Hilo

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 69 to 74 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy with numerous showers. Lows around 71 near the shore to around 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy with scattered showers. Lows 72 to 77 near the shore to around 58 near 5000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with isolated showers. Lows 72 to 77 near the shore to around 58 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 71 near the shore to 60 to 66 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows around 71 near the shore to 59 to 65 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 71 near the shore to 60 to 66 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows around 71 near the shore to 59 to 65 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73 near the shore to around 56 near 5000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to around 73 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 73 near the shore to around 56 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 69 to 74 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy with numerous showers. Lows around 71 near the shore to around 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 75 near the shore to 54 to 61 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tuesday: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 30 percent.

Tuesday Night: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to 54 to 61 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally breezy trade winds will continue to bring humid and somewhat wet conditions tonight, especially for windward areas. Drier trade wind weather will prevail Tuesday into the weekend, with moderate showers focused over windward slopes.

Discussion

After a very wet night for most windward areas, diurnal trends led to a significant decrease in rainfall by mid-morning, and during the past 3 hours, only a few stations on Kauai have registered more than a quarter of an inch of rain. Isolated heavy showers are flaring on the upper slopes of Mauna Loa this afternoon, but other leeward areas have seen little shower activity today. The fuel for the rainfall is moisture accompanying a mid-level trough that is drifting westward over the island chain. Precipitable water remains quite high, between 1.6 to 2 inches based on satellite and sounding data, and an increase in shower frequency is expected over windward areas tonight. With some drier trade wind flow moving in from the east and undercutting the moisture, rainfall totals should be significantly less than last night. However, expect humid conditions to linger as dew points remain elevated in the low to mid 70s.
The deeper moisture will move off to the west on Tuesday, bringing a less active shower pattern. Surface high pressure north of the state will drive moderate to locally breezy trade winds, with a brief decline in the trades possible around Thursday and Friday. While a ridge aloft will bring stability, the mid- level trough will linger nearby into Wednesday, which will keep shower chances a bit higher than normal. However, dew points will fall into the upper 60s over most leeward areas, bringing some relief from the humidity. Drier conditions are due Thursday and Friday and likely into Saturday.
While a ridge aloft will maintain stability over the islands through much of the week, an upper-level trough will persist to the west. The main effect of this feature will be periods of high clouds overhead. Models suggest that a low aloft may develop Sunday and Monday and north of Kauai. At this time, it does not look like it will affect local weather significantly.

Aviation

For the windward terminals expect scattered showers bringing temporary MVFR conditions through tonight and early Tuesday morning. Elsewhere and otherwise, VFR conditions are expected to prevail.
With locally breezy trade winds prevailing across the state, AIRMET Tango remains in effect for low-level turbulence over and downwind of terrain. This AIRMET will likely continue through Tuesday.

Marine

Moderate to locally strong trade winds will continue through Wednesday as strong surface high pressure remains to the north northeast of the islands. Winds are then expected to decrease slightly to moderate levels after Wednesday as the surface high pressure slightly weakens and moves east. A Small Craft Advisory (SCA) is in effect for all waters surrounding Maui County and the Big Island through tonight, and then the typically windy waters around the Big Island and Maui County through Tuesday night. The SCA may need to be extended through Wednesday.
Surf along east facing shores will remain choppy through Wednesday, then decrease thursday and Friday as trade wind speeds decrease. Surf across the other shores will be below seasonal averages through the week. A small southwest pulse out of the Tasman Sea could produce a slight rise in surf Friday. Aside from trade wind wrap, surf along north facing shores will be minimal through Wednesday, and a tiny northwest swell will be possible Thursday or Friday. Then a slightly larger northwest swell will be possible by late Monday next week.
The combination of seasonally high astronomical tides and water levels running around 6 inches higher than predicted will produce localized coastal inundation through Tuesday afternoon. A Coastal Flood Statement has been issued to highlight these conditions.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov