that is clearly the same pattern to me. the times for the peaks vary a little.

i wish i had a clearer understanding of what that represents.

The times for the spikes vary by a day or so, I believe it represents a match.
(Chart members can see the time stamps for each data point)

The radiation was in Seattle WA and then came my backyard

I can not stress enough how helpful my HEPA air purifier with the GMC-200 geiger counter on the intake filter was for detecting this pattern. This would NOT have been visible from inside the house our likely with the geiger counter alone outside.

I understand having the GC outside increases the possibility of measuring any Beta significantly over a similarly acquired indoor measurement, due to the difficulty of Beta traveling through the house structure. But similarly acquired inside or outside Gamma measurements (with air filters on each) (the Washington state graph is of Gamma) should be the same...hmmm, unless the outside filters are trapping Beta that is throwing off Gamma? Do these measurements suggest short-lived radon progeny, since they decay back down to backgrounds levels in relatively short time?

Your suggestion of trapped beta that then throws off gamma sounds reasonable. What I do know is, I DO NOT get these clear of readings from inside the house. As for what isotopes were trapped in the filter, I can not confirm what they are/were. I am waiting to see if that last rise & fall seen on the Seattle graph gets recorded on my graph and then I will replace the filter and do the best I can to test it using my InspectorEXP against background.

At 6:30 pm CST I replaced the air purifier filter right before a storm front blew in from the North West. Currently it is snowing the largest snow flakes I have ever seen fall before. Each flake is like the size of a quarter or larger. I will upload a picture off our deck. I only wish now that I would have thrown down a quarter before taking the picture so it would be easy to compare, sorry.

Just when I thought I had seen my highest reading, things get worse. I guess this is the only trend we will continue to see?

I did have a stretch in this past week (December 20th - 22nd) that is my good baseline, but as you can see it has not stayed there. Currently I have been seeing a rise all day that I can even match with the EPA station in Milwaukee Wisconsin.

You've probably answered this before, but where is your air purifier/GC located? Indoors or out?

It has been outside since April of 2013, the difference in my detections are like night and day. After all, the EPA uses a filter catch system too for their detections so why shouldn't we. Our government gets their best readings using a filter catch system, we should do it too.

Sweet! I would love to put mine outdoors too. How do you protect your purifier, GC, rig from the elements?