On the morning of October 15, just before sunrise, there was something interesting on the Oklahoma Mesonet front page:
What was happening to cause Medicine Park to be such an outlier?
First, we had very calm winds across the state overnight. This allowed a large inversion to form near the surface, as indicated by the balloon sounding made at around 6 a.m. in Norman:
The red line is temperature in degrees C. Notice how it increases rapidly from around 5 degrees C near the surface to about 16 degrees C as height increases.
Second, Medicine Park is one of the higher sites in that area which allowed it to measure temperatures near the top of the inversion.
Here’s a map showing the temperature at 1.5 meters (about 5 feet) and at 9 meters (about 29.5 feet) above the surface. Also plotted is the station’s elevation above sea level in feet: