Geordiesnow

Out of interest where abouts in the area? I'm in the worst part in terms of snow right near the town, I've seen instances in the marginal events of barely any evidence of snow on the ground here yet as you head a mile or so inland, its a different story. Of course this is in marginal no wind events. I remember the event 2 years back I think it was where we had heavy snow but was struggling to lay and it was virtually wet ground for the most part yet as you got closer to Lancaster it was gradually more notable and in Lancaster itself there was a decent covering for their standards! That was with a easterly flow and uppers of - 6ish so it does have to take something special for snow here hence me doubts about the weekend 'potential'.

Has the classic of too marginal for low ground and especially near the coast but good at any real height, if only the uppers were that touch colder! Either way looks increasingly likely any flow from the sea is going to be brief as an light easterly should come into play. As for tonight, north Cumbria may have a small chance of seeing a dusting and maybe a light covering locally, just depends how that front behaves. It may prevent much of a frost though because of the increased cloud cover.

Yep the Vale of cloud to the north of Scotland is that front that is not expected to produce, the PPN falling in Scotland is not from that cloud but from the shower clouds underneath it, you can actually see the shower clouds underneath on the SAT24 image which tells you how weak that front is. The front may pep up as it heads southwards if it develop a wave which the models slightly hinted at but the possibility of it happening is quite low but expect the unexpected!

In fairness these might be better organised as there be over open water for alot longer and little wind to move them around, do need some sort of westerly flow but not too strong. I think the ECM would give the PPN but not much snow as the flow could be too strong and/or the air is not cold enough. GFS looks better but the window of opportunity looks small before the easterly flow kicks in. If anything does happen I think a line from Fleetwood down to Liverpool bay looks most favoured but it's all down to radar watching.

If there is one advantage of being in a coastal area with not much winds, it's any PPN that makes it to land could well be persistent. Will not rule out surprises for some people that is for sure.

Can't wait for the Irish sea popcorn showers!! In all seriousness I had always like to of experience an set up where you got a light flow from the sea at cloud height but with decent cold air and if possible little or off shore winds would be interesting too see what would happen. Maybe this weekend is the closest I would get too see that albeit the air at Upper heights do look a tad too warm for me.

I think another factor is the very high thicknesses for a northerly, the meteociel charts really flatters to deceive when it comes to thicknesses. For me a unstable northerly and especially an easterly has to to have thicknesses which are showing dark blues and even light purple if possible in the wetterzentrale charts, too much pale blues unfortunately. The high thicknesses I also believe leads to higher 500 millibar temps and therefore higher 850 temperatures and no doubt the warmer than normal SSTS are not helpful in that matter. Its definately not as simple as cold air over warm seas equals lots of moisture, coastal areas can get away with it because the sea track is so large but I suspect if these conditions happened in an easterly, we could of seen stratus cumulus cloud instead. Nevertheless its a decent start to winter, cold, frosty and a threat of snow for some.

It's not the 'BBC', it's the ECM model, I think something is likely to develop, where and what intensity and timings are all subject to change. Its not worth pulling hairs out about it, if it happens then it happens, if it doesn't then life goes on! Barely been in the model thread since the northerly was nailed, I thought the UKMO was a beaut of a run with a channel low and large areas in the south would get a right good old dumping but all the runs are not all that dissimilar really, it's just the variation and its impacts for the UK that is quite variable on the models. Either way, the cold looks more or less locked in until the 13th before there is indications it could turn milder but that is still a long way off.

As I said you can look at any charts and graphs all we like but it's the radar which is what counts at the end of the day, it did feel a little hard to believe you can have kinks in the isobars but nothing showing up for it. Kinks usually mean more instability and I assume its the much talked about cold front. If the isobars were stright it would of went down north to south and likely to weaken as it does so.

Where does it come from? Looking at the ECM PPN chart it seems to come from the west of Scotland yet I thought if anything developed it will be from due north. At least something is popping up again but at the end of the day, it's that live rainfall radar which is what counts.

Which are all set to drop hence the lower temperatures, should be some real sharp frosts during this period.

Yeah by magic it's disappeared without trace, that's ashame, still would not fully rule anything out but the most likely white we are likely too see will be frosty weather which I will take over Atlantic weather any day! Clearly it was there for a reason and I do recall when living in the NE once a weak front came in from the west(albeit) and it was forecast to give a little bit of patch rain yet a wave developed and we ended up with couple of hours of heavy snow instead, this was back in February 2012, memorable event.

The cold is starting getting mixed out unfortunately as we are getting nearer the time with the - 8hpa for example barely making its presence felt across our region nevermind further south. Must say though the 18Z was a surprise mind in terms of a potential easterly and winds seemingly remaining off shore but if we see a NW'ly instead then uppers of - 6 won't be cold enough for most low levels. Thursdays front is interesting, if there is a kink in the isobars which is kinda what the GFS is showing it can enhance the PPN, the colder air is struggling to undercut it mind but timing could be favourable(e.g seemingly looks like its going to hit overnight into the morning). If the GFS is wrong then the front may still be there but will weaken as it heads southwards, will be interesting one to watch, one I can easily seeing the forecasts being wrong on.

