West Side

Today: Cloudy. A 20 percent chance of showers in the afternoon. Highs 76 to 81. East winds up to 10 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 67 to 73. East winds up to 10 mph.

Friday: Partly sunny. A 20 percent chance of showers in the afternoon. Highs 76 to 82. East winds up to 15 mph.

South Side

Today: Partly sunny in the morning, then cloudy with a 20 percent chance of showers in the afternoon. Highs around 83. Light winds becoming north around 10 mph in the afternoon.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 67 to 74. North winds up to 10 mph.

Friday: Partly sunny. A 20 percent chance of showers in the afternoon. Highs around 84. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

North Shore

Today: Cloudy with a 20 percent chance of showers. Highs around 79 near the shore to around 67 near 5000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 71 near the shore to around 53 near 5000 feet. East winds up to 10 mph.

Friday: Partly sunny in the morning then becoming cloudy. A 50 percent chance of showers. Highs around 80 near the shore to around 66 near 5000 feet. East winds up to 15 mph.

Central Maui

Today: Partly sunny in the morning, then cloudy with a 20 percent chance of showers in the afternoon. Highs 79 to 84. Northeast winds up to 10 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows around 69. Northeast winds up to 10 mph.

Friday: Partly sunny. A 20 percent chance of showers in the afternoon. Highs around 82. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Upcountry

Today: Mostly cloudy with a 20 percent chance of showers. Highs around 62 at the visitor center to around 67 at the summit. Light winds.

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then partly cloudy after midnight. Lows around 50 at the visitor center to around 46 at the summit. East winds up to 10 mph.

Friday: Partly sunny with a 20 percent chance of showers. Highs around 62 at the visitor center to around 67 at the summit. East winds up to 15 mph.

East Maui

Today: Cloudy with a 20 percent chance of showers. Highs around 79 near the shore to around 67 near 5000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 71 near the shore to around 53 near 5000 feet. East winds up to 10 mph.

Friday: Partly sunny in the morning then becoming cloudy. A 50 percent chance of showers. Highs around 80 near the shore to around 66 near 5000 feet. East winds up to 15 mph.

Lanai City

Today: Cloudy. A 20 percent chance of showers in the afternoon. Highs 71 to 77. Light winds.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 63 to 68. Northeast winds up to 15 mph.

Friday: Partly sunny. A 40 percent chance of showers in the afternoon. Highs 71 to 78. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Kaunakakai

Today: Partly sunny in the morning, then cloudy with a 20 percent chance of showers in the afternoon. Highs 68 to 84. East winds up to 10 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 58 to 72. East winds around 10 mph.

Friday: Partly sunny. A 20 percent chance of showers in the afternoon. Highs 68 to 84. Northeast winds 10 to 15 mph.

Detailed Forecast

Synopsis

A low pressure system lingers far to the north of Hawaii this morning, supporting continued light and variable winds with chances for light to moderate showers today. A passing high pressure system will bring a brief return to easterly trade winds with subtle drying trends from tonight into Saturday. A series of low pressure systems passing just north of the state will produce light to moderate southeasterly winds from Sunday into the middle of next week along with enhanced shower trends over the western islands on Monday and Tuesday.

Discussion

Looking into the water vapor satellite imagery this morning we continue to see a divergent Sub Tropical Jet stream over the Hawaiian Islands producing extensive high level cirrus and middle level alto-cumulus clouds. These cloudy skies will linger into early next week with enough instability in the atmosphere to support brief chances for passing showers each day.
A high pressure system will pass by just north of the state later tonight into Saturday, briefly building in easterly trade winds across the region. Wind speeds will become strong enough to limit sea breezes to terrain sheltered leeward western slopes of each island. Subtle drying trends will develop during this time period due to a slight increase in subsidence, downward vertical motions creating warming and drying effects, making the atmosphere a bit more stable.
However, the return to easterly trade winds will be fleeting and vanish quickly by Sunday as a series of low pressure systems develop and break down the ridge north of the state. These passing lows appear to track far enough north to limit any heavy rainfall or flooding issues for the islands. A passing upper level trough may increase cloud and shower trends over the western islands of Niihau, Kauai, Oahu and Molokai from Monday through Tuesday. A weak ridge will settle in over the eastern islands producing a fairly stable southeasterly wind pattern across the region. Any additional enhanced showers in this wind driven pattern will favor southeast slopes of Maui and the Big Island with modest additional rainfall amounts. Elsewhere rainfall will be limited as the passing cloud bands will move more parallel to island mountains and the Big Island will produce a leeside rain shadow across much of the islands in Maui County.
The long range forecast guidance shows another round of returning easterly trade winds from next week Thursday into the following weekend. A building upper level ridge will keep shower activity to a minimum, with brief passing showers favoring the typical windward and mountain areas in the overnight to early morning hours.

Aviation

Southeasterly winds should back more easterly today. Can expect some windward and mauka SHRA. While MVFR conds can be expected in SHRA, VFR should prevail.
No AIRMETs in effect.

Marine

A trough lingering to our northwest will maintain gentle to moderate easterly trade winds through today. The strongest breezes will occur through the typical windy channels surrounding Maui and the Big Island. Building high pressure will support moderate to locally fresh easterly trades across the waters Friday into Saturday. Winds may briefly reach Small Craft Advisory thresholds on Saturday. A low pressure system developing to our NW on Sunday will cause the trades to weaken slightly and veer towards the ESE. Gentle to moderate ESE winds are expected Sunday into early next week.
A small, short-period, NNW swell will continue to fade out today. Small background energy from the west will be possible this weekend into early next week from Typhoon Sinlaku, but confidence remains low. A much larger northwest to west-northwest swell is possible towards the end of next week as Typhoon Sinlaku makes an extratropical transition early next week.
A small to moderate, medium-period, SSE swell will boost surf along S shores through Friday then lower over the weekend. Surf along E shores remains below the seasonal average as trades remain light. However, increasing trades by week's end should brings a slight bump to surf. Low pressure advancing S along the W coast of the US next week sends a small, medium period NE swell toward the islands by midweek.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov