Cloud Formations that Precede Tornadoes

The root of the word Tornado lies in the Spanish word of tronada, translated as “thunderstorm” which comes from the Latin word of tronada, meaning “to thunder”. A combination of the two, gives the meaning “to turn”, which aptly describes this rapidly turning column of air that is connected to the base of a cloud with the narrow end connected to the ground.

But how do these incredibly powerful wind vortexes come into being? Sometimes we cannot see a tornado with the naked eye and we only assume it exists because of the debris it leaves in its wake. However, most of the time, due to low pressure and fast wind speed, the rapid twisting motion causes water vapor to condense into what we can see as the familiar tunnel shape.

The wall cloud (or pedestal cloud) often precedes a tornado. You may first notice a blackening to the skyline heralded by a greenish tinge to the cloud formation. Many people have even reported that they can actually “smell” a tornado brewing before its actual manifestation.

Wall clouds are thought to be created when rain cooled air is pushed upwards by lighter air and the updraft will move to replace volumes of fast rising air. The damp air is very humid and quickly disperses to form the lower cloud base. Eventually the air in the upper portion of the updraft becomes colder than the surrounding air and spreads out, forming an anvil cloud.

As downdraft’s are created by precipitation, this is the most likely area that a tornado will form, although they can also develop along the:

Gust front: Most prominent on the leading edge of a coming thunderstorm. Marked by cool, gusting winds which will sometimes bring dust.

Flanking line: Cloud line has a step like appearance it is a line of cumulus usually found on the southwest side of the storm – although tornado’s here are not usually significant it does signal the imminence of a bad thunderstorm.

The wall cloud is seen to develop in the wake of a super cell or multi cell storm, but it doesn’t necessarily always precede a tornado. Wall clouds that do precipitate a tornado are recognized by the powerful, warm, surface inflow from the southeast and east.

Wall clouds can also be recognized by the added feature of a “tail” cloud. This is a tapering, shifting cloud that extends from the wall cloud to the precipitation. Wall clouds that precipitate a tornado are also recognized by the powerful, warm, surface inflow from the southeast and east.

The funnel shaped cloud extends from the base of a significant cumulus or a cumulonimbus cloud. It is recognizable as a twisting funnel of air, yet it has no contact with the ground. The cloud becomes a tornado as soon as whirling dust and debris become visibly dispersed throughout the funnel.

The worst tornado damage comes in April; however tornadoes can be seen to be most prevalent during the month of May. Because the sun takes longer to warm the northern plains, the further north you go the later in the year they will occur.

Tornado’s are a devastating feature of our natural world. Although there is little that we can do to dissipate the wrath of these vicious twisters, it is possible to predict their proximity to built up areas. By using a combination of satellite and radar technology and the data supplied by “storm chasers” it had become much easier to offer an early warning system, enabling people to get to safety before the tornado hits.