Hilo

Tonight: Mostly cloudy. Occasional showers until early morning, then scattered showers late in the night. Lows 64 to 70 near the shore to 49 to 55 at 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 78 to 83 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Partly cloudy with scattered showers. Lows 64 to 70 near the shore to 49 to 55 at 4000 feet. Northeast winds up to 15 mph shifting to the north after midnight. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows around 72 near the shore to 46 to 52 near 5000 feet. Northwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Haze in the morning. Partly sunny with isolated showers in the morning, then cloudy with numerous showers in the afternoon. Highs 82 to 88 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 72 near the shore to 45 to 52 near 5000 feet. North winds up to 10 mph shifting to the northeast after midnight. Chance of rain 50 percent.

Waimea

Tonight: Breezy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 53 to 60 near 3000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 74 to 80 near the shore to 70 to 78 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 40 percent.

Tuesday Night: Partly cloudy. Breezy. Isolated showers after midnight. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds up to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Kohala

Tonight: Breezy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 53 to 60 near 3000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 74 to 80 near the shore to 70 to 78 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 40 percent.

Tuesday Night: Partly cloudy. Breezy. Isolated showers after midnight. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds up to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

South Big Island

Tonight: Partly cloudy. Breezy. Scattered showers until early morning. Haze through the night. Lows around 72 near the shore to around 49 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Haze in the morning. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 63 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy. Breezy. Lows around 72 near the shore to around 49 near 5000 feet. East winds up to 25 mph. Gusts up to 45 mph in the evening.

Puna

Tonight: Mostly cloudy. Occasional showers until early morning, then scattered showers late in the night. Lows 64 to 70 near the shore to 49 to 55 at 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 78 to 83 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Partly cloudy with scattered showers. Lows 64 to 70 near the shore to 49 to 55 at 4000 feet. Northeast winds up to 15 mph shifting to the north after midnight. Chance of rain 50 percent.

Waikoloa

Tonight: Partly cloudy. Breezy and haze. Lows around 73 near the shore to 49 to 55 above 4000 feet. North winds up to 15 mph shifting to the northeast after midnight.

Tuesday: Breezy. Haze in the morning. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 82 to 88 near the shore to 64 to 72 above 4000 feet. North winds up to 25 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy. Breezy. Lows around 73 near the shore to 49 to 55 above 4000 feet. North winds up to 20 mph shifting to the east after midnight.

Detailed Forecast

Synopsis

Moderate to breezy trades will deliver clouds and showers to windward and mauka areas through the week. Trades strengthen slightly beginning Thursday.

Discussion

The weak upper low that has lingered around the area during the last week is presently positioned northeast of the Big Island at 250mb and roughly over/immediately east of the island at 500mb where the center is analyzed at 583dm. The islands reside along the southern periphery of the attendant cold pool and observed 500mb temperatures are approximately -9C and -10C at Lihue and Hilo respectively as of 12 UTC this morning. This low will sag southeast and tend to deepen as the mid-latitude pattern eases southward during the next couple of days. At the same time, energy associated with a progressive mid- latitude trough will pinch off from the westerlies as it crosses 160W and close off in the vicinity of Kauai during Wednesday. The islands, residing between these two rather small scale lows, will be positioned below a narrow band of shortwave ridging aloft Wednesday into Thursday. Attendant height rises in the mid-levels may nonetheless be hard to come by as the overall geopotential height field remains depressed and even further deepens given that the weak low presently over/east of the Big Island is modeled to deepen to 579dm as it drifts eastward. As a consequence, little change in the thermodynamic profile is anticipated today into Thursday with the exception of the aforementioned upper-level ridging helping to quash afternoon thunder potential over the Big Island. Moderate to locally breezy trades will remain weakly stable during this time with pockets of heavier showers developing where low-level convergence is maximized, mainly Leeward Big Island along the sea breeze each afternoon. Here, nuisance flooding is not out of the question.
By Thursday, lapse rates steepen to 6.5 to 7.0C/km over the western end of the state, the GFS being notably colder and unstable aloft compared to the EC which settles the low further west. Regardless of the model differences, ridge amplification east of the Dateline will cause trades to strengthen during this time limiting the potential for areas of enhanced convergence to emerge anywhere except Leeward Big Island. As a result, expect some variety of moderately unstable trades to develop no later than Thursday and continue through at least Friday night. From a sensible weather perspective, this suggests quick-moving/transient trade wind showers some of which may be heavy, especially at night and during the morning. The potential for thunderstorms over leeward/interior portions of the Big Island on Thurs/Fri will be evaluated going forward as this area stands the greatest chance to experience organized heavy rainfall as diurnal convection develops each afternoon.

Aviation

Trade winds will return to a more easterly direction tonight and strengthen into the moderate to locally breezy range from Tuesday onward as the ridge builds in north of the state. Expect passing showers mainly over windward and mountain areas and along leeward convergence cloud bands through Tuesday, with brief MVFR conditions possible within any shower bands. No AIRMETs are currently in effect.

Marine

Trades will persist through the weekend, with the strongest winds expected late Wednesday and Thursday. Currently, a 1032 mb centered nearly 1400 nm northeast of the state is driving moderate to fresh trade winds. Surface low pressure will form far north of the islands tonight and push the surface high eastward on Tuesday. Meanwhile, another area of high pressure from the west Pacific will move into the central Pacific, then stall far north of Hawaii on Wednesday into Friday. As the new high moves in, expect trade winds to increase to fresh to strong levels on Wednesday or Thursday, when a Small Craft Advisory (SCA) will be needed for the typically windy waters around the Big Island and Maui. The high is forecast to retreat westward during the weekend, favoring a decrease in winds.
Surf along south facing shores will remain just below seasonal average into Saturday as pulses of south-southwest and southwest swell move through. Surf will decline Sunday and remain small into early next week.
East shore surf will remain near or just below seasonal average during the next couple of days, followed by a slight increase Thursday and Friday as trade winds build east of the islands. A gradual decline in east shore surf is expected during the weekend and early next week. Tiny surf will prevail along north facing shores this week.

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