The Minnesota Homeland Security and Emergency Management Division (HSEM) highlights information about storms. lightning and hail today.  This is Minnesota Severe Weather Awareness Week.  According to information from HSEM thunderstorms affect relatively small areas compared with most other storms.

The typical thunderstorm is 15 miles in diameter and lasts for 30 minutes.  Whatever their size thunderstorms are dangerous.  Severe thunderstorms produce large hail or winds of at least 58 mph.  Some wind gusts can exceed 100 mph and produce tornado-like damage.

When a severe thunderstorm threatens, stay inside a strong structure.  Mobile home occupants should go to a more permanent structure.

Thunderstorms can produce straight-line winds that exceed 100 mph.  For this reason you should treat severe thunderstorms just as you would tornadoes.  Move to an appropriate shelter if you are in the path of the storm.  Remember severe thunderstorms can produce tornadoes with no warning.  The strong rush of wind from a thunderstorm is called a downburst.  The primary cause is rain-cooled air that accelerates downward, producing potentially damaging gusts of wind.

Strong downbursts can be mistaken for tornadoes.  They are often accompanied by a roaring sound similar to that of a tornado.

Hail is a product of thunderstorms that causes nearly $1 billion in damage every year.  Most hail is pea-sized.  Much of it has been reported to baseball sized, it can reach the size of grapefruit.  Large hail stones fall faster than 100 mph and have been known to kill people.

Lightning is produced by every thunderstorm.  Lightning kills an average of 47 American each year.  Hundreds more are severely injured.

Here are some lightning safety types from Minnesota HSEM:

  • NO place outside is safe when thunderstorms are in the area.
  •  When you hear thunder, immediately move to safer shelter; a substantial building with electricity or plumbing or an enclosed, metal-topped vehicle with windows up.

HSEM has these indoor lightning safety tips:

  • Avoid plumbing, including sinks, baths and faucets.
  • Do not lie on concrete floors, do not lean against concrete walls.

What to do if you are caught outside when there is no safe shelter nearby:

  • Never lie flat on the ground.
  • Never use a cliff or rocky overhang for shelter.