Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 82. Northeast winds 15 to 30 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows 62 to 68. Northeast winds 15 to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 75 to 82. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 83. Northeast winds 10 to 25 mph.

Tonight: Mostly clear. Breezy. Lows around 64. Northeast winds 10 to 20 mph decreasing to up to 15 mph after midnight.

Thursday: Mostly sunny. Highs around 83. Northeast winds up to 15 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 81 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to around 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 81 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 79 to 84. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 64. Northeast winds 10 to 25 mph.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 79 to 84. East winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny and windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 51 to 70. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Windy. Mostly clear with scattered showers. Lows 41 to 52. East winds 10 to 30 mph. Chance of rain 40 percent.

Thursday: Sunny and windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 51 to 70. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 40 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 81 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to around 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 81 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

Lanai City

Today: Sunny and breezy. Highs 70 to 77. Northeast winds 15 to 25 mph.

Tonight: Mostly clear. Breezy. Lows around 62. Northeast winds 10 to 25 mph.

Thursday: Mostly sunny. Highs 70 to 77. East winds up to 15 mph.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 80. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 64 to 72. East winds 15 to 25 mph.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 74 to 80. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy to windy trades will persist today and then show decreasing trends from Thursday onward. A fairly stable atmosphere will allow just a few passing showers to develop, mainly over windward and mountain areas, favoring the overnight to early morning hours. Winds will weaken and shift from a more southeasterly direction by this weekend, allowing sea breezes to expand in coverage along terrain sheltered western mountain slopes. An upper level low moving into the Hawaii Region from the northwest may enhance shower activity across the state from Saturday into early next week.

Discussion

A few bands of low topped clouds are seen on the latest satellite imagery this morning moving into each island on the trade winds. Local doppler radar imagery shows scattered showers drifting into windward island mountains. Brief passing showers will continue through the early morning hours as these cloud bands are forced up our island mountain slopes. Daytime diurnal drying trends will decrease shower activity after 8 AM HST this morning with more isolated showers forecast until the evening hours. Large scale subsidence (downward moving air) from the high pressure ridge aloft will tend to limit shower production over the Hawaii Region over the next several days. The atmosphere remains fairly stable with temperature inversion heights, as measured from weather balloon soundings at 2 AM HST (12Z) this morning, are hovering around the 5,000 foot level at both Lihue and Hilo. These low temperature inversion heights will continue to limit vertical cloud heights and shower activity through Friday.
A strong high pressure system just north of the Hawaiian Islands will continue to produce breezy to windy trades today. The current Wind Advisory for windier areas of Maui County and the Big Island was extended in time until this evening to cover these strong and gusty winds. Wind speeds will noticeably decrease on Thursday and decrease even lower on Friday as the high pressure system north of the island chain drifts slowly eastward farther away from the state. Sea breezes will expand in coverage over all islands by this weekend as large scale trade winds weaken. A hybrid sea breeze and east to southeast wind pattern will produce some wind convergence boundaries and cloud build ups over each island by this weekend.
A weakening cold frontal system approaches the islands from the northwest direction from Thursday to Friday. This system will stall out several hundred miles west of Kauai. Cold air surrounding this system will form an upper level cold core low that will be cut off from the mid-latitude westerlies. This cut off low will slowly drift eastward towards Hawaii over the weekend. Cold temperatures and wind divergence aloft along the east side of the low will weaken the large scale subsidence over the western half of the state, allowing deeper clouds and enhanced showers to develop in this pattern. This upper low will weaken the surface ridge, causing wind speeds to decrease and winds to veer from a more east to southeast direction. Any enhanced showers will tend to form along any wind convergence boundaries in a hybrid sea breeze wind pattern, or leeside island convergence plumes that may potentially be drawn northward into the smaller islands. Instability aloft associated with the cut off low will deepen cloud convection along these boundaries and possibly produce some periods of moderate to locally heavy shower activity. The chances for enhanced showers will increase for the western islands as they are much closer to the low center. Enhanced showers are also expected along east and southeast slopes of the Big Island from Sunday into the first half of next week.
The latest long range model solutions and blends continue to show the upper low and the associated surface trough reflection stalling out near Kauai from Sunday through Tuesday. This means this unsettled weather pattern over the western islands may continue through the first half of next week. Stay tuned.

Aviation

High pressure north of the islands will maintain breezy to strong trade winds across the region. AIRMET Tango remains in effect for moderate low level mechanical turbulence to the lee of the mountains. As breezy trades are expected to persist, this AIRMET will likely remain in place over the next couple of days.
Bands of clouds and light showers off the Pacific will impact mainly north and east facing slopes and coasts. Showers will be most active in the late night and morning hours.
AIRMET Sierra for mountain obscuration is currently in effect for windward exposures of Kauai and Oahu. Conditions are expected to persist through the morning hours, but VFR conditions should prevail statewide by mid afternoon.

Marine

Strong high pressure far north of the state will drift slowly eastward keeping strong to locally near gale force winds today before declining slowly through Thursday. The Gale Warning for Maalea Bay and the Pailolo and Alenuihaha Channels has been downgraded to a Small Craft Advisory and will remain for all zones due to strong trades and elevated seas through the day. A trough looks to develop northwest of the state, which will cause the trade winds to veer toward the east by Friday. Moderate to fresh east to east- southeast winds will likely persist through the weekend.
A moderate size, medium to long period north northwest (330 degree) swell will build through the day, peak this afternoon, and decline Thursday. Long period forerunners have begun to arrive early this morning at PacIOOS Hanalei Buoy as surf looks to peak this afternoon just below High Surf Advisory criteria for north and west facing shores. A similar sized west northwest (300 to 320 degree) swell is scheduled to arrive Thursday night and peak Friday at or near High Surf Advisory levels.
Surf along east facing shores will remain rough and choppy just below High Surf Criteria due to strong trade winds over and upstream of the islands through Thursday before declining slightly Friday and into the weekend.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST this evening for all Hawaiian waters,

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Data Courtesy of NOAA.gov