Thursday is one of those situations that pits different regions against each other in terms of what we want to see, with more northerly areas wanting the front to get as far north as possible; southerners don't want it getting very far north as that would let mild air in over them.

At the moment the northern extent looks to be somewhere between about Birmingham and southern half of NW England. Not sure of the implications of each for those in the south.

I'd say though that a band across the Midlands will be the best place to be. 

People were optimistically hoping for a significant snowfall. The problem is the uppers ahead are just slightly marginal and the wind is from the south ahead of the trough, drawing marginally less cold air  into southernmost parts.  The back edge is likely to bring snow but it’s what happens first and how quickly the rain/sleet changes.  As always in these situations height and precipitation intensity are likely to be key, plus simple random local variation.

I’m expecting Thursday’s frontal trough to keep being shifted south and for it to end up being largely a non-event north of the M4.  Already signs of the trough being less active.

Wouldn't surprise me if we got no lying snow out of this. But I do have some hopes pinned on showery activity tonight. Some of those showers have the potential to be beefy and, if we can get a streamer set-up going, we could get a few cm's. Although I appreciate snow would be less likely over coastal fringes near you.

Thanks Gandalf, makes sense and certainly a situation that means forecasters are on a hiding to nothing!

Raining here in Worcestershire as I expected.

Unless we get something later this week, January 2019 will go down as yet another complete fail.

Normally we expect UK Januaries to be notable winter failures - usually rubbish and the worst winter month for any cold and snow prospects. The problem this winter is that all those teleconnections and strat people, plus longer range outlook from the UKMO - all led us to expect some wintery Nirvana.

Ah, somebody's paying attention!

Updated:

10:49 on Tue 29 Jan 2019 GMT

Reason for update

The start time of the warning has been brought forward to cater for some snowfall during peak travel times Tuesday evening and the expected amounts of snow have been reduced.

Today's system has failed to intensify so far but it may still do so as it engages with the colder air in the East.

Not expecting anywhere near as much as last Tuesday but always a chance.

Thursday through to Saturday looks far more interesting for these parts.

Warnings now out for Thursday covering most of England and Wales: https://www.metoffice.gov.uk/public/weather/warnings#?date=2019-01-31

Rain and snow is expected to move in from the southwest, moving across England and Wales through Thursday into Friday. This is likely to fall as heavy rain at first across the far southwest of England, but as it meets the cold air established over the rest of the country snow becomes more likely. There is a chance of 2-5cm of snow for some places, timings are currently uncertain. 10cm is possible in places, though there is uncertainty at this stage on where is most likely to see the greater snowfall accumulations. Overnight Thursday into early Friday ice may also become a hazard on any untreated surfaces as temperatures fall below freezing.

The jam rolls ever onwards into the brave new tomorrow. 

It's one of those days where the rainfall radar is being optimistic too.

According to the radar it should be raining over this part of Dorset but if it is, it must be evaporating before it reaches the surface because it's dry on the ground as I type this. 

Yes as anticipated this morning the MetO automated forecast for my location has downgraded my rain-to-snow event to a rain-to-sleet event.

Arpege doesn't fill me with hope for here, either for this afternoon or tonight. Icon a little better (although it's got that curious but frequently observed area of rain over the south-west of NW England (covering Merseyside, north Cheshire, western Greater Manchester, south Lancs) but snow to the north, south and east (and it's not an altitude thing, either)

Icon gives more hope, but last week it overplayed the PPN rates and snow chances, so I've got my doubts about it

Hirlam is much like Icon

Reckon this will turn mostly to snow as it moves SE. This applies especially to around 6pm onwards.

What's that based on? It seems likely to be close but no cigar to me... at least in the SE, but I'm probably looking at the wrong factors. I struggle to find the high res data sources for these sorts of things.

2m temps are about 6C in London, 4C outside

850 temps ahead of the band are about -4c with DPs at about 1C by 6pm

The band appears to be arriving slightly earlier than forecast.

Balancing that, the rear edge will probably be nicely undercut, and the precipitation rates seems good.

Using the metoffice snowdar (see their twitter) its actually going roughly on intensity lines. So snow is falling to sea level but only when precip is intense. Its encouraging because the actual snowlevel must be really quite low already so it doesn't need to get much colder for all of it to turn to snow.

If I were to redo the snow risk map I'd increase the snow risk for parts of the SE.

Plenty of reports coming in of rain turning to snow across NW England within the past half an hour.

Nothing substantial at all, and could simply be related to the precipitation intensity, but "the turn" is taking place even in towns and low lying cities. 

Could bode fairly well to those further south and east.

Interesting you say that Q  and I hope your right because I just read the updated met warning and it reads as follows:-

Updated:

10:49 on Tue 29 Jan 2019 GMT

Reason for update

The start time of the warning has been brought forward to cater for some snowfall during peak travel times Tuesday evening and the expected amounts of snow have been reduced.

EDIT: Sorry didn't realise it had already been posted above.

As for Thursday's PPN and the northern extent:

Arpege - Wrexham to Stoke to Nottingham to Grantham

GFS - Lancaster to York

Icon - initially Chester to Sheffield to Lincoln, but then pivots to spread snow to Manchester and Yorkshire

I need the GFS solution to be correct!!

Again I must be looking at the wrong place. I see a fairly accurate representation of the hills. Unsurprisingly looks like altitude is key in the west at least.