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Model output discussion - proper cold spell inbound?


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Evening All  Ice Cold hope your still with us .... So the much touted SSW is coming into view & here’s my thoughts + timelines of when / where to expect it... We have seen lots of p

Well it's probably fair to say that I've been rather quiet on these forums for the last few years really, especially since 2013. After 15 years of internet weather watching, and more importantly,

Well - ho hum - let's have a sit rep. My eyes are hanging out on stalks.  The pacific first - engine of the climate system. How is our AAM looking in the face of the current high amplitude MJO?

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Posted
  • Location: Frome 330ft ASL
  • Weather Preferences: Most(see in interests section.)
  • Location: Frome 330ft ASL
    1 minute ago, NorthernRab said:

    Large swathes of the UK and Ireland might well see significant snow - the detail can't be pinned down at the this range. Certainly though Scotland (including the cities with a combined urban population in the millions), N.Ireland (Belfast) and parts of Wales and Northern England (again, millions in the urban areas) are in the firing line. I certainly would not call this a fuss over nothing. 

    I do agree that North of the M4 probably will see significant falls of snow thats for sure.......

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    Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
    3 minutes ago, offerman said:

    Brilliant post Cat,

    I have been banging on about the azores high being the problem and movement westwards or northwards needed to allow something to develop, so spot on. Also bang on about ignoring F1 as cant be microscale on those ridiculous charts out that far as they always change and downgrade anyway.

    So what you're saying is that you agree with Richard that it has been overhyped, but you also agree with Catacol that it hasn't been overhyped.:)

    Anyway, this morning's JMA short run has strengthened the scandi block in comparision with its 12z run yesterday at short range. The Atlantic is held further back and colder 850s advect into much of England:

    This morning T78

    J78-7.GIF?02-6

     

    Yesterday's 12z at T96

    J96-7.GIF?01-0

     

     

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    Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL

    Looking at Formula 1 charts is not going to help, aerodynamics are irrelevant! :rofl:

    Naturally people will look into fl, as we are looking likely also to see a significant Warming event, that could have a quick response in NWP modelling. Plus it's fascinating viewing.

    We are entering our best cold spell of winter for many, so it's not surprising the levels of expectation have risen a bit, the same can be said for caution, I guess. 

     

    Edited by karlos1983
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    Posted
  • Location: Manchester
  • Location: Manchester
    9 minutes ago, offerman said:

    Fergie is more often right than not on what he says when cold and snow are about. Did Fergie mean Bath Northeast Somerset when he mentioned NW of region or is he talking more Swindon way?

    He meant Cumbria! :D

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    Posted
  • Location: Frome 330ft ASL
  • Weather Preferences: Most(see in interests section.)
  • Location: Frome 330ft ASL
    1 minute ago, karyo said:

    He meant Cumbria! :D

    Thanks Karyo

    I didnt realise that as he is our local forecaster on Points West so thought he meant NW of our region. Thanks for clarification though and good luck up there im sure you will get a lot of snow. and powder snow not slushy rubbish...

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    Posted
  • Location: South Essex
  • Location: South Essex

    Nobody can be accused of overhyping or downplaying as the cold spell hasn't happened yet.

    Lets just agree that some people have higher expectations of this week than others and come the end of next week people can then come to there own conclusions based on the evidence (preferably in a polite and respectful way) :)

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    Posted
  • Location: Coniston, Cumbria 90m ASL
  • Weather Preferences: wintry
  • Location: Coniston, Cumbria 90m ASL
    6 minutes ago, karyo said:

    He meant Cumbria! :D

    works for me!

    All slotting together nicely really, the AH packing its bags and heading west or SW and plenty of cold to tap into from the East as it does so. What could possibly go wrong?

    Maybe an unnecessary SSW to set everything up on end, unless - no it couldn't possibly work IN our favour and keep us in the freezer until April could it?

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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
    7 minutes ago, Yarmy said:

     

    Anyway, this morning's JMA short run has strengthened the scandi block in comparision with its 12z run yesterday at short range. The Atlantic is held further back and colder 850s advect into much of England:

     

    This is a process that is likely to continue. I suspect the models are playing catch up in getting a handle on the impact of steadly rising equatorial AAM, and in addition we are all familiar with model inaccuracy when it comes to micropositioning of a block. Time and again the models overplay the strength of westerly components in the north atlantic, and so in the current global context of the GWO hitting phase 5 and engaging with increased torques - all a signal for high lat blocking - I would expect the strength and retrograde movement of the block to shift further west over time. All the way to Greenland? No. Composite guidance says not in a MJO phase 7 February pattern - we are looking at very much a Scandy affair, but further west than currently progged especially if/when we get the vortex split.

