Photo Credit: James Grenz

Hilo

Today: Partly sunny with scattered showers. Highs around 84 near the shore to around 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. East winds up to 10 mph shifting to the northwest after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 84 near the shore to around 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

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

Sunday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 83 near the shore to 71 to 81 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 83 near the shore to 71 to 80 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 83 near the shore to 71 to 81 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 83 near the shore to 71 to 80 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny and breezy. Scattered showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds 10 to 20 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 70 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers. Highs around 84 near the shore to around 72 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. East winds up to 10 mph shifting to the northwest after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 84 near the shore to around 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 15 mph shifting to the northwest in the afternoon.

Tonight: Mostly clear. Isolated showers in the evening. Lows around 72 near the shore to 51 to 58 above 4000 feet. North winds up to 10 mph shifting to the east after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. East winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to breezy trade winds will continue through the weekend, with clouds and showers favoring windward and mauka areas. An upper low will linger near the state and could enhance showers over windward areas Sunday night into Monday. After decreasing late Sunday through Tuesday night, stronger trades will return by midweek. Expect drier conditions from Tuesday onward.

Discussion

High pressure persists far northeast of the main Hawaiian Islands, driving moderate to breezy trade winds across local waters this morning. Satellite loop shows scattered to patchy broken low clouds across most windward slopes of the smaller islands. Overcast low clouds dominate windward and Kau shores and slopes of the Big Island. An area of overcast low clouds across waters lee of Oahu and the islands of Maui County appear to be moving away within trade flow. Radar shows isolated to scattered showers within cloud cover, with the bulk of shower activity noted within the cloud cover just lee of the central islands. Models show the high will remain nearly stationary for the next several days which means that moderate to locally breezy trade winds will continue across the island chain through the weekend, with only slight diurnal speed variations. Trade winds will decrease late Sunday through Tuesday night due to a brief weakening of the ridge north of the state.
Expect mostly light showers embedded within the trade wind flow today that will favor windward and mauka areas. An upper low about 200 miles north of the islands may deepen and shift slightly south and west by Sunday, possibly enhancing trade wind showers. Models show trade flow will advect increased moisture across the islands within the next day or two. This moisture, combined with instability associated with the upper low, may trigger brief heavy trade showers Sunday night through Monday. This could result in pockets of heavier than normal rainfall for windward areas. Models show a steepening pressure gradient over the islands as the high far to the northeast drifts southwestward. This could result in trade winds increasing into the breezy to windy range by the middle of next week. Expect drier trade wind weather by Tuesday.

Aviation

The ridge to the north of the islands will continue to bring moderate to locally breezy trade winds to the region through the weekend. Satellite shows limited clouds over and immediately upstream of the islands. Additional clouds and showers are expected to be carried in on the trade wind flow, favoring over the windward and mauka areas.
An upper level low just north of the islands may help to enhance some of the showers. The overnight soundings at Lihue continues to show no trade wind inversion in response to the proximity to the upper level low. For the western end of the state, the lack of an inversion is limiting mechanical turbulence to the lee of the mountains.
Meanwhile the trade wind inversion remains strong over Hilo overnight, but has lifted to around 8000 feet. This will allow any showers moving over the eastern end of the state to grow a little taller than yesterday. Lighter winds over the leeward sides of these islands is allowing for some afternoon cloud development.
Surface winds over the eastern end of the state are strong enough to bring the possibility of low level turbulence to the lee of the mountains. However as the trade wind inversion lifts, its less likely that turbulence will be experienced. AIRMET Tango remains in effect for moderate low-level turbulence over and to the lee of Molokai Maui and the Big Island, however it may be dropped later today if the inversion height lifts further.

Marine

Fresh to strong easterly trades will continue through the weekend, then briefly ease into the moderate to fresh category Monday and Tuesday as a weakness in the ridge forms to the northwest. Easterly trades will surge back Wednesday through the second half of the week as the ridge strengthens. Trades could briefly dip below the Small Craft Advisory threshold over the windier waters between Molokai and the Big Island Monday through Tuesday.
Surf along exposed north and west facing shores will rise Sunday morning through early next week, with a peak centered on Monday, as a moderate (medium period), west-northwest swell arrives and moves through from former Typhoon Guchol. Recent satellite data confirmed this potential and showed a decent sized area of strong west-northwest winds aimed at the islands down the 305-315 degree directional band with seas in the 15-20 ft range around 1200 NM from the islands. SOFAR drifter buoys near the fetch region depicted the model guidance is on track or lines up well observations, which has this swell arriving and reaching the 2-3 ft range by late Sunday, then up to 4-5 ft Sunday night through Monday as it peaks. This will linger into Tuesday, then fade through midweek. There is a compact system trailing this feature east of Japan, which could keep the surf from going flat Wednesday through Thursday with a small swell holding out of the same west- northwest direction.
Surf along east facing shores will remain small/choppy and gradually ease early next week as the aforementioned ridge weakens briefly. An upward trend is expected Wednesday through the rest of next week as the local and upstream trades return to fresh levels.
Surf along south facing shores will remain small each day through next week with mainly background south-southwest to south- southeast swell energy moving through. Although high pressure is currently parked in our typical swell window southeast of New Zealand, a powerful gale- to storm-force low currently evolving far south of the Tuamotus and Tahiti will be enough to generate a long-period south-southeast (170 deg) swell for next weekend (24-26).

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov