Winter Weather Terms

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Watches, Warnings & Advisories

  • Winter Storm Watch - Indicates severe winter weather such as heavy snow or ice is possible within the next day or two. Prepare now!
  • Winter Storm Warning - Indicates heavy snow (4”+ in southern IL, 6” + northern or central IL), heavy sleet (½” +), or a combination of winter weather hazards are highly likely or occurring. Stay indoors and adjust travel plans!
  • Ice Storm Warning - Heavy accumulations of ice will create extremely dangerous travel, damage trees and likely cause extended power outages.
  • Blizzard Warning - Strong winds of 35 mph or greater will combine to produce blinding snow, near zero visibility, deep drifts, and life threatening conditions – especially for those that attempt travel.
  • Wind Chill Warning - Life threatening wind chills of 25 to 30 below zero or colder.
  • Winter Weather Advisory - Indicates snow (2-4” in southern IL, 3-5” in northern or central IL) or a combination of winter weather conditions will cause significant inconveniences and may be hazardous, especially to motorists. Use caution if you venture out!
  • Freezing Rain Advisory - Light accumulations of ice will cause hazardous travel.
  • Wind Chill Advisory - Dangerous wind chills of 15 to 24 below zero.

Winter Weather Definitions

  • Freezing Rain - Precipitation that falls from the cloud as rain, but freezes into a glaze of ice on ground based objects (trees, power lines, roads, cars, etc…).
  • Sleet - Small pellets of ice, created by frozen raindrops. Sleet bounces when hitting a surface and does not stick to objects.
  • Wind Chill - A calculation of how cold it feels outside when the effects of temperature and wind speed are combined. Wind chill ONLY applies to bare, human skin. The affects of wind chill are different for animals, and doesn’t apply at all to other objects.

Source:  http://www.crh.noaa.gov/Image/ilx/pdf/08_WINTER%20booklet.pdf