Tornado Outbreak Rakes the South

The National Weather Service has confirmed 164 tornado reports around six states in the southeast Wednesday night. Parts of Alabama and Arkansas felt the brunt of the this late April tornado outbreak. In a month of record-breaking weather, April 2011 may go down in history as the worst tornado month in decades.

So far over 250 people died in the overnight hours, mostly in Tuscaloosa, Alabama, Georgia, Arkansas and Virginia.

With emergency management teams still surveying the damage and confirming twisters, the official April tornado count stands at 453. The all time record for most tornadoes in a month is 543 and was set in May 2003. Many meteorologists believe that record will fall when all the damaged from this week’s three days of twisters is assessed.

If you were in tornado alley when these storms ripped through please post your experience and be sure to include photos. This information will help the National Weather Service confirm tornadoes and measure their strength.

The Weather Channel’s severe weather scorecard puts this week’s storms as the worst tornado outbreak in almost 40 years.

Dr. Greg Forbes says that April has set a record, with a preliminary count of 453 tornadoes during the month. And that number is before counting the April 27 tornado outbreak totals. Clearly April 2011 breaks the old record of 267 tornadoes in 1974. He says an average April tornado total is about 163 tornadoes. And this is the second tornado outbreak this month. A couple of weeks ago 15 states were hit by another tornado outbreak.

And it appears that La Nina is to blame for this latest series of storms. La Niña develops when the surface temperature of the eastern Pacific Ocean cools along the equator. The cooling triggers dry weather in the southern U.S. because it tends to reduce the moisture from the sub-tropical jet stream, which serves as a highway for storms. La Niña also increases the chances for unusually cool and wet weather across the Pacific Northwest and the Midwest by altering the path of the polar jet stream, another high-altitude air flow.

As a result of these two meteorological phenomena the remarkable difference in temperature between the hot Southern Plains and cool Midwest generates the energy to fuel big storms. This month, the south has been pummeled by storm after storm, causing severe flooding and several historical tornado outbreaks, including the one April 27.

“Everything was in place for a major event, and it was very well forecasted as these ingredients were seen days in advance. The very strong wind field contributed to rapid storm motions and aided in the production of long-lived tornadoes.” — Dave Carroll, meteorologist, Virginia Tech