Oh where, oh where did my twister go?

Even though storm chasers are missing tornadoes....
I'm quite positive the public is not!

If you have noticed a lack of tornadoes across the nation so far this spring, you’re not alone.  Many meteorologists and storm chasers have indeed noticed the shortage of twisters across the U.S. so far this spring.  Tornado season usually begins to kick into high gear in March, but this year has been relatively quiet thus far.

If you may recall, last year was quite active.  By early April 2012, there had already been 290 tornadoes (which resulted in 60 tornado-related deaths).  Now fast forward to early April 2013, and the nation has only seen 137 reported tornadoes and, thankfully, only 2 fatalities.  So what is going on?  Why is the amount of tornadoes less than half of what we saw last year?  What changed?

The main reason that is has been so quiet (tornado-wise) thus far is also one of the biggest topics you hear or have talked about among your friends – the colder than normal spring and late winter! The cold air over the central and eastern U.S. can largely be blamed on a stationary high pressure system over Greenland and the North Atlantic which has blocked the normal flow of storm systems across the nation by altering the jet stream.  Normally, the jet stream begins to bring warm, moist air (a critical component for tornadogenesis) from the Gulf of Mexico into the central U.S. this time of year.  But this year, the flow has been the opposite, bringing cool dry air in from the north.

So when will this pattern change?  The process is well underway.  The blocking high pressure system over the North Atlantic has been weakening and warmer temperatures and moist air have moved back in from the Gulf of Mexico in recent days.  As a result, the first significant outbreak of severe weather across the nation could occur early next week as several storm systems slide across the central part of the nation.  The first of these systems will come through the Midwest on Sunday into Monday with the potential for gusty winds and some large hail.  This first system could then set the stage for a much larger severe weather outbreak by Tuesday and Wednesday when a second storm system slides through.

The categorical (left) and probabilistic (right) outlooks for severe weather for Monday, April 8th, 2013.
Courtesy of the Storm Prediction Center.

The severe weather outlook areas for Tuesday, April 9th (in red)
and Wednesday, April 10th, 2013 (in purple).
Courtesy of the Storm Prediction Center.

So what about folks up here in Wisconsin?  Although we can see severe weather and tornadoes now, our tornado season begins to ramp up in late April and continue into August (but they CAN occur anytime of the year, as evidenced by the tornado that hit near Kenosha on January 7th, 2008).  But at least for next week, we should remain safe in the severe weather department (unlike 2011 when the earliest outbreak in WI was on April 10th!).

Just out of curiosity, looking back on the past few years, 2012 was actually a very quiet year for tornadoes in Wisconsin.  According to the National Weather Service, there were only 4 reported tornadoes in Wisconsin in all of 2012 compared to 38 in 2011 and 46 in 2010.  So let's hope for another quiet year in 2013! 

Also, please note that Severe Weather & Tornado Awareness Week in Wisconsin in April 15th through the 19th, with a statewide tornado drill on Thursday, April 18th around 1 p.m. (should severe weather happen on that day, the drill will be postponed until Friday, April 19th).  Next week, I plan on posting regularly informing you how to stay safe in various weather situations, and then during Severe Weather & Tornado Awareness Week, I plan on posting on the various types of severe weather we see!

Hope to see you back here soon!  :)