Ice Storms

Not to long ago I received a question from someone about ice storms.  Today I want to answer the question as well as give a whole picture of what an ice storm is, and how it occurs, and the specific question as to why it occurs more in certain areas of the US.


An ice storm is basically a rain event where the rain falls into air that is at or just below freezing.  When the water makes contact with objects, it then freezes into ice.  This ice continues to build as long as it keeps raining and staying below 32 degrees.  Water is quite heavy so once the ice reaches a certain point, the things the ice is forming on can no longer carry the weight and begin to break.  Tree Branches and power lines are the most vulnerable, and of course anything that happens to be under those falling trees is subject to damage as well. 


An ice storm forms when warm air is moving over the top of a shallow layer of cold air on the surface.  Cold air is generally heavier so you can get very thin layers of below freezing temperatures that collect near the surface while warmer moisture filled air is thrown over the top of that cold layer.  If the surface cold layer is too thick, you end up with ice pellets or snow.  Generally you get ice storms on the north side of a warm front where the warm air is trying to move in.  

You can get ice storms anywhere in the US, but as my questioner asked, why is it the mid south and south seem to get more ice storms than other areas of the country?  These areas are more prone to ice storms because of their geographic location.  You get ample warmth and moisture from the Gulf of Mexico and the cold air streaming down from Canada is generally running out of steam in it push south.  This provides the best environment for major ice storms.

Ice storms do have a beauty to them though, as well as the capability of being highly destructive.  These types of storms can so devastate an area that it can knock it back into the pre-electric area for weeks.  They can also be unbelievably beautiful when not as thick.  It is one of the weather issues that we need to be prepared for as it can knock out power and transportation for extended periods.  We also need to be aware of it's deadly nature.  Falling objects, live power lines, and an inability to navigate are all dangers that can harm or kill us.