A quiet year for tornadoes
The worst part of tornado season is over, and the Wadena area has caught a break compared to last year when there were multiple tornado warnings in the weeks after the June 17 disaster.
Scott Rowe, student intern at the National Weather Service in Grand Forks, confirmed that aside from testing in April, there have been no tornado warnings issued for Wadena County in 2011 so far. Also, there was only one warning for southeastern Otter Tail County on July 30 which did not lead to an actual tornado confirmation.
The Grand Forks office, which covers 18 counties in Minnesota and 17 counties in North Dakota, has issued 54 warnings to date.
Last year, the Grand Forks office issued 118 tornado warnings with the last warning on Aug. 17.
A tornado warning is not to be confused waith a tornado watch, and not all tornado warnings lead to confirmed tornadoes.
"A warning's one thing, but then a verification is something else - if something actually did touch down," Rowe said.
While this year has been quieter for tornadoes, it has been about as active for severe thunderstorm activity.
Warning Coordination Meteorologist Greg Gust said that there were 158 severe thunderstorm warnings this year, and 161 severe thunderstorm warnings by Aug. 17 of last year.
"We stayed in a pretty active pattern all the way through from last year into this year," Gust said. "But there's a difference between tornadoes and not tornadoes."
This spring, the southern plains had two very violent outbreaks with EF5 tornadoes - Alabama and Mississippi and then the Joplin tornado - while the northern plains have had fewer and weaker tornadoes in the summer. None of Minnesota's tornadoes this year have cracked the EF2 level.
In 2010, it was the other way around.
"Last year, the southern plains did not have a lot of tornado activity by comparison to normal, but the northern plains ... had one of the biggest outbreaks that we've recorded in our history," he said.
Gust said that while the environment is conducive to tornado development, there are other factors.
"A lot of the storms that are developing start to produce heavier rainfall and start to become what we call downdraft and outflow dominated. In other words, instead of developing the deep rotating updraft and the mechanism in the storm that tends to produce a long-lasting tornado, these storms instead are producing larger-scale downdraft and heavier rain," Gust said, adding that the difference between last year's sustained and focused updrafts and this year's collapsed downburst events are related to wind shear within the storm and near-surface instability issues.
Gust said that according to the Climate Prediction Center, the area is probably in for a rainy fall and another cold, wet winter.