A dangerous and potentially deadly severe weather outbreak is underway and forecast to last through Tuesday morning across the southern Plains, particularly in northern Texas and across Oklahoma, as a rare and especially volatile mix of tornado and flash flood-producing ingredients combine.
The big picture: The Storm Prediction Center (SPC) has designated a region stretching from the Texas Panhandle to western Oklahoma as having a "high risk" of severe weather, the top rating on their scale. Forecasters have warned of "significant threat to life and property" from this severe weather event, both from tornadoes and flash flooding.
The threat: On Monday evening, the threat to Oklahoma City and Tulsa was transitioning an increasingly worrisome flash flood scenario, along with the continued risk of strong winds and tornadoes, as a line of near-stationary severe thunderstorms inches toward the city. "The areas that receive the heaviest rainfall could see severe, life-threatening flash flooding, especially if it occurs over an urban area," the NWS said regarding central Oklahoma.
- Further southwest, though, towards southern Oklahoma and into Texas, the threat of strong tornadoes will last longer into Monday night.
- The first confirmed tornado of the day touched down near Paducah, Texas at about 3:07 pm CDT.
- Dozen sightings of tornadoes were reported in Oklahoma, Kansas, Texas and Missouri Monday evening — including a large tornado that passed just north of Mangum, Oklahoma, and another near Midland, Texas. Luckily, most have spared heavily populated areas.
Context: The severe weather comes on the sixth anniversary of one of the deadliest days in recent Oklahoma City weather history. On May 20, 2013, Moore, Oklahoma, was hit by an EF-5 tornado, killing 24 and injuring more than 200. Among the dead were 7 children who died at an elementary school, where a wall collapsed.
Between the lines: All of the key ingredients for a major tornado outbreak are present in abundance. An unusually powerful jet stream is roaring above the central and southern Plains, and there is plenty of wind shear (winds changing speed and/or direction with height) and powder-keg-like instability to trigger thunderstorms to erupt.
In addition, large moisture and air pressure contrasts have set up across the region, as a low pressure area of near record intensity for this time of year sets up to the west of the region. In a sign of the clash of airmasses involved, heavy snow was falling over parts of Colorado and Wyoming, to the west of the cold front.
- Computer models show nearly every type of severe thunderstorm — from squall lines that bring damaging straight-line winds to what are known as "discrete supercells" — is likely to form through Monday night.
- A supercell is the most dangerous type of severe thunderstorm since it can produce long-lived, violent tornadoes and up to softball-sized hail.
- In addition, heavy rains on saturated ground could lead to widespread, life-threatening flash flooding, particularly on Monday night as thunderstorms group together into large clusters.
The bottom line: Monday through early Tuesday is going to be a dangerous period for millions in the Plains, and the outbreak has the potential to be remembered for years to come.
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