Severe Weather 101 - Watches, warnings and more - Denver Weather

Last year's Windsor tornado highlighted just how dangerous
weather in Colorado can be. Are you and your family prepared?
Do you know what the watches and warnings all mean?

We’ve all seen TV or Internet news of a weather related watch or warning being issued. But, how many really know what they mean? There is a pretty big difference between the two and it is important to be aware just what it means to you so you can take the appropriate precautions.

Dozens of weather related fatalities occur every year in Colorado, many simply out of ignorance. Taking the time to be aware of the conditions around you and taking appropriate action will keep you from becoming a statistic.

Be sure to check out the video at the end of this story.

Naturally you can get information on current advisories from television as local stations usually do a good job of “crawling” them on the screen when they are issued. This works well if you have a TV available but if not, the radio would be a secondary source. The Internet and the National Weather Service’s website are a great one when at a computer.

NOAA All Hazards Weather Radio For just about anywhere, a special radio that picks up the NOAA’s All Hazard Radio broadcasts is the way to go and provides information from the source. Oftentimes simply called a weather radio, we highly recommend every household have one of these. These radios are relatively inexpensive and allow you to be immediately notified of official Weather Service warnings, watches, and forecasts as well as other hazard information like earthquakes, avalanches, chemical spills, and even AMBER alerts. Be sure to get one with SAME coding so it automatically turns on when something is happening in your area. These can be found at many consumer electronics stores as well as on the Internet at places like Ambient Weather.

This is the first in a five part series on Colorado’s severe weather as part of Colorado Severe Weather Awareness Week.

Type of Weather Alerts

Statements
A statement generally provides additional or follow up information to an existing weather condition. An example could be a short term forecast from the National Weather Service advising of above normal wind speeds – a common one that is issued here on the Front Range.

Advisories
An advisory is for less serious conditions that can cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property. These usually are occurring at the location the advisory covers and the National Weather Service may activate its spotter system to better track and evaluate these systems.

Watches
A watch is used when the risk of a hazardous weather event has increased significantly, but its occurrence, locations, and/or timing is still uncertain. It is intended to provide advance notice of possible inclement weather. Think of these in terms of, “Watch out! Something is coming!” These help to provide enough notice that those who are affected can implement any plans they might need to in order to prepare for the event should it escalate. If you are in an area under a watch, you should plan where to go for shelter, should the weather situation deteriorate, especially for outdoor activities or driving. The National Weather Service may activate its spotter system to better track and evaluate these systems.

Warnings
These are the most severe and critical types of weather alerts and their importance cannot be overstated. A warning is used for conditions posing an immediate threat to life or property. You might read the last part of that previous sentence again - an immediate threat to life or property. This means taking appropriate action and seeking shelter immediately. Severe thunderstorm warnings, tornado warnings and flash flood warnings in particular are serious matters and you need to be proactive to protect yourself and your property. The National Weather Service will almost certainly activate its spotter system to better track and evaluate these systems.

Common Alerts in Colorado: *

Tornado Watch (WT)	Conditions are favorable for the development of severe thunderstorms producing tornadoes in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common. (Also automatically indicates a Severe Thunderstorm Watch)
Tornado Warning (TOR)	Tornado is indicated by radar or sighted by storm spotters. The warning will include where the tornado is and what towns will be in its path. (Also automatically indicates a Severe Thunderstorm Warning)
Severe Thunderstorm Watch (WS)	Conditions are favorable for the development of severe thunderstorms in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common.
Severe Thunderstorm Warning (SVR)	Issued when a thunderstorm produces hail 3/4 inch (20 mm) or larger in diameter and/or winds which equal or exceed 58 mph (93 km/h). Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm is, what towns will be affected, and the primary threat associated with the storm. Tornadoes can develop in severe thunderstorms without the issuance of a tornado warning.
Severe Weather Statement (SVS)	Issued when the forecaster wants to follow up a warning with important information on the progress of severe weather elements.
Flash Flood Watch	Indicates that flash flooding is possible in and close to the watch area. Those in the affected area are urged to be ready to take quick action if a flash flood warning is issued or flooding is observed.
Flash Flood Warning	Signifies a dangerous situation where rapid flooding of small rivers, streams, creeks, or urban areas are imminent or already occurring. Very heavy rain that falls in a short time period can lead to flash flooding, depending on local terrain, ground cover, degree of urbanization, degree of man-made changes to river banks, and initial ground or river conditions.

* Source: Wikipedia, Severe weather terminology.

For a comprehensive list of the types of warnings and advisories that may be issued and what they mean, Wikipedia has a nice list of them here.

Conclusion

I think the point I really want to drive home is that when the National Weather Service issues warnings and watches, it is not a trivial matter. The weather can change very quickly, particularly here in Colorado, and we need to pay attention. In subsequent articles in this series I will talk about specific hazards like tornadoes, thunderstorms, lightning, flooding and more so be sure to check back!

Below is a pretty neat video with time lapse images of supercell thunderstorms. You can really get a feel for the power of these storms - and the danger!