Photo Credit: James Grenz

Hilo

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 67 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 63 to 68 near the shore to around 52 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 20 percent.

Memorial Day: Mostly sunny with isolated showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds around 10 mph. Chance of rain 20 percent.

Kona

Today: Partly sunny. Scattered showers in the afternoon. Highs 79 to 85 near the shore to around 66 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 67 to 73 near the shore to around 53 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Memorial Day: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 85 near the shore to around 67 near 5000 feet. West winds up to 15 mph. Chance of rain 20 percent.

Waimea

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 65 near the shore to 50 to 60 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Memorial Day: Breezy. Mostly sunny with isolated showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Kohala

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 65 near the shore to 50 to 60 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Memorial Day: Breezy. Mostly sunny with isolated showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

South Big Island

Today: Partly sunny. Breezy. Isolated showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows around 69 near the shore to around 52 near 5000 feet. Northeast winds 10 to 20 mph decreasing to up to 20 mph after midnight.

Memorial Day: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Puna

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 67 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 63 to 68 near the shore to around 52 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 20 percent.

Memorial Day: Mostly sunny with isolated showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds around 10 mph. Chance of rain 20 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84 near the shore to 65 to 74 above 4000 feet. Northwest winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 70 near the shore to 49 to 57 above 4000 feet. Southeast winds up to 10 mph.

Memorial Day: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to 65 to 74 above 4000 feet. Northwest winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The trade winds are gradually weakening, which will allow local afternoon sea breezes and nighttime land breezes to develop. An area of high clouds will keep skies partly to mostly cloudy into this evening. Low clouds and brief trade showers will favor east and southeast facing sections. In addition, low clouds and isolated showers may form over some leeward and interior areas this afternoon. Expect the trade winds to gradually strengthen from Memorial Day through mid-week.

Discussion

A northeast to southwest oriented surface ridge appears to be less than 220 miles northwest of Lihue. Elsewhere, a cold front is about 250 miles east-southeast of Midway Atoll. This front will be moving east-southeast at about 15 mph during the next 24 hours, which will cause the surface ridge to weaken and shift down closer to Kauai. As a result, the trade winds are gradually easing, especially over the western end of the state where the background flow may become east-southeast later today.
Loops of water vapor satellite imagery shows a weak mid-level trough west of Kauai. There is also a subtropical jet stream over the eastern half of the state. The upper-level south to southwest flow is transporting high clouds (mainly cirrus) up across most of the state. These high clouds, which are expected to persist across much of the area into tonight, are obscuring most of the low clouds in infrared satellite imagery. Radar reflectivity data indicate isolated to scattered showers are over many east and southeast facing sections of the islands this morning. There are also isolated to locally scattered showers over portions of the coastal waters, especially southeast of the Big Island, Oahu, and Kauai, south of Maui and Lanai, and north of Molokai.
There will continue to be low clouds and brief trade showers over some east and southeast areas today. By this afternoon, the weaker background winds will likely allow local sea breezes to develop over leeward and interior sections of most islands. Note that the daytime heating may be delayed and somewhat reduced anywhere the high clouds are thick enough. Once the sea breezes become fully established over leeward and interior sections, there may be an increase of low clouds and a slight chance of showers this afternoon. This will be followed by local land breezes starting this evening, which will tend to clear out any residual low clouds and showers over leeward sections overnight.
Moderate trade winds will begin to return across most of the state on Memorial Day as the surface ridge starts to shift back further north. The trade winds will continue to gradually strengthen Tuesday, with moderate to locally breezy trade winds expected through the mid-week. A mid-level ridge will also be across the area later this week, which will produce stable atmospheric conditions. There are no significant sources of low- level moisture, so expect low clouds and modest trade showers mainly over windward and mauka areas through mid-week.

Aviation

An increase in shower activity has been noted overnight, but VFR conditions continue to prevail. The high clouds over the islands have started to thin, but are still obscuring lower clouds over the islands. Based on radar and holes in the high clouds, still believe MVFR conditions to be passing in clouds and showers.
Winds are on the lighter side, and expecting some afternoon sea breezes again today. The high clouds could disrupt some of the cloud and shower development over the interior of the islands. No AIRMETs are currently in effect, but will need to monitor things mainly this afternoon to determine if any mountain obscuration develops. Winds are expected to remain on the lighter side through tomorrow, so not expecting any significant turbulence.

Marine

A cold front approaching from the northwest will continue to weaken the high pressure ridge north of the islands today. Trade winds will remain in the gentle to moderate range with wind directions veering a bit from the east-southeast direction today. Near shore winds will become sea breezes along terrain sheltered west facing shores from late morning to afternoon. High pressure will build in north of the region on Monday with slightly stronger trade winds, near Small Craft Advisory thresholds by Tuesday for windier eastern waters, and last through the end of the week.
The current south swell is starting to decline this morning with observations from Buoy 51003 showing a slight decrease in swell height and period as compared to yesterday's observations. The High Surf Advisory (HSA) for south facing shores was cancelled this morning as surf heights are expected to drop just below HSA thresholds. The next south swell will arrive on Monday and likely exceed HSA levels from Monday night into Tuesday, then slowly decline each day through the rest of the week.
A medium period northwest swell is expected to arrive today and hold into Monday. Northwest swell energy will slowly decline through the week and flatten out by Thursday. Surf along east facing shores will remain small and choppy this week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov