Hilo

Today: Mostly sunny with isolated showers. Highs 81 to 86 near the shore to 66 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 73 near the shore to around 57 at 4000 feet. Southeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny in the morning then becoming cloudy. Scattered showers. Highs 81 to 86 near the shore to 66 to 74 at 4000 feet. East winds around 10 mph. Chance of rain 30 percent.

Kona

Today: Mostly sunny. Scattered showers in the afternoon. Highs 83 to 89 near the shore to around 72 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly clear. Lows around 74 near the shore to 49 to 55 near 5000 feet. Light winds becoming southeast around 10 mph after midnight.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 83 to 89 near the shore to around 72 near 5000 feet. Light winds becoming west around 10 mph in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 69 to 89. Light winds. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 54 to 63 near 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 69 to 89. East winds around 10 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 69 to 89. Light winds. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 54 to 63 near 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 69 to 89. East winds around 10 mph. Chance of rain 20 percent.

South Big Island

Today: Sunny. Highs around 86 near the shore to around 69 near 5000 feet. East winds up to 10 mph in the morning becoming light.

Tonight: Mostly clear. Lows around 74 near the shore to around 52 near 5000 feet. East winds 10 to 15 mph.

Monday: Sunny in the morning then becoming partly sunny. Highs around 86 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph.

Puna

Today: Mostly sunny with isolated showers. Highs 81 to 86 near the shore to 66 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 73 near the shore to around 57 at 4000 feet. Southeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny in the morning then becoming cloudy. Scattered showers. Highs 81 to 86 near the shore to 66 to 74 at 4000 feet. East winds around 10 mph. Chance of rain 30 percent.

Waikoloa

Today: Sunny. Isolated showers in the morning. Highs 83 to 91 near the shore to 68 to 76 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 75 near the shore to 50 to 57 above 4000 feet. Light winds becoming south around 10 mph after midnight.

Monday: Sunny in the morning then becoming partly sunny. Highs 83 to 91 near the shore to 68 to 76 above 4000 feet. Light winds becoming northwest around 10 mph in the afternoon.

Detailed Forecast

Synopsis

A cold front will move in from the north this morning, stall near Maui tonight and dissipate Tuesday. Widespread rain and building trade winds are expected to accompany this frontal passage. An area of tropical moisture will move over the Big Island during the second half of this week.

Discussion

An east to west oriented cold front is moving south over the island of Kauai early this morning. Infrared satellite shows this front as a 200 mile wide band of showery low clouds with embedded thunderstorms along the southern edge. The 12Z Lihue sounding shows an unstable vertical profile with a precipitable water value of 1.75 inches. Showers have already picked up over the windward coastal waters of Kauai and Oahu this morning, and will move over both islands in the next couple of hours, and then over Maui County later today.
Trade winds will briefly strengthen today along the front due to high pressure building behind this boundary, but should begin to weaken by tonight. While the trades will focus more of the rainfall across windward areas, both windward and leeward areas of smaller islands will see widespread showers today. Isolated thunderstorms are also possible today and tonight across the smaller islands.
The front will pass Kauai by the end of today, and Oahu tonight with drier air moving in behind. The front will stall over Maui or the northern end of the Big Island on Monday and Tuesday and trades will keep showers moving across this area over the next couple of days as the front dissipates. The rest of the Big Island will stay a bit drier than the rest of the state.
An area of tropical moisture will pass to the south during the second half of the week. The the northern edge of this moisture will likely hit the Big Island Thursday through Saturday and focus showers across the windward and southeast portions of the island. Some of this moisture may spread far enough north that the trade winds will carry a small bit of it over the smaller islands.

Aviation

A front will move into the smaller islands today, bringing numerous to widespread showers and MVFR cigs/vsbys along with it. Windward areas will have the highest potential for reduced cigs/vsbys, with some IFR conditions not out of the question. The front will likely stall out somewhere in the vicinity of Maui County tonight, keeping unsettled conditions in place here, while some improvement will be possible over Kauai and Oahu.
Additionally, a few thunderstorms will be possible along and near the front today and tonight.
Drier conditions will prevail during the next 24 hours over the Big Island as the front should remain north of the area. A few convective showers can be expected as a result of daytime heating however.
AIRMET Sierra is in effect for mountain obscuration over windward sections of Kauai. This AIRMET will likely be required for additional areas, including leeward locales later today.

Marine

The southern advancement of a cold front across the northern Hawaiian offshore waters this morning will maintain moderate to fresh northeasterlies to the north of this boundary…moderate trades south of it. As the front nears the islands today, northeast winds will slightly strengthen over the windward coastal Kauai and Oahu (possibly Maui) waters. The front will stall out and dissipate over the state through Tuesday, with generally moderate easterly trades prevailing through the middle of the week. The mid to late week regional pressure will remain weak across the state from a Gulf of Alaska low blocking high pressure from re-establishing itself north of the area. This will result in late week light to gentle trades.
The recent moderate size, medium period northwest swell that lifted surf along the north-facing shores of Kauai, Oahu and Maui Saturday will shift to a more northerly direction today as it continues to decline through Monday. The next moderate size, medium period north to northeast swell originating from a low northeast of the islands will begin arriving Monday afternoon and evening. Surf associated with this swell should peak surf below High Surf Advisory (HSA) levels by late Monday and hold through Tuesday. A gale in the western Aleutians Sunday will push a north swell southeast toward the islands the next couple of days. This slightly larger, medium period swell may reach the state by Thursday and peak surf to near HSA heights along north-facing shores Friday. A small, medium period south swell arriving today will lead to slightly higher south-facing shore surf that will hold through mid week. Surf along east-facing shores will remain small through the upcoming week in response to lighter trades over and upstream of the islands.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov