West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 87. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 70 to 77. Northeast winds 15 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs 82 to 87. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 90. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 71 to 78. Northeast winds 10 to 20 mph.

Monday: Sunny and breezy. Highs around 90. North winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 81 to 88 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Showers in the evening, then numerous showers after midnight. Lows around 73 near the shore to around 55 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 81 to 88 near the shore to around 70 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny and breezy. Highs 82 to 91. Northeast winds 10 to 25 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 84 to 92. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 69 at the visitor center to around 71 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 53 at the visitor center to around 48 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 67 at the visitor center to around 60 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 81 to 88 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Showers in the evening, then numerous showers after midnight. Lows around 73 near the shore to around 55 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 81 to 88 near the shore to around 70 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 76 to 84. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 66 to 71. Northeast winds 10 to 20 mph.

Monday: Mostly sunny. Isolated showers in the morning. Highs 76 to 84. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 75 to 91. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 63 to 77. East winds 10 to 20 mph. Chance of rain 40 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs 76 to 91. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trades persist through the morning with passing windward and mauka showers. Later today, a low-level trough associated with the remnants of former Tropical Cyclone Ivo will propagate across the islands, bringing increased clouds and shower activity predominately to the windward and mauka areas. By midweek, another plume of moisture is expected to passing into the region, again increasing clouds and showers. Otherwise, drier and more stable conditions prevail through the remainder of the week.

Discussion

Broad area of high pressure remains quasi-stationary north of the islands, allowing moderate to locally breezy trades to prevail with passing windward and mauka showers. Latest deterministic model guidance of the GFS and ECMWF are in strong agreement supporting a quick moving, low-level trough associated with the remnants of former Tropical Cyclone Ivo to propagate toward Maui County later this afternoon before shimmying northwestward.
As the trough approaches, relative humidity levels will increase slightly today into Monday as moisture associated with the trough begins to filter onto the islands. Trades will weaken briefly, maintaining light to moderate trades across the region. The trough will also bring a slight increase in instability to the region, allowing the inversion to lift around 8,000 to 9,000 feet. Expect an uptick in shower activity across windward Maui by Sunday evening, with the moisture plume spreading westward into Oahu and Kauai County Sunday night into Monday. Rainfall totals up to 0.25 inches across windward and mauka areas of the smaller islands with locally higher amounts possible within this fast moving system.
By Tuesday, the aforementioned trough exits the region, with high pressure quickly rebuilding in its wake, allowing moderate to locally breezy trades return. However, latest guidance now showcases another moisture plume propagating into the vicinity Wednesday, which may enhance cloud coverage and shower activity to windward and mauka areas again midweek. Otherwise, expect predominately dry and stable conditions to return for the latter half of the forecast period, with typical summertime conditions yielding limited clouds and showers across the state under moderate to breezy trades.

Aviation

Moderate to locally breezy trades persist through the forecast period. Brief periods of MVFR conditions possible in low ceilings and showers, predominately windward and mauka areas with limited leeward spillover. Otherwise, VFR conditions prevail
No AIRMETs in effect at this time, however, as a low-level trough moves into the region, AIRMET Sierra may become necessary for mountain obscuration due to incoming shower activity.

Marine

Persistent ridging north of the state will lead to a rather stable weather pattern with typical fresh to locally strong trades through a majority of the of the forecast period. The Small Craft Advisory (SCA) will remain in effect from the Kaiwi Channel eastward through this afternoon. Trades are forecast to weaken just below SCA thresholds tonight through early Monday morning as a weak trough from the remnants of Tropical Cyclone Ivo pass from east to west over the smaller islands. Moderate to locally strong trades will restrengthen Monday afternoon and maintain strength through the remainder of the week.
A 2 to 3 foot, medium period south southwest (180-200) swell will hold today and generate waist to chest high surf, near seasonal norms. A series of very similar small, medium period south swells will pass through the local waters through the work week. These swells will help to maintain seasonal surf heights along the south- facing shores, well below advisory thresholds.
Expect chop along east facing shores to remain elevated today, then lower tonight into Monday morning as trades weaken slightly. Fresh trades will once again bring elevated choppy conditions to east facing shores Monday afternoon through mid- week. Flat to tiny surf will persist along north facing shores through the forecast period.

Fire weather

Conditions should remain below critical fire weather thresholds into early next week. A low-level trough associated with the remnants of former Tropical Cyclone Ivo will move across the state later today through Monday, bringing an increase in humidity and shower activity. By midweek, another plume of moisture is expected in the vicinity of the islands, which may increase shower activity again on Wednesday. Otherwise, expect dry and stable conditions for the latter half of the week as high pressure rebuilds across the islands.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov