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Severe Weather Awareness Week 2015 – Severe Thunderstorms

| by Henry Luker

Thunderstorms are a common occurrence each spring and summer across the Midwest and Iowa is not immune. Each year, Iowa sees hundreds of severe and non-severe thunderstorms. Thunderstorms can be extremely dangerous storms which may bring deadly tornadoes and lightning, damaging high winds, and hail and can lead to flash flooding.

The National Weather Service issues Severe Thunderstorm Warnings for thunderstorms that are producing or are capable of producing winds of at least 58 MPH or hail of at least 1 inch in diameter.

Oftentimes, severe thunderstorms may be much stronger than the minimum criteria.

Lightning Dangers

753

Straight-Line Winds

754

 

Large Hail

2009 – Large Hail in Iowa

On August 9, 2009 a large, long-lived severe thunderstorm tracked across Iowa. One of the hardest hit areas was Hardin county, with the town of Eldora receiving significant damage due to large hail and strong winds. Winds topped 100 MPH and baseball sized hail fell with hail measuring between 2-3 inches. Damage in the town of Eldora from the thunderstorm was expected to be more costly than the damage done in the town of Parkersburg, Iowa by the EF5 tornado which struck there in 2008. There were 22 reports of injuries in Hardin County, 11 were serious enough for people to be taken to the hospital.

In addition, a 150 square mile area of crops in Hardin County was also damaged. Total crop losses were reported on 45,000 acres, with 60% or greater loss on another 55,000 acres. Hail damage from Otho to Callender and surrounding areas in Webster County was described as the worst seen in 20 years. Estimates of crop damage were over $175,000,000. Former Iowa Governor Chet Culver declared Hardin and Webster Counties state disaster areas shortly after the storm.

Preparedness

Before the Storm: 

  • Know the county in which you live and the names of nearby major cities.
  • Check the weather forecast before leaving to be outdoors for extended periods.
  • Watch for signs of approaching storms.
  • Have a NOAA Weather Radio with a warning alarm tone and battery back-up to receive warnings.
  • Postpone outdoor activities if thunderstorms are imminent. This is your best way to avoid being caught in a dangerous situation.
  • Check on those who have trouble taking shelter if severe weather threatens.

When Thunderstorms Approach:

  • Move to a sturdy building or car. Do not take shelter in small sheds, under isolated trees, or in convertible automobiles.
  • If lightning is occurring and a sturdy shelter is not available, get inside a hard top automobile and keep the windows up.
  • Get tout of boats and away from water.
  • Telephone lines and metal pipes can conduct electricity. Unplug appliances not necessary for obtaining weather information. Avoid using the telephone or any electrical appliances.
  • Do not take a bath or shower.

If Caught Outdoors and No Shelter is Nearby:

  • Find a low spot away from trees, fences, and poles. Make sure the place you pick is not subject to flooding.
  • Stay away from metal conductors such as wires or fences. Metal does not attract lightning, but lightning can travel long distances through it.
  • If you are boating or swimming, get to land and find shelter immediately!

Some information from this post was taken from National Weather Service Des Moines preparedness documents