Not sure what caused the unusual "hump" in the weather recordings today, but a few things stand out.
The barometer took a "dip", while the wind speed and direction shifted dramatically. The temperature went up twenty degrees for about 2-1/2 hours, and the humidity took a corresponding drop.
I'd put this down to a "Downslope Wind Event", or Chinook, but the wind was from the Southwest this time, so not much "Downslope" from that direction.
Since I wasn't awake at the time, I don't know what the radar was showing.