Spectacular thunderstorms, lightning and flash flooding drifted west to east across the UK today on a blustery unstable SW airstream but the SE and Reigate missed out on any cumulonimbus and we experienced no thunderstorms at all which would please most people but rather upsets weather enthusiasts looking for interesting weather!
Lumpy cumulus congestus and some perky showers with bright blustery conditions in beautiful bubbly convective skies which cleared at night were all the SE could manage. North and West of the region saw amazing convective cumulonimbus with towering cells producing hail thunder and lightning with flash floods here and there. Spotting the clues as to why the SE missed out is tricky… a combination of factors reduced the Tstorm risk.
The general synoptic situation was higher pressure in SE, soundings with lower CAPE values (600 v >1000) and higher lifted index were also evident. Lower 700hPa humidity in the SE was noticeable but possibly irrelevant. The ThetaE map showed considerably higher values away from the SE too.
Soundings for the SE compared with a thundery location (Fairford) to the west show Reigate with less instability through the lower and higher elevations, less depth of saturated air, a stronger cap and less steep lapse rates. Significantly lower dew points in the SE would also reduce humidity and water available for cloud development. Winds were also SSW and thunderstorms developing in the SW early on (Bath and Bristol first) simply drifted to the NW of the area and clipped the North of London missing the SE altogether. More broadly the overall synoptic situation had higher pressure for the SE as well which would inhibit convection. I’ll add to this as more thoughts and ideas arise… why did the SE miss out? Thanks to @MillinMan and @marknealweather with their expert ideas for this quick review! More ideas most welcome @RGSweather. Thunderstorms: edgy stuff but our weather today nothing like as extreme as that in Italy… watch this http://www.youreporter.it/video_Tromba_d_aria_a_Trezzo_Sull_Adda_-_29_Luglio_2013