It's an ominous Monday in the southern Great Plains.
Entire school districts are closed as storm scientists expect "high risk" weather and severe thunderstroms, with conditions ripe for powerful tornadoes throughout much of the Texas Panhandle and Oklahoma. A confluence of robust elements have combined forces to produce an exceptionally dangerous day.
"It's an environment that we don’t see very often," said Bill Bunting, operations chief for the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center. "Maybe once or twice in the career of a forecaster."
Here is a zoomed in image of our High Risk for 20 May 2019 for use in social media. pic.twitter.com/TZd9Fr3atW
— NWS SPC (@NWSSPC) May 20, 2019
Bunting is stationed in Norman, Oklahoma, the dead center of a region that is likely to experience the formations of a dangerous type of thunderstorm with rotating updrafts, called a supercell. These storms can produce tornadoes. "One of our forecasters said last night that it’s the first time he lost sleep thinking of the day ahead," said Bunting.
The (unfortunately) right conditions
It's severe weather season in the Great Plains, but environmental conditions have really ramped up, much more than usual. "What's unique about today is the expected magnitude [of storms]," noted Bunting.
There's a profound amount of instability in the atmosphere, from the ground to around a mile up in the sky, explained Brian Tang, an atmospheric scientist at the University at Albany. This is driven by strong winds blowing from different directions at different heights, notably a parade of potent storms blowing in from the Rockies after deluging Northern California with rare, late-season rain. These storms have now met powerful winds blowing in from the southeast.
Dawn breaks on the Southern Plains and GOES gives us a look at the wind shear part of the severe weather forecast. Low clouds streaming up from the SE are being overtaken by mid-to-high clouds coming from the SW. This turning of the winds helps storms that form start to rotate. pic.twitter.com/qW0NYbR7A0
— National Weather Service (@NWS) May 20, 2019
But this wind-driven atmospheric chaos (technically called "wind shear") is not acting alone. There's an unusual amount humidity in the air. Thunderstorms feed off this moisture, growing more powerful. "There's a ton of energy that can be harnessed that can generate these really intense thunderstorms," said Tang.
And once there are intense supercell thunderstorms circulating through an area, there's greater potential for these storm systems to start spinning, thereby spawning violent tornadoes. "There are going to be several thunderstorms that do reach an intensity that become tornadoes," said Bunting.
"It's like having an All-Star baseball team. It's like having a bunch of sluggers," said Tang. "The chances of hitting a home run are that much higher."
"This is not your normal severe weather day in Oklahoma," the National Weather Service (NWS) office in Norman, Oklahoma said Monday morning.
Exactly what causes a particular supercell thunderstorm to form a tornado, however, is still an area of deep and ongoing investigation.
Midday SPC update added a 45 percent tornado risk for a big chunk of western and central OK. A particularly dangerous situation tornado watch coming for that area. https://t.co/RO92Y2cfmG pic.twitter.com/N2h0Ipq9is
— U.S. Tornadoes (@USTornadoes) May 20, 2019
NOAA's Bunting noted that Monday's weather outbreak comes on the exact anniversary of an EF-5 tornado (the most severe tornado rating) that killed 24 Oklahomans in 2013 while causing billions in damage.
Today's violent thunderstorms won't just bring the likelihood of wide tornadoes in heavily-populated areas, but the risk of deadly floods. These storms dump deluges of water. "More people traditionally die from floods than tornadoes," the Norman NWS said Monday.
Meteorologists and storm scientists have prepared for the worst.
"It's really created a palpable sense of anxiety and just wanting to get done with today," said Bunting.
"There’s definitely certain days when there’s a sense of dread," added Tang, noting that the meteorological community reacted similarly to the approaching Hurricane Michael in October 2018. Michael hit the Florida Panhandle as a Category 5 storm, which is the highest hurricane rating.
"Today has that same feel," said Tang.