The Four Types of Thunderstorms... and the Dangers they Pose!
On average, Kentuckiana recieves approximately 45 inches of precipitation per year and while some of that falls as sleet or snow, most of it comes in the form of rain.
Of the rain that falls, most of it occurs during thunderstorms during the spring and summer months.
There are several types of thunderstorms, but each of them starts out the same. As cumulus clouds!
These cumulus clouds grow as moisture laden parcels of air rise, expand and cool causing water vapor to condense into cloud droplets/ice crystals and then eventually into precipitation. These areas of rising air are called "updrafts" and essentially are what feed the storm.
Once precipitation begins to fall, it carries a doward momentum of air with it known as the "downdraft". The harder the rain/hail, the stronger the downdraft. The downdraft is what you feel when a storm blows in "rain cooled air".
However, this downdraft mechanism is also what essentially kills the storm. You see, in the case of the typical "summertime thunderstorm" the updraft that creates the thunderstorm eventually gets overtaken by the downdraft and it runs out of fuel.
This is the basic life cycle of the thunderstorm and a typical storm will form and then fall apart within an hours time.
Single Cell Thundertorm
When a thunderstorm updraft goes up and then straight back down, as illustrated in the diagram above, it is known as a SINGLE CELL thunderstorm.. Also known as "pop up" or "popcorn" storms, these are very common during the heating of the day during the late spring or summer months.
The single cell thunderstorm can bring brief heavy rain, small hail, gusty winds and dangerous lightning. They also have the ability to bring quick relief from intense summertime heat!
Multi Cell Thunderstorm
Often times, single cell storms will combine and interact with other single cell storms to form a MULTI CELL thunderstorm.
Multi cell storms are also very common during the spring and summer months. In addition to bringing the risk of gusty winds, small hail and lots of lightning, these storms are capable of dropping a tremendous amount of rain over a short period of time especially when they "train" or line up moving continuously over the same areas. This can lead to flash flooding.
Squall Line Thunderstorm
Another common, and often times dangerous, type of a thunderstorm is the SQUALL LINE.
A squall line is a large line of intense thunderstorm activity that can stretch across hundreds of miles of real estate. These storms are common here in Kentuckiana especially during the spring and summer months and although they are capable of producing very heavy rain, lightning, hail and even quick spin up tornadoes, their biggest threat usually comes in the form of wind!
Squall lines often produce winds in excess of 60 mph and have been known to produce wind gusts to over 100 mph! They can be more damaging than even strong tornadoes because of their size that the amount of area they can affect.
When they become particularly strong, they are called a "derecho" which means widespread wind storm in Spanish.
The squall line can be easily identified on radar as well as the cloud structure. The above image features a rather large and ominous looking "shelf cloud" which forms just ahead of the squall line.
The shelf cloud forms in the presence of high speed downdraft winds that race out ahead of the heavy precipitation.
The Supercell Thunderstorm
The other main type of thunderstorm is the supercell. Fortunately, the supercell is also the least common because it is potentially the most severe of all thunderstorms.
The supercell is characterized by having a rotating updraft. This rotating updraft allows the storm to live much longer than normal single cell or mutli-cell thunderstorms and it also allows it to become more organized.
On radar, the supercell often looks like a kidney bean and sometimes can display a "hook echo" pattern which can be an indicator that a tornado could be occuring.
Like the Henryville EF-4 from March 2012, almost all violent or strong tornadoes form from supercell thunderstorms.
In addition to tornadoes, they are also capable of producing extremely large hail, destructive winds, extreme lightning and flash flooding.
WDRB Meteorologist Jeremy Kappell
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