Yesterday much of East Texas was under a moderate risk of severe weather including a 10% chance of tornadoes, which is an elevated risk for tornadoes. We had strong southeasterly winds at the surface with strong westerly winds aloft giving East Texas a significant amount of shear and spin to the atmosphere. All that was missing was the energy to lift the air for convective initiation. If you remember from yesterday’s forecast sounding models were painting a pretty scary picture across East Texas. Temperatures were forecast to reach close to 80 degrees with dewpoints in the middle 60s. This provided a forecast Surface CAPE over 2500 J/kg.
With a little extra sunshine, drier air mixed down to the surface producing dewpoint about 5 degrees cooler than forecast. As you can see if we modify the forecast sounding with the actual dewpoints, the CAPE nearly disappears and the lower levels of the profile experience Convective Inhibition, or a cap.
So with the new cap in place any updraft that tried to originate was quickly forced down to the surface keeping thunderstorms from developing. Many times when everything points to a significant severe weather event, an unforeseen event puts the brakes on severe thunderstorm development.