I’ve been watching weird behavior in propagation over the western USA with curiosity since Hurricane Ida plowed through some weeks ago.
And I’ve been taking screen shots of how the hole in propagation has changed and expanded over time since then.
Early Summer “Normal Propagation”
When I first started on the HF bands back in May, the skip zone around me was a pretty standard 350-550 miles. That left most of the USA accessible to me most of the time, and was pretty consistent for several months.
There were a couple of little “signal black holes” that were hard to get into– Montana, Wyoming, and the Dakotas were just random luck but I eventually got them!
A Turning Point Blows in on the Wings of a Storm
But Ida seemed to mark a turning point where the skip zone started to enlarge gradually. Now the skip zone I see most days is 1200-2000 miles, and covers MORE than HALF of the USA.
I did a spot check of other western grids signal propagation a few days ago to see if it was just Arizona experiencing this issue, and I found that most of the grids I checked in the western half of the USA were seeing a similar sized huge hole in HF band propagation around themselves.
What the heck was causing it? I’m curious about everything, of course, so I’ve been trying to figure it out. (Even more so because it’s causing me problems working for various awards!)
I’ve pored over many different maps, looking for a factor that seems to match the “hole” in the sky I am seeing, and I’ve finally found one that looks close.
It’s a map of the severe drought conditions developing in the USA.
Here’s a map of drought conditions back in late May, when I first started doing HF.
So I have a new theory, which may or may not be accurate in whole or part.
It looks to me as if moisture in the air is an important part of the propagation puzzle by refracting the signals back downward. This also explains why I frequently see signals land on the coasts of land masses, where the moisture content of the air changes abruptly.
I’ve seen this with Asia, Europe, South America, and propagation into Europe pretty regularly.
My friend is starting to call me “The Meteorologist” with all this weather investigation! But isn’t it interesting!!