Don't let the snow fool you, severe weather is on its way this Spring

At a time when snowstorms just won’t quit, a member of the National Weather Service reminded the public about what’s to come.

May and June are the hardest-hitting months for tornadoes in Wisconsin, though the season typically runs from April to September.

NWS-Chanhassen/ Twin Cities meteorologist Shawn DeVinny trained members of the public Wednesday night on how to spot a storm during a two-hour presentation at the courthouse in Chippewa Falls.

As far as the seemingly never-ending winter, DeVinny said it’s not as rare as some people realize. He said on average, about two inches of snow is common in April.

“We’ve had a very cold pattern,” he said. “It has a lot to do with global weather patterns.”

DeVinny told the audience that storm spotters can add credibility to warnings, especially since radars aren’t able to catch everything.

“The spotter confirms that the tornado is on the ground; people … are going to take that a lot more seriously,” he said.

How to spot a storm

DeVinny said there are certain factors to watch for when gauging a storm.

In a thunderstorm system, an inflow of air is sucked up towards the stratosphere where it is pushed back down. These forces are called updrafts and downdrafts, respectively.

Updrafts lie above wall clouds which are often the first development in a tornado formation. Wall clouds tend to tilt downward in the direction of the falling rain and subsequently point to where the storm is headed.

A wall cloud has the potential of turning into a tornado if it is rotating persistently, changing speeds and has a strong inflow.

A tornado must be attached to the wall cloud or an updraft base and the ground. DeVinny said even if the storm watcher can’t tell if the funnel cloud is on the ground, the NWS would still appreciate a call.

“Don’t ever be shy about calling us,” he said. “We want to know.”

Additionally, even if the funnel is not visible, a tornado may still be present, which is evident by visible rotation and debris. The funnel cloud needs moisture and condensation to produce a visible cloud.

DeVinny said sometimes shelf clouds can be mistaken for tornadoes. Shelf clouds can cover long distances and they have horizontal rotation, but they’re often not attached to the main thunderstorm mass. Unlike tornadoes, the skies immediately behind shelf clouds are dark.

“You’re worried about downburst wind potential with shelf clouds and not so worried about a tornado,” DeVinny said.

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