First it was very dark lake-effect clouds in the eastern sky and the sun shining in the west. Then ice pellets fell about 5:00 p.m. to the ground in Arlington Heights. Small little white or translucent pellet smacked the ground, windows and siding of homes. No damage and they melted very quickly.
Ice pellets form when a layer of above-freezing air is located between 5,000 feet and about 10,000 feet above the ground, with sub-freezing air both above and below the thawing layer. This causes the partial or complete melting of any snowflakes falling through the warm layer. As they fall back into the sub-freezing layer closer to the surface, they re-freeze into ice pellets.
That means it was snowing way up there. The snow melted, and then it re-froze and hit the ground as little pellets that looked like Calcium Chloride pellets that are used to melt ice.
Although the National Weather Service refers to ice pellets as sleet, more commonly we think of sleet as rain and snow mixed.
In the United States, the National Weather Service uses wintry mix to refer to a mixture of freezing rain, ice pellets, and snow.
The rest of the night? A chance of rain showers, snow showers, and sleet before 1am, then a slight chance of rain and snow showers. Mostly cloudy, with a low around 31. North northwest wind around 15 mph, with gusts as high as 20 mph. Chance of precipitation is 30%.
Warm weather coming Sunday.