Hilo

Today: Partly sunny with scattered showers. Highs around 80 near the shore to around 66 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 64 near the shore to around 50 at 4000 feet. Northeast winds 10 to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 66 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 84 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 64 to 71 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to 48 to 57 near 3000 feet. Northeast winds 10 to 15 mph shifting to the east after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63 near the shore to 48 to 57 near 3000 feet. Northeast winds 10 to 15 mph shifting to the east after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Lows around 65 near the shore to around 50 near 5000 feet. East winds up to 20 mph.

Sunday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Puna

Today: Partly sunny with scattered showers. Highs around 80 near the shore to around 66 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 64 near the shore to around 50 at 4000 feet. Northeast winds 10 to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 66 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Breezy. Highs around 84 near the shore to 65 to 72 above 4000 feet. Northeast winds up to 20 mph increasing to 10 to 25 mph in the afternoon.

Tonight: Mostly clear. Lows 65 to 71 near the shore to 45 to 53 above 4000 feet. Northeast winds 10 to 15 mph shifting to the east after midnight.

Sunday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84 near the shore to 65 to 72 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trade winds will decrease into the moderate to locally breezy range today, and then further decrease into the light to moderate range from Sunday through Tuesday. Local scale land and sea breezes will develop over each island during this light and variable wind period. A low level convergence band will enhance clouds and showers over the eastern islands this morning. Another low level convergence band will move into Kauai and Oahu from Sunday night into Monday. Otherwise developing clouds and brief showers will tend to favor island mountain and interior sections in a sea breeze pattern mainly in the afternoon to early evening hours through Tuesday. Trade wind weather returns from Wednesday onward with wind speeds slowly increasing into next weekend.

Discussion

This mornings satellite imagery shows a band of clouds and showers drifting through windward Oahu, Molokai, Maui and the Big Island, expect passing showers from this cloud band through the morning hours along north and east facing slopes. More stable clouds are drifting into Kauai and northwestern Oahu under a building high pressure ridge aloft as the trade winds begin to weaken and veer more easterly. Another convergent cloud band is forming up just 300 miles north of Kauai.
Two low level convergence bands of clouds will produce a brief increase in shower activity over portions of the state this weekend. The first of these convergent bands is currently moving through the eastern half of the state. Expect enhanced shower activity over these islands through the morning hours with decreasing shower trends this afternoon. A second low level convergent band, currently north of Kauai, will drift into Kauai and Oahu from Sunday night into Monday providing increasing shower activity over both islands lasting through Monday morning. Otherwise a building ridge aloft will limit shower potential in areas not affected by these low level convergent cloud bands.
Breezy northeast trade winds will veer to a more east-southeasterly direction and weaken through the weekend. Winds will become moderate to breezy easterlies today, and then weaken to light to moderate east to southeasterlies from Sunday into Tuesday. This southeasterly wind direction typically places the smaller islands, from Maui to Kauai in a wind and rain shadow of the Big Island. Allowing land and sea breezes to develop and cloud trends shifting towards island mountain and interior sections. Outside of the previously mentioned low level convergence bands, brief shower activity remains in the forecast mainly during the afternoon to early evening hours. Stable land breezes will develop after sunset, driving clouds over island interior sections offshore from the islands into the coastal waters.

Aviation

Moderate to locally strong trade winds will persist through the weekend. AIRMET Tango for moderate low level turbulence to the lee of higher terrain will remain in effect for all islands.
Although they have decreased in coverage slightly overnight, ragged showery broken to overcast low clouds bands continue to affect Oahu and the islands of Maui County, while lingering moisture persists near Kauai. These conditions may reach windward Big Island later today. AIRMET Sierra, for intermittent mountain obscuration, remains in effect for northwest through northeast facing slopes of Kauai, Oahu, Molokai and Maui.

Marine

Fresh to strong northeast trades will hold today, then shift out of the east and ease into the light to moderate category tonight into Sunday as high pressure passes to the north. This pattern will continue into the first half of next week due to a couple of fronts passing to the north.
Surf along south facing shores will remain up today, then ease through the second half of the weekend as a south swell moves out. Morning observations at the offshore buoys to the south reflect this southerly swell energy moving through within the 14 and 15 second bands slowly trending down. As this moves out, another pulse early next week should be enough to keep the surf from going flat.
Surf along north facing shores should clean-up by Sunday as the winds weaken and shift out of a more typical easterly direction. A short-period, northerly pulse associated with a decent gradient that has setup between high pressure to the northwest and low pressure passing to the north will support a rising trend tonight into Sunday. This should linger into Monday along exposed coasts as the swell direction shifts out of the north-northeast.
A long-period, northwest swell associated with a developing storm west of the Date Line is expected to arrive late Monday, then peak Tuesday through midweek. The swell direction will shift out of the north-northwest by Wednesday. If this comes in larger than predicted, surf along exposed north and west facing shores will reach low-end advisory levels as it peaks.
For the long-range, guidance is advertising the active trend continuing as a broad area of gales setup over the far northwest Pacific near the western Aleutians focused at the islands within the 310-330 directional bands early next week. If this unfolds, expect a long-period, northwest swell late next week that could drive surf heights back to around advisory levels.
Surf along east facing shores will remain rough today with the strong northeast winds holding. Although a downward trend is expected as the winds back off Sunday, surf will trend back up for shores exposed to the aforementioned north-northeast swell expected early next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov