Hilo

Today: Mostly cloudy with numerous showers. Highs 76 to 82 near the shore to 62 to 67 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Numerous showers in the evening, then frequent showers after midnight. Lows 63 to 70 near the shore to around 56 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Sunday: Cloudy. Frequent showers in the morning, then frequent showers and slight chance of thunderstorms in the afternoon. Highs 75 to 80 near the shore to 61 to 66 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Kona

Today: Partly sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 69 to 74 near the shore to 49 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Partly sunny. Scattered showers and slight chance of thunderstorms in the afternoon. Highs 81 to 86 near the shore to around 67 near 5000 feet. Light winds. Chance of rain 30 percent.

Waimea

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 63 to 84. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 64 near the shore to 55 to 62 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Breezy. Numerous showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs 62 to 84. East winds 10 to 25 mph. Chance of rain 70 percent.

Kohala

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 63 to 84. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 64 near the shore to 55 to 62 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Breezy. Numerous showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs 62 to 84. East winds 10 to 25 mph. Chance of rain 70 percent.

South Big Island

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon.

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

Sunday: Partly sunny. Breezy. Scattered showers and slight chance of thunderstorms in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 30 percent.

Puna

Today: Mostly cloudy with numerous showers. Highs 76 to 82 near the shore to 62 to 67 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Numerous showers in the evening, then frequent showers after midnight. Lows 63 to 70 near the shore to around 56 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Sunday: Cloudy. Frequent showers in the morning, then frequent showers and slight chance of thunderstorms in the afternoon. Highs 75 to 80 near the shore to 61 to 66 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Waikoloa

Today: Partly sunny. Breezy. Highs 78 to 87 near the shore to 64 to 70 above 4000 feet. Northeast winds up to 25 mph.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 67 to 74 near the shore to 50 to 56 above 4000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs 78 to 87 near the shore to 64 to 70 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Fresh to strong trade winds will continue into the new week, with an uptick in wind speeds starting Sunday. Showers will favor windward and mauka this morning. Look for a wetter, more unstable airmass expected Sunday into Wednesday with an upper level disturbance approaching from the north.

Discussion

No significant changes to the forecast with the morning package. Cleaned up some erroneously high winds on the Big Island and Oahu today and tonight. Winds will be on the increase, but that increase is expected Sunday, with some areas like the Kohala Mountains on the Big Island approaching wind advisory levels.
The upper level trough to the north of the islands and the one to the far west continue to usher in high clouds over the islands in the westerly upper level wind flow over the islands. The feature to the north is expected to sink southward, and will bring with it some instability.
High pressure far to the northeast is still expected to strength later tonight and Sunday which will result in an uptick in our trade winds. As mentioned above, some areas will approach advisory levels. At this time no wind advisories have been posted, but will be monitoring the situation.
The upper level trough to the north will begin to have an impact on the rain chances beginning Sunday. The trough will erode the trade wind inversion, allowing cloud tops to rise, leading to enhanced showers. The stronger trade wind will help to push showers to interior and leeward areas. The instability associated with the upper trough will bring the possibility of some thunderstorms near the islands. The instability combined with the natural forcing on the Big Island will lead to that end of the state having the greatest chance for some thunderstorms. Currently the greatest chance is for Sunday afternoon and evening, possibly into Monday, which is reflected in the forecast. The ECMWF has continued to be wetter and more unstable that the GFS. The latest runs of the high resolution models are beginning to go out into Sunday afternoon, and agree in general with the global models of the best chance being near the Big Island.
The upper low is expected to linger into Wednesday or Wednesday night keeping the more active trade wind driven showers through at least the middle of the week.

Aviation

Moderate to locally strong trade winds will persist through twenty-four hours and beyond. Low topped clouds and light showers will favor east and northeast facing slopes and coasts, especially during the late night and morning hours. In the afternoon and early evening, leeward sea breezes will help to focus most shower activity over island interiors.
AIRMET Sierra for mountain obscuration is currently in effect for Windward Big Island south of Laupahoehoe. Conditions are expected to persist through late morning and possibly beyond. Elsewhere, VFR conditions will prevail except for brief MVFR in passing showers.
The AIRMET for low level mechanical turbulence immediately south through west of higher terrain has been expanded to include all islands, and will likely remain necessary through the remainder of the weekend. The AIRMET for moderate upper level turbulence also remains in effect, but conditions are expected to improve later today as the associated jet streak slowly exits to the east.

Marine

A surface high centered far northeast of the islands is expected to build as it moves slowly westward over the next day or two, sustaining fresh to locally strong trade winds. Currently, the Small Craft Advisory (SCA) is in effect for the windier waters around Maui County and the Big Island. However, the SCA will likely need to be expanded to more waters by Sunday.
A small northwest swell arriving today will likely cause a modest increase in surf heights along exposed north and west facing shores of the smaller islands this weekend. A new moderate, long- period northwest swell arriving Sunday night into Monday is expected to boost surf along most north and west facing shores early next week. The latest wave model guidance continues to show this northwest swell gradually building, and surf may approach the High Surf Advisory criteria along some north and west facing shores of the smaller islands from late Tuesday into Wednesday.
Small south and southwest swells will keep small background surf along south facing shores through the day. A new, long-period south-southwest swell arriving Sunday is expected to cause surf to increase well above the summertime average along south facing shores from Monday through most of next week.
Expect modest, choppy surf along east facing shores. However, the strengthening trade winds will produce increasing surf along east facing shores this weekend. The strong trade winds in the vicinity, as well as upstream, of the islands will likely result in above average, rough surf along east facing shores from Monday into mid-week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov