Stan Gosnell wrote:
Cloud bases are seldom perfectly level. They are lower in some places
than in others. If you get the airport in sight right at MDA, then it's
likely that there will be areas where the cloud bases will be below MDA,
and you'll probably fly through them as you circle.

Clouds can do some weird **** (especially near bodies of water). I
once flew into UUU (Newport, RI) for a practice approach. The plan
was a low approach and go missed. The airport is near the coastline,
and the approach is from over land towards the water. Inbound to the
airport, I was in decent visibility and little bits of scattered scud
here and there. What I didn't realize was that there was a low
overcast layer on the water side, that ended just about at the
airport.

I reached the MAP, had a perfect view of the runway, started my climb,
and almost immediately found myself in solid IMC. Had I been doing a
circling approach, I could have easily found myself suddenly in cloud
while circling below the MDA.