What do we mean when we say that the atmosphere is "unstable"? And why can this lead to thunderstorm development? We are talking a fair bit just now in our forecasts about atmospheric instability leading to the development of thunderstorms so I thought I'd just take a quick moment here to

There's a chance of some thunderstorms developing on Saturday bringing gusty winds, lightning and hail for some of us. Here is the latest forecast from the GFS indicating where these are most likely to form and when. Please note this is just a guide as to the most likely development