I am not sure we actually disagree Matty. It has not been especially cold for a cold snap, my thought is more not to judge the next few days of this "cold spell" until they have passed. 

My comments were not about my area but the UK as a whole. I said it was not especially cold yet but the airmass is forecast to get colder. There is nothing remotely IMBYish about that so I am not sure how it could be interpreted that way. It may end up getting colder and then it will no longer be a "relatively warm northerly". It may also be largely dry in places but that is yet to be determined.

My point is that is that is has not been shown to be especially cold just yet despite silly media comments about bitterly cold conditions. It has been wintry in places though.

hi will hay . wow u live close to me. I live at Sutton avenue /southdown rd  . I use to live in peacehaven

You are looking there at humidity as defined by wet bulb temperatures and lapse rates.

Agree that "relatively warm" is a daft a phrase as the "bitterly cold" that keeps being banded around. It is neither for most. 

Also agree that anything can happen. I will remember this winter as one where a lack of deep cold to tap into watered down some good snow potential 

Thanks, one other thing that made it even more unusual was that it was tipping down and flat calm. You'd assume evapourative cooling would have played a part

Coldest air of the winter should be across the south-east for a while next week.

It can be maddening at times.  In the SW quadrant (and more widely) the enemy of snow is in these scenarios is the extra moisture and hence smaller lapse rates derived from the proximity of the Irish Sea Bristol Channel and Atlantic edge, and just about any water body surrounding our maritime isle.

But there again when the air is cold enough it can be the snow maker.  In marginal situations you need drier air which is why in a NWly parts of the E and S are doing better (in the scheme of the thus far marginal parameters) at the moment.

Had some light sleet/wet snow early this morning none settled.

Most likely to be the wet bulbs temps Matty which are above freezing, snow will fall as rain no matter what the dew point says.

It's still a decent rough guide to whether it'll snow or not but experience shows it's far from perfect!

In particular, it assumes that there's a linear decrase in temperature with height and that there are no troublesome moist/milder layers aloft. You can see these on upper air charts, but they're not regularly posted on here (or anywhere, for that matter).

With this current spell there have been all sorts of complications, as shown by this midnight ascent from the south coast of England (Herstmonceux this morning):

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=TEXT%3ALIST&YEAR=2015&MONTH=01&FROM=3100&TO=3100&STNM=03882

Note how at around 750 feet there's milder air, temperatures are well above freezing and the dewpoint + temperature formula would give a positive result. It was so very, very marginal!

-----------------------------------------------------------------------------
   PRES   HGHT   TEMP   DWPT   RELH   MIXR   DRCT   SKNT   THTA   THTE   THTV
    hPa     m      C      C      %    g/kg    deg   knot     K      K      K 
 1000.0   -148                                                               
  975.0     52    0.0   -0.7     95   3.74    270      4  275.1  285.5  275.8
  974.0     60    0.6   -0.3     94   3.86    272      5  275.8  286.5  276.5
  968.0    111    1.6   -0.3     87   3.88    285      7  277.3  288.2  278.0
  961.0    170    1.7   -0.8     84   3.78    300     11  278.0  288.6  278.6
  950.0    264    1.8   -1.5     79   3.62    303     20  279.0  289.2  279.6
  942.0    333    1.7   -2.2     75   3.46    305     27  279.6  289.4  280.1
  937.0    377    1.6   -2.7     73   3.36    306     26  279.9  289.5  280.5
  925.0    482    0.8   -3.7     72   3.16    310     24  280.1  289.2  280.7
  921.0    517    0.8   -4.1     70   3.08    308     23  280.5  289.3  281.0
  913.0    587    0.2   -4.6     70   2.99    305     21  280.6  289.2  281.1
  895.0    746   -1.1   -5.8     70   2.78    299     22  280.8  288.9  281.3

20cm level snow 

Was it not today the milder layers were supposed to be mixing out, leaving a more linear gradient from ground up?
Or was that Sunday, or Monday, etc?
My point is it is virtually impossible to forecast whether it will be rain or snow beyond a few hours in these very borderline set-ups. Give me a straight easterly with sub zero dps any day over this annoyingly fragile flow.

Excellent, thanks Darren. Milder air aloft is not something I'd thought of. 

I think it was supposed to be later today and into tomorrow from North to South - but I may have imagined that. 

No, its later today and overnight Neil do keep up when the proper cold air arrives.

See Met/o watches.

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=map&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1422662400

Got new yellow warnings for snow and ice issued 12:27 For here.

It's still a decent rough guide to whether it'll snow or not but experience shows it's far from perfect!

In particular, it assumes that there's a linear decrase in temperature with height and that there are no troublesome moist/milder layers aloft. You can see these on upper air charts, but they're not regularly posted on here (or anywhere, for that matter).

With this current spell there have been all sorts of complications, as shown by this midnight ascent from the south coast of England (Herstmonceux this morning):

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=TEXT%3ALIST&YEAR=2015&MONTH=01&FROM=3100&TO=3100&STNM=03882

Note how at around 750 feet there's milder air, temperatures are well above freezing and the dewpoint + temperature formula would give a positive result. It was so very, very marginal!

-----------------------------------------------------------------------------
   PRES   HGHT   TEMP   DWPT   RELH   MIXR   DRCT   SKNT   THTA   THTE   THTV
    hPa     m      C      C      %    g/kg    deg   knot     K      K      K 
 1000.0   -148                                                               
  975.0     52    0.0   -0.7     95   3.74    270      4  275.1  285.5  275.8
  974.0     60    0.6   -0.3     94   3.86    272      5  275.8  286.5  276.5
  968.0    111    1.6   -0.3     87   3.88    285      7  277.3  288.2  278.0
  961.0    170    1.7   -0.8     84   3.78    300     11  278.0  288.6  278.6
  950.0    264    1.8   -1.5     79   3.62    303     20  279.0  289.2  279.6
  942.0    333    1.7   -2.2     75   3.46    305     27  279.6  289.4  280.1
  937.0    377    1.6   -2.7     73   3.36    306     26  279.9  289.5  280.5
  925.0    482    0.8   -3.7     72   3.16    310     24  280.1  289.2  280.7
  921.0    517    0.8   -4.1     70   3.08    308     23  280.5  289.3  281.0
  913.0    587    0.2   -4.6     70   2.99    305     21  280.6  289.2  281.1
  895.0    746   -1.1   -5.8     70   2.78    299     22  280.8  288.9  281.3