Hilo

Today: Partly sunny with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 78 near the shore to 63 to 68 at 4000 feet. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy with showers likely. Lows around 62 near the shore to around 48 at 4000 feet. North winds up to 10 mph. Chance of rain 70 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 77 near the shore to 62 to 67 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny. Scattered showers in the afternoon. Highs 78 to 83 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 62 to 68 near the shore to around 49 near 5000 feet. Light winds. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs 77 to 82 near the shore to around 68 near 5000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Waimea

Today: Partly sunny with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 77 near the shore to 69 to 76 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with showers likely after midnight. Lows around 61 near the shore to 47 to 55 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday: Mostly sunny with scattered showers. Highs around 76 near the shore to 68 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 77 near the shore to 69 to 76 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with showers likely after midnight. Lows around 61 near the shore to 47 to 55 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday: Mostly sunny with scattered showers. Highs around 76 near the shore to 68 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 81 near the shore to around 70 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 64 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs around 80 near the shore to around 69 near 5000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Puna

Today: Partly sunny with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 78 near the shore to 63 to 68 at 4000 feet. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy with showers likely. Lows around 62 near the shore to around 48 at 4000 feet. North winds up to 10 mph. Chance of rain 70 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 77 near the shore to 62 to 67 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny with isolated showers. Highs around 80 near the shore to 64 to 71 above 4000 feet. East winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows around 66 near the shore to 44 to 52 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs around 79 near the shore to 63 to 70 above 4000 feet. East winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Moderate trade winds will hold in place today, then ease slightly tonight through Tuesday. Showers will favor windward slopes and coasts, mainly during nights and mornings, with a few showers spilling leeward from time to time. Trade winds will strengthen around mid week and a more typical trade wind shower pattern will return. Rather wet trade wind weather is expected Wednesday night through late next week, with breezy to windy conditions possible Friday into next weekend.

Discussion

Currently at the surface, a 1028 mb high is centered around 1350 miles north of Honolulu, with a ridge axis extending southwest to a position around 500 miles west of Kauai. Meanwhile, a cold front is positioned around 1000 miles west-northwest of the Garden isle, and a 1010 mb low is located near 29N151W or around 650 miles north-northeast of Hilo. These weather features will be the main influences on the local weather during the next few days. The high north of the islands remains the dominant weather feature at the moment, and is driving moderate northeasterly trade winds across the island chain early this morning. Infrared satellite imagery shows partly cloudy skies in most areas, with a bit more cloud cover at times over windward areas. Radar imagery shows scattered to numerous showers moving into windward areas, with some of the showers reaching leeward locales at times. Main short term focus during the next few days revolves around rain chances and trade wind trends.
The high and associated surface ridge north and northwest of the islands, will remain the dominant weather features today, maintaining moderate northeast trade winds. The low currently to the north-northeast of the state will drop southwestward, and weaken into a trough as it moves into a position a couple hundred miles north of the state tonight, relaxing the gradient and easing the trades into the light to moderate range. The trough will continue to slide westward Monday, and eventually merge with a stalling out front a few hundred miles northwest of Kauai on Tuesday. Light to moderate easterly trade winds will prevail during this time. Surface ridging will begin to strengthen both northwest and northeast of the islands Tuesday night and Wednesday, bringing a return of moderate trade winds. The trades are expected to strengthen through the remainder of the week as high pressure builds in north of the state, with breezy to windy conditions possible Friday into the weekend.
As for the remaining weather details, after a fairly showery start to the day, conditions should dry out in most areas this afternoon, although some shower coverage will remain a bit higher over windward Big Island. Fairly dry conditions should then prevail tonight through Tuesday as precipitable waters values hover around an inch or less and the best upper level forcing remains east of the state. Showers will favor windward and mauka areas, particularly during nights and mornings, with a few showers reaching leeward areas at times. A shortwave trough will pass eastward through the islands on Tuesday then close off into an upper low over the eastern end of the state Tuesday night and Wednesday. This will elevate inversion heights and lead to a gradual moistening up of the airmass across the state. The upper low will linger over the eastern islands through Thursday, then open up into a trough as it shifts southeast of the Big Island Thursday night and Friday. The strengthening trade winds and moistening up of the airmass will likely bring a return of a more typical trade wind shower pattern Tuesday night and Wednesday. Current model solutions then indicate a period of rather wet trade wind weather Wednesday night through late in the week. The wettest weather during this time of course will be over windward slopes and coasts, but given the strength of the trades, showers will reach leeward areas more frequently as well.
With the upper level forcing in place over the eastern end of the state, an isolated thunderstorm or two can't be ruled out over the Big Island each afternoon Tuesday through Friday. Additionally, it will be plenty cold enough for some snow to fall if convection develops over the Big Island summits.

Aviation

Light to moderate northeasterly trades will continue over the state through early Monday morning, which will confine most cloud cover and chances for showers to windward slopes and coasts through the TAF period. However, a few leeward locations could still potentially see sea breeze development and isolated showers this afternoon across more sheltered locations. Expect mainly VFR conditions to continue again at most TAF sites, with periodic MVFR conditions also expected within developing bands of trade wind showers.
AIRMET Tango for moderate upper turb conditions between FL280-FL420 within the air routes and flight areas within 40nm of the main Hawaiian Islands, is expected to improve this morning as upper jet dynamics continue to push eastward of the region.
AIRMET SIERRA for MTN OBSC may become needed today across some windward sections, as NE trades potentially generate an expanding area of MVFR ceilings within bands of trade wind moisture.

Marine

High pressure north of the region will help to increase trades a bit today, but expect a downward trend tonight. The current west- northwest swell will continue to decline today.
A hurricane force low more than 1650 nm northwest of the islands will have an impact on the coastal waters over the coming days. The associated cold front is expected to approach and stall to the northwest, which will weaken the pressure gradient over the coastal waters, leading to the above mentioned downward trend in the winds. This system will also be send an advisory level west- northwest swell our way. This swell is expected to arrive Monday, peak Tuesday and Wednesday, and then slowly lower through Thursday. Some of the coastal waters could see seas in excess of the 10 foot Small Craft Advisory (SCA) threshold with this event.
During the second half of the week, high pressure will build north of the islands, bringing SCA level winds to at least the typical windier locations. Models indicate additional coastal areas could see SCA level winds at the end of the new week and into the weekend.
Models show a gale force low forming near Japan that will send another west-northwest swell to the islands late in the week. Current projections are for this swell to arrive late Thursday, peaking near advisory levels Friday.
South shore surf will remain small through the rest of the weekend, before a moderate, out of season south-southwest swell arrives late tonight and Monday. This swell will hold at moderate levels through Wednesday, then lower through late next week. East shore surf will gradually rise through the upcoming week, with rough and slightly above normal surf possibly returning by Friday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov