The process by which a tornado develops is complex and requires
a lot of variables to come together at the same time. The following
provides a summary of the process we go through on a daily basis and
what we look for to see the final tornado form in front of our eyes.
Find out ALL the details and see it happen for yourself when you join
us in 2010.

Our daily ritual always begins with the morning forecast. Our on-board
meteorologists will look at the current conditions across the central
plains and then we look into the future to find out where the best chance
for tornadoes will be later that day. F5! feels the key ingredient
to tornadic development is upper level support, or super-fast winds
in the upper levels of the atmospshere. Although tornadoes can form without
strong upper level support, we look for this key ingredient to increase
the chances of tornado viewing later in the day. After a complete analysis
and forecast is produced each morning, that day's "Target City"
is announced.
The first sign of tornado development comes out of the clear blue sky.
When the conditions are right for thunderstorm development, the first
cloud we see is a puffy cumulus cloud (see fig. 1). These types of clouds
are very common across the country, but typically they do not grow into
monster thunderstorms that drop tornadoes. For that, you need much stronger
instability in the atmosphere. The setup in the central portion of the
United States, known as "tornado alley," is perfect during
the spring months as cold, dry air moves south out of Canada and the
warm, moist air moves north from the Gulf of Mexico.
As the two air masses clash, the atmosphere becomes even more unstable,
meaning the parcels of air in a certain area become more buoyant than
the surrounding air, so the cumulus clouds begin building vertically.
We call these towering cumulus or TCu (see fig. 2). Since all clouds
require upward moving air, you can imagine that a TCu requires even
faster moving air to allow it to shoot up that quickly, often rising
hundreds of feet in less than 20 minutes.
Usually we'll see several TCu's building around our target city in
the afternoon hours. The next step is to find the best updraft to begin
inspecting more closely. As the towering cumulus clouds continue to
grow, they begin to bulk up and, with luck, turn into supercell thunderstorms (see fig. 3).
Although only a small number of cumulus clouds or towering cumulus clouds
become supercells, we look for supercells to increase our chance of
witnessing a tornado.
Supercells are the perfect parent thunderstorms for tornadoes because
they already include strong updrafts that often are rotating. A supercell
thunderstorm develops its own complete system with an updraft and a
downdraft, which provides a nice generator for tornadoes. These supercell
thunderstorms are responsible for most of the tornadoes that drop in any
given year.
As the supercell continues to churn, we watch for a lowering under
the updraft, where the updraft becomes more focused and drops closer
to the earth. This visual representation of a tighter updraft is called
a wall cloud (see fig. 4). Updrafts in supercells typically rotate, but wall clouds
always rotate.
The tornado will then drop out of the wall cloud (see fig. 5). However, we have
witnessed several occasions where a tornado drops out of the updraft
right next to the wall cloud! Every storm is different, so this is not
a hard and fast rule, but typically, the tornado will drop out of a
wall cloud. A tornado is a connection from the earth all the way into
the upper levels of the atmopshere and the stronger the upper level
support (jet stream), the more potential for a larger and more destructive
tornado.
After dropping to the ground for an average of a few minutes, most
tornadoes will begin to die in what we call the roping out phase (see fig. 6). Rather than simply disappearing, tornadoes will typically rope
out and dissipate under the thunderstorm.
As we mentioned, there are many ways tornadoes can form and dissipate,
but the typical situation is as outlined above. The best way to understand
the process of tornado development is to join our tour and witness it
yourself--with a full education from our meteorologists! Any questions
you have will be answered and you'll be able to watch the next tornado
touchdown along with the experts!

Photo credits: #1-4, #6 - David Dildine, F5! Tornado Chasing Safaris; #5 - Geoff Mackley; sunset - Tim Tonge, F5! Tornado Chasing Safaris