Severe Thunderstorms

• Often thunderstorms are severe, producing hail, damaging surface winds, flash floods and tornadoes
• The NWS defines a severe thunderstorm as one that produces 3/4" hail and/or surface wind gusts of 50 knots.
• severe thunderstorms form in an environment characterized by:
  • large instability
  • large amounts of environmental vertical wind shear. Vertical wind shear is when the winds increase in strength with height
• severe thunderstorms usually extend all the way to the tropopause and can be seen in satellite imagery as storms producing overshooting tops.

Types of severe storms

The atmosphere generates a number of different types of severe storms. Some examples include:

• Supercell thunderstorms
• Squall lines
• Mesoscale Convective Complexes
• Bow Echoes
• Derechoes