Photo Credit: James Grenz

Hilo

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. North winds up to 10 mph. Chance of rain 80 percent.

Monday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Partly sunny. Scattered showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 71 near the shore to 48 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Mostly cloudy with scattered showers. Highs 65 to 84. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy with scattered showers. Highs 65 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly cloudy with scattered showers. Highs 65 to 84. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy with scattered showers. Highs 65 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Partly sunny. Breezy. Isolated showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 71 near the shore to around 51 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. North winds up to 10 mph. Chance of rain 80 percent.

Monday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Highs 79 to 87 near the shore to 65 to 72 above 4000 feet. North winds up to 10 mph.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 67 to 73 near the shore to 49 to 55 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny in the morning then becoming partly sunny. Highs 79 to 87 near the shore to 65 to 72 above 4000 feet. North winds up to 10 mph.

Detailed Forecast

Synopsis

Expect breezy trade wind conditions to continue into the middle of the week as high pressure persists to our north. Cloud cover and scattered showers will favor windward and mountain areas, but leeward areas my also get wet from time to time given the strength of the trades. Trades may decrease around the middle of the week as a weakness develops in the subtropical ridge.

Discussion

A broad area of overcast low clouds lies across the islands this morning and will likely linger through this afternoon. Radar shows isolated to scattered showers within this cloud cover, favoring windward areas but, with the breezy trades, blowing leeward from time to time. Overnight soundings continue to show a neutral airmass with a strong inversion near 6500 feet, likely capping deep convection and keeping total rainfall light. Beneath the inversion, misty showers will continue to occur across almost all of the islands until the the overcast cloud area passes west of the islands later today or this evening.
High pressure northeast of the state will continue to drive moderate to locally strong trade winds into the middle of the week, with little variation in speed. Scattered light showers will mainly affect windward and mountain areas of the islands. Models continue to show the potential for a decrease in trade winds around the middle of the week due to a weak surface trough moving eastward north of the state, creating a weakness in the subtropical ridge.
Models show that trades will stay around through the end of the week, but differ on wind strength. We will continue to use a model blend for winds in the extended period, keeping the slightly weakened trades in place into next weekend. Models also show an upper trough over or near the state toward the end of the week, but differ in its strength and location. This could at least weaken the strong inversion and allow for more vertical cloud development, though confidence remains low on trough location and specific impacts at this time.

Aviation

Breezy easterly trade winds will continue into Monday as a strong ridge of high pressure remains in place north of the islands. This moist trade wind pattern will continue to force a majority of showers and low level clouds toward favored windward and mauka areas. The radar trends this morning support the idea of rain showers stretching across windward slopes and in channels between mainly the central and eastern islands, in weakly organized convergent low level flow. Additionally, sea breeze clouds and isolated showers are expected once again today across leeward Big Island. A mix of VFR/MVFR cigs continue across TAF locations this morning, though cigs will continue to deteriorate toward more widespread MVFR conds as the band of moisture north of the islands becomes concentrated along windward zones. AIRMET Sierra continues for tempo mtn obsc across most wind ward zones through this afternoon.
AIRMET Tango remains in effect for moderate low level turbulence below 8000 feet over and downwind of the terrain for all islands. These turbulent conditions are expected through today.

Marine

The large, long-period northwest swell (330 degrees) is expected to peak this morning. A High Surf Advisory remains in effect for exposed north and west facing shores of the smaller islands through tonight. Expect the surf to then gradually lower through Tuesday, and remain small through much of the remainder of the week. A moderate, long period south swell (170-180 degrees) will boost surf to slightly above seasonal averages today, before gradually lowering during the start of the new work week.
High pressure to the northeast of the islands continues to bring locally strong trade winds to the region, and this is expected to continue over the next several days. These winds will continue to produce moderate, choppy surf along east facing shores. A surface trough approaching from the northwest will first enter the offshore waters around Wednesday, and help to weaken the pressure gradient over coastal and offshore waters during the middle to latter half of the week leading to a decrease in wind speeds.
A Small Craft Advisory (SCA) is in effect for all Hawaiian coastal waters through today for a combination of the locally strong trade winds and seas generated by the northwest swell mentioned above. As the northwest swell declines tonight, the SCA will be scaled back to the typically windier waters near Maui County and the Big Island. The SCA for the winds may need to be extended into the middle of the week, however will hold off on that extension to monitor the trend of the winds in the model with the approaching trough mentioned above.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Monday 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 Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov