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Model Output Discussion - Snow for some, but what else is in store?


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Ok, I have a bit of an update. Looks like the correction westward for today got the predicted snowfall about right . Nowcasting really comes into its own for this weekend. The team think another corre

Please allow me this small divergence mods... I feel like the last 3 weeks have been a bit of a blur. I caught Covid tail end of 2020 and was really rough with it. Low oxygen levels leading to in

I have had it once in October and again December the 30th. Theres a bit of chat over whether i have had it once had long covid and tested positive again as symptoms came back in December or caugh

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Posted
  • Location: Stoke
  • Location: Stoke

    Hi folks, would anyone be able to explain to me how and why the strong pacific high (pushing into the Arctic) has materialised on the recent model outputs...

    regards

    dave

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    Posted
  • Location: Nottingham, UK
  • Weather Preferences: Cold and snowy or warm and sunny
  • Location: Nottingham, UK
    3 minutes ago, daz_4 said:

    What's so boom about that? The cold air never makes it south.

    Was looking good north of UK, but the Azores is spoiling the party  on this run

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    Posted
  • Location: Coventry
  • Location: Coventry
    8 minutes ago, reno said:

    Hi folks, would anyone be able to explain to me how and why the strong pacific high (pushing into the Arctic) has materialised on the recent model outputs...

    regards

    dave

    I believe this is a semi permanent feature, similar to the Azores high and goes though bouts of amplification in tandem with the Aleutian low.

    The MJO may affect it also... I'm sure someone with more technical knowledge can expand on this further

    Edited by Battleground Snow
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    Posted
  • Location: Brighton, East Sussex
  • Location: Brighton, East Sussex

    GEFS mean highlights the stagnant pattern, signs of the heights to our south creeping closer longer term with a southerly sourced airflow which would be relief from this vile weather, at least IMBY anyway, we’ve had endless amounts of cold rain and this mean doesn’t inspire much confidence in change within 10 days at least.

    2322311E-5481-4253-B89A-D226CB75FBEE.png

    6D97F16B-C511-4B42-A62D-60A57DB2D940.png

    7A473866-E9E2-41A2-B689-FB6870EC9575.png

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    Posted
  • Location: Netherlands
  • Location: Netherlands
    8 minutes ago, Battleground Snow said:

    I believe this is a semi permanent feature, similar to the Azores high and goes though bouts of amplification in tandem with the Aleutian low.

    The MJO may affect it also... I'm sure someone with more technical knowledge can expand on this further

    MJO phase 3 teleconnects with a positive NAO.

    Based on a simplified nonlinear model and reanalysis data, the lagged connection of the North Atlantic Oscillation (NAO) with the Madden–Julian Oscillation (MJO) in boreal winters is investigated. The positive NAO is observed to occur more frequently about 8–20 days after the onset of the MJO phase 3. A series of heating forcing experiments and initial-value experiments are conducted by utilizing the Geophysical Fluid Dynamics Laboratory (GFDL) dynamical core atmospheric model. The extratropical responses to the tropical heating associated with the MJO phase 3 are characterized by a wave train over the Pacific–North American region with an anticyclone anomaly over the northeastern Pacific and then followed by a positive-NAO-like pattern over the North Atlantic sector. These circulation anomalies generally match the observed lagged-connection well. At the earlier stage, the Rossby wave train excited by the MJO convection propagates into the North Atlantic, leading to a planetary wave anomaly with a low-over-high dipole prior to the positive NAO. At the later stage, the anomalous synoptic eddy vorticity forcing (EVF) streamfunction tendency has a negative-over-positive dipole, which plays a key role in the development of the positive NAO. Further analysis of the initial-value experiments indicates that, for the subsequent formation of the positive NAO, the anomalous circulation over the Indian Ocean aroused by the MJO phase 3 is more crucial than that over the northeastern Pacific.

    704.jpg
    LINK.SPRINGER.COM

    Based on a simplified nonlinear model and reanalysis data, the lagged connection of the North Atlantic Oscillation (NAO) with the Madden–Julian Oscillation (MJO) in boreal winters is investigated. The positive NAO is...

     

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    image.thumb.png.107ac8fdaacbefcb4a5fcc40b9ce8230.png

    How long will the MJO hang out in phase 3?

    Nobody knows.

    Where will it go afterward?

    Nobody knows! 🙄

     

    Point being, we don't know if those model runs & ensemble members that inflate a high over W. Europe have much credibility or not.

    Couple this with there being a fair chance the jet stream out of the USA is being overdone in week 2 - as it's one of the most reliable model biases - and who's to say where we might go?

    Long story short, I have a suspicion that subtropical ridge inflation could happen further west and perhaps yesterday's 12z GFS was onto something (as opposed to on something).

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    Posted
  • Location: Near Gouda, Holland 6m Below sea level
  • Weather Preferences: Sun, snow, ice. Very hot or very cold.
  • Location: Near Gouda, Holland 6m Below sea level

    Not much change in the output this morning. I stick to my reasoning that the roots of a good Greenland High should 'grow' in a location nearer to North/Northwestern Europe first.

    We have seen the crazy swings that were expected as a result of the SSW and I can imagine that going on for a while, especially since the changes higher up are still an ongoing event.

    Is there still hope for coldies? I would say yes.
    - The NH troposphere is still in a meridional state, models don't have it nailed yet.
    - The Arctic High is traditionally poorly modelled and observed, note that the models are struggling with it. Significant changes in its shape and location can still result in significant changes in our weather.
    - The SSW effects are still a wildcard.
    - As noted above, the MJO isn't helping now, but later on?

