It’s officially springtime in Virginia – which means usually means it's severe weather season across the Commonwealth.
You hear the term “severe weather” from meteorologists a lot, so it’s probably a good idea to define what exactly that means, especially that the spring and summer months bring a higher chance of it.
“Severe convective storms are thunderstorms that produce large hail, tornadoes and damaging winds,” says Maria J. Molina, an assistant professor at the University of Maryland in College Park.
Molina and other colleagues with the Climate Matters program – a group that provides graphics and climate science reporting resources to meteorologists and journalists across the country – have been looking into the connection between severe storms and a warming climate.
Molina says that research is thriving – with some things we know really well, and others that still need plenty of investigation.
What research is revealing:
First things first, Molina admits this kind of research is particularly difficult.
“Some of those challenges come from the fact that to record a tornado occurrence or large hail occurrence – often times that requires a human on the ground that observed it and reported that event. So suddenly, you have certain biases from let’s say population density, road networks and other factors that are non-meteorological in nature.”
But we do know pretty well that a warming climate means the atmosphere can hold more moisture – the all-important fuel source for thunderstorms, which would presumably point to more thunderstorms in a future climate.
There are other things we have a pretty good grasp on, Molina says. Research appears to show peak activity for hail and tornadoes in North America is moving east. We also know that there are certain areas of the United States that are particularly vulnerable to severe convective storms. Molina says folks living in mobile homes in the southeastern U.S., for example, would see devastating impacts from even a weaker tornado.
Urban and suburban sprawl have also increased the chances that one tornado could have an outsized impact for those populated areas.
Additionally, there is data that suggests more tornado-related fatalities are happening at night – when most people are sleeping.
What's not clear:
One area of research that is not clear is how a warming climate will impact wind shear – another necessary component for storm development. Wind shear is the change of either wind speed or direction as you move higher into the atmosphere. High shear environments can cause storms to rotate – which better supports hail formation and tornadic activity.
Molina adds that it’s also unclear how warmer conditions at the surface will interact with layers of the atmosphere higher above that are dry and hot.
“These are called elevated mix layers. And that can serve as a lid on that moisture that’s at low layers that doesn’t allow it to rise. So, some element of that cap is really important for severe convection because you don’t want thunderstorms to form too early in the day – that would lead to no buildup of energy throughout the day and would lead to thunderstorms that may not produce severe weather as a result of being a little bit weaker. So, how that cap is changing over time is really important – if the cap is too strong, there may be no thunderstorm. So, that is something we need to continue studying.”
What's always important:
She says one thing will always be important when it comes to severe weather – even amidst a warming climate: it’s vital to be prepared and know what to do when there is a Severe Thunderstorm Warning or Tornado Warning issued for where you live. Safety measures like going to your basement or a storm shelter during a tornado are proven.
Molina stresses storms could happen at times when we aren’t typically expecting them with a warming climate, though. So, it’s important to always be weather aware.
Looking back at the 1974 tornado outbreak
2024 marks the 50th anniversary of the April 3rd-4th tornado outbreak – which still holds the record for the most F5 tornadoes to occur on a single day.
On April 4th, nearly a dozen tornadoes touched down in West Virginia and southwestern Virginia – resulting in significant damage.
The National Weather Service offices in Blacksburg and Charleston, West Virginia put together this incredible breakdown of that event(which is definitely worth a look if you haven’t seen it already).
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