A mixed bag amongst the 18z GEFS but some cold and snowy runs definitely feature. 

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Mean chart for Christmas Eve.

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Last post from me tonight. 

Definitely the chance of a white Christmas for northern parts of the UK - quite a few of the GEFS show a cold northerly. The mean for Christmas Day shows the airmass boundary to be around the M62, so could end up being much further north , or indeed south of that! 

https://www.wetterzentrale.de/maps/GFSAVGEU18_186_2.png 

https://www.wetterzentrale.de/maps/GFSPANELEU18_186_1.png 


 

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Scottish ski centers will be very happy. 

https://www.meteociel.fr/cartes_obs/gens_display.php?x=&y=&run=18&lat=56.963562753&lon=-3.67924528302&runpara=0&type=10&ext=0 

Further south (imby) Still hold out hope that a brief northerly coincides with Christmas day. 
Over all the man story is much milder and wetter in  the south. With winter holding on in parts of the north with a risk of snow at times. 

indeed, a grim outlook for the majority of the UK population. No dressing it up. 

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Based solely on the GFS 12z ensembles for London it is clear that it will be mild until Christmas. But what the 12z shows thereafter is that it is unlikely to be average. There is about a 50/50 split between very mild and very cold. Rarely will you see an ensemble with so few runs actually around the mean. Almost none. It is a hot /cold chart and they don't have a scoobie doo which it will be right now! 

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https://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=186&mode=26&carte=3&proba=1&ext=0 

Christmas day snow risk. 

Dose anyone know if there is data for each day that has had snow?? Whould be interesting to see what day is the most snowy and what is the least. Ive never seen snowfall yet on Christmas day. 

Both GFS and GEM nudging the cold that little bit further south this morning.  Its looking like a very cold and snowy spell for Scotland between 22nd the 30th. GEFS look much  better for the south from 26th this morning. 

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ECM once again the Christmas Grinch this morning. 
 

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GEFS definitely signaling a festive period cold spell for the South now.  Colder and more prolonged the further north you go.




 

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As Bruce Forsyth used to say, GEMs my favourite 😊

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GEFS 2m temperatures are more instructive this morning. There's quite a strong signal for a cold period post Xmas from mid latitude blocking.

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GFS 00z suggesting that even parts of the south, including London, could record a white Christmas. (One flake of snow observed falling at the location in the 24 hours of December 25th.)

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Overall the pattern on today’s output is similar to yesterday’s although probably marginally cooler overall.

Finely balanced with lots of uncertainty with cold air to the north and mild to the south with the UK somewhat in the middle.

The 00z ensemble data (GFS and ECM)  for here indicate another spell of below average temperatures is probable after the next few days.At a glance I think the data further south show fewer mild and more cool options than before.

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WX temp charts shows a general retreat of cold weather E-wards in week 1,  and a diminution in severity over E Europe; but it bulks up again in week 2 with lower temps in that region and a tongue of colder air across to the Alps. Britain goes from mild in week 1 to quite cold in week2, with the Hihlands holding on to 0C throughout. Lots of rain on the Atlantic and as far E as Germany in week 1, fragmenting in week2 with Britain mainly dry.

FAX shows a first LP W of Scotland projecting a mas s of fronts across Britain, mainly in the S, until Tues; a brief let-up with troughs, then a sceond LP W of Ireland does a repeat on Thu but with some colder air reaching Shetland.

GFS Op : LP W of NI on Mon with SW-lies for all. This moves NE leaving another LP in its wake, 975mb Fri 23rd on the Atlantic.  This links to Lp over Scandi but then fills, allowing N-lies to reach Scotland on Christmas Day, with England under a col. The N-lies slide off the the E while pressure rises over Britain, 1035mb Scotland  Wed 28th moving SE and becoming part of a ridge from Spain to Norway with SW-lies on its western flank.

ECM : brings the second LP closer, to Wales 990mb Sat 24th and develops it N-wards 980mb Orkney Wed 28th with greater penetration by N-lies. Quite a difference from GFS

GEFS : in the S a couple of mild interludes Mon 19th and Fri 23rd, then a cold spell around Wed 28th (esp marked in op & control), back to norm with the usual scatter amongst ens members for the New Year. Rain for the first week, gradually less appearing in various ens members after that.  Similar pattern for temps in N, rain/snow concentrated a few days later with a good chance of a white Christmas even on low ground

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Jet remains amplified on most outputs, with GFS showing this remaining so for 10 days. Slight indication of a more concentrated polar vortex by day 10 in FI but the amplified jet helps to keep it fragmented until then - which provides the ingredients for blocking and cold spells to develop so long as we are on the right side of the jet loops. Gfs finished with an alarmingly summer like jet loop, but probably
wont verify.

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Snow chances in Midlands increase and hope models keep pushing south trending slowly not fast otherwise France get it.  Your other post show 28th might be snowy in London need monitoring due my wife will drive me to Slough for my work 1 day then she and her friend planned to go to London via train for day trip then back at 10pm when I finish work to go home. 

I hope today has once and for all dispelled the misbelief that cold air can be ‘hard to shift’. I’ve even read that models somehow find it ‘difficult’ to account for entrenched cold air. That might of been true in the 80s but not now.
The outlook continues to be one where the new a la mode of significant heights across Iberia and points east will prevent Arctic incursions, or at least any lasting ones. We might sneak a day or two out of the next few weeks, but it’s generally a set up with a flow between SW and NW until the end of the year - as it stands.

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Morning all. 🙂 

The theme is continuing disappointing op runs but interesting ensemble data sets. Why is this happening? Are the ops picking up on small scale spoilers that aren’t present in the ens? 

the 00z EPS show a clear cooling trend for Liverpool for example 

some of the 00z GEFS are mouth watering with a cold, convective northerly over Christmas with uppers down to -10C , not uniform though by any means. There are just as many that are mild and non-descript. 

these two corkers for example 

https://www.wetterzentrale.de/maps/GFSP25EU00_192_2.png 
https://www.wetterzentrale.de/maps/GFSP08EU00_192_2.png 

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If the trend of the last day or so continues I would expect the ensemble mean t850 value to reach -10°C here. That is a big “if” however!

https://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&lat=57.2&lon=-2.25 

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any risk of you posting something actually based on model output, i dont even know what this post means, grim in what way ?

Agree there is no truth to it, even the best setups can be quickly blown away with the power of the Atlantic and the models generally get breakdowns correct these days.
Also, entrenched cold simply doesn't exist on a small island surrounded by warm seas. Yesterday it was milder here and in the rest of the North as warmer air seeped in very easily from the Atlantic. Today the wind has changed to SE and it is -2c and cloudy , cold air back but it can change and always will so quickly. 

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Um, I think that he has done exactly that.He has looked at the operational runs of all thr major models and has drawn the conclusion that the weather looks grim. It does look grim, unless wind and rain is your thing.​​​​​​​   

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it does seem that way, a few days of wet and wild weather to get through first though!

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Indeed - although I take the point that some do relish such weather (not my cuppa but I know some do like it)

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