Severe weather spotters know that they can observe a false tornado or a false funnel cloud, that is, they will eventually see a funnel-shaped cloud feature that appears to be funnel cloud, or even a tornado. Jerry Verveka, a trained severe weather spotter in the Briggsville area of Marquette County, took a great picture of a fase funnel cloud while storms were moving west to east across Marquette County on July 7, 2008. Jerry is a member of the Milwaukee Area Skywarn Association (MASA). Here's his picture:
Jerry indicated that the false tornado in the picture above showed absolutely no signs of rotation on a vertical axis. It sure looks like a tornado, doesn't it? He mentioned that the cloud fragments that comprised the false tornado were rising up into the base of the thunderstorm - in other words - into the updraft tower. Thunderstorms have two main parts: an updraft tower and a downdraft tower (where the rain, hail, and gusty, straight-line winds are generated).
So, the question is - if you were watching that false tornado like Jerry was - would you be fooled? Would you start to get exicited and call a dispatcher at the 911 Communications Center and tell them that you saw a tornado?
Trained severe weather spotters who really know their 'stuff" can anticipate false funnel clouds and/or false tornadoes without getting excited. They know they have to continue observing cloud features and look for signs of persistent rotation within that cloud feature, on a vertical axis. If they see persistent signs of rotation within a funnel-shaped, cloud feature on a vertical axis, then they have a true funnel cloud, or if there are ground-based rotational dirt/debris effects associated with cloud-base rotation, then they have a tornado. If they do not see signs of persistent rotation, then what they are looking at is nothing more than a "scary-looking cloud", or what we meteorologically refer to as 'scud."
In the picture above, you can see a a row of tall trees. Trees, hills, and buildings can block your view of what's happening at the ground level. This is why trained severe weather spotters have to be very careful - it looks like we have a tornado in the picture, but since we can't see what's happening at the ground we can't assume we have a tornado. Besides - the funnel-shaped, scary-looking, cloud feature in this picture wasn't even rotating! Conclusion: no tornado, no funnel cloud, just scud.
If you are not a trained severe weather spotter - will you be fooled if you saw what Jerry observed that day? Would you be tempted to call the 911 dispatcher and tell them that you see a funnel cloud, or even a tornado? This does happen - every year many local National Weather Service offices receive false funnel cloud or false tornado reports from the generall public that have been relayed from the 911 dispatchers.
Below is another picture taken by Jerry - but in this picture he indicated that he saw clear signs of cloud-base rotation. He didn't see a true funnel cloud or a true rotating wall cloud, but he did see the base of the storm slowly rotating on a vertical axis. Obviously, this storm cell should be monitored by trained severe weather spotters in case things become better organized at the cloud base and a true rotating wall cloud develops, and/or a true funnel cloud develops, and/or an actual tornado spins up.
A thanks is extended to Jerry and MASA for sharing these pictures that give us a chance for some education!
Note: for more information about severe weather spotting, to the Storm Spotter Page on the Milwaukee/Sullivan web site at: http://www.crh.noaa.gov/mkx/?n=spotters
Free, 2-hour, severe weather classes are conducted by the Milwaukee/Sullivan NWS office in March and April each year. You don't have to be a severe weather spotter in order to attend. The class schedule is posted on the Milwaukee/Sullivan web site by February 1st each year on the Storm Spotter Page, or in the Top News of the Day section.