When winter weather threatens, your National Weather Service in Birmingham issues watches, warnings, and advisory products to warn you of the impending hazard.  Winter weather is often the most difficult weather for central Alabama, both because it causes travel problems, and because it is difficult to forecast.


· Winter Storm Outlook (HWO)

 

A "Winter Storm Outlook" may be issued when there is a 30% or greater chanceof a major winter storm, but the occurrence is expected to be within 3-7 days.  It is intended to provide information to those who need considerable lead time to prepare for the event.  This statement will be part of the Hazardous Weather Outlook (HWO).


· Winter Weather Watch (WSW) 

 

A "Winter Storm Watch" will be issued when conditions are favorable for hazardous winter weather conditions to develop.  Unlike a Tornado Watch or a Severe Thunderstorm Watch, Winter Storm Watches are issued by the local office.  Generally, this type of watch is issued for weather conditions that could occur 12 to 48 hours in the future.  Information in the watch will include the affected area, the weather threat involved, potential precipitation amounts, explanation of what a watch is, the uncertainty involved, precautions recommended, and the storm's potential impact. NWS Birmingham issues a Winter Storm Watch when one or more of the following is possible (50% or greater confidence) during the next 12 to 48 hours:

  • Snowfall of greater than 2 inches in 12 hours
  • Accumulation of freezing rain (ice) greater than 1/4".
  • Accumulation of sleet (ice pellets) 1" or greater.

· Winter Weather Warning (WSW)

 

A "Winter Storm Warning" is issued when a combination of hazardous winter weather is occurring, is imminent, or is expected.  Winter Storm Warnings are issued when one or more of the following is expected:

  • Heavy snow and blowing snow (near blizzard conditions)
  • Snow and Ice
  • Heavy snow (snowfall amounts greater than 2 inches in a 12 hour period
  • Sleet accumulations of 1 inch or greater
  • Sleet and Ice
  • Snow, Sleet and Ice
  • The following three warnings are also issued as Winter Storms Warnings (WSW), with specific headlines within the WSW

 

· Blizzard Warning (WSW)

 

A "Blizzard Warning" will be issued when there is:

  • Sustained wind or frequent gusts of 35 mph or greater AND
  • Falling and/or blowing snow reducing visibilities to less than 1/4 mile for at least 3 hours

 

· Ice Storm Warning (WSW)

 

An "Ice Storm Warning" is issued when there is:

  • Ice Accumulations of 1/4 inch or more

 

· Wind Chill Warning (WSW)

 

An "Wind Chill Warning" is issued when there is:

  • Wind Chill is expected to be -10 F or colder

 

· Winter Weather Advisory (WSW)

 

A "Winter Weather Advisory" is issued for a winter weather situation that causes significant inconveniences, but does not meet warning (see above) criteria.  The winter weather can still be life threatening if caution is not exercised.   A Winter Weather Advisory is issued if more than one type of hazardous winter weather is expected, is occurring, or is imminent:

  • Sleet accumulations of less than 1/4 inch
  • Snowfall accumulations of 1/4 inch to 2 inches over a 12 hour period  (A dusting of snow does not require an advisory)
  • Sustained wind or frequent gusts of 25 to 34 mph accompanied by falling and blowing snow, occasionally reducing visibility to 1/4 mile or less for 3 or more hours
  • The following two advisories are issued as Winter Weather Advisories (WSW), with specific headlines within the WSW

 

· Wind Chill Advisory (WSW)

 

A "Wind Chill Advisory" is issued when:

  • Wind Chill is expected to be between 0 and -10 F

 

· Freezing Rain Advisory (WSW)

 

A "Freezing Rain Advisory" is issued when:

  • Ice accumulations of less than 1/4 inch

 


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