Sunday, May 1, 2011

5/1 - 5:15pm - Southern Tornado Outbreak Aftermath

Absolute hell. That's about the only way to describe last week's historic severe weather outbreak in the South. It started on Monday the 25th in Texas and Arkansas as a fairly significant rash of tornadoes and slowly spread eastward on the 26th with an increased amount of tornado reports over a larger area. As the system made its way into the untapped unstable air of Mississippi and Alabama on the 27th, dozens of supercell thunderstorms exploded into existence on a scale that hasn't been seen since the Super Outbreak of 1974. The Storm Prediction Center issued a HIGH Risk for severe weather for much of Alabama and Mississippi. Numerous PDS (Particularly Dangerous Situation) Tornado Watches were in place. Since the National Weather Service and media had exhausted just about every option to inform the public of the impending tornado outbreak, all that was left to do was to hope that it wouldn't turn out to be as bad as feared.

Around 2:45am CDT: My NOAA weather radio jolts me out of bed as a Tornado Warning is issued for Oktibbeha County, Mississippi, which is where Mississippi State University is located. The ugly bow echo/embedded supercell structure line of storms that crossed the Mississippi River just as I went to bed for the night held its strength well into the early morning hours as it passed through Northeast Mississippi. The rotation in a cell near the MSU campus appeared to be passing just to the south after watching the radar for a few minutes, so I was ready to head back to bed (had a differential equations final exam scheduled for 8am). That's when a cell to the north of Starkville caught my eye. The rotation as indicated by the base velocity input on this cell was extremely strong. I felt it was very odd to see rotation this pronounced in a storm that was embedded in a mess of other storms this late at night, but this was no run-of-the-mill outbreak. This is what I saw (Thanks NWS JAN for posting these):

It was a forgone conclusion that this storm was putting down a tornado based on the radar and reports coming in. To the bottom right of the storm is Starkville, so Mississippi State was within a short drive of this tornado. One fatality and 20 injuries occurred before the tornado lifted in Clay County. It was rated an EF-3 with 140mph winds after a storm survey.

After my final exam, I packed my entire dorm room into my car and checked out so I could head back home to Louisville for the summer. The early morning storms were long gone to the east by that point, but a slew of supercells were already forming in the afternoon heating of the day and dry
line push near the Mississippi River. I raced northward on US 45 trying to beat a majority of the storms before they cut off my route into Tennessee. One of these supercells would go on to produce the first EF-5 tornado in Mississippi since 1966. This tornado hit Smithville, MS head-on and caused 14 fatalities with 40 injures in Monroe County before 4pm CDT. Here's a panoramic photo taken by Mississippi State University's Director of Broadcast Meteorology Renny Vandewege of the Smithville damage:

I realized rather quickly that my good fortune was going to run out north of Tupelo, MS, but I kept traveling north in hopes of possibly catching up with the updraft base of a supercell that was going to cross the road right in front of me. This cell had definite rotation in it and reports of grapefruit-sized hail were coming across the wires, so I knew I had to calculate my position delicately. An image of my position (blue cross-hairs) compared to the velocity couplet on radar is below:

I was within a mile of the updraft base when the rain and hail from a cell just to the south and west of the one I wanted to intercept began overspreading my route. It looked like I was heading into a giant black wall of cloud and precipitation, almost cave-like in the way that it extended from the sky to the ground. Wind gusts of over 40mph began to hit my car and that's when I knew to turn around and head toward Baldwyn, MS to avoid damage to my vehicle. Visibility was horrible because of the rain being thrown into the path of my storm by the other, so I would have not been able to see a tornado until it was too late had I continued on. After waiting a few minutes near Baldwyn, it was was safe to drive north again due to a gap that had formed between storms on US 45. The rest of my drive to Louisville was uneventful due to calmer weather in West Tennessee and Kentucky.

On the way home I listened to the audio of Birmingham's ABC 33/40 severe weather stream. Hearing James Spann's coverage of the Tuscaloosa/Birmingham wedge tornado and seeing the images after the fact was heartbreaking. It is nearly impossible to not have mass fatalities from a wedge tornado that hits two major cities head-on, especially when most residents do not have basements. The visibility of the tornado may have saved many lives that Wednesday because TV stations, including ABC 33/40, were able to show viewers live pictures from their outdoor sky cameras of the tornado wreaking havoc on the cities:

Multiple-vortex wedge tornado hitting Tuscaloosa from ABC 33/40's Sky Cam

These pictures made much more impact on the residents of the area than a radar image, so the motivation to take cover from this storm was far greater than usual. The path of this storm took it from Kemper County, MS to western North Carolina, lasting over seven hours. This tornado has been rated at least an EF-3, but ongoing damage surveys could increase this preliminary rating.

The 342 confirmed deaths from this outbreak has already eclipsed the Super Outbreak of 1974, and this number is sure to rise with the number of people still missing. Sorting out the actual number of tornadoes remains a tedious task for multiple NWS offices, but so far 121 have been confirmed from the 25th to the 28th. Up until last week most severe weather outbreaks were compared to the Super Outbreak of 1974. From now on, the Super Outbreak of 2011 will be an additional basis for comparison.

175 tornadoes were reported on April 27th. Many of those reports are duplicates.

If you would like to help the thousands of residents in Mississippi, Alabama, Georgia, Arkansas and more affected by this outbreak, please consider donating to the American Red Cross by clicking the link on the right-hand column of this blog.

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