Photo Credit: James Grenz

Hilo

Today: Mostly sunny with scattered showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 65 near the shore to around 50 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with scattered showers. Highs around 80 near the shore to around 71 at 4000 feet. South winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then cloudy with numerous showers in the afternoon. Highs around 83 near the shore to 63 to 70 near 5000 feet. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 72 near the shore to 50 to 56 near 5000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Partly sunny. Numerous showers and isolated thunderstorms in the afternoon. Highs around 83 near the shore to 65 to 71 near 5000 feet. Northeast winds up to 10 mph shifting to the west around 10 mph in the afternoon. Chance of rain 70 percent.

Waimea

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 79 near the shore to around 70 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with isolated showers after midnight. Lows around 67 near the shore to around 54 near 3000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 73 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 79 near the shore to around 70 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with isolated showers after midnight. Lows around 67 near the shore to around 54 near 3000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 73 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny with isolated showers in the morning, then cloudy with scattered showers in the afternoon. Highs around 81 near the shore to around 63 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 67 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Tuesday: Partly sunny. Breezy. Isolated showers in the morning, then scattered showers and isolated thunderstorms in the afternoon. Highs around 83 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Puna

Today: Mostly sunny with scattered showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs around 80 near the shore to around 68 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 65 near the shore to around 50 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with scattered showers. Highs around 80 near the shore to around 71 at 4000 feet. South winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 80 near the shore to 64 to 71 above 4000 feet. Southeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with isolated showers after midnight. Lows around 69 near the shore to 49 to 57 above 4000 feet. Light winds. Chance of rain 40 percent.

Tuesday: Partly sunny. Scattered showers and isolated thunderstorms in the afternoon. Highs around 82 near the shore to 67 to 74 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest around 10 mph in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Weak easterly background trade winds will continue into Wednesday, allowing local scale land and sea breezes to develop over each island. This hybrid wind pattern will produce clouds and brief showers along wind convergence zones over island mountain and interior sections mainly in the afternoon hours through Wednesday. Brief passing showers overnight will favor windward mountain slopes. Trade winds will slowly strengthen from Wednesday into Friday, then becoming breezy over the weekend. An upper level low will form west of the state and drift over the islands from Wednesday through Friday increasing shower trends. A stronger upper level low moves into the area by this weekend, enhancing showers statewide through Sunday.

Discussion

The satellite picture over the region shows a fading convergent band of clouds and enhanced showers just north of Kauai. Some of these showers are drifting over Kauai this morning. Otherwise a cold front located far northwest of the state will stall out before reaching the islands later today. Cirrus clouds west of the islands will drift eastward over the area today enhancing sunrise and sunset colors through Wednesday.
A weakening cold front approaching the islands from the northwest will stall before reaching Kauai today. This frontal trough will continue to weaken the high pressure ridge north of the islands into Wednesday resulting in light to moderate background east to southeast winds. Lighter large scale winds will allow local scale afternoon sea breezes to develop due to island surface heating and wind convergence. Clouds will build over island mountain and interior sections each day, these cumulus clouds will start to lose surface heating by mid afternoon and collapse into brief interior rain showers. Down slope land breezes will push these clouds and showers into the coastal waters a few hours after sunset. An upper low will produce enough instability for surface heating to trigger isolated thunderstorms on Tuesday and Wednesday afternoons over the higher elevation mountain slopes on the Big Island.
Wednesday through Friday, we transition from sea breezes back to trade winds on Wednesday as the high pressure ridge strengthens north of the state. Sea breezes will linger over terrain sheltered leeward slopes on Wednesday afternoon. More typical trade wind weather returns on Thursday and Friday with wind speeds in the moderate to locally breezy range. A weak upper level low will linger over the state increasing cloud and shower trends, mainly over windward and mountain slopes in the overnight to early morning hours.
A stronger high pressure system builds in north of the region this weekend producing breezy trade winds. An upper level low dropping into the region from the north will keep wet trade winds in the forecast on Saturday and Sunday. Island by island enhanced rainfall impacts will depend heavily on the location and strength of this upper level low relative to the islands. However, for now we will show breezy wet weather conditions in our long range weekend forecast. Stay tuned.

Aviation

VFR conditions will prevail through the 24-hr TAF period with light to moderate east-southeast trades. Clouds and showers will favor windward locations, except over sheltered leeward locations through the afternoon periods where sea breezes form.
Tempo moderate turb above FL280 is expected through tonight. There is an increasing likelihood this will be upgraded for severe turb later today into tonight as an upper trough approaches.

Marine

Light to moderate E winds will veer to the SE later today into Tuesday, and remain that way into Wednesday, as passing fronts support surface troughing NW of the islands. As the fronts and trough weaken Wednesday, high pressure building NW of the islands will bring increasing ENE trade winds that will may become quite strong by next weekend. Winds and seas are expected to remain below Small Craft Advisory (SCA) levels for most of the week, but will likely be required in the windier zones as winds increase after mid-week.
A relatively small N swell will turn toward the NE today, and continue into Wednesday. A larger, long-period NW swell will build today and tonight, peak Tuesday, then gradually diminish through Thursday as it turns toward the N. Peak surf heights with this swell will approach, but will likely remain below, High Surf Advisory (HSA) heights. Another long-period NW swell is possible by the end of the week, with peak surf heights likely large enough to warrant a HSA for exposed N and W facing shores. Another pulse of small long-period S swell is expected the next couple of days, providing some surf to S facing shores.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov