predicting thunder/thunderstorms

[timeless]

my knowledge is less than basic, recently l found a site which gave me a basic understanding of lifted index using colour codes (weatheronline site to be specific), however ld like to know a little more about how to work out if there is a thunderstorm comming if that makes sense as lve seen allot of other readings being used, while l dont expect it to all be simple it would be interesting to know some basic readings that might help me work out when l need to be about to turn off sensitive equipment l have running.

 

main reason l ask is because the met office hasnt really predicted anything with great accuracy recently as their predictions seem to change hourly.. like yesterday it was supposed to rain all day but we only got a spot at 4pm and some of their predictions of thunder dont really match what lm seeing on weatheronline if l go by lifted index.

 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=lftx&HH=6&ZOOM=0&ARCHIV=0&RES=0