DETROIT – After the deadly tornadoes that struck Southwest Michigan on March 6, many people have been asking an important question: why wasn’t a tornado watch issued before the storms arrived?
Michigan Governor Gretchen Whitmer has called for a review of the situation. But before that process plays out, it helps to understand the difference between two types of alerts meteorologists use during severe weather: tornado watches and tornado warnings.
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Knowing what each alert means and how to respond can help protect lives when storms move in.
What is a tornado watch?
A tornado watch means conditions are favorable for tornadoes to develop across a large region.
Watches are issued by the Storm Prediction Center, a national forecasting center that monitors severe weather across the United States.
A watch can cover multiple counties or even several states and typically lasts several hours. It signals that the atmosphere has the ingredients needed for severe storms capable of producing tornadoes.
Think of a tornado watch as a heads-up to stay alert and be ready if storms begin to develop.
However, tornado watches are not issued for every storm that produces a tornado.
Watches are generally issued when forecasters believe there is a greater chance of multiple storms producing severe weather across a broad area.
If tornado potential is expected to be very isolated or uncertain, forecasters may not issue a tornado watch ahead of time.
That means it is possible and not uncommon for a tornado warning to be issued even when a tornado watch was never in place.
What is a tornado warning?
A tornado warning means a tornado is happening or about to happen.
Warnings are issued by local offices of the National Weather Service when radar detects strong rotation within a storm or when a tornado is reported by trained spotters, emergency managers, or the public.
Warnings usually last 20 to 45 minutes and focus on specific communities in the storm’s path.
When a tornado warning is issued, immediate action is needed. People should move to a basement or an interior room on the lowest floor of a sturdy building and stay away from windows.
It’s also important to understand that severe thunderstorms themselves can sometimes produce tornadoes.
A storm may first be under a severe thunderstorm warning because it is producing damaging winds or hail. If meteorologists detect rotation within that storm, a tornado warning may then be issued for areas in the storm’s path, while the severe thunderstorm warning may still remain in effect.
Severe thunderstorms can produce powerful winds capable of causing major damage and becoming deadly, and in some cases, they can also produce tornadoes.
What Happened on March 6
On the afternoon of March 6, a powerful thunderstorm developed in northern Indiana and moved northeast into southern Michigan.
The storm produced four tornadoes along its path through Cass, St. Joseph, Branch and Calhoun counties. The strongest tornado struck Union City, where winds were estimated at 160 miles per hour.
In total, four people were killed and more than twenty others were injured.
Even though a tornado watch had not been issued earlier that day, tornado warnings were issued as the storm developed, alerting communities along the storm’s path.
Meteorologists will continue reviewing the event to better understand how conditions evolved that afternoon.
Important takeaway
A tornado warning is the signal that a tornado is imminent or already occurring and that people should take shelter immediately.
Experts also stress the importance of having multiple ways to receive warnings, including:
- Wireless emergency alerts on smartphones
- Weather apps
- NOAA weather radios
- Local television and radio broadcasts
Storms can develop quickly, and alerts may arrive with little warning.
Even if a watch has not been issued, people should still stay alert when storms approach and be ready to act if threatening weather develops.
When a tornado warning is issued, the message is simple: take action immediately.