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Spring 2012 Outlook: Another Year of Twisters?

By Shawn Crowe

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My winter outlook, issued back in late November, called for a relatively mild December with increasing cold and snow chances in January and then a mild February. That prediction has pretty much been spot-on, except that admittedly I thought it would get a little colder in January than what it did, but so far most of what little snow we have seen happened in January. Winter as a whole has been mild so far, checking in as the sixth warmest winter on record. To this point, it has also been the least-snowy winter we’ve ever recorded. People who dislike snow are really enjoying this.

In my outlook, I mentioned that March would be the wild card.  It could be a brutal month with snow, ice and cold temperatures or it could be warm with tornado outbreaks. I still think this is true and it could go either way... but I am increasingly leaning toward the tornado outbreak scenario as being the more likely outcome.

Let’s not forget what a horrible year 2011 was. The National Oceanic and Atmospheric Administration reports that 552 fatalities from tornadoes were confirmed in the U.S. last year, making it the second most deadly year in our recorded history from tornadoes. The year also brought the single highest number of tornadoes ever recorded here, and also set the record for the most fatalities caused by a single tornado which occurred in Joplin, Mo. The atmospheric flow created by the La Nina conditions we saw combined with the low pressure pattern over North America turned out to be the perfect recipe for thunderstorm outbreaks. We also saw a lot of large cities struck by twisters last year, which is a little unusual too. It was the kind of year that most citizens of the south hope to never see again. 

My fear is that we are going to see that happen again, and it could be just months away. The problem is that we are once again in a La Nina winter, except this one is following a more textbook look of a La Nina than what we saw last year. There are many variables that come into play when setting up the weather of a given season, but let’s focus on just a couple of basic reasons why things could get extreme again in the next few months. 

For the past 8-12 weeks, the mean position of the jet stream has been one with a trough digging into the southwestern U.S. and then a streak from Texas toward the Great Lakes/Ohio Valley region. This is predicted to continue by the Global Forecast System weather model, as you can see in the image I’ve posted valid Feb. 15.

The darker blue shading indicates where the speed of the jet stream is really howling in the upper levels of the atmosphere. This is sort of like the “railroad” that storm systems generally will develop along and follow. The reason we’ve seen so much rainfall this winter (2011 also finished as the wettest year ever recorded in Kentucky) is because of this position of the jet stream. It keeps directing storms to track directly into the Ohio Valley. Typically, you see this pattern change every few weeks. This year has been uncanny. The jet stream has basically remained in this flow regime for the entire season. During the middle of winter, what you get is a lot of rain in this case. But if you have this setup in the March-May timeframe, it’s a recipe for thunderstorms and lots of problems. My fear is that we may see this atmospheric flow continue into spring.

The other thing is the temperatures in the Gulf of Mexico. The waters there are the fuel that powers our thunderstorms here. For the same reasons that our winter has been extremely mild, the Gulf waters are also running very warm. Water temperatures are in the 70s down in the Gulf right now and this warm water will be primed and ready to create powerful storms this spring when southerly winds bring the evaporation northward into the Ohio Valley.

With plenty of fuel, and a storm track persistently spinning up storms and pushing them into Kentucky, the stage could potentially be set for another year of tragic tornado outbreaks and severe weather damage. I am personally going to be reviewing my homeowners insurance policy in the next few weeks, and I strongly recommend that anyone who still does not own a NOAA weather radio should go and purchase one.  The Midland WR-100 or WR-120 are excellent choices and are easy to find for under $30 dollars at stores such as Kroger, Walmart and RadioShack. Now is the time to prepare and plan in case the weather this spring does indeed go wild on us again.