West Side

Today: Mostly sunny. Breezy. Highs around 78. East winds up to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 64 to 71. East winds 10 to 20 mph decreasing to up to 15 mph after midnight.

Friday: Mostly sunny. Highs around 79. East winds up to 15 mph.

South Side

Today: Mostly sunny. Highs around 83. North winds up to 15 mph.

Tonight: Partly cloudy. Lows 63 to 72. Northeast winds up to 15 mph shifting to the northwest after midnight.

Friday: Mostly sunny. Highs around 84. Light winds becoming northwest up to 15 mph in the afternoon.

North Shore

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 78 near the shore to around 62 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68 near the shore to around 49 near 5000 feet. Southeast winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs 78 to 84. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon.

Tonight: Partly cloudy. Breezy. Lows 63 to 68. East winds 10 to 20 mph decreasing to up to 15 mph after midnight.

Friday: Mostly sunny. Breezy. Highs 80 to 85. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Highs around 58 at the visitor center to around 67 at the summit. Northeast winds up to 15 mph.

Tonight: Mostly cloudy. Isolated showers after midnight. Lows around 44 at the visitor center to around 46 at the summit. East winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Highs around 59 at the visitor center to around 67 at the summit. East winds up to 15 mph.

East Maui

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 78 near the shore to around 62 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68 near the shore to around 49 near 5000 feet. Southeast winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny in the morning then becoming partly sunny. Highs 70 to 77. Northeast winds up to 15 mph.

Tonight: Partly cloudy. Lows around 63. Northeast winds up to 15 mph.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 70 to 78. Light winds. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 66 to 83. East winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 56 to 70. East winds 10 to 20 mph.

Friday: Mostly sunny. Highs 67 to 83. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon.

Detailed Forecast

Synopsis

An elongated area of high pressure north of the Hawaiian Islands will maintain stable trades through Friday, then decrease slightly over the weekend. Shower activity will be limited through Sunday, with main focus along windward and mauka areas. A front will approach with an upper-level disturbance thereafter, stalling just northwest of the islands and may bring an increase of showers and clouds to Kauai during the early part of next week. A slow moving disturbance aloft will produce higher chances of heavy showers during the middle of next week as trades rebuild.

Discussion

An elongated area of high pressure north of the Hawaiian Islands remains set between two flanking areas of low pressure along the US west coast and along the International Dateline will maintain stable and locally breezy trades through the remainder of the week. This stability is well depicted in the latest upper-air balloon soundings launched around 12z (2 AM HST) from Lihue and Hilo, showing an inversion across the state between 5000 and 6000 feet today. As a result, many areas across the state remain relatively drive during the overnight period, with little to no precipitation recorded in the last 24 hours.
Trades will begin to decrease in strength ever-so-slightly over the next couple of days as the aforementioned high meanders eastward. Ridging aloft will continue to maintain stability, which lines up really well with the latest model guidance, suggesting dry conditions will prevail across the islands, with the exception of typical windward and mauka showers in association with the trades. Overall, not much change is expected through Friday.
As the weekend approaches, trades will ultimately diminish, with remaining winds now veering to the southeast. The ridging aloft will also start to erode away, reintroducing some sense of instability to the islands. Latest model guidance depicts the area of low pressure, originally along the Dateline, will propagating northeastward in the wake of the area of high pressure. As the low continues toward the Gulf of Alaska, it will usher a front into the vicinity of the islands. Models currently differ on the timing and position of the front, with the European model (ECWMF) stalling the front well off of Kauai. Conversely, the American model (GFS) portrays the front stalling overtop of Kauai, supporting a high chance of shower activity to the Garden Isle through early next week. Meanwhile, the remainder of the Hawaiian Islands should remain mostly dry with the exception of some daytime breezes producing spotty interior showers during the afternoon hours.
The remainder of the outlook period is full of uncertainty. Model guidance has been depicting a strong, zonal jet stream in the western Pacific bifurcating just west of the Dateline, both amplifying an upper-level trough as well as the subtropical jet over the state. Guidance displays this trough slowly moving over the state by midweek next week at differing magnitudes of strength, leaving quite a bit of uncertainty in the forecast. On one hand, this may result in increased instability and heavy rainfall potential; while on the other hand, some model hint at a surface high pressure redeveloping north of the state, suggesting trades reestablish. However, at this time, the uncertain pattern favors unstable and wet trade winds, with greatest emphasis of heavier rainfall over windward and mauka areas. That said, further analysis will be needed to refine the most likely solution given the low confidence.

Aviation

Trade winds will gradually decrease over the next few days as high pressure to the north begins to weaken. Limited shower activity is expected, with VFR conditions prevailing.
No AIRMETs are in effect at this time.

Marine

A high pressure system north of the islands will continue to build a surface ridge over the Hawaii region . Expect keep moderate to fresh trade winds blowing across Hawaiian waters through tonight, then decreasing wind speeds veering from a more southeasterly direction from Friday into the weekend. A low northwest of the islands will drive a weak cold front into the northwest offshore waters this weekend. Wind speeds will decrease and veer from a more southeasterly direction during this time period. Gentle to moderate trade winds return next week in an unsettled weather pattern due to a passing upper level disturbance.
A Small Craft Advisory (SCA) remains in place for the windier waters and channels around Maui County and the Big Island through tonight. Wind speeds will fall below advisory thresholds on Friday and the SCA will likely be cancelled before sunrise tomorrow.
A moderate, medium period north-northeast (010-030 degrees) swell continues to boost surf heights along north facing shores through tonight. This swell will peak today just below High Surf Advisory levels, before declining on Friday. A Marine Weather Statement remains in place for moderate harbor surges at Kahului and Hilo through tonight. A combination of the declining north-northeast swell and a small long period west-northwest swell will keep smaller surf in the forecast this weekend. West facing shores will see a tiny, moderate period west swell hold through the day. The next large long period northwest swell is expected over the first half of next week but stay tuned as the next system deepens northwest of the island chain.
Rough and choppy surf along east facing shores will gradually declining as trade winds ease over the next few days. Some wrap around energy from the medium period north-northeast swell will create choppy rough surf conditions along east sides of all islands. Surf along south facing shores will remain very small through the week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov