Photo Credit: Tyler Rooke

West Side

Today: Isolated showers before noon. Mostly sunny, with a high near 82. Breezy, with an east northeast wind 18 to 22 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 69. Windy, with an east northeast wind 21 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

Thursday: Isolated showers before noon. Sunny, with a high near 81. Windy, with an east northeast wind 16 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

South Side

Today: Isolated showers after noon. Mostly sunny, with a high near 82. Northeast wind around 6 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 67. Calm wind becoming east around 6 mph after midnight. Chance of precipitation is 20%.

Thursday: Isolated showers after noon. Mostly sunny, with a high near 81. Breezy, with a light and variable wind becoming east northeast 10 to 15 mph in the afternoon. Winds could gust as high as 21 mph. Chance of precipitation is 20%.

North Shore

Today: Scattered showers. Mostly sunny, with a high near 80. Windy, with an east wind 18 to 24 mph, with gusts as high as 33 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 68. Breezy, with an east wind 18 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 20%.

Thursday: Isolated showers. Mostly sunny, with a high near 79. Windy, with an east wind 18 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Central Maui

Today: Isolated showers. Mostly sunny, with a high near 80. Windy, with an east northeast wind 10 to 15 mph increasing to 18 to 23 mph in the afternoon. Winds could gust as high as 32 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 66. Breezy, with a northeast wind 11 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Thursday: Isolated showers. Mostly sunny, with a high near 79. Windy, with a northeast wind 14 to 19 mph increasing to 21 to 26 mph in the afternoon. Winds could gust as high as 37 mph. Chance of precipitation is 20%.

Upcountry

Today: Mostly sunny, with a high near 68. East southeast wind 5 to 8 mph becoming light and variable in the afternoon.

Tonight: Partly cloudy, with a low around 56. Breezy, with a light and variable wind becoming east southeast 10 to 15 mph in the evening. Winds could gust as high as 21 mph.

Thursday: Mostly sunny, with a high near 68. Breezy, with a west wind 5 to 10 mph becoming east 15 to 20 mph in the afternoon. Winds could gust as high as 28 mph.

East Maui

Today: Occasional showers, mainly before 1pm. High near 78. Breezy, with an east wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 64. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 77. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Scattered showers after noon. Partly sunny, with a high near 75. Breezy, with a northeast wind 13 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Partly cloudy, with a low around 63. Windy, with a northeast wind 15 to 25 mph, with gusts as high as 36 mph.

Thursday: Isolated showers after noon. Mostly sunny, with a high near 74. Windy, with an east northeast wind 22 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Mostly sunny, with a high near 81. Breezy, with an east wind 13 to 22 mph, with gusts as high as 31 mph.

Tonight: Partly cloudy, with a low around 70. Breezy, with an east wind 14 to 20 mph, with gusts as high as 29 mph.

Thursday: Sunny, with a high near 79. Windy, with an east northeast wind 11 to 16 mph increasing to 20 to 25 mph in the afternoon. Winds could gust as high as 36 mph.

Detailed Forecast

Synopsis

High pressure north of the state will keep breezy to locally windy trades in place through Friday, with a slight decrease in the trade wind speeds expected over the weekend. Showers will favor windward and mauka areas with a few showers reaching leeward areas from time to time. An old front may bring an increase in showers to the islands on Friday however. The trades will diminish and shift southerly early next week in advance of a cold front, with a more widespread rainfall event possible Tuesday into the middle of next week as the front moves into the area.

Discussion

Currently at the surface, a 1032 mb high is centered around 1200 miles north of Honolulu, while a trough of low pressure is located around 550 miles west of Kauai. The resulting gradient is producing moderate to breezy trades across the island chain early this morning. Infrared satellite imagery shows a mix of high and low clouds resulting in mostly cloudy conditions across the state. Meanwhile, radar imagery shows scattered to numerous showers moving into windward areas, with a few showers spilling leeward from time to time. Main short term focus revolves around the strengthening trade winds during the next couple days.
High pressure will build slowly southward and closer to the islands today through Thursday, before becoming absorbed into a new re-enforcing high building southward far to the north of the state Friday through the weekend. The gradient will remain rather tight across the islands through the period, particularly Wednesday through Friday, with breezy to locally windy conditions can be expected, peaking on Thursday. The trades will only slowly ease over the weekend, diminishing into the moderate to locally breezy range by Sunday. The trades are forecast to diminish further into the light to moderate range Monday, then become disrupted and shift southerly next Tuesday in advance of a cold front.
As for the remaining details, more typical trade wind weather is expected today, with this pattern generally holding in place through the weekend. Showers will favor windward and mauka areas and a few showers will reach leeward areas from time to time. We could see an increase in shower coverage on Friday however, particularly over windward areas, as both the GFS and ECMWF show some old frontal remnants sliding southward through the islands. This would likely send a few more showers into leeward communities as well. Showers should continue to favor windward and mauka areas on Monday, but as the trades ease, some leeward shower development will be possible in the afternoon hours as a result of localized sea breeze development. An approaching cold front could bring more widespread rainfall to the islands Tuesday into Wednesday of next week.
Some lingering high clouds are expected today, although they should be thinning out with time. This should bring more sunshine to the islands today then has been seen in the past couple days, with the high clouds expected to have vacated the area by Thursday.

Aviation

Breezy trades will continue today with tempo MVFR and isol IFR conditions along windward slopes in CLD and SHRA. Leeward slopes of the Big Island may see afternoon convection bringing ISOL MVFR visibilities.
AIRMET Sierra for tempo mountain obscuration is in effect for Windward Big Island.
AIRMET Tango remains in effect for low-level mechanical turb and strong surface winds.

Marine

A strong high pressure system far north of the state will keep fresh to locally strong easterly trade winds in place through Friday. A slight decrease in trade winds into the moderate to breezy range will develop by this weekend, as a weaker high passes by far north of the island chain.
Large surf along east facing shores will continue through Friday morning. The easterly trade wind swell will gradually decrease from Friday afternoon through the weekend as the high pressure system north of the area weakens. A Small Craft Advisory (SCA) for all Hawaiian waters was extended through early Friday morning. A High Surf Advisory (HSA) for exposed east facing shores was also extended through late Thursday afternoon. This HSA may extend into Friday due to continued strong trade winds.
The current northwest swell will continue to hold through Thursday. A small, short-period north-northeast swell arriving Thursday will likely continue through the weekend. A new moderate, long- period northwest swell will spread across the area late Friday, and continue through Saturday night. Northwest swell heights will slowly lower from Sunday into early next week.
A small out-of-season southwest swell from the Tasman Sea will produce a slight bump in surf heights along south facing shores today. Otherwise, expect small surf along south facing shores from Thursday through the weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Thursday for Kauai Windward, Oahu Koolau, Olomana, Molokai Windward, Maui Windward West, Windward Haleakala, Big Island North and East.
Small Craft Advisory until 6 AM HST Friday for all Hawaiian waters,

Data Courtesy of NOAA.gov