Super Outbreak 5 years later: My story and the meteorology (Part 3)

Good afternoon.

All this week, I have been writing on the devastating tornado outbreak 5 years ago, my own recollections of what happened and how it was a turning point in my future. As we get closer to the climax, we already knew that five people had lost their lives in a tornado on April 25, and more tornadoes were hitting today on April 26. Meanwhile, I was finalizing – and changing – plans at the last minute based on increasingly ominous forecasts.

While I write this, severe weather is underway in the central and southern Plains, with extremely large hail and strong tornadoes possible. If you are in that area or know someone who is, you should keep aware of all warnings and keep in tune with local meteorologists (there are many who I know) in order to be prepared if severe weather does threaten your community and family. In addition, scattered severe weather is ongoing in parts of the mid-Atlantic; high winds and large hail are the main threats (one or two tornadoes cannot be ruled out but they are not a major threat).

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Surface weather map on the morning of April 26, 2011 (Weather Prediction Center/NOAA). Remnants of Rounds 1 and 2 were still present at this time, as they tracked eastward. Meanwhile the strengthening Midwest low and warm sector was setting the stage…

April 26: From bad to much worse

At midnight local time as we entered Tuesday, April 26, 2011, there had already been 42 confirmed tornado touchdowns. Several communities in Arkansas, Texas and Louisiana were hard hit by strong tornadoes and there had been five fatalities from Round 1 of the activity. As those cells started to weaken, the activity shifted farther north as new cells formed in Round 2 in response to the strengthening low pressure area, affecting the middle Mississippi Valley and the Mid-South in the pre-dawn hours closer to the warm front and low center.

Several tornadoes resulted from those storms, with isolated tornadoes spreading into other parts of the Southeast that morning. Once again, some of the tornadoes were strong and destructive, but thankfully no fatalities or serious injuries resulted from this round of tornadoes. It did, however, worsen the flooding situation which resulted in several fatalities in itself. The closed low had deepened to 991 mb over Iowa with the frontal boundaries largely remaining in place, acting as catalysts for severe weather development. By noon, the tornado total increased to 52.

The Storm Prediction Center knew that another destructive day, followed by yet another tomorrow, was in store. The previously issued moderate risk of severe weather for Tuesday was initially maintained, then upgraded to a high risk (the highest category that is rarely issued for the greatest severe weather days) shortly after sunrise. The wording specifically mentioned that intense tornadoes were likely and it would be a dangerous day. Likewise, for Wednesday, the situation was the same – the moderate risk previously issued was maintained and enlarged twice, with considerations made to a quick upgrade to high risk (which most agreed was almost certain by the initial Day 1 outlook). The wording mentioned that placement issues and behavior of early morning convection were the only limiting factors. All indications now suggested that two long, frightening days were upon us and it would be a long 48 hours ahead. Models were coming into agreement that large parts of the South were going to see a massive tornado outbreak with rarely seen parameters – the questions remained whether other activity could hamper that extreme potential.

As for the Northeast, most inland areas along and west of Interstate 81 were upgraded to (what would now be) an enhanced risk of severe weather for Wednesday with mentions of tornadoes, a couple possibly strong, as well. Uncertainty remained great for Thursday on whether or not the warm sector would rebuild with daytime heating. It’s not very often we see risk levels that high in the Mid-Atlantic, particularly based for tornadoes, so it was clear we had to pay attention closely. While the headlines were down south, the threat extended well north.

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April 26, 2011 storm reports (SPC/NOAA).

When looking at the reports map (SPC) above, it is important to note this was a multi-faceted event with several rounds. Also many of the tornadoes shown were after midnight local time, which I will get into tomorrow. A few of the tornadoes were the last vestiges of Rounds 1 and 2. However, far to the west as warm air continued to push against the cold front over Texas into Arkansas, severe weather once again redeveloped shortly after noon. This will be called Round 3A. Isolated tornadoes also occurred in several other regions, including Michigan near a developing secondary low center and in the Northeast and Mid-Atlantic.

Round 3A occurred as tornadic supercells began to form over eastern Texas, northern Louisiana and southern Arkansas on Tuesday afternoon, just slightly south of the focal point of Monday’s activity. Fortunately, none of these supercells were particularly destructive, with no tornado in that region rated stronger than an EF-2 (although a couple had fairly long tracks), as the enormous wind shear was slower to arrive. By late evening, those cells would start to form into a quasi-linear convective system (QLCS) but with increasing wind shear, they would actually continue to produce tornadoes (some strong) across the South. That late night squall line with embedded supercells, which I consider to be Round 3B, played a major role in Wednesday’s weather, which I will explain tomorrow.

That afternoon and evening, at least 45 tornadoes touched down. Some reports of severe weather even reached the Northeast, as instability there was quite high too. Fortunately, most were not particularly strong, but in just over 36 hours, nearly 100 tornadoes had already touched down by midnight. Any other time and that would be an impressive tornado outbreak in itself. But unfortunately, the worst was still to come…

Making changes on the fly

It was becoming obvious that I would have significant challenges regarding travel. As mentioned, I had long set aside April 27 as the start of a vacation to Florida. But as the enhanced risk pushed northward, and the moderate risk (with mention of strong tornadoes) entered the picture in the Midwest in the afternoon Day 2, it was time to make changes. The fact that we didn’t have to be in Cape Canaveral until Saturday evening gave us an extra few hours to work with, and even if we tried to keep to the schedule, it would be next to impossible while potentially dodging intense tornadoes.

Several options were considered including an eastern route (through the inland Mid-Atlantic along I-81/77) and reshuffling of hotels on the western route (I-75) to make the trip slower. In addition, course changes were possible by cutting through the Appalachians if a last minute decision was made. Hotels were rebooked, with no island getaway on Friday night (which was the initial plan). As nice as that was, safety came first. No matter what route was chosen, severe weather was going to be a major issue, and there was no way we could wait until Thursday to leave given the cruise timing.

As the situation became clearer and more dire, I had to warn my parents heavily and actually gave them safety lessons for severe weather. In addition, I mapped out the route with many locations that could be places of refuge if necessary. I had watched this from elsewhere for many years, but it was very rare that we had to put it in action ourselves. I upgraded my phone plan that night, and also purchased a new weather radio the previous day. A long Wednesday was in store…yes, the destination was Florida (including a cruise and Disney World), but it was hardly on my mind.

Conclusion

Already by Tuesday, a significant tornado outbreak was underway. However, the violence of the system had yet to be realized. The forecasts were extremely dire for Wednesday, but again I have seen a few other instances where such was forecast and did not materialize. It also happened to be on the day that we started on vacation, and we were heading right for the trouble zone. The stage was clearly set, but there were still short-term questions to be asked. A long day was ahead, as I will explain tomorrow. But how bad would it be? When I woke up the next morning, we would find out.

Forecaster Craig Ceecee

Remainder of the series:

Part 1 (Sunday, April 24) – Introduction and strong warnings

Part 2 (Monday, April 25) – The outbreak begins and stronger warnings

Part 4 (Wednesday, April 27) – The day everything changed forever

Part 5 (Thursday, April 28) – The last vestiges and initial aftermath

Part 6 (Friday, April 29) – Conclusion, lessons learned and the future

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