Wednesday, November 27, 2013

Reports of Ice Pellets north of Atlanta.


A cold core low pressure system is passing over the area this afternoon.  That low has generated only a few showers in the area this afternoon.  The low also has some very cold air aloft.  Even though temperatures at the surface have been in the 60s, the cold air aloft has been cold enough to develop some ice pellets that have fallen in some spots today.

We've only had a few reports, but some folks actually saw some of these pellets make it to the ground.  We had a report of small ice pellets in Lavonia and Jasper.  One viewer reported a quick "very cold rain" in Milton, Georgia.  This type of ice pellet is also referred to as "graupel."  Graupel forms when we have warm air at the surface and very cold air aloft.  In that cold air aloft, snow flakes can develop.  When those flakes encounter supercooled air, ice crystals form on the flake.  That ice buildup on the snowflake is also referred to as "rime coating."  It is different from hail.  Hail is solid.  Graupel breaks up as you touch it.  

This cold core low will sweep to the east taking this disturbed weather away for tonight.  We will have clearing skies and colder air moving in overnight.  We will wake up to temperatures in the lower 40s in Atlanta by morning.  Many areas outside the city will be in the upper 30s by morning.

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