I'm going to report a bit early today because we have some smoke moving in from Canadian wildfires soon. It's been clear all morning so far.
Just looking at the past 2 hours of data (11AM - 1PM EDT) the 7714 is dead even with the FARS in avg temp (0.08F diff). However, the FARS max temp in those 2 hours was 0.5F warmer than the 7714. Avg wind speed at 28ft was 3.33mph. I'd guess 3mph or less at 20ft (7714) and under 2mph at 5ft (FARS).
So.... my guess is the height differential plays in significantly here. The FARS is about 20 ft from a two lane residential paved road. It's about 30 ft from a 3 car width driveway (that's about 25 feet long). Perhaps being up and away from that radiation in a more mixed environment gives a truer picture of mesoscale conditions? Could also just be the old rule of higher is cooler (standard lapse rate under high pressure). Hard to say what is the ideal siting here. Although the agreement overall, especially at night, between the two shields is remarkable.
I can't easily move my FARS up to 20', but I suspect that if I did, though, the FARS would run even cooler than the 7714. Although the point for me isn't to find the coolest spot on the property. It's to find where a passive, backup shield best matches my active shield. I think I may have found the spot, but it's still early going. Need to see some clear nights and, ideally, some clear days with a blanket of fresh snow. That'll be awhile assuming the snow gods aren't in a perverse mood
.