Severe weather spotting can be physically dangerous due to lightning and the actual severe weather event impacting spotters. However, it is very easy for trained severe weather spotters to mis-identify cloud features that foretell the development of tornadoes or just damaging, downburst, straight-line winds. In fact some trained severe weather spotters may have difficulty telling the difference between tornadoes and funnel clouds. That is, they may be viewing a legitimate funnel cloud, but for some reason the spotter believes they are looking at a tornado, and they relay their report to the National Weather Service (NWS) or to the 911 Dispatchers as a tornado.
To set the record straight - there is a HUGE difference between a funnel cloud and a tornado situation. Let's review the basic facts as we currently know them:
1) Funnel Cloud - In a funnel cloud situation we have a funnel-shaped cloud feature that is actually rotating and it's typically attached to the base of a convective cloud. Additionally, in a true funnel cloud situation, nothing is happening at ground level below the funnel cloud. That is, structural or vegetative damage does not occur underneath funnel clouds. The use of the phrase "funnel cloud" when relaying reports to the NWS implies that damage is not occurring at ground level.
2) Tornado - A tornado is a violently rotating column of air extending from the ground to the base of a convective cloud. The violently rotating column of air results in observable structural and/or vegetative damage at ground level. Remember that we can not see rotating air - air is invisible. What complicates tornado situations for both trained spotters and the untrained general public is that one can have a tornado but not have any visible, condensation funnel within the tornado. Other than the visible rotating spray or swirl of debris and dirt at the ground level along with some kind of cloud base rotation, there may not be any other visible clues that one is looking at a tornado. Once the violently rotating column of air results in ground level damage you have a tornado, whether there is a visible condensation funnel inside the tornado or not. In the meteorology world, once you have a tornado, you no longer have a funnel cloud situation and any visible, funnel-shaped cloud within the tornado becomes known as a condensation funnel. In some tornado situations it may take several minutes for the condensation funnel to develop and grow from cloud base to the ground, and in others there may only be a weakly defined condensation funnel if at all. Meanwhile the tornado will be moving along and chewing up structures and vegetation at ground level. Another factor we haven't mentioned yet is that hills and trees may block the ground view of a spotter so that they may not be able identify the visible, ground-level, rotating spray or swirl of debris and/or dirt that accompanies all tornadoes. Are you still with us? - is this getting complicated?
Okay, now that we have set the record straight, it is recommended that all severe weather spotters, first responders, and 911 Dispatchers:
Although the document is aimed at 911 Dispatchers in order to assist them, everyone should read it. If everyone involved with the severe weather warning process is on the same page, we minimize the relay of false funnel cloud or false tornado reports to the NWS.
We have a related web page feature that everyone should review as well - it's about Scary Looking Clouds (SLC). SLC's result in false funnel cloud and false tornado reports. We even have a Scary-Looking Cloud Club.