Weather Forecast

Hawaii County Weather Forecast for October 15, 2021

October 15, 2021, 7:15 AM HST
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Hilo

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 76 to 82 near the shore to 61 to 68 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 52 to 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Saturday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 76 to 82 near the shore to 61 to 67 at 4000 feet. Northwest winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 71 near the shore to 49 to 55 near 5000 feet. Light winds. Chance of rain 50 percent.

ARTICLE CONTINUES BELOW AD

Saturday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

ARTICLE CONTINUES BELOW AD

Today: Breezy. Partly sunny with scattered showers. Highs 63 to 83. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 62 to 70 near the shore to 54 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy with scattered showers. Highs 63 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

ARTICLE CONTINUES BELOW AD

Today: Breezy. Partly sunny with scattered showers. Highs 63 to 83. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 62 to 70 near the shore to 54 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy with scattered showers. Highs 63 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 83 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 71 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 76 to 82 near the shore to 61 to 68 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 52 to 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Saturday: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 76 to 82 near the shore to 61 to 67 at 4000 feet. Northwest winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 81 to 88 near the shore to 65 to 71 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73 near the shore to 49 to 55 above 4000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Saturday: Sunny in the morning then becoming partly sunny. Breezy. Highs 82 to 88 near the shore to 65 to 70 above 4000 feet. Southeast winds up to 20 mph shifting to the northeast in the afternoon.

Detailed Forecast

Synopsis

Trades will be a bit lighter the next few days…but still quite breezy, especially in the afternoons. Trade wind showers will continue to focus mainly windward and mauka, during the nights and mornings, through the weekend. Fewer showers and weakening trades are expected early next week as drier and more stable air overspreads the Aloha State. A dissipating front may reach the northern main islands with an uptick in trade winds and increasing showers about Thursday.

Discussion

Surface ridge is nearly stationary about 750 miles to the N of PHNL. The ridge has been driving windy trades the last few days, but it continues to gradually weaken this morning. 24 hour pressure falls of about 1.5 to 2 mb suggest that today should be a notch less windy overall…but still breezy (and locally windy in those normal trade wind acceleration areas).
The small area of broken clouds and showers riding in on the trades has been bringing showers to windward Haleakala and the windward side of the Big Island this morning. Over an inch of rain has fallen at a couple of the windward rain gauges there in the last six hours. The cloud coverage immediately upstream appears to be slightly more stable and less showery than earlier, so a fairly nice day and night appear to be in store for the smaller islands. A little more PW near the Big Island could result in a few more showers there, but nothing out of the ordinary with a bit of a drying trend for today.
A fairly typical distribution of windward and mauka trade wind showers favoring nights and mornings is expected through the weekend. Details are tough to pin down, but model consensus is that one minor area of slightly deeper moisture and cooler mid- level temperatures looks to move across the smaller islands later Sat and Sat night, which should bring some additional showers for those areas.
Fewer showers are expected Sunday through Wednesday as drier and more stable air moves in. Model consensus is that the moist layer depth will become quite shallow, only about 5000 feet or so, which should result in generally fine weather during this period. However, the combination of a mid- upper level low developing near the islands later Wed, and shallow moisture convergence coming in from the north in the form of a dissipating cold front should increase rain chances for the northern main islands on Thu if the models are correct.
Breezy trades will continue through the weekend as the ridge reorganizes and begins to shift south toward the islands. After that the trades will weaken, and by Wed morning the model progs show the surface ridge axis near 23N…or only about 50 miles N of Kauai. This will probably lead to a hybrid pattern of gentle trades with considerable diurnal terrain-driven wind circulations. The trades will begin to increase once again on Thu along and ahead of the diffuse front or frontal remnants.

Marine

Trades have come down a notch, but remain fresh in many areas, with locally strong winds remaining in the typical windier areas near Maui County and the Big Island. As a result, the Small Craft Advisory (SCA), and as expected, has been scaled back to those typical windier waters. The SCA is in place through Saturday afternoon, but expect winds to remain above advisory a bit longer than that, so it will likely be extended into Sunday/Sunday night later today or tonight.
As the trades ease, expect the elevated surf along the east facing shores to slowly subside to average heights by the weekend, and to below average heights early next week. Small, medium period band energy continue to be seen at the CDIP Hanalei buoy. This northwest swell is expected to peak late today into Saturday, providing a minor foot or two of surf along north and west facing shores. A larger north swell is forecast to arrive Tuesday and may produce advisory level surf along north facing shores by mid- week. Small surf along south facing shores will slowly subside into the weekend. The next small, long period south swell is forecast to reach the islands Wednesday and slowly subside through late next week.

Aviation

Breezy trade winds will remain in place across the state today, though wind speeds will be slightly less than the previous few days as high pressure northeast of the state continues to gradually weaken throughout the forecast period. The strongest winds are expected across Maui County and the Big Island, particularly over mountain ridges, through valleys, and in the channels. For now, AIRMET Tango remains in effect for moderate low-level mechanical turbulence over and immediately south through west of mountains of all islands. This AIRMET is likely to remain in effect through today, but may be cancelled by late tonight or early Saturday as wind speeds continue to gradually wane.
Satellite and radar imagery early this morning show a band of enhanced clouds and showers across windward sections of Oahu, Molokai, Maui, and the Big Island (including adjacent waters). Occasional MVFR ceilings and visibilities are expected to persist for these locations throughout the morning, though models indicate some improvement is possible after sunrise. AIRMET Sierra remains in effect for tempo mountain obscuration for north through east sections of all main Hawaiian Islands at this time, though at least portions of this AIRMET will likely be able to be cancelled later this morning. Elsewhere, showers and MVFR conditions will remain more isolated in nature. Isolated to scattered showers will return to the Kona slopes of the Big Island again this afternoon, though VFR conditions are expected to prevail.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST early this morning for Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov

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