Greg Perkins [KC9GHZ]

This week is Winter Weather Preparedness Week for Illinois.  For a few preparedness guides, you can visit the education section of our site.  Before you read those, let’s just review some basic winter weather definitions.

DEFINITIONS

• Winter Storm Watch - Conditions are favorable for hazardous winter weather conditions including heavy snow, blizzard conditions, or significant accumulations of freezing rain or sleet.  These watches are usually issued 12-36 hours in advance of the event.
• Winter Storm Warning - Hazardous winter weather conditions that pose a threat to life and/or property are occurring, imminent or likely.  The generic term, Winter Storm Warning, is used for a combination of two or more of the following winter weather events: heavy snow, freezing rain, sleet, and strong winds.  The following event-specific warnings are issued for a single weather hazard:
• Blizzard Warning - Sustained winds or frequent gusts of 35 MPH or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile or less for a period of three hours or more.  There are no temperature criteria in the definition of a blizzard, but freezing temperatures and 35 MPH winds will create single digit wind chills.
• Heavy Snow Warning - Snowfall of 6 inches or more in 12 hours or less, or 8 inches or more in 24 hours or less.
• Ice Storm Warning - Accumulations of 1/4 inch or more of freezing rain.
• Heavy Sleet Warning - Accumulations of 1/2 inch or more of sleet.
• Winter Weather Advisory - Hazardous winter weather conditions are occurring, imminent, or likely.  Conditions will cause a significant inconvenience and if caution is not exercised, will result in a potential threat to life and/or property.  The generic term, Winter Weather Advisory, is used for a combination or two or more of the following events: snow, freezing rain or drizzle, sleet, and blowing snow.
• Wind Chill Advisory - Dangerous wind chill values of -20 to -30 degrees Farenheit.
• Wind Chill Warning - Extreme wind chill values of -30 degrees Farenheit and below.

WIND CHILL TEMPERATURE CHART