Hilo

Today: Scattered showers, mainly before noon. Mostly cloudy, with a high near 77. West southwest wind 5 to 9 mph becoming northeast in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after midnight. Cloudy, with a low around 63. North northeast wind 5 to 9 mph becoming light and variable after midnight. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers, mainly before noon. Mostly cloudy, with a high near 77. Light and variable wind becoming north 5 to 9 mph in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Partly sunny, with a high near 79. Calm wind becoming south southwest 5 to 8 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly cloudy, with a low around 61. Calm wind becoming east 5 to 7 mph after midnight. Chance of precipitation is 20%.

Thursday: Isolated showers after noon. Partly sunny, with a high near 79. East wind 5 to 7 mph becoming calm in the afternoon. Chance of precipitation is 20%.

Waimea

Today: Isolated showers. Partly sunny, with a high near 74. Breezy, with a northeast wind 17 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 52. Breezy, with an east northeast wind 16 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Thursday: Isolated showers. Partly sunny, with a high near 74. Breezy, with a northeast wind 6 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

Kohala

Today: Scattered showers, mainly before noon. Mostly cloudy, with a high near 70. Breezy, with an east northeast wind 18 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after midnight. Mostly cloudy, with a low around 45. Breezy, with an east northeast wind 18 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers, mainly before noon. Mostly cloudy, with a high near 70. Breezy, with an east northeast wind 13 to 18 mph becoming light east. Winds could gust as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 76. Breezy, with an east wind 17 to 22 mph, with gusts as high as 28 mph.

Tonight: Partly cloudy, with a low around 70. Windy, with an east wind 16 to 23 mph, with gusts as high as 30 mph.

Thursday: Mostly sunny, with a high near 75. Breezy, with an east wind 7 to 17 mph, with gusts as high as 22 mph.

Puna

Today: Scattered showers. Mostly cloudy, with a high near 76. West northwest wind 7 to 11 mph becoming north northeast in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Cloudy, with a low around 61. North wind 7 to 11 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Cloudy, with a high near 76. Northwest wind 7 to 10 mph becoming north northeast in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Sunny, with a high near 80. Breezy, with an east wind 18 to 22 mph becoming north northeast in the afternoon. Winds could gust as high as 31 mph.

Tonight: Mostly clear, with a low around 61. Breezy, with an east northeast wind 16 to 22 mph, with gusts as high as 31 mph.

Thursday: Mostly sunny, with a high near 80. Breezy, with an east southeast wind 6 to 16 mph becoming west northwest in the morning. Winds could gust as high as 23 mph.

Detailed Forecast

Synopsis

Moderate to breezy northeast trade winds will prevail through Thursday, then ease into the light to moderate range Friday through Saturday as a band of moisture associated with a dissipated front moves in from the north. Windward shower coverage will remain limited into Friday due to the cool and dry pattern in place, but should trend up Friday night into Saturday as the band of moisture arrives. A warmer pattern is expected early next week as the trade winds shift to a more typical easterly direction on Sunday, then out of the east-southeast early next week.

Discussion

Dry and stable northeast trade wind conditions will continue into the second half of the week due to the persistent pattern across the northern Pacific featuring a blocking pattern to the northwest over the Date Line and deep low pressure to the northeast. Dewpoints will hover in the upper 50s to around 60 degrees into the weekend. These low dewpoints combined with the north-northeast low-level flow advecting air into the area from the cooler ocean temperatures (upper 60s) nearby to the north are the main ingredients supporting the pleasant conditions. Limited shower coverage will be the result – with the best chances expected overnight through the early morning periods for north and east facing slopes.
Shower coverage may increase late Friday into the weekend in response to lowering upper heights and a remnant band of moisture associated with an old front moving into the area from the north. Guidance shows this band moving over Kauai and Oahu Friday night, then stalling and diminishing around Maui County by Saturday night. Northeast winds may trend down into the light category ahead of this band through the day Friday, but return to moderate levels following it on Saturday.
A transition pattern appears possible over the northern Pacific Sunday into next week. High pressure is shown building northeast of the state as the previously discussed low pressure moves out. Trade winds should veer to a more typical easterly direction Sunday, then to the east-southeast early next week as the ridge weakens in response to a cold front passing far to the north. This pattern will translate to a moistening/warming trend with dewpoints surging back into the mid-to-upper 60s. Winds may become light enough for a land and sea regime to develop early next week. This combined with increasing moisture will support the best rainfall chances shifting to interior/leeward sections through the afternoon hours.

Aviation

A surface trough east of the Big Island will maintain a moderate to locally strong northeast wind flow across the islands through tonight. AIRMET Tango is in effect for low level turbulence south through west of mountains below 7k feet. It is likely to continue beyond 150400z.
The latest satellite imagery shows a couple of pockets of scattered showers upwind of all the islands. These clouds and showers will bring on brief MVFR ceilings and vis to the windward and mountain areas throughout today, although the frequency of these showers will drop off a bit by late morning. Isolated showers along the leeward coast of the Big Island will be ending shortly. Clouds and isolated showers are then expected to return this afternoon across the lee side of the Big Island, lasting into the evening hours. Tops of the clouds/showers are 7k to 8k feet. AIRMET Sierra is not expected today.

Marine

A large area of surface high pressure northwest of the state is producing a tight enough pressure gradient down upon the islands to maintain moderate to locally strong northeast trade winds. These winds will persist through tonight as the high moves east and keeps the north pressure gradient tight across the Hawaiian coastal and offshore waters. A Small Craft Advisory remains in effect through tonight to account for stronger winds around Maui County, through the Alenuihaha Channel and those waters south of the Big Island. Trades will subside late in the week as a weakening cold front approaches from the north. Weekend trades will veer more east and slightly pick up from gentle to moderate Saturday to more moderate to fresh speeds on Sunday.
Today’s small northwest swell will slowly fade through tonight. A larger, short period north swell will arrive by Friday morning. This will pick up north facing shore surf this weekend with a gradual decline early next week. Surf from this northern swell will remain well below high surf advisory thresholds. Surf will stay small along east facing shores through Thursday. The late week north swell may wrap around into some eastern exposures to provide a small increase to weekend surf along east facing coasts. Small south facing shore surf will hold through Thursday. Distant long period swell energy from the southern hemisphere will provide a small bump to southern shoreline surf from Friday into the weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov