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Model output discussion - Closing in on Christmas


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One post ..... The ECM scenario is modelled once / twice a winter & rarely comes off > maybe once in 15 or so times - This is because in the toppler scenario theres not normally enough ini

As Mucka says quite a mixture in the ensembles, but I did find some that must be a sign, as it’s Christmas.  We have  Gold    Frankenstein And Murr

Great model watching at the moment. Momentum products are generally neutral - but the key here is that the GWO hasn’t descended (yet) into a Niña style orbit, meaning the kind of forcing that would he

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    JMA T192:

    DA526953-2B46-4D46-A142-D1563E084254.thumb.gif.d501e047480f042a79d802ee13edd2d4.gif

    7CD36F31-D844-403C-850A-794D9EC5477E.thumb.png.4911446d6325b7e0ba0819182769cf44.png

    But ECM just that bit of room west of Greenland, in comparison, so JMA will probably topple.

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

    The cold signal if anything has strengthened on Xmas we now have greens. Ridge quite close though so perhaps not much in the way of precip needed for snow.

    B844F0A9-BAF2-412A-8C45-C314698DF246.thumb.png.8a8b28163072da21c16d16268a6d492d.pngDF6AD78D-2782-45F1-8088-38E646E10D6C.thumb.png.e09940b6f00b1af0cd2b62d9cd46d6d4.png

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    ECM mean and spread T240:

    7C4C152E-55A1-45DE-9196-6DFCC59E3CEB.thumb.png.136c852c0afd713a57712fb56ffc1d54.pngAFFD1E68-7F3F-4821-8835-91127C5EF2C7.thumb.png.d45213f0bd51614bea3c9f363055448d.png

    The spread is interesting in that uncertainty is now also high in that region just to the west of Greenland.  

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    Clusters in T192-T240 range from ECM:

    1054A359-31E4-468E-A366-14F57D39D405.thumb.png.9c93a104abb7d57252d4fce1b345b502.png

    ECM op in cluster 2, the 1/3 minority one, but that’s some support for something we haven’t seen on the last run.  

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    Posted
  • Location: North West of Ireland
  • Location: North West of Ireland

    I think there is going to be a lot of disappointed here by the time of the Next ECM run.  That low in Canada will end up ruining things. We've seen this so often before. I fear the ECM will end up being similar to the GFS run . I am more than happy to be wrong about this.

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    Posted
  • Location: BIRMINGHAM B6 ASTON WM. About 112MASL 367.36FT
  • Weather Preferences: SNOWY WINTERS AVRAGE SPRING HOT SUMMERS WITH THUNDERSTORMS.
  • Location: BIRMINGHAM B6 ASTON WM. About 112MASL 367.36FT
    34 minutes ago, SLEETY said:

    I have lost count of day 10 ECM cold looking  charts that never verify and are completely different the next run.

      when I looked at the GFF I thought we go wasn’t very inspiring looking at the ECM I think to myself an excellent run however this is 10 days away yet and going by the ECM over the last few winters to my mind it screams garden path. also the update from the Met office does not fill me with confidence or hope for the up coming cold period they even took wintry showers out of the update now let’s hope the text forecast changes soon and reflects the 30 day outlook from ECMWF. 😐😬

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    Posted
  • Location: Salzburger Sportwelt Lungau/ Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Salzburger Sportwelt Lungau/ Pongau Region. Somtimes Skipton UK
    42 minutes ago, northwestsnow said:

    Nice EC ...

     

    Let's get 120-168 straightened out first though...

    Go on NW. Have a bet on a white Christmas. Manchester in firing line. Bookies stopped taking bets ! Seriously, your part of the world usually does well in that set up modelled by ECM for Xmas Day.  Historically, think I have read 29th December on record is the snowiest day . We will see.

    C

    snowdepth_20201215_12_240.jpg

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    Posted
  • Location: Broadmayne a few miles north of Weymouth in Dorset
  • Weather Preferences: Snowfall
  • Location: Broadmayne a few miles north of Weymouth in Dorset

    Good to see Mr Murr posting again, and like he says this particular evolution is rare in succeeding , however the back ground signals for it to evolve that way are there and why shouldn't this be one of the rare times it actually happens.  Rare doesn,t mean never it means seldom and this probably hasn't happened since the famous  Mr Brown wtf moment back in 2013. So perhaps just perhaps we are due another wtf moment.. This ecm evolution has already appeared recently, the the outrageous gfs 00z control a couple of days back kicked off from this particular evolution so the ecm is not completely on its own in that sense.   We shall see but at least it keeps things interesting going into Christmas. We could be in a much worse place.

    Edited by Broadmayne blizzard
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    Posted
  • Location: East Ham, London
  • Location: East Ham, London

    Evening all 🙂

    Plenty to cheer cold fans in the longer term yesterday evening but the short to medium term looks like the typical winter fare of recent times - plenty of rain but mild.

