Now I am not a meteorologist by trade or university, but I am pretty
confident that the level three and higher returns showing up on radar ahead
of this cold front today were not falling from a stratus layer.

Don't be so confident. I recall one trip from Destin back to Houston
where I nearly drove a controller who was just as certain as you are
into a conniption fit. It so happened he was wrong too.

I was flying my PA-30, which doesn't have RADAR of any sort (not even
the XM kind) but does have a good Stormscope. I had already deviated
North to avoid an area of convection (the screen was lit up) but headed
West once I was North of the activity. The controller almost did not
allow me to turn West - he insisted I would be flying through an area
of Level II and III returns, with small areas of IV (that's red) in an
area covered by a convective SIGMET. And he was right. However, all
the actual convective activity was now South of me. I flew through
some moderate and even heavy rain - with no turbulence to speak of.
Nothing worse than occasional light chop. I flew in and between
stratus layers. The controller was checking on me every few minutes,
asking if I needed to deviate - because all he had was the RADAR and
the SIGMET.

There really are times when you can have areas of yellow and red, in
conditions that look like they favor convective activity, and in fact
right next to convective activity, which are nonetheless stratiform and
quite comfortable to penetrate. The key is knowing that convection is
not there. Now how one is to know that without a good 'spherics device
is beyond me.

Michael