Watch, Warning or Advisory?
A goal of the National Weather Service is to provide information on winter storms, with enough advance notice to allow the whole community to take actions needed to prepare for and deal with adverse and sometimes dangerous weather conditions. As the threat of severe winter weather draws closer, and the confidence in the location and timing of the event increases, the National Weather Service will issue various bulletins that become increasingly more specific. Here is what these bulletins mean, and what precautions you should take:
NOAA's National Weather Service uses a four-tier approach to alert the public for the potential for severe weather or high fire danger. This four-tier approach consists of outlooks, advisories, watches and warnings.
1) Winter Storm Outlook...
A winter storm outlook is issued when conditions are favorable for hazardous winter weather to develop within the next 3 to 7 days. It is intended for those groups that require considerable lead time to prepare for the event.
ACTION: Stay tuned to local media or monitor NOAA Weather Radio for updates. Evaluate your emergency action plan and the resources you have in your home, car or work place to deal with a winter storm.
2) Winter Storm Watch...
A winter storm watch is issued when the risk of hazardous winter weather has increased, but occurrence, location and timing is still somewhat uncertain. Generally, a watch is issued when there is a significant threat of severe winter weather in the next 12 to 48 hours.
ACTION: You should prepare now and ensure that all emergency plans and resources are in place.
Note: Winter Storm Watches may be upgraded to Winter Storm Warnings, if conditions warrant.
3) Winter Weather Advisory...
Winter weather advisories are issued for less serious winter weather conditions that are occurring, or have a high likelihood of occurring. These products are used for winter weather situations that are less severe than a Warning, but will cause significant inconvenience. These situations should not be life threatening, damage is usually localized and the main danger is hazardous travel.
Note: This advisory may be upgraded to a Winter Storm Warning if conditions warrant.
4) Winter Storm Warning...
A winter storm warning is issued when a hazardous winter weather event is occurring, imminent, or has a very high probability of occurrence. Warning products are used for conditions that pose a threat to life or property. Winter Storm warnings are issued for several types of hazardous winter weather, including heavy snow, sleet, or a combination of snow and wind.
ACTION: YOU SHOULD ACT NOW. STAY INDOORS IF POSSIBLE UNTIL THE STORM ENDS. LIMIT TRAVEL TO ONLY WHAT IS ESSENTIAL.
5) Ice Storm Warning...
An ice storm warning is issued when freezing rain will accumulate at a rate that causes a coating of ice that will make outdoor activities dangerous. Tree limbs and power lines fall under the weight of the ice. These conditions are fairly rare but, when they occur, can be especially dangerous.
6) Blizzard Warning...
Blizzard warnings are issued when:
- There are sustained wind speeds of 35 mph or more, or frequent wind gusts of 35 mph or more.
- Considerable falling and/or blowing snow is occuring, reducing visibility to less than 1/4 of a mile.
7) Dangerous Wind Chill Warning...
Wind chill warnings are issued when the wind chill of -20 degrees or colder are expected or occurring and:
- Expected to last one hour or longer.
- Wind speeds of 10 mph or more are expected or occuring.
8) Avalanche Warning...
Avalanche warnings are issued by the Northwest Avalanche Forecast Center, located in Seattle. These products are issued when there is a significant threat of avalanches in the Cascades and Olympics backcountry, possibly affecting mountain roadways and other high country interests.
[For more info, see the NW Avalanche Center's website]
Additional Links of Interest...