Photo Credit: James Grenz

Hilo

Today: Frequent showers in the morning, then frequent showers and slight chance of thunderstorms in the afternoon. Highs 79 to 86 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Frequent showers and slight chance of thunderstorms early in the evening, then numerous showers in the late evening and overnight. Lows 65 to 73 near the shore to 55 to 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 90 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 87 near the shore to 65 to 72 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Kona

Today: Mostly sunny with scattered showers in the morning, then partly sunny with scattered showers and slight chance of thunderstorms in the afternoon. Highs 85 to 91 near the shore to around 72 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows around 75 near the shore to 50 to 56 near 5000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 85 to 90 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs 65 to 86. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers and slight chance of thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows 65 to 74 near the shore to 57 to 65 near 3000 feet. East winds up to 20 mph. Gusts up to 40 mph after midnight. Chance of rain 70 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to 70 to 81 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs 65 to 86. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers and slight chance of thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows 65 to 74 near the shore to 57 to 65 near 3000 feet. East winds up to 20 mph. Gusts up to 40 mph after midnight. Chance of rain 70 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to 70 to 81 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Partly sunny. Breezy. Scattered showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 87 near the shore to around 69 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers and slight chance of thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows around 75 near the shore to around 53 near 5000 feet. Northeast winds up to 25 mph increasing to 10 to 25 mph after midnight. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 87 near the shore to 66 to 71 near 5000 feet. East winds up to 25 mph. Chance of rain 40 percent.

Puna

Today: Frequent showers in the morning, then frequent showers and slight chance of thunderstorms in the afternoon. Highs 79 to 86 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Frequent showers and slight chance of thunderstorms early in the evening, then numerous showers in the late evening and overnight. Lows 65 to 73 near the shore to 55 to 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 90 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 87 near the shore to 65 to 72 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny with scattered showers in the morning, then partly sunny with scattered showers and slight chance of thunderstorms in the afternoon. Highs 85 to 91 near the shore to 68 to 73 above 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Breezy. Scattered showers and slight chance of thunderstorms early in the evening, then isolated showers in the late evening and overnight. Lows around 76 near the shore to 53 to 58 above 4000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 85 to 91 near the shore to 67 to 74 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Expect increasing showers state-wide today, mainly across windward areas, with the greatest shower coverage expected over windward Big Island and east Maui. Leeward areas, including the Lahaina and Kula areas of Maui, will remain mostly dry with a few light showers possible. Breezy and increasingly dry trade wind weather will return Tuesday through the rest of this week.

Discussion

Recent satellite and radar imagery show increasing clouds and showers moving into windward areas of most islands early this morning, associated with the remnant moisture from former Tropical Cyclone Fernanda. The greatest shower activity is occurring over the windward coasts and slopes of the Big Island, where 0.01 to 0.25 inches of rain has already fallen in some locations over the last 6 hours.
As we head through the rest of this morning, windward areas of the Big Island and Maui will continue to see the bulk of the rainfall. Despite decreasing trends in model rainfall amounts, we could still see event totals around 2 to 4 inches of rain over windward Big Island through tonight. Brief periods of heavy rain are possible during this time, which could lead to some nuisance- level flooding. On Maui, 1 to 2 inches of rain will be possible, primarily focused over the east Maui windward slopes and coastal areas. Leeward areas of Maui (including Lahaina and Kula) will remain mostly dry, with a few light showers possible through the evening hours. For rest of the state, mainly light to moderate showers are expected to move into windward and mountain areas through Tuesday morning. Humidity levels will be higher than normal during this time, which will make daytime temperatures feel hotter than usual.
Trade winds will also trend up over the next couple of days as surface high pressure far north of the state strengthens and drifts slightly farther south. Moderate wind speeds this morning will steadily rise to breezy levels through tonight. Tuesday afternoon through Wednesday, the atmosphere will dry out, as a mid-level ridge develops over the area. A mostly dry and breezy trade wind regime will likely hold through the rest of this week.

Aviation

Moderate to breezy easterly trade winds will continue, with clouds and showers favoring windward and mountain areas. Shower coverage has been steadily increasing overnight, which will continue today as an area of deep tropical moisture moves in. Expect periods of MVFR CIGs/VSBYs for windward and mauka areas, especially for the eastern end of the state. Elsewhere, VFR conditions will prevail.
AIRMET Sierra for mountain obscuration is now in effect for the windward areas from Oahu to the Big Island, which may continue through a good portion of the day today.

Marine

Trade winds will gradually increase today as a surface high centered about 1600 nm NNE of the islands strengthens, and the remnant of Fernanda passes well S of the islands. Fresh to locally strong trade winds are then expected to continue through the week, and a Small Craft Advisory will remain in effect for the windier zones around Maui and the Big Island.
Surf along all shores will remain relatively small today. A long- period E swell generated by former major Hurricane Hilary in the distant E Pacific is expected to arrive by tonight, peak near 4 feet Tuesday and Wednesday, then lower Wednesday night and Thursday. Confidence remains low in the details, but E shore surf will likely remain below advisory-levels, with the largest surf focused on the Big Island and Maui. As the longer-period E swell diminishes, short-period trade wind swell will build to near seasonal norms. A small, medium-period SSE swell (with a pinch of SW swell energy as well) will bring small surf to S facing shores the next couple of days.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM 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