Winter Storm Outlook - Winter storm conditions are possible in the next 2 to 5 days.
Winter Weather Advisory - Winter weather conditions are expected to cause significant inconveniences and may be hazardous. When caution is used, these situations should not be life threatening.
Winter Storm Watch - Winter storm conditions are possible within the next 36 to 48 hours. People in a watch area should review their winter storm plans and stay informed about weather conditions.
Winter Storm Warning - Life-threatening, severe winter conditions have begun or will begin within 24 hours. People in a warning area should take precautions immediately.
For more information on preparing for winter storms you can check out the following websites:
Red Cross Winter Storms Preparedness Site - http://www.redcross.org/prepare/disaster/winter-storm
CDC Winter Storms Preparedness Site - http://emergency.cdc.gov/disasters/winter/