WhiteFox

Must be a bit of a temperature gradient. Showing 2.6 here in Three Mile Cross (just south of Reading). Think you mentioned you're about 20 miles south of Reading?

Temperature 2.8 dp -1. As @kold weathersays marginality is not the issue, but PPN! Looking hopeful...

Temperature up to 0.9 here own with a dewpoint of -1. Pressure falling as system approaches, now down to 989.1. High cloud building in from west turning sunshine hazy

You're right. But they will almost certainly have a matrix of probability which defines when and where warnings should be placed. Clearly the levels of uncertainty were high as we saw across all runs over the past few days, so I suspect the ensemble scatter was giving enough indication for possible snow further north for the yellow warning to be activated further north. I'm sure that ICON ensembles would also have had some runs further north too. But, yes, if it transpires as it currently looks then the ICON operational run fared better than the UKMO operational in terms of PPN. We don't know what mogreps was showing though, or the ensembles for that model so again there must have been a number of ensemble runs showing PPN further north. I'm guessing the scatter must have been immense judging by what we were able to see on publicly available models!

My first proper car was a T reg Corsa. It was a great little run around car for snow chasing!

We have no idea what ensembles were showing on met office or ICON so it's difficult to know really.

Ha ha! Was sitting in traffic. Although the car in front pulled away and I hadn't noticed so the car behind was getting impatient. Desnt he know there are more important things in life?

The yellow warning is really there to catch the possibilities of snow at a longer range; you can tell by the level of certainty they apply. Once they get closer to the event and certainty increases they will remove yellow warnings from some areas and place amber warnings over smaller areas where likelihood is higher. Anyway, beautiful sunrise over the River Loddon this morning near Shinfield. Managed to get a quick snap from the car whilst sitting in traffic. Bit of mist over the fields.

I haven't looked in depth yet this morning. But, it depends on temperatures through the vertical plane of the airmass. Perhaps it shows a slightly different wind direction somewhere between the surface layer and the 850 level which creates a 'nose' of warm air coming from a more southerly direction from the sea? Who knows! Haven't seen any downgrade on met office app for here: it's been varying between 1 and 2 flakes from about 20z to 1z for the past 24 hours. Temperature is -5.3 dewpoint -6 here in Reading, so coldest night of winter so far.

To be fair to the ECM, it got the 500 heights pretty close in the grand scheme of things. It largely picked up the general flow, but was slightly out with the little wave over Europe which has made a big difference with the track of the low at the local scale. Goes to show that the 500mb charts were fairly reliable 7 days out in this case.

Have to say that I totally agree with xmetman's rant in the comments. It really is ridiculous that a state broadcaster is forced to use data from somewhere other than a highly respected government agency which has developed a model that is geared towards the UK'S position. They should be trumpeting the quality of the met office, not forcing them to save a few quid..

I have a feeling it may be good for West Berkshire, but at the moment I'm not expecting too much here in Reading. The output seems to indicate around 1-3cm which is better than nothing I guess! Still time for that to change, but at the moment PPN looks less intense the further north and east you are with the possible exception of the wave of increased vorticity nearer to the south coast highlighted by @kold weatherearlier. Of course, even that is subject to variation!

They must have access to a high resultion model. I suppose it depends how much cost-cutting went on when they negotiated the last contract; hard to picture the BBC forecasters scouring the free high resolution models the same as we do! Wouldn't be surprised though....

Not sure I really buy the ECM totals. Mogreps must be showing something different and I'd take their amounts over the lower resolution ECM at this stage. However, ECM maybe closer in terms of vorticity, so maybe further south than met office forecast, but then we have no idea of verification stats on PPN for Mogreps v ECM at this range! Still lots of possibilities.

I think your estimates are probably spot on based on what the various models are saying this evening. Be interesting to see the ECM 18z charts later to see if there is any more movement.

Meanwhile, temperature wise here south of Reading we have 2.7 with a dewpoint of 0. We have some cloud cover so that is keeping the temperature a bit higher.

I wouldn't trust the GFS PPN charts over higher resolution models or the ECM PPN charts. ECM is far less liberal with amounts and is further south. The real deal would be mogreps of course, but none of us have access to that!