    Does the MetO update at 12.00 today suggest Glosea is seeing a reversal? I can count on the fingers of one hand the number of times I have seen the Met use "Very Cold" as a descriptor. At least it feels that way. I'm not quite so obsessed with weather following that I have saved every single MetO outlook.... :-)

     

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    Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
    7 minutes ago, offerman said:

    Well i hope the cold comes in as quick as an F1 cos i have been waiting for what seems like eternity, then hope it sticks about for a while....

    The models are certainly looking very encouraging / exciting for coldies again which is the main reason I came back out of hibernation, even phil the groundhog saw his own shadow so six more weeks of winter it is..hopefully longer!!:D:cold-emoji:

    Edited by Frosty.
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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    Just now, offerman said:

    Hi Daniel,

    Agree there will be many most likely up North That get a foot or more, The only foot down south is a foot up the weeble from the Northerners for our road closures on just a diddly 1/2 cm....

     

    But good luck to them all up there and hope they enjoy it :-)

    No as a matter of fact ECM 00z the SE according to that will be at greatest risk of deepest snows. 

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    Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
    25 minutes ago, Yarmy said:

    So what you're saying is that you agree with Richard that it has been overhyped, but you also agree with Catacol that it hasn't been overhyped.:)

    Anyway, this morning's JMA short run has strengthened the scandi block in comparision with its 12z run yesterday at short range. The Atlantic is held further back and colder 850s advect into much of England:

    This morning T78

    J78-7.GIF?02-6

     

    Yesterday's 12z at T96

    J96-7.GIF?01-0

     

     

    I think I'll until it's over...then I'll know whether or not it's been 'over-hyped'!:D

    And we are about to enter the F1 season...:hi:

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    Posted
  • Location: Ramsgate,East Kent.
  • Weather Preferences: BEASTERLYS
  • Location: Ramsgate,East Kent.
    12 minutes ago, Daniel* said:

    It seems some folks aren’t even willing to give the cold spell the benefit of doubt it’s not even initiated yet.... madness. 

    From ECM it’s really a rather snowy run as soon as T96: That seems like an organised area of snow possibly getting into SE England or just going south?

    76301AA9-135D-4182-A0D4-1559FCD986DB.thumb.gif.49cc5134f2abdf7908af5181fda4f58a.gif

    T120 again rather snowy with a low of sorts sitting there possible some organised snowfall again across the S/E. 

    E4C0747A-B4C3-43EF-92B2-C522249BD6BC.thumb.gif.bdd282c8d3137422b70a05cc34613c16.gif

    T144 again possibly slow moving snow in similar areas in Southern England. The snow would seriously start to build up.

    C60CA512-26D3-4B11-A74B-2CA374C38C5D.thumb.gif.9a7d10e73e51454a8535e3e8831323d1.gif

    T168 heavy slow moving snow across most of the country. 

    E82E1C74-85F9-4BAC-A51D-8F42273911AB.thumb.png.3ea437e90d1cc4f5600e94db8fed0d39.png

    Words fail me that some folk do not serious potential for disruptive snowfall. I would not be surprised if some locations see over a foot over a period of week.

     

    God i love your post & Im praying you are right..if half this comes off i will be in La La land. ( after a 5 year snow drought.) So its ECM for please Bob...

    Edited by craigore
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    Posted
  • Location: Rhoose, South Wales
  • Weather Preferences: snow, thunderstorms
  • Location: Rhoose, South Wales

    why are some folks talking about snow depths at this range ...12-24 hours before the event yes, but not now surely ! ...the cold is coming, that's for certain ..when it's here then we can discuss snow potential 

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
    2 minutes ago, Phantom2 said:

    why are some folks talking about snow depths at this range ...12-24 hours before the event yes, but not now surely ! ...the cold is coming, that's for certain ..when it's here then we can discuss snow potential 

    At long last a touch of realism

    Some of the comments are OTT, without even checking to see IF the model has ppn over their part of the world it seems to me?

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    4 minutes ago, johnholmes said:

    At long last a touch of realism

    Some of the comments are OTT, without even checking to see IF the model has ppn over their part of the world it seems to me?

    I don’t need to see precipitation charts from ECM you can draw a lot that from synoptic itself. 

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    I do wonder if some of you talking about depths of snow, effect on major cities etc have actually looked at what, GFS for instance, is actually predicting in ppn?

    This is the predicted accumulation out to T+144 h.

