Harsh weather of all kinds is often called severe, but the word takes on a very specific meaning when it comes to thunderstorms.
Harsh weather of all kinds is often called severe, but the word takes on a very specific meaning when it comes to thunderstorms. About 100,000 thunderstorms rumble across the United States each year, but just 10% intensify into a severe thunderstorm, according to the National Oceanic and Atmospheric Administration. A storm’s threats must be fierce enough to check at least one of three criteria boxes before the National Weather Service issues a severe thunderstorm warning or a tornado warning. Some storms check two or all the boxes at once.
3 ways a storm can turn severe
Tornado
This first criterion is the most straightforward: Producing a tornado of any strength, size or duration automatically makes a storm severe. It’s the ferocity of a storm’s hail and wind where we have to dig a bit deeper.
Hail size
If a thunderstorm drops hailstones that are at least quarter-sized, it’s officially severe. This 1-inch diameter is the size at which hail can start to cause damage, like denting cars, siding or cracking windshields, especially if strong winds increase the force of its impact. The damage really escalates once it reaches the size of golf balls, and especially baseballs and softballs. Forecasters describe hail that is 2.75 inches or larger as “destructive.” National Weather Service warnings of this severity automatically trigger wireless emergency alerts on smartphones. The bar for severe hail was lower — around penny size —until 2010, when the weather service determined that size usually wasn’t damaging.
Wind speed
All storms have bursts of strong winds, but 58 mph is the key threshold for a severe thunderstorm warning. Winds that strong are likely to cause minor damage to trees, power lines and structures. The impact really escalates once gusts hit 80 mph; these winds can destroy less sturdy structures, cause serious damage to mobile homes and tear away material from the roofs of even well-built homes. Winds at this speed or higher are deemed “destructive” and will also trigger a wireless emergency alert. Only around 10% of severe thunderstorms in the US reach this level each year. Some of the strongest severe storms can have gusts over 100 mph, which produces damage similar to a strong EF1 or EF2 tornado, significantly damaging or destroying mobile homes and roofs of sturdier structures. It’s rare, and usually happens in a long-lived, widespread windstorm called a derecho. One of the most powerful derechos in recent memory produced gusts between 120 to 140 mph in Iowa on August 10, 2020. The derecho’s 14-hour journey had a much larger footprint that spanned from southeast South Dakota to Ohio. Its path of destruction caused $13.8 billion in damage, according to Climate Central.
United States Latest News, United States Headlines
Similar News:You can also read news stories similar to this one that we have collected from other news sources.
3 Overlooked Movies You Should Stream in April 2026: ‘Kinds of Kindness’ and MoreCheck out these overlooked gems streaming in April 2026, like 'Kinds of Kindness' starring Emma Stone and Jesse Plemons on Hulu
Read more »
Trump Says US to Sever Key Iran Lifeline With Blockade of StraitEscalation will likely worsen oil and fuel shortages globally as peace talks with Tehran fail
Read more »
Trump Orders Strait of Hormuz Blockade, Escalating Tensions with Iran After Ceasefire FailureThe United States is set to blockade the Strait of Hormuz, following the failure of ceasefire talks with Iran. This move, announced by President Trump, raises the stakes in the ongoing conflict, threatening global energy supplies and potentially leading to further escalation. Iran has responded with warnings of harsh consequences for any breach of the ceasefire.
Read more »
How compassionate responsibility can replace harsh self-blame after mistakes.Many people respond to their own mistakes with harsh self-blame. Learning the difference between accountability and blame can change how you treat yourself after you fall short.
Read more »
Republican Brian Fitzpatrick condemns Trump’s attack on Pope Leo XIV as ‘offensive to Catholics in every corner of the world’The Bucks County Republican offered a harsh rebuke after the president suggested the pope owed his position to him.
Read more »
Ryan Lochte's estranged wife and new girlfriend feud after brutal email from swimmerReid shared the harsh message to her Instagram story and called it the “tip of the iceberg.”
Read more »