Trade winds will continue to produce short period choppy surf arond knee to waist-high levels along east facing shores through Saturday with a downward trend in heights early next week as winds diminish. Tiny north-northwest swell may be found at select north shore breaks but wave heights will be inconsistent and only around knee-high levels. Most breaks will stay closer to flat. A series of small southerly swells can be expected through the weekend and on into the middle of next week. No other significant swells are expected.
High tide at Kahului was 1.9 foot at 3:30 AM late last night, dropping to a low of 0.1 foot at 9:28 AM this morning, then rising to a high of 2.5 foot at 4:02 PM late this afternoon, before once again dropping to a low of 0.3 foot at 10:27 PM late this evening
The sunrise was at 06:05 am this morning and will set at 06:51 pm this evening. The Moon is currently 17 days old, and is in a Waning Gibbous phase. The next Last Quarter will occur at 3:44 AM on Thursday, August 25th.
Sunset: 6:46 PM
High pressure northeast of the state will keep a light to moderate trade wind flow in place through the weekend, with clouds and showers favoring windward and mauka locales. An upper level trough northwest of the state will weaken the trades and draw some deep tropical moisture northward over the island chain early next week. Deep layer ridging will then build northeast of the state by late next week, increasing the trades and bringing a more typical windward and mauka shower pattern back to the island chain.
Currently at the surface, a 1032 mb high is centered around 1700 miles to the north of Honolulu, while off to the south of the state a series of troughs are embedded within the Intertropical Convergence Zone (ITCZ). Infrared satellite imagery shows partly cloudy skies in place in most areas, with some enhanced cloud cover over windward areas as well as leeward sections of the Big Island. Radar imagery shows scattered showers drifting into windward locales, with some of the showers spilling over into leeward areas. Additionally, some locally heavy showers continue to affect leeward sections of the Big Island near Kona. Main short term concern for tonight revolves around rain chances.
High pressure northeast of the state will continue to drive moderate trade winds across the island chain through Friday evening. Infrared satellite imagery shows a nice band of showery cumulus developing upstream of the islands, and MIMIC total precipitable water (PW) imagery shows some increase in moisture, with PW values in the 1.3 to 1.5 inch range within this band. 00z soundings indicated inversion heights of 7-8 kft at PHLI and PHTO, but these should rise to 10+ kft overnight as a mid-level trough moves over the state. As a result, we should see an increase in trade wind showers, with the most frequent shower activity over windward and mauka areas. Due to the moderate trades and the elevated inversion, some of the showers will make it into leeward areas as well. Over leeward sections of the Big Island, showers should diminish over the next couple of hours as drainage flow sets up, shifting most of the shower activity offshore.
Saturday through Sunday, High pressure well northeast of the state will weaken, while an upper level trough digs to the northwest of the island chain. As a result, we expect moderate trades to continue through Saturday, with winds decreasing for Sunday. We should see a fairly active trade wind shower pattern continue through mid morning Saturday, with showers decreasing in coverage and intensity Saturday afternoon as PW values drop back down into the 1.1 to 1.3 inch range. A few showers may still reach leeward areas however given the presence of the mid-level trough over the islands. Trade wind showers are expected to pick up once again Saturday night and continue through Sunday as the mid-level trough remains over the state and PW values rise into the 1.4 to 1.6 inch range. Some of the shower activity may be heavy over the Big Island Sunday afternoon as the inversion is eroded, with thunder not out of the question.
Sunday night through Wednesday, Model guidance has come into better agreement for the first half of the week, showing a weak wind regime feature light trades over windward areas and localized land/sea breezes over leeward areas. Some deep tropical moisture will get drawn northward over the islands during the first half of the week, with PW values rising into the 1.6 to 2.0 inch range, with even higher values than this over the Big Island. As a result, we should see a more convective pattern setting up with the potential for some locally heavy rainfall at times, particularly over the interior of the islands during the afternoon and evening hours. With the deeper moisture in place over the Big Island, a few thunderstorms will be possible as well, mainly during the afternoon hours.
Wednesday night through next Friday, Deep layer ridging will build to the north and northeast of the state, shifting the deep tropical moisture to the west of the islands and bringing a return of moderate trade winds. As a result, we should see a more typical trade wind pattern, with clouds and showers focused primarily over windward and mauka locales.
Central Valley (Kahului, Spreckelsville):
Mostly sunny. Breezy. Isolated showers in the morning. Highs 85 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.
Leeward West (Lahaina, Ka`anapali):
Breezy. Mostly sunny with isolated showers. Highs 81 to 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.
Windward West (Wailuku, Waiehu):
Breezy. Partly sunny with scattered showers. Highs 70 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.
Windard Haleakala (Hana, Haiku, Makawao):
Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs around 82 at the shore to around 69 at 5000 feet. East winds 10 to 15 mph with gusts to 30 mph. Chance of rain 70 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 87 at the shore to 71 to 77 upcountry. South winds around 10 mph. Gusts up to 30 mph. Chance of rain 20 percent.
Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 65 at the visitor center to around 61 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.
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