It’s no wonder that we are seeing snow showers in May across the north of Scotland after looking at this mornings 11 UTC ascent from Lerwick. The 1000-500 hPa thickness at that time was just 517.5 dm, and the 1000-850 hPa is 1278 metres. It’s a real shame that none of the NWP available on the web provide thickness charts. I make the freezing level their around 500 feet. It’s unstable, but it does seem to be limited by an inversion at around 10,000 feet. Having never been on the Initial Forecasters Course I can’t say much more although I have plotted enough of the bloody things in my time.