Thursday, February 07, 2008

Winter southern tornadoes: this has happened before; global warming?

The ferocity of tornadoes that roared across several southern states and killed at least 55 people om Super Tuesday certainly brings back the global warming debate. Some authorities are attributing this to La Nina. But the outbreak of so many tornadoes, along several SW-NE lines, so early in the season, well before really hot temperatures develop even in the South, has people wondering. The center of low pressure seemed to be to the north, and the outbreak did not follow that of hurricanes, where most tornadoes are on the NE side.

When I had started living in Minneapolis, I went up north on Sunday March 30, 1998 with a friend (to the wineries as I remember), celebrating getting off crutches from my accidental fracture. On the way back, we suddenly encountered hail and sleet at around Anoka, with incredibly black clouds overhead. We stopped to eat at something like an Applebees, when the cloudburst occurred. Afterward we heard about the sensational "March tornadoes", unheard of that far north, on the car radio. I lived in a downtown highrise (the Churchill) for six years, and even with the most violent storms we never had any concerns about power outages, with all the utilities underground, or even wind damage. People believe that downtowns of cities break up tornadoes, but Nashville and St. Lake City have been struck, and the Weather Channel has a fictitious account of what could happen to downtown Dallas.

When I was living in Dallas, a December (1987) tornado struck (probably F2 or F3) less than a mile east of my condo on Lake June Road "in the Grove". I had no damage at all.

On April 11, 1965, the Ohio Valley states had a huge outbreak of the "Palm Sunday" tornadoes, where the town of Pittsfield (near Wellington, OH) was wiped out. My family visited Oberlin that spring for some reason, and I recall in-person accounts from the victims, of dirt and debris being ground into their skin by the winds. Here is a picture of that event.

So is an outbreak like that on Super Tuesday of so many "super" thunderstorm cells trailing an Ohio Valley "land hurricane" low pressure system (the kind that brings record warmth to the southeast, on the "warm side" of the storm, unlike the case with Noreasters) a symptom of global warming? At this point it's hard to say. But the spells of midwinter mild weather in the East seem to be lengthening and increasing.

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