That's brought tremendous rain, winds and even tornadoes to states like Illinois, Ohio and the Carolinas. But it's also left Tornado Alley out of the loop, yawning under a ridge of high pressure and cool, sunny skies. A cold front scoured out all the moisture. And the surface winds are all wrong. The winds today are blowing from the northwest, pushing along cool, dry air and creating a stable air mass.
Tornadoes require damp winds from the Gulf of Mexico, creating unstable conditions.
Shearing winds get a storm rotating, which sets the stage for a tornado and puts stormchasers on red alert. In a typical year the jet stream undulates like a snake across country, alternately rising north, then slithering south. The jet stream has grown inordinately fond of its northern route, and has decided to take off its shoes and stay a while. Why the jet stream spurned Tornado Alley this year no one really knows. There's talk of El Nino and idle speculation about global warming.