This is the scariest weather alert ever issued in the United States.
20 years ago today, at 10:11 a.m. on Sunday, August 28, 2005, the National Weather Service in New Orleans, Louisiana released the infamous "doomsday statement." It was a first-of-its-kind warning, and is downright chilling.
Moments earlier, Katrina had intensified into a Category 5 behemoth with 175 mph winds, and was on a crash course with southeast Louisiana. Forecasts called for a Category 4 or 5 strike on New Orleans within 24 hours.
Robert Ricks Jr., a forecaster at the New Orleans NWS office, issued the following dire warning:
National Weather Service New Orleans LA
10:11 AM CDT Sun Aug 28 2005
...Devastating damage expected...
Hurricane Katrina, a most powerful hurricane with unprecedented strength, rivaling the intensity of Hurricane Camille of 1969.
Most of the area will be uninhabitable for weeks, perhaps longer. At least one half of well-constructed homes will have roof and wall failure. All gabled roofs will fail, leaving those homes severely damaged or destroyed.
The majority of industrial buildings will become non-functional. Partial to complete wall and roof failure is expected. All wood-framed low-rising apartment buildings will be destroyed. Concrete block low-rise apartments will sustain major damage, including some wall and roof failure.
High-rise office and apartment buildings will sway dangerously, a few to the point of total collapse. All windows will blow out.
Airborne debris will be widespread and may include heavy items such as household appliances and even light vehicles. Sport utility vehicles and light trucks will be moved. The blown debris will create additional destruction. Persons, pets, and livestock exposed to the winds will face certain death if struck.
Power outages will last for weeks, as most power poles will be down and transformers destroyed. Water shortages will make human suffering incredible by modern standards.
The vast majority of native trees will be snapped or uprooted. Only the heartiest will remain standing but be totally defoliated. Few crops will remain. Livestock left exposed to the winds will be killed.
An inland hurricane wind warning is issued when sustained winds near hurricane force, or frequent gusts at or above hurricane force, are certain within the next 12 to 24 hours.
Once tropical storm and hurricane force winds onset, do not venture outside!"
Within an hour, the mayor of New Orleans issued the first-ever mandatory evacuation of the city.
Katrina came ashore on August 29 as a slightly-weakened 125 mph Category 3 hurricane. The worst damage didn't come from wind, but rather levee failures.
Rob Perillo, a longtime meteorologist in Lafayette, Louisiana, described the statement as "one of the first hurricane bulletins that ‘humanized’ the forecast."
Josh Morgerman, the world's most prolific hurricane chaser, concurred.
"It turned out that Katrina’s winds were nowhere near as strong as what’s described in that bulletin, the water impacts were actually *worse* than feared—both the levy failures in the city and the gargantuan storm surge in Mississippi," he wrote. "So, in the end, despite how crazy it sounded, the bulletin was right. It correctly predicted a massive, catastrophic, generational impact."
Bryan Norcross, the "Hero of Hurricane Andrew", which hit South Florida in 1992, discussed the challenge of communicating an "extreme, unsurvivable event" like Katrina.
"The only choice is to assume the odds are 100% that it will occur," he wrote. "If you're responsible for communicating the hazard, you don't want to leave any room for 'maybe it won't be so bad.'" He said the New Orleans NWS office had taken the same approach.