TEITS

Very much doubt that. According to the chart below many will see temps around or just above freezing. http://www.wetterzentrale.de/pics/Rmgfs814.gif Those who do see snowfall tonight are likely to keep it for a few days. The mistake many make when referring to thawing snow is to look at the predicted 2m temps. However dewpoints make a massive difference to the rate of thawing snow and these are predicted to be around -4C. The short daylight hrs will also help. As for tonight and im just waiting to see what happens rather than looking at the models. I shall tell a little story as to why this is the case. Many years ago a marginal snow event was forecast for my area but sadly only heavy rain fell during the entire period. I went to bed gutted that night and the following day traveled into the city centre. On my journey I noticed some cars driving around with a foot of snow on the roofs of these cars. I learn't that just 5 miles to the E of the city, heavy snow fell. Now my conclusion to this was although Peterborough isn't big enough to create a heat urban affect like London for example, the temp difference in the city of Peterborough was enough to keep this as rain whilst 5 miles E into the countryside was just cold enough for the rain to turn to snow. This type of localised snowfall could well occur tonight!

Another quick one from me before I retire to bed with a box of rennie! I wish to comment on whether less data than normal can affect the model output. The answer is yes and I am astonished some people dismiss this. Let me tell you why the model runs in F.I vary significantly. This is caused by the chaos theory because slight changes in the early part of the run increase and as the run progresses these changes become greater. You will notice this in every run because if you notice at say +24 the runs are nearly identical but this isn't the case at +168 and even more so at +240. My point is at this time of year I prefer to compare the model runs after xmas to what they were showing before xmas. Let me also say that the same people who dismiss this lack of data also tell you to compare the 12Z with the previous days 12Z. This to me is an incredible contradiction!

Merry Christmas to you all. I would comment on the models but as its xmas day I cannot be bothered and im more interested in stuffing my face and enjoying the day. Also I have learn't to take very little notice of the models during this period. Some dispute this but in my opinion they are ignoring the simple basics of how computer modelling works. Right back to the Ferrero Rocher!

Another quickie from me with my latest thoughts on how the model output will progress over the festive period and beyond. For starters we have already seen alot of changes in the model output and the current trend i.e HP to our NE is only going to complicate matters. Remember an E,ly via a Scandi HP causes more drama than an episode of Eastenders at xmas! Personally I feel the period between after xmas into the New year will bring surface cold rather than bitter E,lys and snowfall. However like I said last night this HP will remain in situ but eventually we shall see the classic synoptic set up which is undercutting of Atlantic LPs and the block migrating towards Greenland. Dates to keep an eye on! 28th Dec- beginning of Jan - Surface cold. 1st week jan into 2nd week colder E,lys as the high begins to move NW. 2nd week jan onwards bitter N/NE,lys. Merry Xmas to you all.

Just as quickie from me. Delighted with the trend although this does not surprise me as the hints of an E,ly were there a few days ago. The most pleasing aspect is it could become even better. What I mean by this is the high pressure could be centred further N resulting in a colder, more prolonged cold spell than currently modelled. Even further ahead and the classic synoptic pattern of the block remaining in situ with the Atlantic undercutting the block before pressure begins to rise towards Greenland. Probably getting ahead of myself but as i've said for a few days now it will turn colder towards the end of the year into the New Year.

Well it now appears the low pressure will take a more S,ly track rather than an E,ly track. However whether this tracks SSE, SE, ESE is still uncertain and the exit point of the low could range from SW England or towards the SE into Belgium/Holland. Beyond this the models suggest high pressure will become centred over the UK. This would bring settled, frosty weather but unlikely to bring any prolonged cold as a Scandi HP now looks doubtful. Overall I would be happy with 1cm of lying snow followed by a few frosts after last winter!

You have to laugh! http://www.wetterzentrale.de/pics/Rpgfs2401.gif Never in all my years of model watching have I seen wildly different synoptic patterns being displayed by the models for this timeframe. We have seen everything but the kitchen sink varying from E,lys via Scandi HP, SW,lys from Jamaica, N,lys from the Arctic. I am awaiting a SE,ly from Australia!

