Kevin Myatt is The Roanoke Times' weather columnist.

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• We got graupel, but not on official record
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• Forecast for Weather Journal: Partly print, with frequent Internet
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• Sprinkles or flurries possible Tuesday, but maybe something bigger for the weekend?
• For now, it looks like a quiet, mostly mild week ahead for SW Virginia
• Coldest morning of winter so far likely across much of Southwest Virginia; Tuesday precipitation looking doubtful
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Temperatures rose into the 80s on Sunday, and yet, chunks of ice fell out of the sky in parts of Southwest Virginia, covering the ground like snow in some areas.

Hail can seem weird and mysterious, but the mechanics of its formation are relatively simple. Hail forms when thunderstorm updrafts lift rain droplets high enough to freeze.

Newly formed hailstones start falling, but can continue to be lifted if the updrafts are strong enough, developing new layers of ice until they become heavy enough to fall. This is how a hailstone gets bigger and why it has rings reminiscent of an onion.

Hail forms more readily if freezing temperatures dip low in the atmosphere, or if there are especially strong updrafts. On Sunday, temperatures were unusually low in the atmosphere for this time of year, and daytime heating and moisture below that cold air produced strong updrafts.

Rotation in a thunderstorm to separate updrafts and downdrafts can cause very large hail -- golf ball-sized or bigger -- to occur. In most of Southwest Virginia's storms, a strong downdraft wipes out the updraft, unleashing a barrage of wind, rain and hail, but killing the storm. Rotation lets updrafts continue unimpeded, lifting hailstones repeatedly.

Though hail becomes a little less frequent as the air heats up in midsummer, a severe thunderstorm on a 100-degree day in August is fully capable of imitating an ice machine.