West Side

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 88. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers. Highs 76 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 89. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 67 to 72. Northeast winds up to 15 mph.

Friday: Mostly sunny. Highs 78 to 89. Northeast winds 10 to 15 mph.

North Shore

Today: Breezy. Showers in the morning, then numerous showers in the afternoon. Highs 79 to 86 near the shore to around 66 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy with scattered showers. Lows 69 to 74 near the shore to around 54 near 5000 feet. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 81 to 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 69. East winds 10 to 15 mph.

Friday: Mostly sunny. Highs 82 to 89. East winds 10 to 15 mph.

Upcountry

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 54 to 69. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 46 at the visitor center to around 43 at the summit. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny with scattered showers. Highs 54 to 69. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Showers in the morning, then numerous showers in the afternoon. Highs 79 to 86 near the shore to around 66 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy with scattered showers. Lows 69 to 74 near the shore to around 54 near 5000 feet. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 70 to 80. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 59 to 67. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 70 to 80. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 71 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 59 to 74. East winds 10 to 15 mph.

Friday: Mostly sunny. Highs 72 to 89. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

A high pressure system remains locked in place north of the state for the next several days. Expect day to day changes in the trade winds speeds with increasing wind speed trends this weekend, peaking on Sunday near advisory thresholds in the breezy to locally windy range. Brief periods of passing showers will continue this week. Drier conditions are expected this weekend, followed by increasing shower trends again from Monday onward.

Discussion

The satellite imagery shows bands of fairly stable clouds drifting into the windward mountain slopes of each island on the moderate to locally breezy trade winds. A low level trough, currently west of a north to south cloud band shown on satellite at approximately 143W to 145W longitude, will continue to drift westward towards the islands. This easterly wave will pass through the islands from Thursday night into Friday, briefly increasing shower trends as it continues to drift westward down the island chain. Strong subsidence with stable dry air is evident following this low level trough, which will contribute to lower humidity levels with less clouds and near zero shower activity across the Hawaii Region this weekend.
In the big picture, the high pressure ridge will remain locked in place north of the Hawaiian Islands for the entire forecast period. Day to day changes in trade wind speeds are expected with moderate to locally breezy trade winds through Friday, strengthening to breezy to locally windy trades this weekend peaking on Sunday near Wind Advisory levels. Temperature inversion heights may drop to the 4,000 to 5,000 foot range this weekend, helping to increase wind speeds, and limit clouds and showers. Much lower humidity levels due to the drier air mass and locally windy trade winds will elevate fire concerns across the state on Sunday. Wind speeds drop back to more moderate to breezy levels from Monday onward.
Fairly stable cloud bands will continue to move into the islands today producing brief passing showers possible, mainly over windward and mountain areas. One wrinkle in the latest forecast guidance is the presence of an easterly wave, shown on 700 mb streamlines, moving into the islands on the trade winds from Thursday night into Friday. Model cross sections suggest this passing trough will lift the boundary layer with temperature inversion rising into the 8,000 to 9,000 foot range. At this level, deeper clouds will likely increase shower trends across all islands with some of the stronger showers drifting into the typically drier leeward areas. Rainfall amounts will still remain on the low side with the best chances for shower activity occurring during the typical overnight to early morning hours.
More stable trends develop this weekend as the ridge builds back into the Hawaii Region, decreasing island cloud cover and shower trends. Finally, expect a subtle increase in shower trends by early next week as a combination of upper (500 mb) and lower level (700 mb) troughing move into the region. This brief passing shower activity remains in the latest forecast of both operational and blended model guidance solutions through at least next week Thursday.

Aviation

Moderate to locally breezy trade winds will continue through Friday. Shower activity will be limited to windward and mountain areas, favoring the overnight to early morning hours.
AIRMET Sierra remains in effect for mountain obscurations along north and east slopes of Oahu, Molokai, Maui and the Big Island. These low cloud ceilings will likely diminish later this morning.

Marine

High pressure north of Hawaii will slowly move eastward and drive moderate to locally strong trades across the local waters. The Small Craft Advisory (SCA) for typically windier waters and channels near Maui and the Big Island has been extended until early Friday morning. Trade winds may weaken slightly Friday but then are forecast to strengthen this weekend as the high strengthens. SCA conditions may become more widespread over the weekend into early next week. Trade wind speeds could then decrease slightly by middle of next week.
A small, long period, south swell appears to be peaking early this morning and will hold through much of the day providing a slight boost in surf along south facing shores. Surf heights will gradually drop Friday into the weekend. Back to back pulses of slightly larger south swells are possible starting Monday which could build surf near to above advisory levels (10 ft) along south facing shores as early as Monday night into Tuesday then remain near to above average through much of next week.
Rough and choppy conditions along east facing shores may drop a notch Friday as winds ease slightly, but will pick up back up over the weekend and persist into early next week as winds strengthen. Surf will remain nearly flat along north facing shores.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Friday for the windier waters and channels near Maui and the Big Island.

Data Courtesy of NOAA.gov