    On then to tonight's circumnavigation of the models starting as always with the Canadians:

    12Z GEM: last night GEM didn't phase the LP moving up from the lower latitudes with the LP to the west of the British Isles while both GFS and ECM did. On first look, the T+120 has a stronger HP coming in to Iberia and makes a little less of the next Atlantic HP but we'll see. By T+180, the new LP has phased with the original and the centre is to the north-west of Scotland with a ridge upstream. The airflow over the British Isles is switching to a cooler PM as the cold front passes through.  BY T+240 it's all looking a bit messy - the LP has moved into Scandinavia and we have a N'ly for Christmas Day. There's a ridge from Greenland through Iceland to an HP to the west of Ireland but a new trough has come out of Canada while a new HP has developed at lower latitudes. All a bit uncertain going forward. 850s of minus four on Christmas day so anyone catching s shower might see the white stuff. 

    image.thumb.png.9ab0cd7a77dfcef6135de03cae2b0ee5.pngimage.thumb.png.f7ea70353946978eca5d256ac0528d90.pngimage.thumb.png.29ea47a4c11e4549fd78c2454c13cc74.png

    12Z GFS OP - GEM shows the first signs in the medium term (still FI of course) of a change from the current pattern. Let's see where GFS takes us. At T+120 not a great difference from the GEM - a ridge approaching the British Isles followed by a deepening mid-Atlantic LP. The new LP flatters to deceive but still zips through southern Britain as a secondary feature followed by the onset of the PM airflow which is happening quicker than GEM suggests. Last night's hoped-for amplification doesn't happen with a renewed push of LP out of Canada forcing the HP back south so while Christmas Day could be cold and crisp milder air is spilling back in from the west. By T+300, it's a very different chart with a stormy looking Atlantic and the HP suppressed to the south. Fairly mild but increasingly unsettled. By T+384. it's a poor outlook for cold fans with a new LP approaching and heights to the south.  Still plenty of signs of warming on the 10 HPA chart at the end of the year.

    image.thumb.png.0612d863bb7403126a0095d4cd43fd36.pngimage.thumb.png.526d34b32bb30733f82df1ec5ad86a64.pngimage.thumb.png.14fa635ed218b4cea97d97da58baf64a.pngimage.thumb.png.7daf271e0c9b28da4d02e2dd43ccdfbd.pngimage.thumb.png.17f28ba2236ec34694d27d382dbe3c30.png

    12Z ECM - a thoroughly disappointing GFS OP - could be an outlier of course and we often see GFS re-set to a traditional Atlantic pattern in lieu of any strong signals.  No great surprise on the T+120 but the T+192 is quite messy with shortwaves around Iceland but a weak N'ly over the British Isles between Atlantic heights and the trough over Scandinavia. As for T+240, all I'll say is "I haven't a clue". It's very different from GFS or GEM - the Atlantic LP is filling as HP builds to both north and south. The Christmas Day N'ly remains with -4 to -8 uppers and IF that Atlantic LP slides south-east, well, it could get interesting.

    image.thumb.png.3731a8a0d0b24884e73dce27321277fe.pngimage.thumb.png.2a10d8b081016ef8f02f425c25a2de78.pngimage.thumb.png.9fcd89bfca7fee7a555e8a1a9e17329b.png

    12Z Control ends with a more or less direct N'ly and -8 Uppers but it doesn't look more than transient. 

    Conclusion: - I'll be honest, I've no idea where this is all going. GFS is a salutary warning nothing is settled yet by any means and it's a worrying sign. However, GFS has been wrong before and both GEM and especially ECM are more encouraging for fans of cold. Keeping the Atlantic quiet and the PV weak seems to be the way forward - the GFS OP evolution may be right but until I see more evidence I'm going to be more optimistic and hope we get the N'ly for the big day. 

     

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    I posted the T192-T240 clusters from ECM earlier, here’s the next time step T264-T360:

    B5DBFC77-E826-475B-9415-C625816ED030.thumb.png.3fa57a38190776b2bd15d4968dec3dd1.png

    Cluster 3 here the one showing lasting blocking and cold, 10 members so 1/5 chance.  Seen much worse! And it isn’t that the other clusters are bad initially,  just not sustaining.

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    Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
    38 minutes ago, bluearmy said:

    I’m still unconvinced about the mid Atlantic ridge to greeny managing to gain enough traction - I currently expect it to be flattened somewhat which won’t bring really cold uppers across the U.K. ..... could well end up with a cold high over the U.K. for Xmas. however, there is still a lot of spread to our west which means the festive period (and beyond) could still bring a blast of proper winter. 

    Note that even if ridge 1 doesn’t quite make it, there are plenty of hints that a second one a couple days later will maintain our interest and potentially retrogress any mid lat high that results from ridge attempt one 

     

    20 minutes ago, phil nw. said:

    My glass is still very much half full for a cold Christmas.

