Re: the Easyjet photo's on page one of the thread .. I have some rather more unpleasant ones of a Windjet A 320 at Catania taken in 2009, radome gone and the antenna trashed ... they were flying very blind, and probably very scared.
I have seen some impressive weather, particularly over my native Alps in the summer: on one occasion I tried to pick my way through and had a most unpleasant experience, we were out of the high overcast, plotting the tops visually and trying to filter the cells from the ground returns by vertical scanning .. then there was this moment when we looked up and saw a very large shadow way way above us.. all looked fine on the radar but oh dear ... never again .. and we THOUGHT we were ok.
So next time we saw the same conditions kicking off ... lots more fuel, and a plan around the area .. it added another 30 minutes flight time, then we heard the calls from the direct routers and knew we were in a better place.
PLAN to stay clear, delay, talk to ops, take more fuel, re route, hold, whatever, but do not take on conditions that you cannot possibly reasonably predict. If you do, and are lucky.. you will only scare yourself, if you are not .... ?