What are Ice Storms?

An Ice Storm Warning is issued when mostly freezing rain is expected with ice accumulations of ¼ inch or more within a 12-hour period. Take necessary precautions – consider canceling travel plans.

Ice storms occur when a layer of warm air is between two layers of cold air.  Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground.  If the precipitate is partially melted, it will land on the ground as sleet.  However, if the warm layer completely melts the precipitate, becoming rain, the liquid droplets will continue to fall, and pass through a thin layer of cold air just above the surface.  This thin layer of air then cools the rain to a temperature below freezing (0 °C).  However, the drops themselves do not freeze, a phenomenon called 'supercooling' occurs.  Supercooling is when the droplets strike ground below 0 °C or anything else below 0 °C (power lines, tree braches, aircraft, etc.), they instantly freeze, forming a thin film of ice.

Facts About Ice Storms

• According to most meteorologist, just one quarter of an inch of ice accumulation can add about 500 pounds of weight per line span.
• Damage from ice storms is highly capable of shutting down entire metropolitan areas.
• The loss of power during ice storms has indirectly caused numerous illnesses and deaths due to unintentional carbon monoxide poisoning.
  
• Freezing rain from an ice storm covers everything with heavy, smooth glaze ice making driving and walking conditions slippery and hazardous.
• Branches or even whole trees may break from the weight of ice causing road blocks, tear down of power and telephone lines and other damages.
• Aside from falling trees and tree branches, the weight of ice can easily snap power lines and also break down power/utility poles.

Power Outages