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Understanding severe weather alerts is crucial to being prepared for possible weather emergencies.
Warning Signs for Severe Weather
Weather alerts are provided by local and regional authorities and passed on to you by the media when threatening climate conditions arise. Meteorologists are trained professionals equipped to analyze natural indicators of weather conditions that may be threatening and advise you to seek safety when necessary. But do you know what those alerts mean? You hear the warnings but might ask, “Now does that mean we are in the midst of bad weather or is bad weather just a possibility?”
In the event of severe weather predictions, always stay tuned to your radio or television and become familiar with the warning signals they pass on to you from the National Weather Service. While it’s good for you to be able to judge cloud formations and other natural signs, don’t assume you will have time to assess weather conditions and to act properly in the event of bad weather. It’s more important to be prepared to take shelter when advised and to pay attention to the warning process. Do NOT put your family’s life at risk by relying solely on the outdoor siren systems since they are designed only by relying solely on the outdoor siren systems since they are designed only to alert people participating in outdoor activities. You should have a weather radio at home or rely on your television or radio weather reports — and FOLLOW THEIR INSTRUCTIONS!
Just as most things in life have become more complicated — from smartphones to televisions — so have weather reports. Beginning on page 3 is an updated list of terms used by the United States National Weather Service that describes severe weather you and/or your family may one day face. Post this list somewhere handy so you can reference it when you hear one or more of these watches, advisories, or warnings announced. That way you can be ready and STAY SAFE!
National Weather Service — Severe Weather Alerts
- Tornado Watch: Tornado watches are displayed in RED boxes on your television screen. A tornado watch means that conditions are favorable for severe thunderstorms and tornadoes in the watch area. Watch areas are large geographic areas and a tornado watch is valid for 5 to 8 hours.
Note: A particularly dangerous situation tornado watch means that a major (EF-4 or EF-5) tornado outbreak is possible.
- Tornado Warning: A tornado warning means that a tornado has either been indicated by Doppler radar or actually sited by trained personnel. Tornado warnings are currently issued to areas within a designated polygon shaped area and not countywide as in the past.
Note: A particularly dangerous situation tornado warning is issued only when a large tornado is currently producing damage and moving through the warned area. A previous tornado warning may be reissued.
- Tornado Emergency: A tornado emergency is an upgraded tornado warning indicating that a violent tornado is expected to hit a heavily
- Severe Thunderstorm Watch: Severe thunderstorm watches are displayed in YELLOW or BLUE boxes on your television screen. It means that conditions are favorable for the development of severe thunderstorms within the watch area. Severe thunderstorm watches may include large damaging hail 1-inch in diameter or larger and/or damaging winds in excess of 58 mph. Isolated tornadoes may occur but are not expected. Watch areas involve large geographic areas and a severe thunderstorm watch may be valid for 5 to 8 hours.
Note: A particularly dangerous situation thunderstorm watch is rare and issued only when conditions are favorable for severe thunderstorms with winds greater than 90 mph. It also means that isolated tornadoes are possible but not expected. Again, watch areas include large geographic areas; a severe thunderstorm watch is valid for 5 to 8 hours.
- Severe Thunderstorm Warning: A severe thunderstorm warning is indicated by Doppler radar or sighted by trained spotters. It may contain large damaging hail 1 inch or larger and/or damaging winds in excess of 58 mph. Severe thunderstorm warnings are now issued in polygon-shaped areas and not countywide as in the past.
- Significant Weather Advisory: Significant weather advisories are issued when a strong thunderstorm is indicated by Doppler radar that may contain hail smaller than 1 inch and/or strong winds of 39-57 mph. A significant weather advisory is issued on a county by county basis as a short-fused warning.
Winter storms are weather hazards associated with freezing or frozen precipitation such as rain, sleet, snow, and possible strong winds.
- Blizzard Warning: Blizzards are sustained winds or frequent gusts of 35 mph or greater with large amounts of falling or blowing snow. Visibility is reduced to ¼ mile or less for 3 hours or more. There is no temperature restriction, but the wind creates a sub-zero wind chill.
- Blizzard Watch: A blizzard watch means that sustained winds or frequent gusts of 35 mph or greater with large amounts of falling or blowing snow are possible along with reduced visibility to ¼ mile or less for 3 hours or longer is possible within the next 48 hours.
- Winter Storm Warning: Hazardous conditions with heavy snow, freezing rain, sleet or strong winds that threaten life or property are likely, imminent, or occurring.
- Winter Storm Watch: A winter storm watch involves significant accumulations of snow and/or freezing rain and/or sleet are possible in the next 48 hours.
- Winter Weather Advisory: Hazardous winter weather conditions are likely, imminent, or actually occurring over a specified area. Conditions include two or more of the following: snow, freezing rain or drizzle, sleet, and blowing snow. A warning may specify snow or blowing snow and caution must be exercised.
