Friday's Weak Tornado
Friday afternoon, shortly after 2:30 pm, a developing thunderstorm just southeast of Moorhead produced a funnel cloud. The thunderstorm was not a strong one at the time and there had already been a few reports of cold air funnels with scattered showers in the region. Shortly before 3 pm, the thunderstorm had strengthened slightly and the funnel cloud lowered until it touched the ground in an open field.
At this point, the cold air funnel, by definition, had become a tornado. By all accounts, it was a very weak tornado. It picked up some dust and threw around some corn stubble and may have damaged a couple of trees. The tornado was on the ground about a minute.
Cold air funnels form in weaker thunderstorms and showers that have weaker updrafts than are found in severe thunderstorms. Vertically moving columns of air rotate. The speed of the rotation is related to the speed of the updraft, so cold air funnels usually present no threat.
This was a somewhat hybrid situation, however. Although the thunderstorm was not severe, it had strengthened a bit. Also, the atmosphere had a generous amount of spin today due to the low pressure system passing through. At one point, there were several funnels at the same time. It was as if the atmosphere was trying hard to build tornadoes, but just didn't quite have enough stuff.
Had this tornado touched down in Moorhead or Fargo instead of an open field, it certainly would have been frightening. But it is not likely that damage would have amounted to more than a bunch of tree limbs and backyard wooden fences. It would have made a mess, but this was not a tornado that had the capacity to level houses and cause fatalities.
Nevertheless, the tornado warning, the sirens sounding, and the school children who gathered in tornado-safe places all were good ideas. Weather, and especially tornadoes, have a certain built-in unpredictability. It was not possible at the time to have said with certainty that the situation would not get worse. Fortunately, the tornado remained weak and in an open field and all anybody lost was a little time.
Meteorologist John Wheeler