Hilo

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 65 to 71 near the shore to around 57 at 4000 feet. East winds up to 10 mph shifting to the southwest after midnight. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. South winds up to 10 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 64 to 71 near the shore to around 57 at 4000 feet. East winds up to 10 mph shifting to the north after midnight. Chance of rain 50 percent.

Kona

Tonight: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 50 percent.

Friday Night: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to 50 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Scattered showers in the evening. Lows 65 to 73 near the shore to 57 to 64 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 67 to 86. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 73 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Kohala

Tonight: Partly cloudy. Scattered showers in the evening. Lows 65 to 73 near the shore to 57 to 64 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 67 to 86. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 73 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

South Big Island

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 75 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Friday Night: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to around 53 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 65 to 71 near the shore to around 57 at 4000 feet. East winds up to 10 mph shifting to the southwest after midnight. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. South winds up to 10 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 64 to 71 near the shore to around 57 at 4000 feet. East winds up to 10 mph shifting to the north after midnight. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to around 55 above 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs 85 to 91 near the shore to 68 to 75 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Friday Night: Mostly clear. Lows around 75 near the shore to 53 to 58 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Our east to east-southeast trade winds will decrease a touch on Friday with localized sea breezes possible during the day over select leeward areas. Trade winds should restrengthen over the weekend out of our typical east-northeast direction with a few light showers possible over windward areas. Trades should ease early next week with light to moderate winds possible by Tuesday of next week.

Discussion

This afternoon's satellite imagery shows showers over the windward slopes of the Big Island and over the Ko'olau and Waianae mountains. These showers have been fairly stationary and for areas that have been seeing rain today, we have seen some light to moderate rainfall. For example, the Kahana gauge did show nearly 0.75 inches of rain during the past 3 hours. As we head into the evening, we should eventually see the shower activity decrease tonight as drier air moves in across the state. But until then, we could see stationary light to moderate showers along the Ko'olau mountain range through rest of this afternoon.
For Friday, we should see the trade winds decrease a touch from today with moderate east to east-southeast trades expected. With this wind direction, some of our leeward areas should be sheltered from our typical east-northeast trades with some localized sea breezes expected to develop by late morning on Friday. Some scattered afternoon clouds are expected over leeward areas with some light showers possible Friday afternoon over a few leeward areas. Otherwise, we should see the inversion strengthen a bit more on Friday, which should limit rainfall amounts.
Over the weekend, we should see breezy trade winds return by Saturday afternoon with stable and mostly dry conditions expected. The dry and breezy weather conditions may elevate fire weather concerns this weekend, but at this time we are expecting winds to stay below our Red Flag thresholds but minimum humidities could get close to our threshold of 45% during the early afternoon especially on Sunday. At this time, Red Flag warnings are not expected over the weekend, but the fire weather risk will likely be higher than normal.
For next week, a trough developing northwest of the state should cause the trade winds to gradually weaken Monday into Tuesday. By Tuesday, the latest GFS and ECMWF have come into better agreement and we should see gentle to moderate trades with sea breezes developing during the day. Some shower activity should be expected at times during the first half of next week, but should remain light to moderate in intensity due to stable conditions aloft.

Aviation

East-southeast trades are expected to ease a bit into the light to breezy range tonight through Friday. The slight southeasterly component of the wind direction may make the winds light enough for localized sea breezes and inland clouds to develop in the more sheltered leeward areas into this evening and again Friday afternoon, with land breezes clearing those areas out overnight. The area of enhanced low clouds/showers near the Big Island is beginning to taper down this afternoon and is expected to return to a more typical scattered windward showers coverage tonight through Friday.
AIRMET Sierra remains in effect for mountain obscuration across windward sections of the Big Island, though can likely be canceled within the next few hours.

Marine

The latest ASCAT readings from late this morning indicate winds below Small Craft Advisory (SCA) areawide. The SCA has therefore been cancelled with the issuance of the afternoon forecast package. Winds will continue to veer to SE, eventually becoming light and variable over the waters of Kauai and Oahu. Fresh to strong easterly trades then return statewide over the weekend before weakening again again early next week.
Surf along north-facing shores will steadily fade through the second half of the week as a NNW swell moves out. A small, medium-period pulse is possible over the weekend and into early next week, which should be enough to prevent the surf from going flat. An upward trend is possible late next week due to the aforementioned gale forming northeast of the state from Monday through midweek.
Surf along south-facing shores will remain small, with mainly a mix of short-to medium-period SSE and SSW swells moving through. The next small, long-period SW swell is expected over the weekend with a similar pulse arriving early next week.
Surf along east-facing shores will remain small and choppy each day through the weekend, then trend down as the trades ease locally and upstream early next week.
Peak monthly tides could lead to minor coastal flooding in the typical low-lying vulnerable areas around or just before daybreak each day through the weekend, beginning on Friday morning. A Coastal Flood Statement has been issued for all coastal zones.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov