West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 77. East winds up to 15 mph. Chance of rain 20 percent.

Sunday: Sunny. Isolated showers in the morning. Highs 81 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Breezy. Mostly sunny with isolated showers. Highs around 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 70 to 78. North winds up to 15 mph. Chance of rain 20 percent.

Sunday: Sunny. Highs around 90. Northeast winds up to 15 mph.

North Shore

Today: Breezy. Mostly cloudy with showers likely. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 83 to 90. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 70 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 83 to 91. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly cloudy with scattered showers. Highs around 65 at the visitor center to around 69 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 51 at the visitor center to around 45 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 65 at the visitor center to around 67 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly cloudy with showers likely. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 83. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 65 to 70. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Sunny. Isolated showers in the afternoon. Highs 75 to 83. Northeast winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 90. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 62 to 76. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Sunny. Highs 74 to 90. Northeast winds 10 to 15 mph.

Detailed Forecast

Synopsis

Trade winds will push in moisture from an old front that will move across the islands through Saturday, while a cold pool aloft weakens the inversion and enhances showers and brings a slight chance of thunderstorms. Some enhanced showers may continue into Monday due to troughing aloft with trades focusing along windward areas.

Discussion

Visible satellite and radar shows an area of low clouds and showers over windward areas and waters. These showers are associated with an old front with breezy trades driven by the subtropical high. Cold air aloft is creating somewhat unstable conditions in the atmosphere over the western islands, which is enhancing the incoming showers. 00Z sounding at Lihue nearly 1000 J/kg mixed layer CAPE and decent precipitable water of 1.64 inches.
Trade winds will push in moisture from the old front through Saturday, while a cold pool aloft weakens the inversion and enhances showers and brings a slight chance of thunderstorms. Showers are expected to fill in a bit more overnight tonight and then shift focus on Maui and Big Island on Saturday and Saturday night. Sunday into Monday night a new upper low will track from the northeast over the islands and continue to enhance the trade wind showers from below. So expect a the wetter weather to continue especially for all windward areas.
Drier conditions expected Tuesday into Wednesday as the trades begin to taper off due to some disturbances moving across the northeast Pacific.

Aviation

The remnants of an old front are moving towards the island chain this afternoon on moderate to breezy easterly trade winds. As this feature approaches, an increase in clouds and showers along mainly windward and mountain locations is expected. The best chance for increased shower coverage and prevailing MVFR ceilings and visibilities will be tonight through early Saturday, especially for the western end of the state. An isolated thunderstorm or two can also not be ruled out for Kauai and Oahu through tonight.
Meanwhile, moderate to breezy trade winds will continue for the next several days. AIRMET Tango remains in effect for moderate low level turbulence over and downwind of island terrain. This AIRMET will likely through the weekend as breezy trades persist.

Marine

High pressure far north of the state will maintain moderate to locally strong trade winds through at least early Sunday, and a Small Craft Advisory (SCA) is in effect for the typically windy waters around the Big Island and Maui through that time. Trades will gradually weaken Sunday and Monday, and the SCA will likely be dropped. Trades should remain in the moderate to locally fresh range through the middle of next week, as developing low pressure northeast of the islands keeps the local pressure gradient somewhat weak.
A pair of south-southwest swells are expected during the coming week. Long period forerunners of the first swell will arrive tonight, and as 16 second energy builds during the day on Saturday, south shore surf should rise to around seasonal average by afternoon. The swell will peak Saturday night and Sunday, with surf remaining well below the High Surf Advisory level. As this swell declines early next week, a smaller south-southwest swell is expected to build on Tuesday and peak on Wednesday.
Small north and northwest swells are due through much of the week. As the current north swell fades on Saturday, a small northwest swell will build in. This swell will peak Saturday night and decline late Sunday. Recent guidance is depicting a sharp trough developing several hundred miles northeast of Hawaii on Tuesday and Wednesday, potentially generating a short period north-northeast swell that could reach the islands by Thursday.
East facing shores will experience near seasonal average surf through Sunday due to a mix of trade wind swell and the wrapping north swell. Even as local trade winds start to ease on Sunday, east shore surf should hold due to a narrow fetch of short period wind swell aimed at the islands. Surf along east facing shores will gradually decline Monday through Wednesday, followed by a potential increase on Thursday from the above mentioned source from the north-northeast.

Fire weather

Humidity levels and wind speeds will remain just below critical fire weather thresholds this week. A few periods of unsettled weather conditions will increase humidity levels, clouds and shower chances starting later this afternoon through Saturday, with another round from Tuesday morning into Wednesday. Temperature inversion heights near the Big Island and Maui today will range from 7,000 to 8,000 feet elevation.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov