I've done an update to USA-regional-maps-inc.php V1.01 - 17-Dec-2020 to use the available images at
https://radar.weather.gov/ridge/lite/Sadly, only Alaska and Hawaii regional images are now being produced (along with individual NEXRAD sites 10 images and loop), so the script now defaults to using your local radar (specified in $SITE['GR3radar']) for the 'regional' image selected. Best I could do with what little they now offer.
Update from
the update tool using query Base-USA, Plugin-*, 17-Dec-2020
It looks MUCH more bleak for the wxnwsradar.php set of scripts .. while there are images available, all the overlays are now not available, so I'd recommend you comment out a link to wxnwsradar.php (which stopped working 17-Dec-2020) in your flyout-menu.xml for now. Maybe Jerry and I can resurrect that script (or replace it with some others using map software instead).
Sigh...