Figure 2. Ice storm leaves trees coated with ice. Stock image by Stephen Barnes.
- Ice Storm Warning: Indicates that heavy ice accumulation (amount varies from ¼ to ½ inch of freezing rain) on trees and wires is imminent.
- Freezing Rain Advisory: Indicates that a trace to a ¼ inch of freezing rain is expected in the specified area.
- Freezing Drizzle Advisory: Indicates that a trace to a ¼ inch of freezing drizzle is expected in the specified area.
- Freezing Fog Advisory: A widespread dense fog is in the area that reduces visibility to less than ¼ mile, occurring in a sub-zero environment and leaving a thin glazing of ice.
- Wind Chill Warning: Extreme, life-threatening wind chills are threatening or occurring over a specified area.
- Wind Chill Advisory: Dangerous wind chills are coming or actually occurring over a specified area.
- Wind Chill Watch: Life-threatening wind chills might occur over a specified area.
Heavy Snow Warning: Replaced with Winter Storm Warning
Sleet Warning: Replaced with Winter Storm Warning Heavy Sleet
Snow Advisory: Replaced with Winter Weather Advisory
Blowing Snow Advisory: Replaced with Winter Weather Advisory for Blowing Snow
Extreme Cold Watch: Replaced with Wind Chill Watch
Extreme Cold Warning: Replaced with Wind Chill Warning
Figure 3. Flooded neighborhood streets. Stock image by irin717.
- River Flood Warning: Stream or river flooding is highly likely, imminent, or occurring. The warning is issued on a county by county basis and could be in effect for a couple of days or longer.
- Areal Flood Warning: General (areal) flooding of streets, low-lying areas, urban storm drains, creeks, and small streams is occurring or imminent. The warning is issued for flooding that occurs more than 6 hours after excessive rainfall OR when flooding is imminent or occurring but not rapid enough to call for a Flash Flood Warning. It is in effect for 6 to 12 hours and issued on a polygonal basis.
- River Flood Advisory: Stream or river flooding is highly likely, imminent, or occurring. A river flood advisory is issued on a county by county basis and remains in effect for a couple of days or longer.
- Areal Flood Advisory: Minor general (areal) flooding of streets, low-lying areas, urban storm drains, creeks, and small streams is occurring or imminent. The areal flood advisory is in effect for 3 to 6 hours and issued on a polygonal basis.
- Urban & Small Stream Flood Advisory: Ponding of water on streets, low-lying areas, highways, underpasses, urban storm drains and elevated creeks and small streams is imminent or occurring. This advisory usually occurs within 3 hours after excessive rainfall and is in effect for 3 to 4 hours when issued.
- Fire Weather Watch: Conditions are expected to become favorable for the rapid spread of wildfires.
- Red Flag Warning: Conditions are favorable for the rapid spread of wildfires
- Fire Warning: A fire is currently burning in the watch area and evacuation is necessary.
- Heat Advisory: Heat index forecast to exceed locally defined criteria for 1 to 2 days, typically between 100 to 105° and above 75° at night.
- Freeze Warning: Widespread temperatures at or below 32° during the growing season.
- Hard Freeze Warning: Widespread temperatures at or below 28° during the growing season.
- Frost Advisory: Widespread temperature forecast to be 33 to 36° during the growing season on nights with light winds and clear skies.
- Dense Fog Advisory: Widespread or localized fog reducing visibility to ¼ mile or less.
Information Resource List
- “Get a Disaster Supplies Kit” – www.extension.org/pages/9366
- “Reducing the Impact of Disasters through Education” – www.eden/lsu.edu
American National Red Cross. (2009). Be red cross ready. Three Essential Steps to Disaster & Emergency Preparedness. Retrieved from http://www.nyredcross.org/?nd=be_ready_cross_ready.
Centers for Disease Control and Prevention. (2006, August 16). Chemical agents: Facts about sheltering in place. Retrieved from http://www.bt.cdc.gov/planning/shelteringfacts.asp.
Centers for Disease Control and Prevention. (2007, October 18). Tornadoes: Being prepared. Emergency Preparedness and Response. Retrieved from http://www.bt.cdc.gov/disasters/tornadoes/prepared.asp.
Dwyer, J. H. (2015). Maintaining Your Health During a Disaster Situation. Metro News 14(2). Extension Disaster Education Network. (2015). During and Following a Disaster. Teaching module under review January 12, 2015.
Foremost Insurance Company. (2005). What belongs in an emergency kit. Retrieved from http://www.mygreathome.com/safety/severe_weather/emergency_kit.htm.
United States Department of Homeland Security. (2011, April). National terrorism advisory system public guide. NTAS Public Guide. Retrieved from http://www.dhs.gov/files/publications/ntas-public-guide.shtm.
Wikipedia, The Free Encyclopedia. Severe Weather Terminology (United States). (2014, December) Retrieved from https://en.wikipedia.org/wiki/Severe_weather_terminology_(United_States).