Photo Credit: Tyler Rooke

West Side

Today: Partly sunny. Breezy. Highs 77 to 87. East winds 10 to 20 mph.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 66 to 72. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 77 to 86. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny in the morning then becoming partly sunny. Highs around 87. North winds up to 15 mph shifting to the northeast in the afternoon.

Tonight: Mostly cloudy. Lows 65 to 72. North winds up to 15 mph.

Saturday: Partly sunny. Highs around 86. North winds up to 15 mph.

North Shore

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Cloudy and breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 67 to 72 near the shore to 47 to 53 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 75 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 70 percent.

Central Maui

Today: Partly sunny. Breezy. Highs 79 to 86. Northeast winds 10 to 25 mph.

Tonight: Mostly cloudy. Breezy. Isolated showers after midnight. Lows around 67. East winds up to 20 mph. Chance of rain 20 percent.

Saturday: Partly sunny. Breezy. Isolated showers in the morning. Highs 80 to 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Partly sunny. Isolated showers in the morning. Highs around 63 at the visitor center to around 70 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 43 to 53. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 61 at the visitor center to around 69 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Cloudy and breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 67 to 72 near the shore to 47 to 53 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 75 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 70 percent.

Lanai City

Today: Partly sunny. Highs 70 to 79. Northeast winds 10 to 15 mph.

Tonight: Mostly cloudy. Lows around 64. Northeast winds up to 15 mph.

Saturday: Partly sunny. Isolated showers in the afternoon. Highs 70 to 79. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kaunakakai

Today: Partly sunny. Breezy. Highs 67 to 86. East winds 10 to 25 mph.

Tonight: Mostly cloudy. Breezy. Lows 56 to 72. East winds 10 to 20 mph.

Saturday: Partly sunny. Breezy. Isolated showers in the morning. Highs 66 to 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure ridge north of the islands will keep moderate to breezy easterly trade winds over the islands, peaking today and then decreasing slightly into the middle of next week. Clouds and showers will favor typical windward and mountain areas, trending higher in the overnight to early morning hours.

Discussion

Satellite imagery this morning continues to show a large band of high level cirrus clouds produced by the subtropical jet stream are spreading over the Hawaii region from west to east today. Fairly stable low level clouds are drifting over the islands in moderate to breezy easterly trade winds. These high level cirrus clouds may enhance sunrise and sunset colors through the weekend.
Trade winds will continue to blow across the Hawaiian Islands at moderate to breezy levels through much of next week. Breezy wind speeds will peak today as the high pressure ridge builds in slightly, and then decrease slightly by this weekend as the surface pressure gradient weakens a bit. Trade winds will drive clouds up and over windward island mountains into the middle of next week. Brief periods of showers remain in the forecast mainly over these windward and mountain areas, trending higher in the overnight to early morning hours. Drier leeward areas will see less clouds and only isolated showers due to the subsidence caused by the down sloping trade winds immediately leeward of the eastern mountain ranges of each island. Drying and warming effects produced by this small scale atmospheric compression tends to keep leeward areas more stable and dry in typical trade wind weather patterns.
Only subtle changes are expected in the day to day weather forecast for each island in a fairly stable trade wind weather pattern. Weak upper level troughing north and west of the island chain will bring a slight increase in passing shower activity this weekend, mainly over windward areas in the overnight to early morning time periods. The highest chances for clouds and showers statewide will linger over eastern Maui near Hana, and over the eastern slopes of the Big Island from the Hamakua Coast to Hilo to the Puna District.

Aviation

Moderate to breezy easterly trade winds will persist across the Hawaiian Islands into the weekend. Isolated to scattered showers will favor windward coasts and slopes, with greater coverage expected during the overnight hours. Brief MVFR conditions are possible in moderate showers. Otherwise, VFR conditions will prevail.
AIRMET Sierra for mountain obscuration remains in effect for windward areas of Kauai, Oahu and the Big Island this morning. Conditions may improve later today, but an uptick in windward showers tonight may require AIRMET Sierra once again. No other AIRMETS are in effect and none are expected.

Marine

High pressure will gradually build westward well to the north of the state today and tonight, keeping fresh to strong trade winds in place across the island chain. A Small Craft Advisory (SCA) remains in effect for most waters around Maui County and the Big Island as well as the northwest Kauai waters through 6 AM Saturday. For the windiest waters around Maui and the Big Island the SCA extends through 6 PM Saturday. A trough of low pressure will amplify and linger west of the islands this weekend into early next week, resulting in a slight easing of the trades and a shift to a more east-southeasterly direction over the western end of the state. Moderate to locally strong easterly trades will prevail over the eastern waters.
South shore surf will remain small and below the summer average through the middle of next week, with only small and inconsistent pulses of southwest swell expected. The next significant south- southwest swell (200 deg) appears to move in toward the end of next week. East shore surf will remain near the seasonal average through Friday, followed by a slight decrease this weekend through the middle of next week as the trades ease over and upstream of the islands. Surf along north shores will remain very small with a slight bump possible late Sunday through Monday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest Waters, Kaiwi Channel, Maui County Windward Waters.
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov