Wednesday, April 19, 2006

April 7, 2006 Severe Weather Forecast and Preparedness Issues

Was the High Risk Forecast a Bust?In hindsight, the high risk area might have been centered a little too far south. Nevertheless, the facts will bear out that this event met the criteria for a high risk. One of the problems was that this was the first time the SPC issued the high risk that far in advance. That, in itself, made many people think this might be the worst outbreak ever. I'm not saying it should have had that effect, but it did. I am amazed at the accuracy of the SPC. They do an amazing job of predicting large areas of severe weather. The problem remains pinpointing where that weather will be. That is the biggest challenge in forecasting tornadoes and severe weather and probably always will be. I remember back on 4/8/98, the Oak Grove tornado was in the south portion of the high risk area, and much less severe weather was reported further north in the bulk of the high risk area. That didn't make it a bust. We need to look at is what is meant by "bust". To me, it would have been a bust if there were a couple of F0-F1 tornadoes and very little damage. I'd like to here other opinions. There have been at least three F3's reported. According to the SPC, a "High Risk" is defined, in part, as, "a major severe weather outbreak is expected, with great coverage of severe weather and enhanced likelihood of extreme severe (i.e., violent tornadoes or extreme convective wind events over a large area). Within a high risk area, expect at least 20 tornadoes with at least 2 of them rated F3+". When all the surveys are completed, I have no doubt that this event exceeds those criteria. Read the attached from Huntsville NWS, Nashville NWS, and the NSV NWS Blog before jumping to conclusions about the accuracy of the SPC. Nine lives were lost in Gallatin, TN and three were lost in McMinnville, TN. I would grade the SPC at least an "A-" on this forecast. I think the high risk was issued too soon and that it would have been better if it was centered 50-100 miles further north. Nevertheless, it was an amazingly accurate forecast, several days in advance. I think the SPC has set such a high standard of success that we are a bit spoiled.Was it a mistake or an overreaction for Alabama school administrators to dismiss school early?I for one agree with the schools closing early. Schools are not the safest place in the world to be during a tornado, but the real danger was in children travelling home from school during severe weather. Where I work, my director closed our office early at 1:30 because she did not want any of us to be on the road in our cars while there was a PDS tornado watch and a high risk of severe weather. The Tennessee storms began forming around 10 a.m. between Pine Bluff, AR, Memphis, TN, and Clarksville, TN. I think that's where the cap was able to break first. What if conditions were slightly different and the first wave formed 50-100 miles further south, as predicted by the SPC? The tornadoes would have been much more intense and numerous in Alabama. Not only that, but they would have been on the ground while children were travelling home from school between 3 and 4 p.m. No one knew exactly where and when these tornadoes would be until about 10-20 minutes before they hit. Therefore I support and applaud school administrators for "erring on the side of caution" and "taking the course of least regret". They followed the forecast of the SPC and I cannot fault them for that. I think we should all be thankful that things were not much worse in Alabama this time. Our time will come, though, and I hope we all learn some lessons from this experience, so that when our time does come, we have no loss of life. Alabama WILL have more F3-F5 tornadoes. My hope is that when those occur that no lives are lost.

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