Last week, I wore shorts. Yesterday, it snowed. Meanwhile, down in Texas, there are heat-induced wildfires. This morning, I really enjoyed the catharsis provided by this interesting look at the science of volatile Spring weather, written by my fellow Minneapolitan Emily Sohn.
Sohn's take is refreshingly non-sensational. First, she points out, Spring is just a volatile season. The change from winter to summer, cold to warm, will do that. But this Spring has been different in some important ways—some natural, some man-made, and some that are just confusing.
The current weather map fits pretty well with a typical La Niña year, in which cooler than normal waters gather beneath the surface of the eastern equatorial Pacific off the west coast of South America. The phenomenon influences the positioning of the jet stream. And that, in turn, affects weather patterns around the globe.
But La Niña, which is natural and cyclical, is not the only driver behind weird weather reports lately. For the last two years, for reasons climatologists do not yet understand, a strange pocket of warm air has lingered over the Arctic, Douglas said, making the dead of winter a full 10 to 20 degrees warmer than normal in Greenland and northern Canada. The bubble has displaced cold air southward.
"If you leave the refrigerator door open, you warm up the refrigerator, and all that cool air kind of spills on to the floor," Douglas said. "That's what's happened."
On top of all that, a general rise in global temperatures has boosted levels of water vapor in the atmosphere by four percent, Douglas said. That basically loads the dice for more storms to form. Meanwhile, Twitter and Facebook can accentuate and accelerate the sense that severe weather is worse than it is.
I also really liked this quote from meteorologist Paul Douglas, "The weather is inherently wacky. Personally, I'm seeing an increase over time in the wackiness."