I'm not worried about PPN charts, I actually do find the GFS is probably best at picking up features whereas the UKMO is usually more clean in its set ups, whether that's down to the model I don't know? What I will say though, Thursdays potential front aside, I hope it is bone dry because as soon as those winds veer NW'ly then that's it, snow chances greatly reduce as we pick up slightly less cold air - 6 uppers with above average sea temperatures for our region especially are just not cold enough for snow except for higher ground. We really needed a proper - 10hpa Northerly to reduce the affects of the air mixing out but the initial northerly in terms of how far south the - 8hpa gets is getting more and more diluted with every run(even the GFS is picking up a pocket of - 4hpa in the North East for example! I have to remind meself this is December and not November. Comparisons to 1981 in that model thread are just laughable.

This upcoming spell could well prove that unfortunately, we are now seeing from more and more GFS runs the - 8 hpa struggling to make its presence felt, I mean its no magic number but its showing the cold is getting diluted because the current SSTS in the northern hemisphere are way above average. Any flow off the sea will mean uppers of - 6 won't be good enough for most areas on low ground. The only snow risk I can see from this set up is from the front heading southwards, how much PPN will be on our side of the pennines is debatable and how much of it will be of snow is also questionable. High ground should have no issues really. Hopefully the front could potentially 'wave' so it sticks around for longer and the coldest air undercuts it.

It's the warm Autumn's in my view is more damaging along with the general warming of our climate. One thing I have noticed during this period of model watching is how high the thicknesses are(the meteociel charts really do flatter to deceive, much prefer wetterzentrale for thicknesses values), light blues at best, the real deep convective northerlies are deep dark blues. Also how quickly the deep cold gets mixed out in the Norwegian sea is incredible, we got a pool of around - 25 to - 28 degrees uppers to the west of Svalbatd and by the time it reaches Iceland its - 15 or so which is incredible too see. No doubt part of it will be meteological but the warm SSTs will surely be playing a part in all this.

Just looked at the uppers for the current easterly and that has been watered down now(some forecasts had - 6 uppers but now its a very patchy - 4 at best) , quite simply the SSTS around the UK are too warm. Now the northerly is developing huge 'mild' sectors within it, would not surprise me at all if the - 8hpa fails to end up over us although even if it does, its looking dry at that point. Kinda sad too see a northerly in December more or less straight from the Arctic is struggling to maintain its strength, can't help but feel a similar set up in the 80s would have no issue with mixing of the upper temperatures.

I got admit, I'm slightly less confident of snowfall, we seem to of lost the slack low pressure set up to an extent and pick up a NW'ly with winds off a warm Irish sea means the uppers get mixed out more, yesterdays runs had more off shore winds with mini lows spiraling around. The front coming down from the North on during overnight into Wednesday smacks of a rain turning to snow event so some areas may see some evidence of snowfall either on the ground or if your awake and catch it. I'm talking here at lower levels in the NW any modest elevation areas(like over 100M ASL) should see snow aslong as the PPN is there.

Yep that's the fear unfortunately. And the problem comes with the over ridging of the high into Greenland and that occurrs at 72 to 96 hours, at that range I just can't see how there is going to be any significant changes to the downstream pattern of having the northerly further eastwards as per yesterday runs. I think it's almost time to accept it looks more likely its going to be a cold snap rather than spell and that if we are not careful, snow may barely be a feature. Still let's see what the morning runs bring but if I'm living on the east coast especially I be bitterly dissapointed with this afternoon trends.

Should of posted the two charts on the same day so you don't (probably unintentionally) over exaggerate the trend. Either way, all today's runs have done is shift where the risk of snowfall is, less in the east and more chance in the west, could still change again. The issue with the current trend is that the risk of mixing out the coldest uppers will mean less of a snow risk even for Western areas so I can understand the dissapointment in some posts.

I don't think it's to do that, it's more to do with the Greenland ridge being too good so it's pulling things more northwestwards generally speaking. If anything we need too maybe see some PV heading into Greenland to stop it linking up into the Arctic itself.

Can totally understand the slightly deflated mood, its small margins reletively speaking but it makes some difference going forward. Still time for adjustments but the ridging into Greenland starts earlier at around 96 or so hours so not alot of time until its fully nailed. Would be typical if things do go too far west. However despite all that at the moment, some places will see snow showers and it will still be cold, especially at night with frosty weather around and the situation upstream is still promising. I probably won't mind things going slightly West if the initial cold blast was stronger so it takes more to mix the cold out somewhat which is what is likely to happen if the main instability northerly flow misses us.

It takes a while to get the significant cold in(uppers of -8) and if its too ENE'ly early on then the warm north sea will come into play. Feels likes it's "jam tomorrow" type of stuff on this GFS run.

Just because something is an outlier, it does not mean it's wrong so no... It should not be binned. There is an element of risk of getting the northerly in quicker however it could be high reward but only if the cold air gets far enough south and has enough depth to it! The ECM 00Z op seems fairly simple, it pulls the set up too far north and west, still a very good run mind but because of that it does open the door to milder air in the south, high reward potentially if your in the right spot but dissapointment for others. Pleasing UKMO after yesterday's run but today's GFS is a dissapointment and I still have that feeling there's a chance the northey could end up being too weak to bring significant cold. GFS run has a feel your rewards will come if your patient enough but it never will. Getting not too far off the stage where even the details to an extent will be nailed on, I think the northerly is nailed but how cold will it be and what happens after if the trough does end up over the UK.

Very good 18Z slightly better amplification and a cleaner northerly too boot. Sure if your nit picking on details you want it further south and east in the 120 to 144 hour range so its a slightly quicker and smoother transition to the colder air but no complaints from me. Hopefully the UKMO will come back on board with its ridge into Greenland in the morning.