Severe weather, including a massive series of tornadoes, roared across the American Midwest on Sunday.  These powerful storms caused widespread damage and knocked out power to tens of thousands of people.  Numerous injuries and at least eight fatalities have been reported so far.

NWS survey teams are currently on the ground evaluating the damage, but early reports estimate that several dozen twisters touched down across seven states. The two strongest have been preliminarily rated EF-4, the second highest ranking on the Enhanced Fujita Scale.  With winds raging between 166 and 200 mph, they devastated the towns of Washington and New Minden, both in Illinois.  Officials say these were the strongest and deadliest November tornadoes on record in the state.

This historic outbreak was the result of an explosive mix of atmospheric conditions, including instability generated by the collision of a cold front with warm, moist air moving up from the south.  In addition, the combination of a powerful jet stream aloft and a strong area of low pressure near the ground – with winds blowing in the opposite direction – helped generate spin in the atmosphere.

While autumn, the so-called second season for tornadoes, has been known to produce severe storms, they usually occur in the warmer climates of the Southeast and Gulf Coast. Twisters further north, especially powerful ones, are very rare for this time of year.

Damage from tornadoes near Washington, IL                                                                                     Image Credit: A. Koury

Image Credit: NOAA