Yesterday a comment was made of the old rule that if the dewpoint+air temperature is zero or below, you're likely to see snow falling. This works if there are no milder layers aloft and is an approximation of several much more complicated formulae.

http://www.sciencebits.com/SnowAboveFreezing

I've plotted these values below. It might be worth saving a copy of this as a "ready-reckoner" when snow is heading your way and conditions are looking marginal! NB, these aren't be-all and end-all figures as every snowfall is different. However, they're a notch above the old "air and dewpoint" method.

Superb! Thanks. 

Will put this in the library section when everyone has had a chance to see it in a week or so

Thanks Darren, I shall put it on my office wall together with all the other useful bits of info I have gleaned. All we need then is the right temp, DP and some precipitation (and probably 100 other factors too)

I was getting all excited, thinking I was about to open a map with crayon outlnes/boxes drawn over it, indicating where in Kent snow was going to be falling.....

Cheers Darren, we need more of this sort of useful info 

One chart to refer to for years.. If not this year. Thank you for being so thoughtful and a boon for all.  ... aZm ...

Useful that.

Cheers Darren

Thanks for posting this.

It helps greatly in understanding why this spell has turned out as poorly as it has in terms of snowfall for the majority. It was always much more marginal than appeared by just a cursory examination of the charts. One always needs to look at the numbers in detail, and even then applying a large pinch of salt, especially regarding dew point charts in the model output.