Photo Credit: Tyler Rooke

West Side

Today: Isolated showers. Mostly sunny, with a high near 81. Breezy, with an east northeast wind 7 to 12 mph increasing to 15 to 20 mph in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 67. Breezy, with an east northeast wind 15 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Saturday: Isolated showers before noon. Sunny, with a high near 81. Breezy, with an east northeast wind 11 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

South Side

Today: Scattered showers after 1pm. Mostly sunny, with a high near 81. Light and variable wind becoming west 5 to 7 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 7pm. Partly cloudy, with a low around 65. West northwest wind around 6 mph becoming calm in the evening. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Isolated showers after 1pm. Sunny, with a high near 81. Calm wind becoming west southwest around 6 mph in the afternoon. Chance of precipitation is 20%.

North Shore

Today: Scattered showers. Mostly sunny, with a high near 79. Breezy, with an east northeast wind 15 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: Isolated showers. Partly cloudy, with a low around 66. Breezy, with an east wind 15 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

Saturday: Scattered showers, mainly before noon. Mostly sunny, with a high near 79. Breezy, with an east wind 15 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 30%.

Central Maui

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 79. Breezy, with a northeast wind 11 to 16 mph increasing to 17 to 22 mph in the morning. Winds could gust as high as 31 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 64. Breezy, with a northeast wind 10 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Saturday: Isolated showers. Mostly sunny, with a high near 79. Breezy, with a northeast wind 11 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Upcountry

Today: Isolated showers. Mostly sunny, with a high near 66. East southeast wind 5 to 7 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 54. Light and variable wind becoming south southeast around 5 mph after midnight.

Saturday: Mostly sunny, with a high near 67. Breezy, with a southeast wind 5 to 10 mph becoming east northeast 12 to 17 mph in the afternoon. Winds could gust as high as 24 mph.

East Maui

Today: Occasional showers, mainly before noon. High near 77. East northeast wind 6 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 62. East wind 9 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Saturday: Scattered showers. Partly sunny, with a high near 77. East wind 9 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 74. Windy, with a northeast wind 16 to 24 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.

Tonight: Partly cloudy, with a low around 62. Breezy, with a northeast wind 17 to 22 mph decreasing to 6 to 11 mph after midnight. Winds could gust as high as 31 mph.

Saturday: Isolated showers after noon. Mostly sunny, with a high near 74. Breezy, with a northeast wind 6 to 11 mph increasing to 13 to 18 mph in the afternoon. Winds could gust as high as 25 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Isolated showers. Mostly sunny, with a high near 79. Breezy, with an east northeast wind 8 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 69. Breezy, with an east wind 8 to 17 mph, with gusts as high as 24 mph.

Saturday: Sunny, with a high near 79. Breezy, with an east wind 8 to 13 mph increasing to 16 to 21 mph in the afternoon. Winds could gust as high as 29 mph.

Detailed Forecast

Synopsis

High pressure north of the state will keep breezy trades in place through the weekend. An old front will bring an increase in showers to the islands today, with a more typical trade wind pattern featuring windward and mauka showers and the occasional leeward spillover returning tonight and holding through the weekend. The trades will diminish and shift southerly early next week in advance of a cold front. Fairly dry conditions should prevail on Monday. Rain chances will then be on the increase particularly over the western islands in advance of the cold front Tuesday. The cold front is expected to bring a widespread rainfall event to the state Tuesday night through Wednesday night, before possibly hanging up over the eastern end of the state on Thursday. Locally heavy rainfall and thunderstorms will be possible as the front moves through the area, with cooler conditions expected in its wake.

Discussion

Currently at the surace a 1028 mb high is centered 850 miles north-northeast of Honolulu, while a stronger 1038 mb high is located around 1550 miles north-northwest of Kauai. The resulting gradient is producing breezy trade winds across the island chain early this morning. Infrared satellite imagery shows a band of low clouds moving into windward areas resulting in mostly cloudy skies here, while partly cloudy conditions prevail in most leeward locales. Radar imagery shows scattered to numerous showers moving into windward slopes and coasts, with some of these showers making it into leeward communities. Main short term focus revolves around the trade wind trends, while longer term attention is centered around the progression of a strong cold front through the area during the early to middle part of next week.
High pressure north-northeast of the state will weaken and become absorbed into the stronger high north-northwest of the islands today. This high will then gradually weaken as it slides southeastward well to the north of the islands over the weekend. The gradient will remain rather tight across the state through the weekend, with breezy conditions expected, although a subtle easing is expected Saturday into Sunday. The trades will ease more noticeably into the light to moderate range on Monday as a cold front begins to approach from the northwest. As the cold front draws closer, light to moderate southerly winds will develop on Tuesday, followed by moderate to locally breezy northwesterly winds and cooler weather behind the cold front late Wednesday through Thursday.
As for the remaining weather details, the band of low clouds and showers has steadily approached the islands from the east- northeast overnight, and is expected to move into the islands later this morning. This will bring an increase in shower coverage particularly to windward areas, while quite a few showers will make it into leeward areas as well. This old frontal band is expected to shift south of the islands tonight, and this should bring a return of more typical trade wind weather that will last through the weekend. Showers will favor windward and mauka areas during this time, particularly at night and during the morning hours, with a stray shower reaching leeward areas from time to time.
With the easing trades on Monday, some localized sea breeze development will be possible Monday afternoon, bringing the chance for a few leeward and interior showers. As the flow turns southeasterly and southerly Monday night and Tuesday, we should begin to see an increase in pre-frontal convergence showers, particularly over the western islands. Both the GFS and ECWMF continue to show some minor timing differences with the front moving through the islands. Overall however, a widespread rainfall event still appears likely in the Tuesday night through Wednesday night time frame, as the front moves from west to east across the state. Locally heavy rainfall and thunderstorms will be possible in association with the front as it moves through as well. The front may hang up over the eastern end of the state on Thursday, keeping some unsettled weather in place here, while improving conditions are expected over the western islands.

Aviation

Breezy to locally strong trades will be accompanied by prevailing VFR through the early morning hours. An organized band of shower- bearing stratocu positioned immediately upstream of the Islands is poised to work into the area between about 15-18z /5AM-8AM HST this morning bringing increasing windward showers and a high likelihood of MVFR to windward coasts and slopes.
There are no AIRMETs in effect, but AIRMET Sierra for mountain obscuration may be needed later this morning.

Marine

A strong high far north of the state will sustain breezy to strong easterly trade winds through the day. Trade winds are expected to trend down to moderate to locally strong tonight through the weekend, as high pressure far north of the area weakens, and a front approaches the area from the northwest early next week.
A Small Craft Advisory is in effect through early Saturday morning for all coastal waters due to the strong trades. Also, moderate to large surf along east facing shores will continue due to the strong trade wind swell. A High Surf Advisory for east facing shores thus remains in effect through this afternoon. As indicated above, the easterly trade winds and swell are expected to gradually ease later today through the weekend as the high pressure system north of the area weakens.
A new moderate, long-period northwest swell will spread across the area today, peak tonight into Saturday, and slowly subside Sunday into early next week. A small, long-period north- northeast swell will continue to fill in through the weekend. Looking ahead into next week, the most recent model runs show a large northwest swell arriving by midweek.
Expect small background south swells through the middle of next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening 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 Saturday for all Hawaiian waters,

Data Courtesy of NOAA.gov