Photo Credit: James Grenz

Hilo

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Cloudy with showers likely. Lows 64 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.

Monday: Cloudy with showers likely in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 60 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 71 near the shore to 52 to 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Windy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 66 to 86. East winds 15 to 30 mph. Chance of rain 30 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 63 to 69 near the shore to 55 to 63 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers. Highs 67 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Windy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 66 to 86. East winds 15 to 30 mph. Chance of rain 30 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 63 to 69 near the shore to 55 to 63 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers. Highs 67 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 73 near the shore to around 52 near 5000 feet. Northeast winds 10 to 20 mph.

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

Puna

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Cloudy with showers likely. Lows 64 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.

Monday: Cloudy with showers likely in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 60 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Windy. Highs 82 to 90 near the shore to 66 to 74 above 4000 feet. Northeast winds up to 30 mph increasing to 10 to 30 mph in the afternoon.

Tonight: Windy. Partly cloudy with isolated showers. Lows around 72 near the shore to 49 to 57 above 4000 feet. Southeast winds up to 30 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 82 to 88 near the shore to 65 to 74 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy to locally strong trades will focus cloud and showers over windward and mauka areas through Tuesday. The arrival of remnant moisture from a decaying tropical system will favor an increase in shower coverage Wednesday and Thursday.

Discussion

Opted to post a Wind Advisory for portions of the Big Island, Maui and Kahoolawe today and tonight. Bradshaw on the Big Island briefly touched advisory criteria yesterday. The high resolution models still show a small uptick today and tonight. The ASCAT pass missed the islands overnight, so decision was based on model guidance. It is expected to be a low end and short lived event.
As expected, there has been shower activity focused on the windward sides of the islands overnight. Several windward rain gages on the Big Island got a third to half an inch of rain overnight. Satellite derived precipitable water, and satellite imagery suggest a drier and more stable airmass moving over the islands later today, so expect shower activity to be on a downward trend today.
Mid to upper level ridging will be overhead over the next couple of days, helping to maintain a stable airmass over the islands. Combined with the drier airmass moving in, expect this relatively drier period to last into midweek. This may further suppress the inversion, which could cause an uptick in winds for the typical windier locations in Maui County and on the Big Island on Sunday. The overnight sounding at Hilo showed a higher inversion than yesterday afternoon, so time will tell how much of an impact it will have on the Big Island winds today.
The remnants of former tropical cyclone Bonnie look to arrive near the islands midweek. Have boosted the QPF towards the National Blend of Models for Wednesday and Thursday, but felt the existing PoPs were still in line with the global models, with the focus of the showers being the Big Island and Maui County.
In the East Pacific, Tropical Storm Darby is forecast to move to the west over the next 5 days, and enter the Central Pacific basin at 140W sometime late Thursday. Any local impacts from Darby would not be anticipated until next weekend, and its much too early to discern any of those impact with any certainty. See bulletins issued by the National Hurricane Center in Miami for the latest on Darby.

Aviation

A high pressure system far north of the islands will continue to produce breezy trade winds across the region. Passing showers will continue to produce brief periods of MVFR conditions over windward airfields, elsewhere VFR conditions will prevail.
AIRMET Sierra in effect for mountain obscuration for N thru E sections of Maui and the Big Island. Sierra will likely continue through the early morning hours.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of island mountain ranges. Tango will continue at least through tonight.

Marine

Large surface high pressure anchored far north of the islands will maintain a tight enough pressure gradient back toward the state to continue support of sustained fresh to locally strong trade winds. A Small Craft Advisory (SCA) remains in effect for the windier bays and channels around Maui and Big Island. An SCA is also in effect for the windward Maui and leeward Maui and Oahu coastal waters through at least early Monday morning.
A small, short period southeast swell will travel through the nearshore waters from Monday into late week. Along with the arrival of new southern swell forerunners, this will slightly bump up surf along more eastern and southern exposures Monday. Several pulses of long period south swell are expected to arrive through the week. These swells will generate near to above normal summertime southern facing shore surf heights. A slightly higher, long period south swell will begin arriving Monday afternoon and peak Tuesday and Wednesday's surf. Long range guidance has a gale low passing east of New Zealand early Tuesday that will provide a nice source or fetch region for even higher southern swell. This larger swell may produce High Surf Advisory level surf along southern exposures when it reaches the islands next weekend. Trades will continue to push relatively small, short period wind waves onto east facing shores. Small, medium period east swell emanating from former Hurricane Bonnie may arrive Monday and Tuesday.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 AM HST Monday for Kahoolawe, Maui Windward West, Kohala, Big Island Interior, Big Island North.
Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST Monday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

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Data Courtesy of NOAA.gov