I'm no meteorologist, and I do not know the definitive answer hence why I'm asking, but would you fly a light aircraft underneath a cloud that looks like this?
Photos: ATEC Zephyr 2000 Aircraft Pictures | Airliners.net
In all of my flying so far I would avoid something like that with a very large margin. Visibility still looks good through to the other side so I don't think I'd be too concerned about heavy rain/hail at that moment in time, but I'd be more concerned about the potential updrafts. Am I being too cautious, or have I not understood my Met studies too well?
Considering in the UK we're faced with such a mixed bunch of weather which quite often doesn't match the forecasts on the ground, I'd be interested to learn some people's opinion/observations based on the face of it without any further information available to us.