Brief Post Mortem
 

Rather busy y'day so wasn't able to follow what was going on,storm broke on the train back home.
Most amusing to see a 'tide'of commuters (dressed only in summerclothes)forced back into Hither
Green station by a wave of flood water rising out of drains (prob already blocked).
Seems to me the MO and AVN got it wrong at 24+ as from the forecasts I was expecting the trough to
the NW to move SE with a few showers breaking out over S/SE England ahead of it.Dunno how well the
mesoscale model did at short range.
As it was the cut off low seemed to develop more strongly and earlier over N France and the front to
the NW broke up.
A plume of higher theta e air seems to have been advected off the continent around the northern edge
of the low .
http://weather.ou.edu/~oscarvdv/maps...hetae_eur6.png
http://bricker.met.psu.edu/trop-cgi/...nom&hour=006hr
Heat from London no doubt provided further low level energy.First cells seemed to have broken out
over E/SE London and over orography on the southern and SW ern peripheries.Prob the strong updrafts
over the low hills produced the small to large hail reported.
In this PV field-
http://bricker.met.psu.edu/trop-cgi/...ity&hour=006hr
there appears to be a lobe of PV over SE England on the left side of the main jet exit,over
France,so that wld have provided the upper air forcing.
Any a few potted thoughts,dunno if anyone has a different view,

--
regards,
david
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