Not much, Jan 2007 was 8 days above avg; 15 below and 7 avg.
Two and one half days were 20F above but were canceled out by the greater number of days below.
What is unusual is that when there were days above they were much above, reflecting a large movement of warm gulf air ahead of a steep gradient from the north and very cold air.
I don’t understand how the graph you presented is so smooth in its analysis.
While I have serious issues with the surface station locations and placement and the collapsing numbers of the total sites, I still think we must use the raw data before we make all the corrections to better fit the modeling process.
Are you still referring to the anomaly plot for January? I'm not sure exactly what you mean, but any kind of averaging process over time reduces the influence of variability within that time interval. (palmer always reminds me about this for ice-core data, because the CO2 in ice cores is essentially an averaged sample over whatever time interval is represented by the sampled ice core layer.)
I still think we must use the raw data before we make all the corrections to better fit the modeling process.
Taking that statement at its basic level, I can't imagine any environmental observational data set that won't have an occasional outlier that would get tossed by a simple Q-test or similar. The data has to be QA/QC'ed to some extent. How much and how its done -- that is a process that is, and should be, constantly scrutinized.