Saturday, December 31, 2011

The Top 11 of '11: Mid-South weather stories from MWN (part 5)

Here we go!  The top 2 Mid-South weather stories of 2011 are revealed below.  To read about the other 9, follow the links below:
  • Part 1 (#11 Aurora Borealis appears in Mid-South skies, #10 MWN at the forefront of social media nowcasting, #9 Addition of key team members helps MWN expand it's presence)
  • Part 2 (#8 Dual early-season accumulating snow events, #7 debuts mobile apps, then raises the bar with StormWatch+)
  • Part 3 (#6 Early April severe weather events foreshadow a busy season, #5 Severe weather season ends with one last round of storms in late May)
  • Part 4 (#4 January-February snowstorms contribute to the snowiest winter in 25 years, #3 "The Summer of '11" - third hottest Memphis summer in recorded history)

#2. Effects of the April 25-28 Super Outbreak on the Mid-South
It has gone down in the history books as the super outbreak to rival the original of 1974.  In fact, many of the stats indicate that it has surpassed the Super Outbreak of 1974 in many respects. The month of April was the most active tornado month in U.S. history and the 4-day period from April 25-28 saw over 200 tornadoes produced in 5 southeastern U.S. states, killing 316 and injuring more than 2,400.  15 of the tornadoes were rated violent (EF-4 or 5).  Total damage is estimated at $4.2 billion from storms on this day alone (all statistics from "The Historic Tornadoes of 2011," a NOAA Service Assessment).

Memphis area severe weather reports from April 25-27, 2011
The nearest significant damage from this outbreak was not the highly-publicized Alabama tornadoes, but a monster EF-5 that nearly wiped Smithville, MS (130 miles southeast of Memphis) off the map.  It was the first EF-5 recorded in the U.S. in three years and occurred almost simultaneously with another EF-5 about 100 miles south near Philadelphia, MS. Maximum wind was estimated at 205 mph along the 37-mile path of the twister.  In all, 17 people lost their lives and 40 more were injured.  A recap of the event, authored by WTVA meteorologist Jennifer Watson and MWN meteorologist Erik Proseus, appears on the MWN Blog and a video tribute can be found here.  Below are photos taken in Smithville three months after the storm by Erik.

Indeed, even though there were dozens of severe weather reports in the metro over the 3 day period (see image above), the Memphis area was actually spared from what could have been utter chaos similar to what was seen in places like Smithville, MS, Tuscaloosa/Birmingham, AL, and many other places in the southeast.  The greatest effect on Mid-Southerners from this outbreak though, in our opinion, was not from property damage, but on our psyche.  The extended period of destructive weather was well-forecast, beginning nearly a week ahead of time, and it received a lot of airtime (and a lot of hype) leading up to, through, and after the events that occurred.  The Memphis area was under a moderate risk of severe weather for two days, upgraded to a high risk on one of those, and then a slight risk on the day that all hell broke loose in MS and AL.  Multiple waves of severe storms, all capable of producing damage and potentially loss of life, passed through the region and at times it seemed the tornado sirens would never stop sounding.

All of this affected the psyche of the general public in different ways.  Some grew weary and began ignoring the warnings, which led to a complacency that is far more dangerous than the Weather Service missing a tornado warning.  Others grew fearful and became paralyzed, which leads to indecision during critical times.  Both of these have the opposite effect of what SHOULD be the public's reaction to severe warnings, which is to take action.  Part of MWN's mission is to ensure that the public is properly informed and prepared in case of severe weather; another part is to make sure that the public knows when to exercise their safety plan.  Through our severe weather nowcasting on social media, we hope to accomplish both of these. Our stats for the months of April and May indicate that we are doing a good job in both regards.  However, if we can reach more people, our hope is that the sense of complacency is replaced by preparedness on a broader scale. If it saves one life, it is well worth the effort.

#1. Mississippi River rises to within inches of an all-time record at Memphis
We now come to the #1 event in our countdown of the Top 11 of ’11 and without a doubt it’s an event Memphians and Mid-Southerners are sure to remember for years to come. With a long, snowy winter for much of the country in the rearview mirror, the warmth of spring began the annual melt of the deep snowpack in the northern states, sending large amounts of water into area rivers and tributaries. All of this water would begin flowing downstream into the Mississippi River by April. Meanwhile, multiple excessive rain events during the spring across the Ohio Valley (300% of normal) and Mid-South led to even more water pouring into the Mississippi River watershed. This combination of events led to a “perfect storm” of sorts, setting the table for an historic flooding event for the area.

While flash flooding and tributary flooding of rivers like the Wolf and Loosahatchie were a significant problem early on, especially in areas of northern and eastern Shelby County, the impacts from flooding on the Mississippi became much more severe and widespread. Record or near-record crests were forecast at multiple points, including Memphis. Making matters worse, backwater flooding from the Mississippi into the area tributaries would keep those water levels high as well, putting even more people at risk. As the waters began rising and homes and businesses became threatened, people evacuated to higher ground, waiting to see how high the river would go. That day came on May 10, and with much of the national media in Memphis, the river crested at 48.03 feet, just inches short of the all-time record of 48.7 feet during the Great Flood of 1937.  Pictures taken by MWN meteorologist Erik Proseus are contained in the photostream below.

In the days following, the waters would slowly recede, allowing people to return home and begin the cleanup process. Slowly but surely, affected businesses reopened, including the Tunica casinos which had been closed for weeks.  While the floods were devastating for many, they also brought people in our area together. Whether it was to donate to those affected or fill sandbags to keep the high waters at bay, it presented a classic example of the community spirit we often see in the area. Though the Great Flood of 2011 is now a memory, it’s an event that will be well-recorded in the history books and a memory that will remain with many of us for the rest of our lives.  For NOAA's perspective on this billion-dollar weather disaster, watch the video below.

Thanks for following along on this five-part blog series.  It's definitely been an amazing weather year in the Mid-South and across the nation.  In fact, the U.S. experienced a record ELEVEN billion-dollar weather disasters in 2011.  Let's hope that 2012 is a quieter year weather-wise!  I also want to thank MWN intern Kevin Terry for contributing to this series, as well as his dedication as a blog and social media poster for MWN!  Kevin is signed on with MWN through the first half of 2012 and will continue with his regular duties through that time.

Follow along with on Facebook and Twitter throughout 2012 for the latest weather conditions, forecasts, stats, and nowcasts.

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