Morning.  Many people across the country face the prospect of driving in icy snowy conditions for the first time in 3 years this weekend:

Here is the situation at 2am Sunday from Arpege as the shortwave stalls and fizzles:

There are weather warnings out too:

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=map&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1452902400

Well worth a look.  Its going to be  a busy weekend for some, who may need to check out their nearest lamp post!

Just had a wander through the HIRLAM and GFS precip charts and was surprised to see that showing lightish snow down here too - will be nice if it comes off.

Looks like quite a reasonable fall for some in the Midlands

And Hirlams take for the SE

Quire a bit of the ppn is rain .......any ideas why

Not quite cold enough away from the core of England I think...and to the S and W of the feature milder air is mixed in.  south and west of a line Stoke to Hastings rain looks much more probable.

Yes indeed Phil. From a SE England perspective our roads forecast provider are talking about 1-2cm in West Kent and Sussex with 3cm possible over higher ground, confidence is still low. East Kent likely to be too far east to see anything of note. 

An exciting prospect in desperate times. I may make the 100 mile round trip with the kids and the camera to witness it in the morning. 

I'm walking in the Chilterns so might see some snow

Looks good further East, totally ruined my frosty weekend by the looks of it!

I normally do ok in these types, bugger if I miss out

Go with experience Marcus.  Bugger the models - what do they know

The warmer air aloft is picked up well on this chart. I would have thought that the rain/snow boundary would probably sit around the -5c 850Hpa isotherm.

I can see me being very frustrated overnight watching the snow slip past West of me!

Its trending eastwards Jonesy. Keep the faith..yesterday this was more of a Birmingham to Bristol event with the eastern edge roughly Portsmouth. 

Hope ya right matey, Meto warning doesn't cover me..yet!  Just a gut feeling that this cols spell will be one I'll look back on thinking if only because everything seems to go slightly West or East of us.

Morning Steve - Given the slack set up I would be more bullish and put the boundary further west. It'll be all about any milder intrusions lower down in this case given that it will still be sub-zero over much of the uk at the 850hPa level. Such a fine line though but I am hopeful of snowfall in Alton

What crumb of comfort can you offer me then Steve?! I'm watching that snow edge ever further east - even my height won't help me now. I'm going to have to move back to the thar hills (Hawkinge!)

I remember you came to Surrey to visit the 1ft depth after we had a amazing Thames streamer and we are now well over due to occur again at some point.

Morning Dave. Good point. I hadn't fully factored in the cold surface and diurnal factor. Maybe -3c should be the boundary on reflection. 

I would still rate your chances tonight better than mine Dave. Them thar hills have been green for too long now. My advice is to stay put. 

Amazing event for Leatherhead that was Jiries. Well worth the 150 mile round trip to see 30cm of laying snow one day after it had fallen. 7 years ago already.

Yes really time going quick and today I am 43 so there no snowfall on my day but likely to come after mdnight unless if arrive at 11.55pm!  We are well overdue for something that deep nationwide. 

Hi Dave and Steve

In this particular episode (22z - 08z Sun), absolute 2m T and 850s are not as important as dp and 950Hpa T, with a dose of thetaW thrown in. If you look at the Euro4 at 03z, the temperature at any given grid point is more or less the same as at surface, which infers altitude will not matter. Also although dp is marginal, they do fall towards morning as a dryer pull is modelled from the NNE. Winds light so evaporate cooling comes into play along the margins (further west) but whether intensity is high enough to trigger rid effect is doubtful.

in conclusion - a pesky little thing to model but unfortunately as of now I won't be issuing an advisory for S Hampshire/SW Sussex so you can take my snow line as Brighton to Swindon to Evesham say. Might change though lol.

Edit: just as I post this I get a few tweets that an extension back west may be required which of course brings more of Hants into play. Basically tonight is one of those 'when it occurs' events as so many of our snowfalls are in this country.

Hi Neil. Good discussion here.

Based on this link parameters at Southampton look more conducive for a rain event rather than snow. 925Hpa's and dewpoint are above 0c during the wettest part of the event and only tend to fall back towards the end as drier air is brought back in. Wise move not to issue and advisory ....for now. 

http://wxweb.meteostar.com/sample/sample.shtml?text=EGHI

Meanwhile here we appear to be on the right side of marginal with -3c 925Hpa's but any precipitation is much more restricted.

http://wxweb.meteostar.com/sample/sample.shtml?text=EGMD

9 pm tonight according to the gfs with the snow sliding down the country over night.

http://www.theweatheroutlook.com/twodata/chart.aspx?chart=/charts/gfs/06_15_preciptype.png?cb=965

6z has trended everything slightly further east.