Well let me start with some location information, give you some current and past history, and then a surprise I had.
I am located in central California. We had some nice storms on Friday that knocked my neighbors tree across my power and internet lines. So I have been running on generator with internet tethered internet off my phone for the last two days. Anyway three separate power line cuts just in the neighborhood.
So when the power company was running the lines back from the HV lines to my transformer I mentioned I have had a nasty hash at times from transformer input arcing. If you have ever had a really foggy day and heard (or seen) an buzzing around your pole pig transformer you know what I am talking about.
Anyway the surprise I got was when they cleaned up the power connections and added a nice no-ox layer to them my power came back on. I fired up my CHIP and outernet and my SNR to RSSI had shifted.
Before I have had 5-6 at -118 or so, but now with the antenna not moved at all I have a 8-9 at -115.
So the Lesson there is don't discount the broadband noise that a minor spark gap can cause even up into the GHz range from power distribution issues.
When I get a bit of time I will check if my HF background has dropped as well, I am thinking they may well have.