Minnesota awaits jet-stream shift, for better and worse

When it comes to moaning about Minnesota's recent cool and drizzly weather, be careful what you wish for.

"People complain about a crummy spring, but the flip side is what's happening down South," said Todd Krause, warning coordination meteorologist for the National Weather Service's Twin Cities office.

Indeed, the two weather regimes, separated by 1,000 miles and ranging from devastating to merely discouraging, are related. Both have been generated by a strong and stubborn jet stream that has been spawning a continuing, storm-producing clash of warm and cool air masses across the South, while walling up cool air and cloudy conditions across the northern U.S.

The jet stream will move northward sometime soon, as it always does, Krause noted. That will force a change to balmier spring weather across the Upper Midwest.

Will that bring tornadoes?

"There's no way to tell, really," Krause said. "What we don't know is how long [the jet stream] will be when it gets here."

The stampede of storms across the South on Wednesday killed close to 300 people, making it the deadliest outbreak in nearly 40 years. Led by April's total alone, 2011 has already become the deadliest tornado year since 1974.

The atmospheric conditions are so unsettled that this could prove to be another busy tornado year in Minnesota, said Kenny Blumenfeld, consultant, severe weather researcher and visiting geography professor at the University of Minnesota.

Minnesota's warning systems are very effective, he said, which ought to minimize deaths and injuries.

Wednesday's toll in Alabama and Mississippi was likely elevated because those states have many more medium-size cities and a greater rural population than Minnesota, presenting tornadoes with more targets, Blumenfeld noted. But a massive outbreak, which can overwhelm any region, is possible anywhere, any time, he said.

"We have a weather-savvy public, a good Skywarn organization, and a good outdoor warning system," Blumenfeld said. "It gives us a bit of an edge. But then again, it's been a while. If you were running even one those [southern] tornadoes over the metro area, you'd see a kind of destruction we haven't seen in a long time.

"Does that mean it's coming this year? There isn't really any evidence that because of the big tornado outbreaks in the deep South, we'd get that up in the Minnesota area. But at some point in the next 20 years, yeah. It's inevitable."