers traversing windward and mauka slopes of Maui County and Oahu with lighter showers frequently drifting leeward, especially over Oahu. The primary adjustment to the forecast for today was to adjust pops and sky cover upward in these areas for the remainder of the morning. Decreased shower coverage is noted over Windward Kauai along the northern fringe of this band. The same can be said for the Big Island where the land breeze has cleared downslope areas of clouds and showers for the time being. The morning soundings out of Hilo and Lihue confirm the arrival of the well- advertised band of mid-level dry air around centered around 700mb. The presence of this drier air aloft will ensure continued stability and will limit rainfall amounts away from the most favored locales even as shower coverage remains high. The diurnal heating will bring some improvement by this afternoon, causing showers to trend downward until this evening. Showers then increase in coverage over roughly the same areas again tonight.
The mid-week period will be characterized by slight weakening of trades as the expansive high that has dominated the circulation over the north central Pacific begins to lose its grip over the area. Some degree of upper-level troughing will be a fixture during the coming week as the jet nestled within its southern flank directs a steady dose of cirrus from the lower latitudes and into area skies. As has been the case during the last couple of days, cirrus will be mostly transparent but even batches of partially opaque high cloud will be sufficient to take the edge off of daytime heat. Locally breezy trades will deliver periods of trade wind showers to windward zones for the remainder of the week, but continued stability will help limit rainfall amounts.

Aviation

Strong easterly trade winds will prevail into tonight, with clouds and showers favoring windward and mountain locations. Periods with MVFR CIGS/VSBYs are expected in and around passing showers through the early morning hours.
AIRMET Sierra remains in effect for mountain obscuration over windward areas of Maui County and Oahu. Conditions may improve through the late morning hours.
AIRMET Tango remains in effect for low-level mechanical turbulence leeward of mountains due to strong trades.

Marine

A strong surface high will remain centered far N of the islands through Friday, then build eastward next weekend. Except for a brief period of somewhat lighter trade winds around midweek, when the pressure gradient over the area may ease a little, fresh to strong trade winds will prevail for the foreseeable future. As a result, a Small Craft Advisory (SCA) for the windier zones around Maui and the Big Island has been extended into Friday. All other waters have been removed from the SCA except the Kaiwi Channel.
No significant swells are expected over the next several days. The strong trades will support rough and choppy surf along E facing shores for the next day or so, with surf and seas easing somewhat Wednesday and Thursday as the upstream fetch diminishes. Minimal swell energy from the S and SE is expected for most of this week, but a long-lived run of near- to above- average surf along S facing shores is expected to begin late next weekend, as a strong low pressure passing SE of New Zealand sends long-period swells our direction. A small, long-period swell from the E may arrive early next week, generated by east Pacific Hurricane Bonnie.

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.
Small Craft Advisory until 6 AM HST Wednesday for Kaiwi Channel.

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Data Courtesy of NOAA.gov