Hilo

Today: Occasional showers. High near 76. West southwest wind around 7 mph becoming east southeast in the afternoon. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers. Low around 61. East wind 5 to 9 mph becoming light southeast after midnight. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Frequent showers. High near 75. Light and variable wind. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers. Widespread haze. Partly sunny, with a high near 79. Light and variable wind becoming west northwest 5 to 8 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Widespread haze. Mostly cloudy, with a low around 59. Southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Scattered showers, mainly after noon. Widespread haze. Partly sunny, with a high near 78. West wind around 6 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Widespread haze. Partly sunny, with a high near 74. Breezy, with a northeast wind 11 to 17 mph, with gusts as high as 29 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Widespread haze. Mostly cloudy, with a low around 50. Breezy, with a northeast wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Showers likely, mainly after noon. Widespread haze. Mostly cloudy, with a high near 73. Windy, with a northeast wind 24 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a temperature falling to around 61 by 5pm. Windy, with an east northeast wind around 30 mph, with gusts as high as 55 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers. Low around 43. Windy, with an east northeast wind around 30 mph, with gusts as high as 44 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Frequent showers. High near 69. Strong and damaging winds, with an east wind 40 to 44 mph, with gusts as high as 65 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers. Widespread haze. Mostly sunny, with a high near 79. Windy, with an east northeast wind around 30 mph, with gusts as high as 39 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after midnight. Widespread haze. Partly cloudy, with a low around 67. Windy, with an east northeast wind 26 to 30 mph, with gusts as high as 39 mph. Chance of precipitation is 30%.

Friday: Scattered showers. Widespread haze. Partly sunny, with a high near 78. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Puna

Today: Scattered showers. Partly sunny, with a high near 75. North northwest wind 6 to 10 mph becoming east northeast in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers. Low around 59. Northeast wind 6 to 11 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Frequent showers. High near 74. North northwest wind 6 to 10 mph becoming northeast in the afternoon. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers. Widespread haze. Mostly sunny, with a high near 80. East southeast wind 6 to 9 mph becoming west northwest in the afternoon. Chance of precipitation is 20%.

Tonight: Widespread haze. Partly cloudy, with a low around 59. North wind 5 to 9 mph becoming east southeast after midnight.

Friday: Scattered showers and thunderstorms after noon. Widespread haze. Mostly sunny, with a high near 79. Light and variable wind becoming southwest around 6 mph in the afternoon. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Detailed Forecast

Synopsis

Breezy to locally windy trade winds will continue into next week. Showers will remain focused over windward slopes, but a disturbance aloft will enhance shower activity Friday through the weekend.

Discussion

An exceptionally strong 1046 mb surface high centered about 1500 miles north of the state is driving strong easterly trade winds. A Wind Advisory remains posted for portions of the Big Island and Maui, where wind gusts around 50 mph are expected over and downwind of terrain. A narrow upper level trough is building over the area from the east, eroding the inversion and leading to some instability. As a result, few heavy showers are flaring this morning within a band of moisture moving onto windward Big Island and Maui and skirting just north of the other islands. Expect an uptick in mainly windward rainfall as this band moves through today, though a few showers will spread over leeward areas on the gusty trades. There is also enough instability to produce an isolated thunderstorm on the leeward Big Island slopes this afternoon.
Winds will ease slightly on Friday and the weekend, while instability leads to periods of active showers. The high to the north will weaken and be displaced by another surface high approaching from the west Pacific. Trades will weaken slightly as early as Friday, creating border line Wind Advisory conditions for the Big Island and Maui, and trades will decline to locally breezy strength during the weekend. The upper level trough will settle over the state, essentially wiping out the inversion and producing instability. As a result, expect pockets of moisture moving in the trade wind flow to become enhanced, and deeper moisture developing near the Big Island and Maui could produce more widespread heavy showers and a few thunderstorms.
The current run of breezy trades will persist into early next week. High pressure will dominate far north of the state, but the GFS and ECMWF differ on some important details. The GFS shows the upper level trough overhead weakening, while the ECMWF suggests that this feature will be reinvigorated, leading to weaker trades and higher chances for enhanced shower activity. For now, the forecast favors the GFS.

Aviation

Strong high pressure far north of the state is producing strong easterly trade winds across the area. AIRMET Tango remains in effect for low level mechanical turbulence for areas over and immediately south through west of mountains. This AIRMET will continue into the overnight hours.
VFR conditions prevail across most of the area with brief periods of MVFR conditions over some windward locations in low clouds and showers. Expect these conditions to continue on into the evening hours.

Marine

Strong high pressure NE and N of the islands will maintain strong to near gale force trade winds over and upstream of the islands into next week. A Small Craft Advisory (SCA) for all waters has been extended through the weekend as winds and/or seas will continue to meet criteria, and an ongoing Gale Warning for the Alenuihaha Channel is in place through tonight. A subtle decrease in wind speeds from Friday into the weekend may allow the Gale Warning to be dropped. Winds may increase again early next week as a new high builds N of the area.
The strong trade winds extend well upstream of the islands, and are driving a well-developed (10-11 second period) wind swell toward the islands from the E. A High Surf Advisory for E facing shores will remain posted for the next several days. Elsewhere, surf will be below advisory levels, but several long-period NW swells are expected over the next week. Peaks in these swells can generally be expected tonight and Friday, Saturday night/Sunday, and Wednesday/Thursday, with the last swell expected to be the largest of the three.
Some trade wind swell will wrap into exposed shores/reefs along N and S facing shores, and a small long-period S swell is also expected the next couple of days.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Monday for Kauai Windward, Oahu Koolau, Olomana, Molokai Windward, Maui Windward West, Windward Haleakala, South Big Island, Big Island North and East.
Wind Advisory until 6 PM HST this evening for Molokai, Kahoolawe, Maui Windward West, Maui Leeward West, Maui Central Valley, Windward Haleakala, Leeward Haleakala, South Big Island, Big Island North and East, Kohala, Big Island Interior.
Small Craft Advisory until 6 PM HST Sunday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.
Gale Warning until 6 AM HST Friday for Alenuihaha Channel.