It's all varying so much across the outputs. The only thing we know for now is that it the forecast extent of the front has shifted south over the past few days. Most runs have the heaviest falls further west, with lower amounts as you head east. As for the different models they have so much variety I don't think we'll really know until we get a look at the forecast vorticity and PPN rates tomorrow. Really a case of nowcasting!

No, definitely all time low records. I was reading the NWS discussion for IL and MN earlier. The max could be daily record though. Addit: Here "all ingredients in place for an extremely and likely record cold temperature night. Continue forecast lows in the -20s and -30s, with the coldest values in north central Illinois and exposed, favored areas. Rockford will likely drop to colder than what they are this morning, and so confidence in a record all-time low is increasing there. Chicago looks to be very close to reaching their record and have undercut guidance slightly with a low right at all-time record level."

I think potential all time record low minima and Maxima probably count as once in a generation! Just as interesting is that parts of Minnesota could be looking at record lows Wednesday/Thursday and record highs at the weekend. Now that's a rollercoaster!

Yes, that is the case sadly! The GFS and ICON (possibly the UKMO as well) seem to be sniffing around the idea of further trough disruption over the UK. It seems to me that with the building Siberian high and a lack of momentum for systems coming from the west we are at the crossroads. The ECM has another take on the 0z with the draining of the Canadian vortex towards the end of the run. If we were to see continued troughs dropping south over the UK as per the ICON/GFS/UKMO (possibly) with the draining of the vortex then it *could* imply heights building in to the north east. Whether this came from a trigger low dropping south and heights building in from the east or the Azores high ridging NE and linking up to Scandinavia who knows, but it would open the door for something a little more interesting than marginal snow events from the Atlantic running into the coldish trough over us as we are currently seeing. Just a few thoughts as we see another hint that the trend towards mild may not be as mild or long lasting as was suggested a couple of days ago...

Thought I'd stick this here as it will be buried by moans and sniping in the other thread as the 18z rolls out. Based on 18z icon and 168 UKMO charts, so looking for some other thoughts! Seems to have been a running theme so far. Models keen to push systems through the UK taking us into a milder theme, but as we get closer to the time they start to show troughing down through the UK to the south. It's a bit of a stalemate situation, especially with the Siberian high now out to the east preventing any further inroads. As we have seen, it's not a lot of good for us if it's prolonged snow you are looking for as the trough is just too far east leaving us in a cold, yet not cold enough, NNW to NW flow. The situation almost looks like a phase 6 MJO setup on our side. If the Canadian vortex ever decides to take a hike west or towards Siberia then we could see some action; towards Siberia would be good as it would drive very cold air down the eastern side of the high pressure as the latter pushed west. On the other hand, it may be a case of waiting for it to wane enough as it naturally weakens into February. Finally, we could be left with the stalemate for a while yet. I thought it looked like the UKMO 166 charts showed some signs of disruption so perhaps the cold but not cold enough pattern could stick for a while yet. We shall see.

Seems to have been a running theme so far. Models keen to push systems through the UK taking us into a milder theme, but as we get closer to the time they start to show troughing down through the UK to the south. It's a bit of a stalemate situation, especially with the Siberian high now out to the east preventing any further inroads. As we have seen, it's not a lot of good for us if it's prolonged snow you are looking for as the trough is just too far east leaving us in a cold, yet not cold enough, NNW to NW flow. The situation almost looks like a phase 6 MJO setup on our side. If the Canadian vortex ever decides to take a hike west or towards Siberia then we could see some action; towards Siberia would be good as it would drive very cold air down the eastern side of the high pressure as the latter pushed west. On the other hand, it may be a case of waiting for it to wane enough as it naturally weakens into February. Finally, we could be left with the stalemate for a while yet. I thought it looked like the UKMO 166 charts showed some signs of disruption so perhaps the cold but not cold enough pattern could stick for a while yet. We shall see.

It's hard to tell on that chart. The 144 had a wedge (yes, I know!) of high pressure just to the east of the low with the system being neutrally tilted. It's a shame we can't see further north and east, because it could be about to disrupt judging by the shape. Also note the kinky isobars on the east of the Azores high.

Steady light snow. Temperature 1.3 dewpoint-1. No accumulation as ground is too wet and snow too light.