Photo Credit: James Grenz

Hilo

Today: Showers likely, mainly before noon. Partly sunny, with a high near 76. Light and variable wind becoming east northeast 5 to 7 mph in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 62. East northeast wind around 6 mph becoming calm. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers. Mostly cloudy, with a high near 77. Calm wind becoming east southeast 5 to 9 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after 1pm. Partly sunny, with a high near 78. Calm wind becoming west southwest 5 to 7 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before 1am. Mostly cloudy, with a low around 60. West northwest wind around 5 mph becoming calm. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers after 1pm. Mostly cloudy, with a high near 79. Calm wind becoming west northwest 5 to 7 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers, mainly before noon. Mostly sunny, with a high near 74. Breezy, with a northeast wind 14 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 46. Breezy, with a northeast wind 14 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Scattered showers, mainly before noon. Mostly cloudy, with a high near 76. Northeast wind 7 to 14 mph becoming east southeast in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a high near 71. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 41. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely, mainly after noon. Mostly cloudy, with a high near 73. Windy, with an east wind 21 to 26 mph decreasing to 9 to 14 mph in the morning. Winds could gust as high as 38 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Widespread haze. Mostly sunny, with a high near 79. Windy, with an east wind 24 to 26 mph, with gusts as high as 34 mph.

Tonight: Widespread haze. Mostly cloudy, with a low around 70. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph.

Sunday: Isolated showers after noon. Widespread haze. Mostly cloudy, with a high near 81. Windy, with an east northeast wind 21 to 26 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. Partly sunny, with a high near 75. Northwest wind 6 to 11 mph becoming east northeast in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 60. Northeast wind 6 to 10 mph becoming west after midnight. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Showers likely, mainly after noon. Mostly cloudy, with a high near 76. West wind 6 to 10 mph becoming east in the morning. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 79. Breezy, with an east southeast wind 8 to 16 mph becoming northeast in the morning. Winds could gust as high as 22 mph.

Tonight: Partly cloudy, with a low around 57. East wind 8 to 14 mph, with gusts as high as 18 mph.

Sunday: Mostly cloudy, with a high near 80. East northeast wind 5 to 10 mph becoming light and variable in the afternoon.

Detailed Forecast

Synopsis

A surface high passing far north and northeast of the islands will maintain a trade wind flow through the first half of next week, although the pattern may weaken slightly on Monday and Tuesday. Showers riding in with the trade winds will favor the windward and mountain areas of most islands. High clouds, dense at time, will be present across island skies over through Sunday.

Discussion

Trade winds will be gaining strength through today, becoming moderate to strong area-wide and lasting between tonight and Sunday night. This comes about as a broad 1045 mb surface high passes far north of the islands tonight while heading toward the west coast. A wind advisory is not likely but will be monitored closely. Satellite imagery shows a large area of layered clouds to the west and south of the islands, in association with a deep upper level trough/low just east of the dateline. The islands will be under this layer of dense high cirrus clouds time to time through Sunday, effectively cutting down the sunshine.
Trade showers have increased overnight, favoring the windward and mountain areas of most islands. Most of these showers are on the light side. Do expect more trade showers to come in tonight through Sunday night, in tandem with the stronger trade winds. With this said, the lee side of the smaller islands can expect a little more showers during the overnight hours. Over on the lee side of the Big Island, the light winds, day time heating, will lead to some afternoon showers, and isolated showers along the coast overnight. A mid level ridge will support a stable air mass with a low level inversion at around 8k feet area- wide, which will hold through Sunday. The inversion will limit the intensity of the showers to mainly light.
Come Sunday night, the trade winds will shift slightly to the east and east-southeast over the western half of the island chain, leading to a hybrid mix of trades and land and sea breezes for the islands west of Maui and the Big Island. This lighter wind will promote local sea breezes during the day over the lee and interior areas. Further more, the mid level ridge will weaken area-wide. All these changes are due to the deepening of the upper level trough and a resultant surface low northwest of Kauai. This pattern will favor scattered afternoon showers over the lee and interior areas for particularly those islands west of Maui and the Big Island. This unstable air mass will also produce heavier scattered afternoon and evening showers for the Kona slopes/interior sections of the Big Island as well.
The trade winds and a more stable air mass will return on Wednesday, with strengthening trade winds through the second half of next week.

Aviation

Trade winds will rebuild across the Hawaiian Islands–beginning in the east this morning and spreading westward across the remainder of the state by late afternoon. Ragged low topped clouds and scattered showers will favor east facing slopes and coasts. Brief MVFR CIG and VIS are likely in passing showers, otherwise VFR conditions will prevail all areas.
Strengthening trade winds may warrant an AIRMET for low level turbulence over and to the lee of higher terrain later today.
This afternoon on the Big Island, light sea breezes along the leeward coast will promote cumulus build-ups over the island’s interior. Leeward showers are expected to linger through the evening hours.
A passing upper level jet is triggering areas of moderate upper level turbulence over much of the state. AIRMET Tango has been issued for turbulence between fl270 and fl430, but will likely be cancelled later this morning. The jet is also causing layered cirrus clouds to stream out of the southwest across the whole of the state.

Marine

A trough of low pressure northwest of Kauai will weaken as it shifts northwestward during the next couple days, allowing high pressure to the distant northeast to become more dominant. As a result, fresh to strong trade winds will prevail through the weekend. A Small Craft Advisory (SCA) is now in effect from the leeward Oahu waters eastward through 6 PM Sunday. The SCA continues for most of the waters around Maui and the Big Island through 6 AM Monday. Early next week the trades will ease into the light to moderate range as a storm system develops several hundred miles west of the state, with the lightest winds expected near Kauai and Oahu. The trades should ramp back up to moderate to locally strong levels Wednesday through Friday as the storm system shifts westward and ridging becomes more dominant north of the island chain.
Surf along north facing shores will hold relatively steady today, with a slight boost expected Sunday, before lowering early next week. After a very small day Tuesday, north and west shores will see a boost from a new west-northwest swell Wednesday and Thursday, with surf lowering to very small levels Friday into next weekend.
Surf along east facing shores will hold fairly steady today, with a small increase expected Sunday due to the strengthening trades. East shore surf will lower a notch Monday as the trades ease slightly, then hold fairly steady near seasonal levels through the remainder of next week.
Several overlapping south swells will keep surf above the seasonal average along south facing shores through the weekend. A larger long-period south swell will fill in late Sunday and Sunday night, giving a slight boost to south shore surf Monday through Wednesday. Surf will drop back to near or slight above seasonal norms Thursday into next weekend.
Surf is expected to remain below advisory levels along all shores during the next 7 days.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Sunday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

Data Courtesy of NOAA.gov