November 4, 2022 Tornado

First, let us rewind backward in time. A week before the tornado outbreak, above-average model agreement and forecaster experience led to a Slight Risk of severe weather, or 15% area on the Day 7 Convective Outlook, which was issued by the Storm Prediction Center on October 29 ^th .

This had the meteorological community on high alert as this was a rare occurrence that far out for this time of year. In fact, this product was the first Day 7 Convective Outlook with a 15% probability of severe weather for a fall season.

What did that mean? Well, there was confidence that a severe weather event, potentially significant, was going to unfold on November 4 ^th  in the southern plains.

Fast forward to Day 1 (the day of the event). As can be seen to the left, confidence increased to an Enhanced Risk of severe thunderstorms over southeastern Oklahoma and the Slight Risk shifted to central Oklahoma and western north Texas. As compared to the Day 7 graphic previously shown, the location of expected thunderstorm activity shifted eastward. This is not unusual and the location and timing routinely changes as the weather system speeds up/slows down, and/or as higher-resolution models capture additional details as the event draws nearer.

There was sufficient data to suggest a medium potential for tornadoes over southeastern Oklahoma on this day. This correlates to a 10% chance of a tornado within 25 miles of any location within the yellow shaded area of the bottom right graphic.

So, what were the conditions that allowed this event to take place? Glad you asked.

On November 4 ^th , a potent upper-level trough approached the southern plains as a strong cold front moved through Oklahoma and western north Texas. Pictured left are the 1) 6 AM weather balloon launch in Norman, OK (top left), 2) temperature observation map clearly showing the location of the cold front mid-morning (top right, photo courtesy of the Oklahoma Mesonet), 3) the projected location of the upper trough at 1 PM (bottom left, as rendered by that morning's run of the HREF mesoscale ensemble model), and 4) national surface analysis as of 1:35 PM.

The ingredients were all coming together:

• Lifting mechanism (upper trough and cold front)
• Instability (1540 J/kg of surface based instability, see balloon data to left)
• Wind shear (30 knots of 0-3 km shear, see balloon data to left)
• Moisture (dewpoint temperatures in the 60s, saturated low and mid-levels of the atmosphere - see balloon data to left)

Thunderstorms eventually developed over north Texas and lifted northeast into southeastern Oklahoma.