Photo Credit: Jeni Ji Cousins

West Side

Today: Sunny. Highs 77 to 83. Northeast winds around 10 mph.

Tonight: Mostly clear with isolated showers. Lows 59 to 64. Northeast winds around 10 mph. Chance of rain 20 percent.

Saturday: Partly sunny with scattered showers. Highs 77 to 83. Northeast winds around 10 mph. Chance of rain 40 percent.

South Side

Today: Sunny. Highs around 83. Northeast winds 10 to 15 mph.

Tonight: Mostly clear. Lows around 60. Northeast winds 10 to 15 mph.

Saturday: Mostly sunny with isolated showers. Highs around 83. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

North Shore

Today: Mostly sunny with isolated showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 63 near the shore to around 46 near 5000 feet. East winds around 10 mph. Chance of rain 20 percent.

Saturday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 63 near 5000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Central Maui

Today: Sunny. Highs 79 to 84. Northeast winds around 10 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows 58 to 63. Northeast winds around 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with scattered showers. Highs 79 to 84. Northeast winds around 10 mph. Chance of rain 40 percent.

Upcountry

Today: Sunny and breezy. Isolated showers in the afternoon. Highs around 59 at the visitor center to around 55 at the summit. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 42 at the visitor center to around 38 at the summit. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 59 at the visitor center to around 55 at the summit. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

East Maui

Today: Mostly sunny with isolated showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 63 near the shore to around 46 near 5000 feet. East winds around 10 mph. Chance of rain 20 percent.

Saturday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 63 near 5000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 70 to 77. Northeast winds around 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 61. Northeast winds around 10 mph.

Saturday: Partly sunny with scattered showers. Highs 71 to 78. Northeast winds around 10 mph. Chance of rain 30 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the afternoon. Highs 71 to 81. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 53 to 65. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Partly sunny with scattered showers. Highs 71 to 81. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Expect winds to increase a bit today as high pressure builds north of the state. Winds will further increase to moderate strength this weekend and push an area moisture over windward slopes, followed by brief drying late Sunday into Monday. Another increase in trade wind showers is possible late Monday and Tuesday.

Discussion

A ridge near Kauai will keep winds light this morning. Expect overnight land breezes to give way to daytime sea breezes by this afternoon, especially across the western islands, as light trade winds begin to spread westward. Cloud and shower coverage will increase across mauka areas with sea breeze development, followed by clearing at night. Models show surface high pressure will build north of the state while a front stalls and begins to dissipate just north of Kauai. Conditions will be rather dry at first, but moisture from the dissipating front may affect windward Kauai and Oahu beginning tonight.
Trade winds will continue to increase to moderate strength on Saturday as high pressure holds north of the state. Winds will shift out of the northeast on Sunday as a weak surface low approaches from the east. Moisture from the dissipated front should clear out, leading to a decrease in showers over all islands Sunday afternoon. An upper low dropping southward to the east of the state will produce increased north winds on the high summits of the Big Island.
Expect trade winds to remain in place through next week, possibly becoming breezy and gusty by Wednesday. The surface low will fall apart, but its remaining moisture will fuel windward rainfall for parts of the state late Monday and Tuesday, especially for the Big Island and Maui. Expect a boost in trade winds mid week as a reinforcing area of high pressure passes north of the state.

Aviation

A cold front approaching the islands from the northwest will keep a high pressure ridge in place over state. The stability under this ridge will limit shower activity today. Light large scale winds will allow local scale land breezes to continue this morning. Winds will begin to transition back to trade winds today with sea breezes lingering over terrain sheltered western slopes of each island. Isolated showers remain in the forecast mainly along convergence bands between the returning trade winds and the afternoon sea breezes.
No AIRMETs are in effect, and none are anticipated.

Marine

Light and variable winds will hold today over the western end of the state, while a return of moderate to fresh trades is anticipated over the eastern end. Trades are expected to fill in statewide tonight through the weekend, potentially reaching the strong category over the typically windier locations around Maui County and the Big Island, as high pressure builds north of the area in the wake of a passing front. Trades may shift to a more northeast direction early next week as the islands become positioned between low pressure passing to the southeast and the ridge to the north.
Surf along exposed north and west facing shores will trend up through the day today as a new, west-northwest swell builds down the island chain. Offshore buoy observations (51101/51001) quickly ramped up overnight (mostly in line with predicted levels). This swell has already reached the Hanalei buoy and should begin showing at the Waimea buoy (it's back in action – thanks to the PacIOOS folks) through the morning hours, beginning around or by sunrise. Guidance depicts the surf peaking tonight through Saturday above warning levels (XL category) followed by a gradual downward trend through the second half of the weekend. The warning has been issued for exposed north and west facing shores of the smaller islands and will need to be expanded to include the leeward section of the Big Island in the afternoon package today. Small Craft Advisory has been issued over western end of the state to account for the seas expected to reach the 10 ft threshold today, and will also need to be expanded down the island chain later today.
Although a downward trend is expected through the second half of the weekend, another long-period, west-northwest pulse arriving by Sunday night will support a return of advisory-level (if it dips below Sunday) surf Monday. Heights should then dip below advisory levels for north and west facing shores Tuesday through the second half of next week.
Surf along east facing shores may trend up over the weekend in response to a tight gradient that has setup between low pressure centered more than 1000 miles east of Hilo and high pressure to its north. Recent ASCAT data showed a packet of strong- to gale-force winds focused at the state north of the low. Guidance has this easterly swell arriving by Saturday night, then lingering into early next week before easing.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Saturday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 PM HST Saturday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

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Data Courtesy of NOAA.gov