Tornado season ahead

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Doppler radar reflectivity image from last May 25th shows a classic "hook echo" with the Hugo tornado.

As the sirens wail for today's statewide tornado drill, it's a good time to look back and to look ahead.

Last May 25th was a devastating day for Hugo. About the time the EF3 tornado plowed through Hugo, another even more violent tornado devastated the town of Parkersburg, Iowa. The Hugo tornado killed one, and 8 died in Iowa that day.

Severe weather and tornadoes tend to happen in clusters. When the atmosphere is that unstable, multiple individual tornadic supercells can form and later evolve into dangerous downburst producing squall lines.

It is wise to use today's tornado drill to discuss with your family or coworkers what to do in case another Hugo or Parkersburg happens where you are this year.

Today's first 80 and 90 degree temperatures of the year in Minnesota remind us that severe weather season is not far away. In fact the SPC has issued the first "slight risk" area of the season for Minnesota Friday in the convective outlook.

May and June are the peak months for tornadoes and severe weather in the Upper Midwest. However, as the Comfrey and St. Peter tornadoes on March 29th, 1998 and the Rogers tornado on September 16th, 2006 remind us, tornadoes can happen anytime from March into November.

Since 1953 Minnesota has averaged about 25 tornadoes per year. Since 1990 the numbers have been higher; closer to 40. Last year we had 43 tornadoes reported in Minnesota, and 38 in Wisconsin. Nationally the average is about 1,300 per year. Tornado numbers have been trending up over the past few decades. It may be a change in weather patterns, or it may be that more people are out observing tornadoes.

Regardless of the overall numbers, even one tornado can really ruin your day. Stay aware this season as severe weather works its way back into our lives. We'll do our part to keep you ahead of the storm on KNOW 91.1FM and the MPR regional network of stations.

PH