Was it a tornado or something else?

Hi it’s Rebecca again. In light of the cloud misidentification that occurred in Sidney. I thought I would post on things that are often mistaken for tornadoes.

The sight of low ominous clouds in the summer is fairly common. During a storm people often take very impressive pictures; these pictures are often sent into TV stations and blog sites accompanied with the question “was this a tornado?” This post will discuss things that are often misidentified as tornadoes. If you’ve been guilty of this in the past, don’t feel bad, even experienced spotters can make the same mistake.

Fractus Clouds:

These are the clouds that are most often mistakenly thought to be a funnel cloud or even a tornado itself. Fractus clouds are also known as scud clouds.

Scud clouds are created when the cooler outflow is interacting with the warm air ahead of the storm. when this warm, moist air is lifted upwards. The environment is such that the rising moist air is quickly cooled which forms a cloud. When this happens in front of a thunderstorm, the wind can push the clouds away from an updraft, causing the clouds to away from the storm. This gives the clouds a ragged and wispy look. Scud’s can change shape rapidly. If the scud’s are in a outflow they can move fairly quickly. If they’re caught in an updraft they normally rise and may even show some lateral movement.

Scud clouds are not dangerous taken by themselves. However, their presence often is a good indictor that strong gusty winds are in and around the storm.
Fractus clouds are also mistaken for wall clouds.


This is a picture showing what a wall cloud. Wall clouds can take on many forms but normally they look like this. From looking at it, you can see why shelf clouds are sometimes mistaken for a wall cloud. The presence of a wall cloud can be an indication of a mesocyclone but not always. usually a shelf cloud is on the leading edge of a storm. Whereas a wall cloud is seen more or less at the rear of a storm.


  Photo by CWG photographer Ian Livingston
Wall clouds are often associated with tornadic thunderstorms but not always, and many wall clouds do not rotate. However, the presence of one is more often than not a sign of a mature severe thunderstorm. When the wall cloud is rotating a tornado could drop down. The wall cloud aids in tornado development because it brings the base of the cloud much closer to the ground.



Is this a wall cloud? No this is just a scud. But you can see how the mistake could occur.






A wall cloud accompanied by a tail cloud. The low-hanging, tapering feature at right is called a tail cloud, and is an inflow feature. A tail clouds often forms between the low level mesocyclone and the forward-flank core. A tail cloud forms  below the level of the main cloud base. Tail clouds sometimes have very fast, horizontally tilted rising motions. Because they can hang so low, look a lot like a funnel, and contain rapid cloud movement, they are sometimes mistaken for tornadoes. The key with suspicious cloud features is to look for rapid rotation, and evidence of spinning debris under the cloud base.
NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)

Precipitation shafts:

These are areas of rain and/or hail under a storm. A precipitation shaft can fool people into thinking there’s a tornado. The best way to tell what you’re looking at is to watch the motion around the area Most of the time in a precipitation shaft you will see a downward motion. Whereas if it's a tornado you will notice a rapid rotational motion. A tornado will change shape very quickly, while the area of precipitation in a shaft will change shape very slowly.


Here is a picture of a rain shaft. In this picture there is a very thin but intense rain shaft. This kind of thing can fool untrained people or inexperienced spotters can be fooled into reporting a tornado. In this type of situation you should always look for signs of rotation or power flashes. But sometimes rain shafts can look so much like a tornado that even veterans spotters are fooled.  This type of misidentification is especially true if the storm is a few miles away; because it’s is near imposable to tell if it’s rotating. But in the heat of the moment it’s always best to call in a specious lowering.

Before I close I will show you a few more pictures of scud clouds.

                                                              
                                                       A very impressive scud cloud

                                                
          

Here is a picture I snagged from the NWS Morristown, TN. This photo was taken my Bean Station. It’s one of the most impressive pictures of a tornado lookalikes I’ve ever seen.As is the case of all pictures it hard to tell if this is a tornado because it’s very hard to tell if there is any rotation. Also it's hard to tell which direction the storm is moving.  But there are other clues in the picture that tell us it’s not a tornado. If you look at the pictures of wall clouds above, you will notice there isn’t a wall cloud in this picture (not all tornadoes are accompanied with a wall cloud. However, most tornadoes are associated with a wall cloud). What you’re seeing is a shelf cloud (the arched blue line). Rain is always behind the gusty winds under the shelf cloud. So now we know the direction the storm is moving (shown with the yellow arrow). Now the scud cloud (red arch) is being pushed in the direction of the strong winds. This shows why you should always look for all the clues you can in trying to determine if you’re seeing a tornado or not. Because as this picture shows scud clouds can be convincing enough to fool even highly trained individuals.

As I said in my last post, things like downburst,Rear Flank Downdraft, Roll clouds, and Shelf clouds are also misidentified as tornadoes. The main things to look for when you think you see a tornado are: rapid rotation, power flashes, and debris in the air.

Here a two links to post I’ve done on Tornadoes and severe weather.

The Tornado
Clouds associated with severe weather

I hope you enjoyed this post. As always I will be happy to answer any questions you may have.

Rebecca. 

Clouds associated with severe weather.

