Whatever agency has responsibility for activating tornado sirens in Goshen essentially sounded a false alarm yesterday.
According to a report in the Goshen News, tornado sirens sounded after Goshen Police received reports of a funnel cloud. The Goshen News report does not say who reported the funnel cloud to police, so we don’t know from that story if any of the calls came from normally credible sources or if they came only from untrained members of the general public. We can assume, however, that the people who reported a funnel cloud to police were probably looking at the cloud shown in the photo below.
|Photo of “beaver tail” cloud near Goshen, from NWS website.|
As well-trained SKYWARN storm spotters know, “funnel cloud” has a specific definition in meteorology: It’s a rotating cloud that often exists before or after a tornado. Not every funnel-shaped cloud is a funnel cloud and not every rotating funnel cloud becomes a tornado.
Unfortunately for those in charge of Goshen’s tornado sirens, the cloud that appeared near Goshen was not a rotating funnel cloud and the city was not in danger of a tornado.
National Weather Service (NWS) meteorologists later confirmed that the cloud was a formation known colloquially as a “beaver tail,” which is formed as air cools while being sucked into a thunderstorm, thus allowing water vapor in that air to condense into a cloud. These clouds are normally mostly horizontal. When viewed from a certain angle, however, they can appear to be reaching toward the ground. The northern Indiana NWS office posted an excellent explanation on its website. Their article includes a helpful pair of photos of the same beaver tail taken from two different locations, demonstrating the illusion that can occur.
So, how are people supposed to know the difference? A true funnel cloud rotates. A beaver tail doesn’t. “If it doesn’t spin, don’t call it in,” is a mnemonic I learned in spotter training.
Members of the general public who have never taken SKYWARN training have little way of knowing this. So what’s a public safety agency to do when it gets reports of a funnel cloud from the general public? Here’s my opinion:
- Train public safety dispatchers to be aware that some funnel-shaped clouds that might prompt citizens to call 911 are not actual funnel clouds and therefore represent no danger to the community. This knowledge will help dispatches treat funnel cloud reports with a healthy amount of skepticism.
- Before sounding tornado sirens, seek confirmation from trained field personnel (e.g. nearby fire fighters, law enforcement officers, EMA volunteers and/or others known to have received SKYWARN training).
- Before sounding tornado sirens, place a quick call to the NWS. Ask if atmospheric conditions are right for the formation of tornadoes and whether NWS radar indicates any sign of rotation where the funnel cloud was reported. The NWS office can also tell the local public safety agency whether the NWS office has received any reports from trained spotters that would confirm or contradict public funnel cloud reports.
At the very least, any time a local public safety agency activates tornado sirens on its own (e.g. without an NWS warning), that agency should immediately notify the NWS that it has done so, and why. Why? Because without that notification, nobody who depends on NOAA weather radio or broadcast media for their warnings will know what’s going on!
Not everyone can hear tornado sirens where they live and work. Activating tornado sirens without contacting NWS to activate the entire warning system fails to protect those citizens who are beyond the range of sirens.
What do you think? Please add your comments below. And by the way, please understand that this post represents my personal view, not necessarily the views of any agency or organization.