Wednesday, April 09, 2008

The Next Super Outbreak?

An F-5 tornado bears down on Xenia, Ohio on April 3, 1974, part of the "Super Outbreak" that killed over 300 people. Meterologists warn that another large-scale tornado event may occur over the next two days, across portions of the south and Midwest. (USA Today photo via Wikipedia)

For most Americans, April 3rd has no particular significance. But in places like Guin and Tanner, Alabama; Brandenburg, Kentucky and Xenia, Ohio, the date conjures up memories of menacing clouds, howling winds, wailing sirens and death. On April 3, 1974, those four communities were among those hardest hit by the so-called "Super Outbreak" of tornadoes, a catastrophic weather event that remains unequalled in U.S. history.

While forecasting technology of thirty years ago pales in comparison to the advanced computer models and Doppler radars of today, forecasters expected a rash of severe weather in the first week of April in 1974. Local National Weather Service offices in the Mid West were advised to complete scheduled equipment maintenance, in preparation for possible severe thunderstorms and tornadoes.

Their prediction began to materialize in the early afternoon hours of April 3rd. Over the next 18 hours, meterologists tracked three heavy squall lines that raked 13 states, stretching from the Deep South to the Great Lakes. Thunderstorms associated with the weather system produced scores of tornadoes. At one point, forecasters reportedly put the entire state of Indiana under a tornado warning because they couldn't keep up with the huge number of reported twisters. The tornadoes killed more than 300 people; another 6,000 were injured. It was the greatest number of twisters ever recorded in a single day.

We wrote at length about the Super Outbreak last year, on the 33rd anniversary of the event. Memories of that terrible day raise an inevitable question--could it happen again? Meterologists say the answer is almost certainly yes, but it's unclear how often such onslaughts occur. In its official assessment of the 1974 outbreak, the weather service postulated that such events may happen only once every 150 years.

But that estimate may be wrong--by about a century.

A developing storm in the Great Plains is already drawing comparisons to the system that produced the Super Outbreak of 34 years ago. Henry Margusity, a senior meterologist and severe weather expert for Accu-Weather, is warning of a tornadic outbreak that could rival the 1974 event. According to Mr. Margusity, the forecast for the next 48 hours is particularly ominous for portions of the southern states, the Mid-South, the middle Mississippi Valley and Ohio Valley, with the prospect for large numbers of tornadoes, including long-track, violent twisters. From his weather blog:

Wednesday into Wednesday night - The next storm moves out of the Rockies into the western High Plains. Severe storms will develop along the dry line in western Texas and Oklahoma, and also along the warm front. This will be first day of the tornadoes as EHI values are very high across central Texas into south-central Oklahoma. A wind and hail threat will stretch along the warm front across parts of southern Kansas into Missouri.

Thursday into Friday - Storms moves up into the Great Lakes. Cold front/dry line combination moves into the Mississippi Valley. Supercell thunderstorms will develop with the potential for large-damaging tornadoes. Severe weather may go from southern Michigan to Arkansas. Severe weather will last through the night into Friday and move into the Appalachians and Northeast. We could see 100 tornadoes during the Thursday into Friday time period.

Margusity describes the current patterns as "almost identical" to the one that preceded the 1974 outbreak. He also notes that the expected storms will impact many of the same areas hit in the 1970s, as well as those affected by the "Super Tuesday" outbreak of two months ago. That series of deadly tornadoes killd more than 50 people in Arkansas, Tennessee, Kentucky and Alabama. The National Weather Service reported at least 131 twisters in conjunction with that weather system.

For its part, the Storm Prediction Center isn't quite as far out on the forecasting limb as Mr. Margusity. However, the center is warning of a heightened risk for severe weather over the next 48 hours. The SPC predicts a moderate risk of severe weather today in the Red River Valley of Oklahoma and Texas, with a slight chance of severe thunderstorms, tornadoes, large hail and damaging winds in adjacent sections of those states, as well as portions of Kansas, Missouri, Tennessee, Louisiana and Mississippi.

On Thursday, the area expecting severe weather will be greatly expanded, as the storm system moves east. The SPC is assessing a large moderate risk area that covers much of the Mid-South and mid-Mississippi Valley, with a slight risk extending from the Gulf Coast to the Great Lakes. Meterologists at the SPC also caution that sections of the moderate risk area may be upgraded to high risk, as forecast models become more refined.

Posting on this sort of topic, we always remind readers that we are weather enthusiasts, not forecasters. But, the potential for a major tornado outbreak is clearly at hand. If you live in the southern plains, the middle and lower Mississippi Valley and the Ohio Valley, keep a close eye on the weather over the next two days. Comparisons to the 1974 outbreak are not offered casually, and we may be on the cusp of seeing weather history repeat itself.


J.R. said...

Wow, hadn't seen this in any of the East Coast news. I worked at Wright-Patt for a few years, so I still have friends in the Yellow Springs / Xenia area. Thanks!

S M said...

I had just finished a swim meet in Xenia - we were just on the edge of the city when the storm hit.

Then a few days later, driving home from my grandparents, we spotted 3 funnel clouds - these 3 were still high above the ground.

I do not want to live thru a repeat of that.

M.O. said...

The photo above shows the tornado on the northeast side of Xenia with less than a mile to go before leaving the city, not as it approached. It was snapped from the hospital by its public information officer. As you can see, homes are being destoryed as the beast moves right to left.

Next super outbreak? It has to be at least a hundred year storm, perhaps as much as five hundred. Only time will tell.

scott bowen said...

If it happens it's gonna be hell tryin to survive it