I got another set of exposures of this, and I'm going to see if that works any better. this one's all blocky and weird.
anyway: it did actually look somewhat like this, which is why I stopped to take pictures. to the eye, it gave me the impression of a patchwork quilt of tones.
oddly, this was facing due north. the sun and sunset to the left (west) were totally blocked, but the sky peeking through the gap in the storm was, by comparison, much brighter, so it took on the effect of a sunset.
I like hugin, the pano tool I used, in that it sacrificed the foreground (the curb) to make sure that the interesting bit (the sky) was aligned properly. whoever did these algorithms did a good job on the perceptual considerations. thanks.