Reinhard and Edouard and all my fellow WeatherCatters:
Thank you so much for noticing I was missing in action! I am back online, and here is my saga:
I updated my iMac to Mojave 10.14.6 and a few days later Apple released something called 10.14.6 Supplemental. I updated again. This time the update downloaded and the install progress bar went all the way to the end and stayed there. Nothing happened. I waited overnight and still no action. I turned off the machine and restarted it. It would stay on for 30 seconds and power down. I called Apple. They had me boot up in Recovery mode and reinstall macOS from their server. The install progress bar went all the way the end and hung. They told me to take it to the Store for further diagnosis. This is a 6-year-old iMac and Apple was very helpful on the phone and never mentioned that I am out of warranty, etc.
I took the machine to the closest authorized Apple retailer, which was an hour away. They had it for 10 days before they could get to it, but eventually diagnosed a dead HD. Normally, I would not invest repair money into a machine this old, but I am just a few months away from giving it to my wife who is struggling along with a much older (and much much slower) iMac so I can follow Steve and buy a new one for me. So I had them replace the 3 TB HD with a 2 TB SSD. I figure that this repaired machine will perform well for her for several years. The old HD from Apple was a Seagate Barracuda, so a very decent drive. The new SSD is also a Seagate Barracuda.
I was able to pick it up yesterday and bring it home. I plugged my external dock holding a Carbon Copy Cloner backup of my entire drive into the iMac (thank you, thank you, thank you dfw_pilot for helping me set that up a few years ago). I restarted the iMac on the backup drive, erased the Mojave install on the SSD, and cloned my backup onto the new machine. Five hours later, I was up and running and grateful for a decent backup solution.
As soon as I was back online, WeatherCat fired up, transferred all the data from the logger to the app, and started uploading historical weather for the last 14 days to WU. How cool is that?
My main iMac was down for 14 days but it sure seemed like 2 weeks to me.
I am glad to be back online, and again, thank you Reinhard for detecting my absence.