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Publication Date
16 April 2024

Climate Change May Triple the Intensity of Extreme Precipitation from Mesoscale Storms

Kilometer-scale regional model simulations reveal how flood-producing convective storms may strengthen in a warmer climate over the U.S. Southern Great Plains.
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The historic May 2015 flood event in Texas and Oklahoma was caused by a series of intense mesoscale convective systems (MCSs) (i.e., large convective storms several hundred kilometers wide) that produced record-breaking rainfall and $3 billion of damage in the region. A recent study looked back at this flood using detailed models in order to understand how such heavy rains happened. This study reproduced the event using kilometer-scale regional model simulations and examined how a similar event might unfold in a warmer climate. Researchers found that in a future where the Great Plains are 4 to 6 degrees Celsius (°C) warmer as projected in a high-emission scenario, these storms could bring three times more intense rainfall.


Organized convective storms that grow into MCSs produce precipitation that is about seven times more intense than other storms in the central United States. MCSs that are clustered in space and time produce more floods because they have greater rainfall per unit area. Research shows that with climate change, we might see much more intense rain from MCSs, which could lead to more serious flash floods. The historical flood event in Texas and Oklahoma during May 2015 was caused by an unusually large number of clustered MCSs traversing the Southern Great Plains area.

Researchers at Pacific Northwest National laboratory (PNNL) reconstructed the observed MCSs using a kilometer-scale regional model simulation. They further simulated these MCSs by adding the multi-climate-model-mean projected warming signal of 4–6°C under a high-emission scenario over the region. By tracking the MCSs that produced extreme precipitation in observations and simulations, researchers found that MCSs bring 50 percent more rain and the extreme rainfall intensity could increase three times. This is because a warmer atmosphere can hold more moisture and makes the conditions favorable for stronger storms. This research shows that storms could get more intense, with more heavy rain and less light rain, which could significantly increase the probability of flooding. Flood control and mitigation strategies may need to adapt to the possible strengthening of organized storms. 

Point of Contact
Ruby Leung
Pacific Northwest National Laboratory
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