Very good chart for those N of disturbance crossing the UK. A difference of 12C from S England to Scotland. Still like you say it will change at 4pm to probably a S,ly originating from S Africa! I will add to members ignore some of the ensembles charts posted, NAO charts etc. These are all coming from the same models and are worthless when the operationals are so different between runs.

Here is a good example of why it is futile making any predictions at the moment. The 06Z GFS at +192 has low pressure at the S tip of Greenland. http://www.wetterzentrale.de/pics/Rtavn1921.gif GFSP has 1030mb high pressure at +192. http://www.wetterzentrale.de/pics/Rpgfs1921.gif Im off to inspect my seaweed and count the number of seagulls outside because these are far more useful than looking at the models. Having said this my instincts continue to tell me that after xmas into the New year it will become even colder from the E.

I have to say with regards to the possible storm, I am more concerned with the wind strength than snowfall. At the moment it appears most of the precip would of cleared the UK by the time it is cold enough for snow. Also the models hints at a NE,ly and the warming effects of the N Sea would reduce the chance of snowfall even further for E areas. Obviously the track will make a difference but at this stage only higher ground appears at risk. Moving further on and I cannot see mild returning beyond the storm. I said there is a chance of it turning much colder from the E towards the New year and I continue to believe this. I don't often predict an E,ly

Forget about snow, cold spells as im now more concerned about severe gales and more importantly storm surge for those living on the N Norfolk coast. Now the UKMO is predicting such a storm it must be taken more seriously especially as the next frame of the UKMO would see low pressure move SE and deepen further! As for the potential cold spell and the ECM/GFSP are nowhere near as good as yesterdays 12Zs for the longer term. However its futile to discuss the longer term when the shorter term remains unresolved.

Brief summary from me and the key points I shall highlight below. 1. Christmas day is unlikely to be white for most so I would forget about the models changing towards a white xmas. The day appears mostly settled with slightly below average temps. 2. Boxing day could start very chilly but turning milder from the W but still below average in the E. 3. A return to cold or very cold is likely and the uncertainty for me isn't will it turn colder but how long will the spell of milder SW,lys last. As you can see from the 18Z GFSP it turns cold much sooner than the ECM. 4. The combination of the GFSP & ECM ensembles suggest to me it will turn even colder in the New year but from the E rather than the N. Finally the comments about the ECM backtracking are rubbish as the Ops have been largely consistent. This is why my outlook hasn't really changed!

May I suggest mate that the ECM 12Z is exactly the scenario I described since yesterday morning. Just to summarize again, cold Xmas day, Boxing Day, mild SW,lys for 27th,28th, cold returning 28th, 29th. The ECM OP might be an outlier yet again for the 27th,28th but I believe its on the right track.

The GFS 06Z isn't reading that script! http://modeles.meteociel.fr/modeles/gfs/runs/2014122006/gfsnh-0-348.png?6 960mb low pressure over Iceland and a 1030mb pressure over the Azores! As someone else mentioned I think I shall stick with the Met O for longer term guidance.

Normally I would agree with you but when the ECM operational is constantly an outlier and is followed by the control run then I tend to take less notice of the ensembles.

Still think my post from yesterday morning is the most likely outlook and pretty much reflects this mornings ECM. However a couple of things I am unsure of is how long will the spell of SW,lys last and will a severe storm develop i.e GFS 0Z. At the moment I would say the mild SW,lys will last for around 2-3 days and then the cold returns around the 29th. I am more concerned with the storm that will blow E Anglia away because the GEFS control also develops this. http://modeles.meteociel.fr/modeles/gens/run/gens-0-1-180.png?0 So I continue with the same outlook but im not totally dismissing the storm that the GFS predicts!

Morning mate. The reason the outlook is clearer to me is because don't forget my forecasting style is based on instinct. My approach is to look at the output and figure out what is most likely to occur and where the models might be wrong. The events I detailed in my previous post are very likely to occur in my opinion especially the return of the milder, unsettled W,lys. However I am very confident it will turn much colder towards the end of the year into the New year.

