Kris Bedka

The Great Plains in the USA are one of the most sensitive regions in the world for land surface feedbacks. Essentially, droughts lead to more drought, and floods lead to floods. The reason is that a lot of our precipitation differences can be tied to the low level moisture content. When we get sufficiently dry that low level moisture drops, storms must rise to a higher level than typical to condense and produce rain. In practice this means some situations that would normally produce rainfall do not. And then, even if storms do produce rainfall, they see higher evaporation than would normally occur from the larger dew point depressions and hotter near surface temperatures. This is the situation we are in now. But it gets even worse! Because once the land is sufficiently dried out and moisture has been reduced, the increased heat flux into the atmosphere warms the lower and middle atmosphere more effectively as well. In other words, it somewhat easier to build ridges. So when you have a pattern that supports drought, it feeds back on itself to continue to support drought. Obviously, this will eventually break, and I think El Nino is going to force that this fall. But this is why I said the general dry pattern will stick around for at least a bit longer in the southern Plains. Image from (science.org/doi/10.1126/scie…)