MAUNA KEA, Hawaii -- Winter has arrived on the summits of Mauna Kea and Mauna Loa, where snow began accumulating overnight with up to a foot expected, CBS affiliate KGMB reports.

A Winter Storm Warning is in effect through Friday afternoon for elevations above 8,000 feet. The summits could get six to 12 inches of snow through Friday.

An upper level low pressure area has brought the sub-freezing temperatures and unstable conditions. The low will combine with moisture surging in from the southeast, which could result in bursts of heavy snow, especially above 12,000 feet.

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Conditions on the summits are dangerous. Besides being cold, east to southeast winds of 25 to 40 miles per hour are expected with gusts to 50 miles per hour. The strong winds also will cause drifting snow, and freezing fog will reduce visibility to as low as a half-mile.

It may be a while before you can see the white stuff up close. The road to the summit of Mauna Kea is closed at the Visitor Information Station at the 9,200-foot level due to freezing fog, heavy snow and icy roadways.

Unsettled weather is expected through the weekend.