The outlook this morning is much clearer to me and my observations are based on all the output. So Xmas day a relatively weak N,ly across the UK. During Boxing day a ridge of HP from the S will bring settled conditions but still cold. The 27th/28th/29th will see the return of milder, unsettled W,lys as the HP sinks S and LP becomes centered towards the NW of the UK. Beyond into the New Year a much colder spell could develop.

I think im going to sit on the fence because lets be honest we have seen deep LPs bringing blizzards, cold N,lys and mild S,lys in the past 24hrs! Just looking at the 12Z GEFS mean and it could potentially be 10C warmer if the trend continues. I will add im not as confident as others suggesting the GFS will backtrack to the ECM, because I never dismiss an output just because it isn't what I wish to see. Whilst the ECM mean is impressive I am also concerned how the operational is always milder than the mean. At the moment im not convinced any output is correct and we shall have to wait and see what develops tomorrow.

Morning matey. To save time I just copy and paste my posts GEFS SLP mean for Iceland is now nearly 1020mb which is an increase of 20mb compared to last time I checked. Also worth noting is the GFS continues to be colder than the mean. In my experience when this occurs the rest of the ensembles follow. http://max.nwstatic.co.uk/ensimages/ens.20141218/00/prmslReyjavic.png http://max.nwstatic.co.uk/ensimages/ens.20141218/00/t850Cambridgeshire.png

Considering how uncertain the outlook is no model output should be ignored. The most likely outlook based on the models is cold on Xmas day but at this stage snowfall is unlikely to be widespread with higher elevations exposed to a NW,ly being more likely to see a white Xmas. After Xmas remaining cold but the risk of snow increases due to the proximity of low pressure across the UK and high pressure to our W/NW continuing to bring a N/NW/NE,ly flow. Finally I mentioned this yesterday but in my opinion towards New year the N,ly flow is going to be replaced by an E,ly!

Indeed and to be honest I could not see a pattern change at all until a particular GFS run a few days ago caught my attention. If the current output verifies then yourself, Steve M, Tamara will fully deserve the praise that you will recieve.

Well im delighted my cat woke me up early because the output is very pleasing. When seeking a cold spell we know this far out the models aren't going to be 100% accurate so its all about momentum and which way the models are trending. There is no doubt over the past 48 hrs the momentum is moving towards a cold spell with a few highlights to keep in mind which I shall list below. 1. Real potential for a nasty deep Lp system to form and the potential for this to develop into a real blizzard. The track and the synoptics prior to this are still in doubt. The reason I highlight this isn't just because of the GFSP or ECM because this has been hinted at in previous runs. 2. Chance that the intial N,ly could turn into an E,ly as hinted at by the GEM. http://modeles.meteociel.fr/modeles/gem/runs/2014121700/gem-0-240.png?00

Well despite some saying, a few days ago, there was no chance of a pattern change in the 10-15 day forecast period, the models are certainly trending towards a change. I mentioned a few days ago that a mega cold spell could occur after xmas and I must confess after I made that post I thought using the word "mega" was OTT. However looking at some of the output today especially the GFS P maybe I was correct. Worth mentioning that when it comes to blocking towards Greenland developing then in my experience the GFS is the daddy. Who can forget the excellent performance of this model prior to the 2009, 2010 cold spells and lets not forget the way the ECM was often very poor. I still remember the arguments with Ian Brown when the chart below was being modelled because the ECM intially had the blocking and Lp much farther W resulting in the UK having a very mild SW,ly! http://www.wetterzentrale.de/pics/archive/ra/2010/Rrea00120101218.gif Reason for editing is due to a spelling mistake because I cannot spell lol.

Whilst it seems some have given up on a pattern change, I remain confident this will occur shortly after Xmas. http://www.wetterzentrale.de/pics/Rtavn2761.gif Even a white xmas for some cannot be ruled out yet although I believe the real cold will occur shortly after xmas. http://max.nwstatic.co.uk/ensimages/ens.20141215/00/t850Aberdeenshire.png