Yep. So when you see those huge maps showing the departure from normal, you know these numbers aren't factored in, its all the KATL's and RDU's, and when you factor in one average temperature that calculates off those isolated absurdly high lows, we have lots of orange and red maps.
The coldest nights are often south of Atlanta instead of north
DCA is 53.0/37.2 so a 5 degree difference at night with IAD. Less than i expected.
Flatter terrain?
Correct, the lower elevations. Also the great valley in the northwest, Cartersville to Chattanooga.
IAD probably has enough concrete and air traffic to keep it up some.
Its rapidly changing. Sooo many homes and buildings there compared to just 10 years ago.
Yes, but I’m comparing RDU climo against itself. No doubt MBY has gotten colder, too, but still 27 is not very cold for the min temp for a winter month at RDU. Even Fayettenam had gotten down lower to 26! RDU has had a warm December, well over 5F above normal for the month, much worse than GSO or FAY.
If you take readings from the Atlanta airport during high traffic periods, it's like having kerosene heaters going full blast all around you. If the winds are still, it's going to raise the temperature from that alone. Take in to consideration all of the concrete and asphalt in the area and the real surprise is why KATL is not reading considerably higher than it is. Elevation has something to do with it, too. They sit at about 1,025 ft ASL I believe. A lot of the surrounding sites are lower, 850 to 950 ft ASL. KFFC is in a valley surrounded by trees, a large lake and white TPO roofing. It's gonna get cold when it can radiate on still nights. KPDK is where they should take the readings for ATL. Even driving 2 miles away from the airport will drop the temp about 5 degrees in the morning. I commute right by there and have witnessed it many times.
It was 23 at my house in December, 15 miles south of KATL.
I completely understand, but its the same thing with KATL. RDU has grown substantially in air traffic and overall traffic over the past decade, have they not? Delta has a small hub there now I believe.
Yes, I'm watching this action for signs of what may translate further east.
I have noticed the RDU temp being higher than Sanford, RM, Wilson, Smithfield, etc. over recent years. Now Fayetteville from time to time will be colder in the evenings. I can remember when this was strictly a north/northwest deal with respect to temp drops after sundown. Nothing east nor south of the Triangle was ever colder unless an unusual weather anomaly. The Triangle really has become a metro heat island more so now and did not used to be.
So you're getting snow falling when the HRRR's sounding says it should be rain and there is no output on the map. I'm guessing your temps are in the upper 30's right now? I suspect that the soundings are not going to be reliable for conditions within the 534 DM line. Your thickness should be at about 528 now and that lowest thickness does translate east, but fills to about 534 by the time it's over GA.
