Photo Credit: James Grenz

Hilo

Today: Cloudy with showers likely. Highs around 81 near the shore to around 65 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows around 66 near the shore to around 52 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 80 percent.

Wednesday: Mostly cloudy with occasional showers. Highs around 80 near the shore to around 66 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Kona

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to around 52 near 5000 feet. Northwest winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Mostly cloudy with scattered showers. Highs around 84 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Mostly cloudy with scattered showers. Highs around 80 near the shore to 69 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows around 65 near the shore to 50 to 59 near 3000 feet. East winds up to 10 mph. Chance of rain 80 percent.

Wednesday: Breezy. Mostly cloudy with occasional showers. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

Kohala

Today: Mostly cloudy with scattered showers. Highs around 80 near the shore to 69 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows around 65 near the shore to 50 to 59 near 3000 feet. East winds up to 10 mph. Chance of rain 80 percent.

Wednesday: Breezy. Mostly cloudy with occasional showers. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

South Big Island

Today: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly cloudy with scattered showers. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Puna

Today: Cloudy with showers likely. Highs around 81 near the shore to around 65 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows around 66 near the shore to around 52 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 80 percent.

Wednesday: Mostly cloudy with occasional showers. Highs around 80 near the shore to around 66 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Waikoloa

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 64 to 71 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 72 near the shore to 47 to 55 above 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 84 near the shore to 65 to 72 above 4000 feet. North winds up to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate trade winds will hold in place today through early Wednesday as a front approaches from the northwest. More showers can be expected today through Wednesday as an upper level disturbance moves overhead, with a drying trend expected Thursday through the weekend. Trades will pick up again late Wednesday through Friday, before easing slightly over the weekend. Abundant high cloud cover is expected through tonight, with a decreasing trend expected from west to east across the state on Wednesday.

Discussion

Currently at the surface, a 1028 mb high is centered around 2200 miles northeast of Honolulu, while a cold front is positioned 800 miles northwest of Kauai. The gradient has continued to relax overnight, with moderate trades now present across the island chain. Infrared satellite imagery shows abundant high cloud cover resulting in mostly cloudy to overcast conditions across the state. Radar imagery shows scattered showers moving into windward areas, with a few of these showers spilling over into leeward communities. Main short term focus revolves around trade wind trends and rain chances during the next few days.
High pressure northeast of the state will lift further northeast during the next couple days as a cold front steadily approaches from the northwest. This will allow the trades to ease further this morning, with moderate trades then prevailing this afternoon through early Wednesday. The trades will ramp back up Wednesday, and become breezy to locally windy Wednesday night through early Friday as the front stalls out a couple hundred miles north of Kauai, and a new strengthening high builds east-northeast between 35N and 40N reaching 1040 mb near 40N143W by 18Z Friday. More forecast uncertainty develops later Friday through early next week, as the wind forecast will be highly dependent on how much the low level flow tips to the east-southeast in advance of a new cold front approaching from the northwest. Overall, we should see an easing of the trades into the moderate to locally breezy range during this time. The strongest trades appear to remain near the Big Island, while some sheltering effects could allow for land and sea breezes over leeward sections of the smaller islands.
As for the remaining weather details, shortwave energy will continue to lift northeast into the central islands this morning, then gradually shift eastward this afternoon through early Wednesday, before exiting to the east of the state Wednesday afternoon. This in combination with some entrance and exit region forcing from a pair of upper level jets to the north and south of the state respectively, along with precipitable water values climbing into the 1.5 to 1.7 inch range, should keep scattered to numerous showers moving into windward areas, while also allowing a few more showers to reach leeward areas. Considerable high cloud cover will prevail through tonight, with decreasing high clouds expected Wednesday as the upper level forcing for ascent slides east of the state. We should see a transition back to more typical trade wind weather Wednesday and Wednesday night, although it may be a bit more showery over the eastern islands than over the western end of the state.
As with the wind forecast, uncertainty continues in the extended range Friday through early next week. The GFS and ECMWF have come into better agreement, supporting the maintenance of a forecast featuring normal trade wind weather at this time.

Aviation

Early this morning, trade wind speeds have decreased as surface high pressure far northeast of the state lifts further northeast and a cold front approaches from the northwest. As a result, AIRMET Tango for low-level turbulence has been cancelled. Moderate trades are expected statewide today through early Wednesday before increasing once again by mid-week. Meanwhile, thick cirrus clouds continue to stream across the state from the southwest this morning. Tempo light icing will remain possible statewide between 14,000 and 26,000 feet today with high clouds prevailing throughout the day. Lower clouds and showers will favor windward locations, especially across the eastern islands where models and satellite data suggest the greatest available moisture is located. Overall, VFR conditions are forecast to prevail, but periodic MVFR ceilings and visibilities will be possible over windward locations.
AIRMET Tango remains in effect for moderate upper-level turbulence as an upper jet lifts over the state, though the threat for upper-level turbulence will diminish by mid- to late morning. Additionally, AIRMET Sierra for tempo mountain obscuration remains in effect for north through east sections of the Big Island. Model data suggests some improvement is possible today before low clouds return again later this afternoon and evening.

Marine

The high pressure system to the northeast of the islands has continued to move to the east and slowly weaken, which as expected has resulted in a downward trend to the trades over the region. Winds have fallen below Small Craft Advisory (SCA) levels, so the SCA has been cancelled. Trades are expected to continue to weaken a bit through Wednesday, before a new high passes north of the region Wednesday night through Friday. This new high will allow trade winds to build back to breezy to locally windy levels which will more than likely require another SCA for the typical windier waters near Maui County and the Big Island for the end of the week and into the weekend.
The current small northwest swell will continue to lower today, and then another small northwest swell is expected Wednesday through Friday, with a third small northwest pulse possible around Sunday. Small, mainly background south swells are expected through Friday with a slightly larger south swell expected to arrive over the weekend.
Along east facing shores, the short period choppy surf will continue to gradually decrease through Wednesday as the trades weaken. As the trades once again increase during the second half of the week, expect an uptick in surf heights, which will persist into the weekend.

HFO Watches/Warnings/Advisories

None.

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov