Hilo

Tonight: Cloudy with occasional showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 90 percent.

Tuesday: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs 79 to 87 near the shore to 66 to 71 at 4000 feet. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 90 percent.

Tuesday Night: Mostly cloudy with numerous showers. Lows 63 to 72 near the shore to 53 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy in the evening then clearing. Isolated showers. Lows around 74 near the shore to 49 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 89 near the shore to 65 to 70 near 5000 feet. Light winds. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy in the evening then clearing. Isolated showers. Lows around 74 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with numerous showers. Lows 64 to 73 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 64 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 63 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy with numerous showers. Lows 64 to 73 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 64 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 63 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy in the evening then clearing. Lows around 74 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph.

Tuesday: Breezy. Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy in the evening then clearing. Lows around 74 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Cloudy with occasional showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 90 percent.

Tuesday: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs 79 to 87 near the shore to 66 to 71 at 4000 feet. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 90 percent.

Tuesday Night: Mostly cloudy with numerous showers. Lows 63 to 72 near the shore to 53 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Partly cloudy. Lows around 76 near the shore to 50 to 56 above 4000 feet. East winds up to 10 mph.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs 84 to 91 near the shore to 66 to 74 above 4000 feet. East winds up to 10 mph shifting to the north in the afternoon. Gusts up to 30 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy. Lows around 74 near the shore to 50 to 56 above 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph after midnight.

Detailed Forecast

Synopsis

Persistent high pressure far north of the islands will support locally breezy trade winds this week. Passing trade showers are nearly a certainty for most windward areas as showery low cloud clusters periodically move quickly through. Some showers will occasionally spread leeward, particularly overnight.

Discussion

Afternoon visible imagery reveals mostly cloudy skies over windward and mauka zones with appreciable leeward cloud cover on most islands as well. This is likely due to the combination of a subtle increase in low-level moisture coupled with a weakening inversion. Immediately upstream there resides a shallow and stable, but fairly extensive, corridor of low level moisture. The remnants of T.S. Emilia, centered about 1300 miles ENE of the islands, immediately trail this moisture field as it shallow circulation advances westward within prevailing trades.
Satellite trends suggest the stable upstream moisture reservoir is gradually peeling apart within the trades and individual cloud clusters are encountering a slightly less stable environment over the islands. This has led to a subtle uptick in trade wind shower activity during the last 12 hours or so. This trend will continue and even amplify somewhat during the next few days as broad scale height falls settle over the islands bringing weak large scale ascent and mid-level cooling. Temperatures at 700mb, currently averaging 10-11C across the island chain, will fall by several degrees to 7C or slightly lower by late Tuesday into Tuesday night. As a proxy for the trade wind inversion, this strong indicator that stability will steadily diminish during the next 36-48 hours. As such, stable upstream cloud elements peeling toward Hawai'i will tend to grow in depth resulting in increasing coverage of showers and high confidence that showers will bring beneficial rainfall to windward and mauka zones this week. Any locally deep pockets of moisture will bring periodic light rain to leeward zones, particularly overnight. The remnants of T.S. Emilia will graze the northernmost islands of Oahu and Kauai in the Wednesday-Thursday period leading to another uptick in trade wind shower activity. PWATs will not be particularly impressive, around 1.4″, as these remnants sweep past the island chain, but this will largely be due to the shallow nature of the remnant circulation. High saturation within the lowest levels is anticipated leading to high confidence in a brief period of wetter trades for at least Kauai and Oahu late Wed-Thurs.
Locally breezy trades continue through the period, with trade winds temporarily easing toward the moderate range as Emilia's remnant trough passes north of the area during mid-week.

Aviation

Moderate to locally breezy trades will deliver low clouds and brief showers to windward areas through the forecast period. VFR conditions will prevail with isolated MVFR CIG over windward areas.
No AIRMETs are in effect.

Marine

An area of surface high pressure north-northeast of the state will remain nearly stationary over the next several days, producing moderate to locally strong trade winds across the local waters. A Small Craft Advisory has been extended through Wednesday morning for the typically windier waters around Maui County and the Big Island and will likely be extended through late this week.
A 2 foot south swell is lingering at the nearshore buoys, though surf is down some this afternoon. However, another small, long- period south swell is expected to arrive mid-day Tuesday and peak Wednesday into Thursday morning. This swell will produce another small boost in surf along south facing shores before declining through the rest of the week.
Seasonally flat to tiny surf expected through this week for north facing shores. Near shore buoys indicate swell energy out of the east over a wide part of the period spectrum. The 6-9 second energy is due to the breezy trades and will continue to bring choppy east shore surf through much of the week. Another batch of energy in the 10-11 second range could be due to recent tropical cyclone activity in the East Pacific and looks to linger for another day or so before fading.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov