Watch, Warning, Polygon, What does it all mean?
Just like the everyday tech we carry around in our pockets, weather technology is evolving and so has our warning system in the United States.
One of the most common questions a meteorologist receives when a Tornado Warning is issued; what does that mean? What should I do? Or, where is the tornado?
The warning system has changed several times over the past decades. When Doppler radars were installed/upgraded in the late 80’s and early 90’s, weather offices began to issue radar based tornado warnings.
Today, there are two different ways a tornado warning is issued. First, if a funnel cloud or tornado is spotted and reported back to the National Weather Service in time. Second, if there is a severe thunderstorm and rotation is detected on radar. The meteorologists at the National Weather Service may issue a warning if a storm has the high potential for producing a tornado. A Tornado Warning means a tornado is occurring now or is imminent. Either way, this warning is a signal to the public that this is a dangerous thunderstorm and should be taken seriously. You should be inside a sturdy structure, away from windows and the lowest level possible. Put as many walls between you and the outside as possible. If you’re driving and near or under the storm, seek shelter in a building, do not try to outrun the storm. Mobile homes and trailers are not a safe structure during a tornado.
County based storm warnings have been replaced with polygons or Storm Based Warnings. You may have noticed these colorful boxes on radar maps. This is a way to narrow down the warning to more specific areas so the entire county may not be alerted. Counties can be very large, a warning in Swan Valley may not have anything to do with Idaho Falls. Polygons are based on the storm’s location and direction, regardless of county lines.
A Watch by the National Weather Service will most likely cover a large area and may even cross state lines. This is a signal to the public that dangerous weather could occur and conditions are favorable.