            Clouds can be fascinating to watch. I don't know about you, but I've spent time laying on the ground just watching clouds. OK I will admit it,  I didn't have a lot going on that day,  still watching the clouds was enjoyable. There are 10 Main cloud Types, at sometime in the near future it is my hope to do a couple of post on the subject of clouds.  In this segment, I will give you a little description of a few of the different clouds associated with severe weather. This will help you identify what you're seeing when severe weather is approaching.

Shelf Cloud:

            This type of cloud is common and is found along a storm's gust front. a shelf cloud is attached to the parent cloud and looks a lot  like it's name suggest. A shelf cloud is created by the rain-cooled air from the storm. As most of you know, the air is warmer at the surface and colder aloft.  There is often a atmospheric cap several thousand feet off the ground where the temperature raises briefly. Most of you have heard the WTEN weather team say " The atmosphere is capped" what this means is there's a warm pocket of air aloft that's keeping a lid on things. A cap works like a closed bottle of soda, if you shake the bottle-up all is fine as long as the bottle cap is in place. However, if you remove the cap... the soda inside will explode. An atmospheric cap works the same way, as long as the cap is in place nothing happens. But, if  the cap weakens or breaks the developing thunderstorms will explode. The warm air being lifted above the cap is what you are seeing when you see a shelf cloud.  The process develops like this:  as the rain cooled air rushes outward it becomes a wedge that forces the warm air up. this forms more updrafts in turn the updrafts will form more precipitation which leads to more cold air flowing outward and new updrafts created and so on.

In this image you can see the downdraft behind and the warm air in front moving up and over the shelf cloud

Roll cloud:

            This type of cloud is fairly rare,  unlike shelf clouds, roll clouds are completely unattached from a parent storm cloud. This type of cloud is long and tubular in shape. they can be startling to see because they appear to be rolling across the sky. Although you may think it looks like a tornado turned  sideways, it is not associated with tornadoes at all.

                                                              Image of a roll cloud.

Mammatus:

            These are  rounded sack-like protrusions hanging from the underside of an anvil cloud. This type of cloud doesn't produce severe weather. But, it's normally seen in severe thunderstorms. They like to form upwind of the updraft. As a chaser, you always look for this type of cloud, while it doesn't guarantee a tornado will form,  it does indicate the storm has a good chance to produce one.

                                                  Image of mammatus clouds

Beaver tail and Tail clouds:

            These types of clouds are inflow bands into a storm. Some confuse tail clouds and beaver tails. The major difference is a beaver tail will be attached to storm base area, whereas the tail cloud attached to the wall cloud lowering.

                                                  Above are images of beaver tail and tail clouds

Scud clouds:

            Scud's are low detached ragged looking clouds. They tend to rise and may exhibit lateral movement. Scuds are not dangerous. However, scud clouds can often be mistaken for a developing tornado.  You tell the difference  by watching the cloud to see  if there's any rotation with it;  if you see any rotation then a tornado has a high chance of forming.

                                                     Pictures of scud clouds

Funnel Cloud:

            A funnel cloud is a funnel-shaped cloud spinning at high velocity.  Normally it extends from the base of a cumulonimbus or towering cumulus cloud. A funnel cloud is usually seen as a cone-shaped or needle like protrusion from the cloud base. If a funnel cloud touches the ground it becomes a tornado, or a waterspout it was over water. If you spot a funnel cloud that's nearby take shelter immediately, as it may suddenly become a tornado.  However, if you feel there is time to safely report it you should do so.

                                                    Below are three pictures of funnel clouds

Cold air funnels:

            Unlike the normal funnels associated with severe thunderstorms, cold-air funnels are generally associated with partly cloudy skies after the passage of a cold front. it is very rare for them to touchdown. But if they do they become a weak tornado. My next blog post will be on Non-tornadic severe weather

                                                         Picture of a cold air funnel

Wall Cloud:

            A wall cloud marks the lower portion of a very strong updraft, usually associated with a supercell or severe multicell storm. It typically develops near the precipitation region of the cumulonimbus. Wall clouds can range from a under half a mile wide up to around  five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm. Wall clouds that exhibit significant rotation and vertical motions often precede tornado formation by a few minutes to an hour.

                OK so you think you see  a wall cloud. Here are a few things to ask yourself,  First is it in the right region of the storm? Are you seeing a low hanging cloud on the forward flank of the storm or the rain free base? Another question to ask is  this feature pointing toward or away from the rain? Shelf clouds generally point out away from the precipitation while wall clouds generally point toward the rain. Is this feature rising? Slowly rotating? Intense rotation? Or bowing out? If you determine you're seeing a wall cloud report it to the NWS or local law enforcement.

            One other question I've been asked  Is it possible to have a tornado that doesn’t have wall cloud ? Absolutely!  Also if you're dealing with a  HP supercell the wall cloud could be in the NE quadrant of the supercell. So unless you're close, you would never see it from a distance away because you will be blocked by wrapping rain curtains.

                                                   picture of an developing wall cloud

           Well that's it for this installment. I hope you found this informative. The next installment will be on non-tornadic severe weather.  I will go into more detail on such things as Bow echo's, MCS, Microburst, and Hail.

Rebecca Ladd.