"This is the Emergency Broadcast System. This is not a test." Actor and New Orleans native Wendell Pierce recalls the chill that message sent through his body. Hurricane Katrina had passed, but the city’s levees had broken, filling it up “like a bathtub.” On this 20th anniversary of Hurricane Katrina, Pierce, along with survivor Dr. Courtney Jackson and WDSU New Orleans anchor Travers Mackel join Tom Llamas in a roundtable discussion about what went terribly wrong and why we should never forget. Watch NBC News' Al Roker dive deep into the stories behind Katrina and this century's most notable hurricanes: youtu.be/tN1LpZuKByM "For more context and news coverage of the most important stories of our day, click here: nbcnews.com » Subscribe to NBC News: nbcnews.to/SubscribeToNBC » Watch more NBC video: bit.ly/MoreNBCNews » Subscribe to Here's the Scoop podcast: nbcnews.com/heres-the-scoop-daily-podcast NBC News Digital is a collection of i...