A Closer Look at Winter Weather Advisories & Warnings
There are many types of winter weather advisories, some of which can become confusing. Here’s a detailed breakdown of what each type of advisory means:
Winter Storm Watch - Severe winter weather conditions within 12 to 48 hours including one, some, or all of the following:
More than two inches of heavy snow within a 12 hour period
A quarter of an inch or more of freezing rain or freezing drizzle
Sleet accumulations of an inch or more
Winter Storm Warning – Significant or severe winter weather is now occurring or has a high change of occurring within a short amount of time; Warnings indicate the conditions could pose a serious threat to life. They specific conditions are the same as a Winter Storm Watch, but within a 0 to 12 hour timeframe.
Winter Weather Advisory – Winter weather is about to or is now occurring; advisories are less serious than a warning, but still indicate that winter weather that could cause inconvenience or threaten life and property could still occur. They include:
A quarter of an inch to two inches of snow within a 12 hour period
Sleet of less than an inch
Freezing rain or freezing drizzle of less than a quarter of an inch
Winter Weather Awareness Week from the National Weather Service and the Alabama Emergency Management Agency continues. Tuesday, the focus is the terms used in winter weather warning and forecasting.
Unlike Severe Thunderstorm or Tornado Warnings, a Winter Storm Watch or Warning is typically issued far in advance, from 12 hours to as much as 48 hours. These can warn for freezing rain, sleet, snow, or a combination of these conditions.
For a storm to become officially a blizzard, it must contain winds of 35 miles per hour (by gusts or sustained) and blowing or falling snow must reduce visibility to a quarter of a mile or less for at least three hours.
There are several types of snowfall categories. Flurries are light, can be off and on and generally do not accumulate. Snow showers are stronger, but brief and lead to some accumulations. Snow squalls, typically found in the Great Lakes, are also brief but very intense and often are combined with gusty wind. Finally, snow is considered heavy if it reaches 2 inches or more in 12 hours or less.
The other types of wintry precipitation include:
• Sleet: rain drops that freeze into ice pellets as they are falling to the ground
• Freezing Rain: rain that is not frozen until it makes contact with a surface below freezing
• Wintry Mix: a combination of snow, sleet, freezing rain, and/or rain
Wednesday, Winter Weather Awareness Week focuses on how you can prepare for wintry weather, should it occur.