Hilo

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 76 to 81 near the shore to 60 to 66 at 4000 feet. North winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 59 to 67 near the shore to 48 to 54 at 4000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 74 to 80 near the shore to 61 to 68 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Kona

Today: Sunny in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 79 to 85 near the shore to around 62 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 64 to 70 near the shore to 40 to 49 near 5000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 84 near the shore to around 64 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 57 to 81. North winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 57 to 62 near the shore to 49 to 58 near 3000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Saturday: Mostly sunny with isolated showers. Highs 60 to 81. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 57 to 81. North winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 57 to 62 near the shore to 49 to 58 near 3000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Saturday: Mostly sunny with isolated showers. Highs 60 to 81. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Today: Sunny in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs around 79 near the shore to around 61 near 5000 feet. Southwest winds up to 10 mph shifting to the south around 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Lows around 67 near the shore to around 45 near 5000 feet. North winds up to 10 mph. Chance of rain 40 percent.

Saturday: Sunny. Highs around 79 near the shore to around 64 near 5000 feet. East winds up to 15 mph shifting to the southeast in the afternoon.

Puna

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 76 to 81 near the shore to 60 to 66 at 4000 feet. North winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 59 to 67 near the shore to 48 to 54 at 4000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 74 to 80 near the shore to 61 to 68 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs 78 to 85 near the shore to 60 to 66 above 4000 feet. Southwest winds up to 10 mph shifting to the northwest around 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly clear. Lows 62 to 71 near the shore to 41 to 51 above 4000 feet. Southeast winds up to 10 mph in the evening becoming light.

Saturday: Sunny. Highs 77 to 84 near the shore to 62 to 68 above 4000 feet. Southwest winds up to 10 mph shifting to the northwest around 10 mph in the afternoon.

Detailed Forecast

Synopsis

A deep low pressure system north-northeast of the state this morning will keep light background north to northeasterly winds in the forecast today. A passing upper level trough has drifted east of the Big Island this morning. More stable conditions will prevail into Sunday, as the low drifts further northward away from the island chain. Another low pressure system moves into the region far north of the state, keeping light winds in the forecast through next Thursday. Rainfall trends increase on Monday and Tuesday across the state as an upper level disturbance passes from west to east across the region. Drier trends return on Wednesday and Thursday in a light wind weather pattern.

Discussion

A large cut off low pressure system located roughly 800 to 850 miles north-northeast of Oahu will continue to slowly drift northward away from the state today. This mornings satellite imagery shows a strong upper level trough extending south from the low center producing numerous thunderstorms along the eastern flank of the trough axis. This trough has passed to the east of the Big Island this morning and more stable trends will fill in for most islands. A small area of instability with colder (higher) cloud tops is moving into Kauai this morning with a slight enhancement to shower activity expected along the northern and mountain slopes of the Garden Isle. Big Island Summit winds have fallen and will remain below advisory thresholds today, thus the Wind Advisory for Mauna Kea and Mauna Loa was cancelled with the morning weather package.
Stable and drier conditions will return for most of the state into the weekend. Light northerly winds will veer easterly on Saturday, with only isolated showers expected. As the background winds shift more southerly on Sunday, we could see a slight increase in showers around Kauai.
Another round of unsettled weather remains in the forecast on Monday and Tuesday as an upper level trough moves into the region from the northwest. The GFS and ECMWF models have yet to come into agreement if an associated weak cold front will reach the islands, which gives higher chances for increased rainfall for Kauai and Oahu. Weak surface ridging north of the state points toward lighter winds for the middle of next week. Elevated shower trends remain in the forecast for the first half of next week.
Light and variable winds continue on Wednesday and Thursday as low pressure systems passing north of the region continue to break down the high pressure ridge north of the islands. Shower activity during this period remains in the isolated to scattered range and developing showers will tend to favor island mountain and interior sections in the afternoon hours.

Aviation

Drier and more stable conditions will drift back across the islands from west to east today, while a surface trough lingers east of the state and a strong area of low pressure exits well north of the islands. This pattern will continue the potential for some showers and isolated thunderstorms over southeastern portions of the Big Island through this evening. Otherwise, the weak wind field in place through Saturday will allow for the development of diurnal land and sea breeze circulations, focusing clouds and isolated showers to windward and interior locations. Mainly VFR conditions are expected at TAF sites through the period, with some MVFR cigs possible in showers.
AIRMET Tango for moderate upper-level turbulence remains in effect across the state as upper jet dynamics strengthen in the region. These turbulent conditions are expected to diminish this afternoon.

Marine

No major changes to the marine grids with the morning package. Low pressure to the northeast of the state continues to bring light northerly winds to the region. An upper level trough to the east of the islands continues to bring thunderstorms to some of the eastern offshore waters. Expect both the low and the upper trough to continue to move to the east today.
High pressure passing north of the area Saturday and Saturday night should support some light to locally moderate trade winds, before a front approaches from the northwest. The front will enter the northwest offshore waters Sunday night, bringing southerly winds ahead of the front to the coastal and offshore waters Sunday and Monday. A new high will move in north of the area Monday night and Tuesday with northeast trade winds returning once again.
The current northwest swell continues to fill in, and appears to be peaking at the Hanalei and Waimea Bay buoys. Looking for the swell to gradually lower over the weekend. A High Surf Advisory remains posted for most north and west facing shores from Maui westward. The above mentioned low pressure system will send a small, short period north northeast swell which will move across the area over the next few days. The next northwest swell is expected to fill in on Tuesday, peak Tuesday night and early Wednesday, then lower gradually Wednesday night and Thursday. Surf heights may reach low end advisory levels during the peak of this swell. Mainly background south swells are expected through Tuesday with a slightly larger and longer period south swell possible on Wednesday and Thursday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Saturday 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.

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Data Courtesy of NOAA.gov