    Feet of snow??

    https://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=2a7bfb5fa51def4548f34791cfb6ecfa

    sorry you will have to call up the link and ask for total ppn and simply look at any time scale, compare the last run with the latest.

    I am not trying to be awkward but reading some posts those new to the site must wonder how some predictions are being arrived at.

    Edited by johnholmes
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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    9 minutes ago, Daniel* said:

    I don’t need to see precipitation charts from ECM you can draw a lot that from synoptic itself. 

    I just viewed them from Icelandic site and it backs my ‘prognosis’ possibly some organised snowfall across S/E moving from east to west off continent slow moving this is looking good for SE/EA.

    CAA32C83-41EB-478B-8940-38F472D86A07.thumb.png.b90f13a2c231f6936a5783c740530b05.png

    Edited by Daniel*
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    Posted
  • Location: Strood, Kent, 19 feet above sea level
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Strood, Kent, 19 feet above sea level
    Just now, johnholmes said:

    I do wonder if some of you talking about depths of snow, effect on major cities etc have actually looked at what, GFS for instance, is actually predicting in ppn?

    This is the predicted accumulation out to T+144 h.

    Feet of snow??

    https://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=2a7bfb5fa51def4548f34791cfb6ecfa

    Problem is John, as you should know better than anyone - The GFS PPN charts are utterly useless. In an unstable cold airmass snow will crop up at short notice. I agree people expecting feet of snow are going to be disappointed, but equally people saying "No snow nothing but dry" are going to be wrong too.

    The models are largely in agreement. The cold is coming, the snow will follow, it always does.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
    5 minutes ago, Daniel* said:

    I don’t need to see precipitation charts from ECM you can draw a lot that from synoptic itself. 

    Really, I wish I was able to do that with the ease you seem to feel it is possible

     

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    5 minutes ago, johnholmes said:

    Really, I wish I was able to do that with the ease you seem to feel it is possible

     

    Well you can see ‘kinks’ in the isobars you can’t tell everything but it can be a good indication of snow and where.

    Edited by Daniel*
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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    11 minutes ago, johnholmes said:

    I do wonder if some of you talking about depths of snow, effect on major cities etc have actually looked at what, GFS for instance, is actually predicting in ppn?

    This is the predicted accumulation out to T+144 h.

    Feet of snow??

    https://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=2a7bfb5fa51def4548f34791cfb6ecfa

    sorry you will have to call up the link and ask for total ppn and simply look at any time scale, compare the last run with the latest.

    I am not trying to be awkward but reading some posts those new to the site must wonder how some predictions are being arrived at.

    Probably localised in the North Downs is my feel I don’t think that’s far fetched at all! There is certainly potential there for deep snow cover in places which haven’t seen it in years. 

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    Posted
  • Location: uxbridge middlesex(south east england)
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(south east england)
    5 minutes ago, Daniel* said:

    Probably localised in the North Downs is my feel I don’t think that’s far fetched at all! There is certainly potential there for deep snow cover in places which haven’t seen it in years. 

    With the alternating flows and cold in situ..i find it increadably difficult that snow wont-be an issue.

    Best outlook-via cold -snow...in a long time.

    Factoring in almost anywhere to that equastion....

    Edited by tight isobar
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    Posted
  • Location: Inbhir Nis / Inverness - 636 ft asl
  • Weather Preferences: Freezing fog, frost, snow, sunshine.
  • Location: Inbhir Nis / Inverness - 636 ft asl
    24 minutes ago, johnholmes said:

    I do wonder if some of you talking about depths of snow, effect on major cities etc have actually looked at what, GFS for instance, is actually predicting in ppn?

     

    I have indeed. I said that major urban centres could well see snow and disruption (certainly nowhere near feet of snow!) but some might miss out. It's so difficult to tell at this range and the ppn charts are merely illustrative. 

     

    GFS 06hz Netweather GFS Image Netweather GFS Image

    Glasgow, Inverness, Stirling, Belfast, perhaps Perth (over 2.5 million people) potentially seeing a spell of snow there. 

    GFS 00hz corroborates 

    ukprec.png

     

    GFS 06hz:

     

    Netweather GFS Image

     

    Northern England and Northern Ireland (again) in the firing line there.

     

    Ppn charts at this range are somewhat academic as the closer we get, the more we'll know but certainly I'd say there's potential there. 

    What we do know though is that a NW flow with cold to very cold uppers (for the air direction) is likely from Tuesday. Snowfall to be confirmed but certainly there is the potential for some disruptive (if not exactly record breaking) snow next week. 

    Edited by NorthernRab
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