    A good ECM tonight for coldies.On seeing GFS my first though was ,where's all the blocking gone?,lol.Of course we can never discount it especially at that range but knowing it's tendency for favouring the northern arm of the jet when we get a split off the eastern seaboard i was suspicious of  it's day 6 frames and beyond.

    Having said that even that solution would still give us a cold Christmas but then soon after the Atlantic would be back.

    Just a few words on the  London ensembles and any trends.

    I am taken by their consistency on the projected cool down for the holiday.The overall trend to a cold Christmas with 2 mtr temperatures  below and they have remained steady since i started monitoring the combined London 00z run on the 11/12.Here are the last  4 out of 5. I failed to record one day.

    ensemble-tt6-london.thumb.gif.45cc0b517447684e5d3d5aab173bb5e4.gif1877791686_ensemble-tt6-london(1).thumb.gif.ba45b05fcfd526ed297b0a309e2b8b49.gif964835641_ensemble-tt6-london(2).thumb.gif.5518402cb8408600c7d160a52716dc49.gif348232578_ensemble-tt6-london(3).thumb.gif.158186fdb0473b225d635a9ec1a9b3ce.gif

    Looking at the 850's for here in Warks around -4c for the 850's remains favourite,though chances of any snow would be up north and possibly ne coasts as the high moving in would bring dry conditions for many i fear by the day itself.

    That last graph above is today's btw and it appears we may keep the cold beyond Boxing day.That will likely be from a cold ridge but we will see.

    I would be surprised it the Atlantic moved in so quickly after Christmas with such an underpar pv and ht.anomalies to the north.It doesn't scream a zonal outlook and strong northern jet.Still we will see. 

     

     

     

    Glad to come home from yet another hectic long day in the office to some great discussion, and model watching, even if it only brings a fleeting chance of something more seasonal.

    My next day off is the 24th, but will I be looking forward to something like these?

     

     

    ECH1-240.gif

    gfsnh-0-240 (1).png

    gemnh-0-240.png

    Edited by Griff
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    Posted
  • Location: Rotherham, East Dene
  • Location: Rotherham, East Dene
    44 minutes ago, bluearmy said:

    I’m still unconvinced about the mid Atlantic ridge to greeny managing to gain enough traction - I currently expect it to be flattened somewhat which won’t bring really cold uppers across the U.K. ..... could well end up with a cold high over the U.K. for Xmas. however, there is still a lot of spread to our west which means the festive period (and beyond) could still bring a blast of proper winter. 

    Note that even if ridge 1 doesn’t quite make it, there are plenty of hints that a second one a couple days later will maintain our interest and potentially retrogress any mid lat high that results from ridge attempt one 

    This is my thinking. 10 days ago I touted a UK high due to us needing to see the tropics head to MJO phase 7. If it did this would happen after Christmas the week after. Its all about timing. If you look at the difference in clusters its all down to Arctic High. On the first cluster this joins up with the Siberia high. In the second it joins up with the Greenland.

    There is a chance we get very lucky and see the arctic high phase with the Greenland one. 

    Then the period after Christmas into nee year the second bout of amp reinforces the Greenland High.

    If it merges with the Siberia one our next real chances come from the second bout of amp and we have a second chance of amplification toeards Greenland. The ECM weeklies have been calling this week after Christmas our best chance for a while now. I havnt posted myself because we are still outside this timeframe and i knee there would be fall out in here!

    Edited by Scott Ingham
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    Posted
  • Location: North Newbald , East Riding of Yorkshire 139 f asl
  • Location: North Newbald , East Riding of Yorkshire 139 f asl

    spacer.pngMJO ...... perhaps moving into phase 6 in week 2 but still rather uncertain.

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    Posted
  • Location: Rotherham, East Dene
  • Location: Rotherham, East Dene
    5 minutes ago, chionomaniac said:

    Been too busy at work today to keep up with today’s events. But looking at the 12 z updates at day 10, the GFS looks under amplified and the ECM looks over amplified. And big differences over our sector when looking at NH profile. Good to see both have vortex still disrupted though. Yet again we are in the position of having to wait a bit longer for the MJO to move to the later phases to give the kick. We are mighty close still. 

    Exactly what i just replied to Blue mate. Lag effect always took us the week after Christmas. I forecast a UK high 2 weeks ago Christmas week if you look back on posts. Its the arctic high joining with the Greenland High on cluster 3 giving us an outside chance of squeezing cold a week earlier than the MJO taking effect

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    Posted
  • Location: Rotherham, East Dene
  • Location: Rotherham, East Dene

    Forum

    Calm down!

    Christmas week cold if it happens is a bonus from our friend the Arctic High

    Background signals peak 2 or 3 days prior to New Year!

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