Photo Credit: Jeni Ji Cousins

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 76 to 86. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 71. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 85. Northeast winds 20 to 25 mph decreasing to 10 to 25 mph in the afternoon. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Breezy. Highs around 85. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Lows 63 to 71. Northeast winds 10 to 15 mph.

Saturday: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 84. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

North Shore

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 68 near the shore to 46 to 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 78 to 85. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 64 to 69. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 85. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 60 at the visitor center to around 63 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 47 at the visitor center to around 42 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly sunny with scattered showers. Highs around 60 at the visitor center to around 63 at the summit. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 68 near the shore to 46 to 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Lanai City

Today: Breezy. Mostly sunny with isolated showers. Highs 70 to 78. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 60 to 65. Northeast winds 10 to 20 mph.

Saturday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 70 to 78. Northeast winds 10 to 25 mph. Chance of rain 30 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 65 to 86. East winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 55 to 72. East winds 15 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 64 to 85. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The high pressure center far north of the Hawaiian Islands will build today producing breezy trade winds across the region for the next several days. An upper level disturbance will enhance passing showers in the forecast into early next week, favoring windward and mountain areas in the overnight to early morning hours. A few of the stronger showers will drift into leeward areas. Long range guidance shows an old frontal band moving into the islands from the northeast by early next week Wednesday. This cloud band may bring another brief round of wet weather to all islands from Wednesday morning into Thursday.

Discussion

Radar imagery this morning shows a fairly wet weather pattern over most island windward and mountain areas. These enhanced shower trends will tapper off a bit by mid morning to afternoon, then a return to more showers later this evening. Satellite water vapor imagery continues to track an unstable upper low northwest of Kauai with an upper level trough lingering over the state. A subtropical jet stream is also evident near the islands. Upper level divergent forcing will continue to keep enhanced showers in the forecast for the next several days.
Two high pressure systems in the Central Pacific far north of the Hawaiian Islands will consolidate into one high center today. This high center will build slightly just north of the Hawaiian Islands and increase trade winds into breezy range into Monday. By Monday afternoon the high center begins to drift eastward away from the islands with a frontal trough moving into the Central Pacific basin. This change in large scale pressure patterns north of the islands will decrease trade wind speeds back to more moderate levels from Monday night onward.
Expect continued enhanced showers across the state as the unstable upper level disturbance slowly drifts eastward across the island chain. Most of the rainfall amounts will favor windward and mountain areas as breezy trade winds build clouds up and over the windward mountain slopes. Down sloping trade wind flow over the leeward sides of island mountain ranges will tend to decrease shower activity for leeward areas of each island. Shower trends will tend to increase during our typical diurnal rainfall maximum in the overnight to early morning hours.
In the extended forecast we continue to see a long band of unsettled shallow clouds, remnants of an old Eastern Pacific cold front, drifts into the islands on the moderate trade winds from Wednesday morning into Thursday. This cloud band may produce wet weather over all islands for an 18 to 24 hour time period. The highest rainfall amounts will tend to favor windward areas, however many leeward sites may also see measurable rainfall totals with this next system. This fairly shallow cloud band will likely not be deep enough to produce heavy rainfall, rather more beneficial rain is forecast for all islands. Rainfall chances were increased for the Wednesday into Thursday time period.

Aviation

Moderate to breezy E trades will continue to strengthen through today as high pressure builds in from the NE. A moisture plume riding the trades should bring in SHRA and MVFR conds to windward and mauka locations. While a few SHRA and lowering cigs/vsbys could reach leeward side, they look to be brief even with a slight increase in coverage. VFR conds should prevail.
AIRMET Sierra is in effect for mtn obsc for windward and mauka portions of the island chain.
AIRMET Tango is in effect for mod turb below 080 downwind of island terrain.
AMD NOT SKED in for Midway due to missing wind speed and direction

Marine

Latest ASCAT shows fresh to locally strong winds have arrived as a high pressure builds far north of the state. These stronger trades will continue through the weekend and drop a notch or two early next week as the high moves far northeast of the state. The Small Craft Advisory (SCA) for typical windy waters around Maui and the Big Island has been expanded to all waters through early Monday morning. Some area may drop out earlier as winds begin to ease due to the high shifting northeast.
Tiny surf will persist along north and west facing shores through much of today. Forerunners of a long period northwest swell is expected to fill in this afternoon and peak Saturday, bringing small surf along north and west facing shores. Another small, long period northwest swell will fill in late Sunday, maintaining small surf along north and west facing shores into early next week. Small background south swells will continue into Saturday, providing tiny surf for south facing shores. Forerunners of a small, long period south swell may arrive Saturday afternoon with a slow onset through Sunday providing a boost in surf along south facing shores into early next week. Rough and choppy surf along east facing shores will bump up a notch Saturday and hold hold into early next week as strong trades hold.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters,

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Data Courtesy of NOAA.gov