Photo Credit: James Grenz

Hilo

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 66 to 72 at 4000 feet. South winds up to 10 mph shifting to the southeast around 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 70 near the shore to around 55 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with scattered showers. Highs 79 to 84 near the shore to 65 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 68 to 73 near the shore to 47 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Mostly sunny. Isolated showers in the afternoon. Highs 66 to 84. Southeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 61 to 68 near the shore to 54 to 62 near 3000 feet. Southeast winds around 10 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs 67 to 84. East winds around 10 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny. Isolated showers in the afternoon. Highs 66 to 84. Southeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 61 to 68 near the shore to 54 to 62 near 3000 feet. Southeast winds around 10 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs 67 to 84. East winds around 10 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 83 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 71 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph.

Wednesday: Mostly sunny with isolated showers. Highs around 84 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 66 to 72 at 4000 feet. South winds up to 10 mph shifting to the southeast around 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 70 near the shore to around 55 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with scattered showers. Highs 79 to 84 near the shore to 65 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 82 to 87 near the shore to 66 to 72 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 71 near the shore to 47 to 54 above 4000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 88 near the shore to 67 to 73 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Gentle to moderate east to southeast winds will hold through Friday, with localized land and sea breezes. Modest showers will remain focused across windward slopes, though clouds and a few showers are expected over leeward areas each afternoon as sea breezes overpower the weak trade wind flow. Winds will decline further this weekend, and developing instability could lead to periods of enhanced rainfall.

Discussion

The forecast remains on track in the near term. Overnight a more southeasterly flow has been observed with low cloud and shower movement. Observations show the lighter winds that we were expected.
No change in the forecast philosophy through Friday. High pressure north of the islands is pushing southward and weakening in response to a front to the northwest of the state. A mid level ridge is helping to maintain a stable airmass, combined with below normal moisture, means limited rainfall totals. An upper level trough to the west of the islands is helping to draw some high clouds over the islands tonight. This trough is expected to weaken and move to the east through the middle of the week, which will result in some lingering high clouds.
As the high moves closer to the islands today, the trades are expected to weaken enough for a hybrid trade wind and land/sea breeze regime to take over. While showers will continue to be focused over windward slopes, overnight land breezes could develop and clear out some windward areas late at night. Leeward areas on all islands will experience clearing at night followed by afternoon clouds and a few light showers each afternoon. Rainfall totals are expected to remain on the light side.
Unsettled weather may occur this weekend. The GFS and ECMWF are showing a deep trough developing west of the islands late Friday and Saturday and possibly moving overhead on Sunday. The latest model runs show the ECMWF backing off a little, but it still remains the more aggressive solution. Uncertainty remains high this far out, but unsettled weather could develop on Saturday night or Sunday as winds become light and variable. An increase in shower activity is likely, but many details still need to be flushed out. Areas of thick high clouds could also form as early as late Friday.

Aviation

The low-level trade wind flow will continue to gradually weaken today and tonight. The weaker background winds will likely allow local afternoon sea breeze and nighttime land breeze circulations to develop over each of the individual islands through mid-week. The atmosphere remains stable and relatively dry in the vicinity of the state. Some low clouds and brief trade showers will continue to move into the east and northeast facing sections of the islands this morning. There is a possibility of brief MVFR conditions developing over some windward sections, but VFR conditions will likely prevail over most areas into this evening. In addition to the low clouds, thin cirrus clouds will likely be traveling rapidly from east to west across the state today.
The forecast guidance shows strong westerly flow in the upper levels over the state, as well as a significant potential for turbulence aloft. Therefore, AIRMET Tango remains in effect for TEMPO moderate clear air turbulence between FL300 and FL450. Based on the latest guidance, this AIRMET will likely be needed through this morning. However, these conditions may eventually improve later today or tonight.
Looking ahead to late tonight and early Wednesday morning, the forecast models appear to bring an area of increased moisture toward the eastern Big Island from the east-southeast. The arrival of this moisture may cause increasing coverage of low clouds and showers over portions of the southeastern and eastern Big Island by late tonight, or early Wednesday morning.

Marine

Moderate easterly trades will continue to ease and shift out of the east-southeast as a weakness in the ridge forms in response to a passing front to the north today through Wednesday. Although the winds will ease enough for a land and sea breeze regime to become established near the coasts beginning today, guidance hangs on to moderate to locally fresh east to southeast breezes across the eastern half of the state through the second half of the week. For the upcoming weekend, guidance continues to advertise an upper trough digging southeastward into the region influencing the local weather pattern. If this materializes, unsettled weather will become a possibility. Additional fine tuning of the winds and weather through this time should be expected over the coming days as confidence rises.
Surf along south facing shores will trend up today through midweek as a late season south swell arrives. Overnight observations at the offshore and nearshore buoys have been reflecting this energy within the 18 through 22 second bands. Expect a peak later today through Wednesday followed by a gradual downward trend Thursday as the swell moves out.
Surf along north facing shores will remain small through midweek with mainly a combo of short- to medium-period north/northwest swell moving through. Observations at the nearshore PacIOOS buoys are showing the new northwest swell, which should continue to fill in this morning. An upward trend is expected by Friday for exposed north and west facing shores of the smaller islands as a new, north-northwest swell arrives. Guidance depicts a peak late Friday into Saturday, then lowering by Sunday.
Surf along east facing shores will remain small through the week due to a combo of light winds and limited fetch upstream.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov