Pity there's no Watnall sdg as that wld help a lot,Caistor Bay has dry air aloft which wld overrun
the frontal zone
http://weather.uwyo.edu/cgi-bin/soun...712&STNM=03918
the convection at Chilbolton was v shallow 1-2km ~16Z
http://www.chilbolton.rl.ac.uk/weather/cloudradar.htm
unfortunately there's no data from the Aberystwyth profiler for today ATM..
There is surface convergence at the rear of the front over southern England -
http://weather.ou.edu/~oscarvdv/maps...hetae_eur0.png

IMO insolation wld not be necessary,convergence and orography being enough to release potential
instabilty at the surface cold front underneath the overrunning dry air.The low cloud base and
turbulence of the light to medium showers was striking in SE london and a low level jet seemed
evident.
A later band of lovely Cu con did grow in a gash in the high overcast tho.IMO the low level forcing
was strong in the moist enviroment but capped off by strong descent in the dry air aloft (as I think
Martin suggests)

--
regards,
david
(add 17 to waghorne to reply)