    So all in all, temperatures are average or just below average, and I estimate the chances of that continuing higher than the chances of us staring down the barrel of endless mild SWlies.

    And then there are those two EPS members that surely got it right in De Bilt 😁

    Pluim_14jan_adapted.png

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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

     Next week looks initially to be milder as low pressure phases across the UK bringing in some warmer air, especially across southern areas however as the low transfers eastwards into the N Sea colder air returns southwards. At the moment, there's no immediate sign of "deep cold".

    795336714_Screenshot2021-01-14at12_08_44.thumb.png.4e5bad8096b2cfb0da88d569a2f9f3f7.png

    Given the Clusters, blocking does seem likely to develop in the Scandi region, perhaps a little stronger than the Ops are currently suggesting 

    980227411_Screenshot2021-01-14at12_06_33.thumb.png.1129a5e898ccaba44859587d64ec9a8e.png

    However at the moment there doesn't seem to be anything to advect deeper cold down from the N/NE into the UK. So "cold and wintry" looks to be the continued theme with snow favoured for northern hills, as seems to be the story of this winter so far.

    Hopefully we start to see something being modelled that'll bring deeper cold towards the UK towards the very end of this month/beginning of February, but at the moment I'm thinking that proper cold is becoming increasingly unlikely this month unfortunately. 

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    Posted
  • Location: Uckfield, Sussex
  • Location: Uckfield, Sussex
    1 hour ago, IDO said:

    Although I would love to see that, the Para is not fit for consumption and I cannot see this coming on line as it would be a joke. We have been seeing those para boom charts for weeks! The latest verification:

    1950624176_cor_day10_HGT_P500_G2NHX(7).thumb.png.38ec3550e56413e90a525760374f957e.png

    It only beats the cfs and has some atrocious runs, a 0.1 and a 0.28. These are the sign of a failed model that needs some reprogramming. The current gfs is no world-beater but does not drop below 0.4 on any of the sampling. 

    I dunno. When I look at that chart, I can see that the Para had some stinkers at the end of 2020. But if you look at the chart from New Year onwards, it looks to be doing ok. And even the full chart, if you remove the stinkers (which could be stinkers for any number of reasons unrelated to the quality of the model itself) then it generally looks pretty good - including a period 16th to 24th Dec where it was top of the pile (and again more recently, it's outperformed its older cousin a number of times).

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
    16 minutes ago, Singularity said:

    image.thumb.png.107ac8fdaacbefcb4a5fcc40b9ce8230.png

    How long will the MJO hang out in phase 3?

     

    It's barely Phase 3 though, wouldn't you say? 

    If a super strong SSW cannot overpower weak forcing like that, then we might as well not bother with SSWs.

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    Posted
  • Location: Coventry
  • Location: Coventry
    1 minute ago, mountain shadow said:

    It's barely Phase 3 though, wouldn't you say? 

    If a super strong SSW cannot overpower weak forcing like that, then we might as well not bother with SSWs.

    Some folks have indicated on twitter that it is actually more active than these plots show.

    The waiting goes on....

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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
    1 minute ago, Audaxian said:

    I dunno. When I look at that chart, I can see that the Para had some stinkers at the end of 2020. But if you look at the chart from New Year onwards, it looks to be doing ok. And even the full chart, if you remove the stinkers (which could be stinkers for any number of reasons unrelated to the quality of the model itself) then it generally looks pretty good - including a period 16th to 24th Dec where it was top of the pile (and again more recently, it's outperformed its older cousin a number of times).

    Yes, as an improved version we should all expect performance in more benign and predictable patterns for the Para to surpass the old gfs, otherwise what is the point? But, as with most things if chaos ensues then modelling is harder, then it was a step backwards. The days it failed, other models were verifying much better, so I would suggest it was the model's failing to cope with height rises?

    These difficult phases are usually the key moments in the NH pattern and the times when the models need to be useful rather than useless, and 0.1 is probably worse than any of us could have achieved from the data at hand!

    The gefs for London suggest a split in the ens as to mild or cold (2m temps) post-d10 and that is my thoughts, still some firming up of the pattern from there:

    graphe6_10000_311.68487548828125_152.1133575439453___.thumb.png.65f5b74c16b82f54d7dbe93ed2df1f2b.png

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    Posted
  • Location: Melbourne, Victoria, Australia.
  • Weather Preferences: Snowfall obviously.
  • Location: Melbourne, Victoria, Australia.

    It’s certainly interesting the next few weeks, the prospect for cold and snowfall for the next few weeks is very much alive for the UK, or at least parts of it.

    Afterwards in February, it’s very much at a juncture. On one hand, we have the MJO Phase 3 pointed out by @Singularity, and signs that the SSW forcing is going to wear off later in the month, which would possibly be destructive for the current -NAO.

    However if we stay in the current GWO phases that have been supporting the -NAO for a little while longer, and see the tropospheric polar vortex stay weak into Feb, we might see that period for possible cold and snowfall extend a little more into next month. 
     

    But yes, it must come to an end at some point, it’s just a matter of working out when....

    More here: https://longrangesnowcenter.net/2021/01/14/europe-on-the-long-term-14th-jan/

    🙂 

     

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    Posted
  • Location: CARDIFF
  • Location: CARDIFF

    MJO appears to have peaked in phase 3 around 8th Jan,  I would expect the influence of phase 3 to start to ease (weaken) around 18th - 23rd.

    (My study of this indicates 10-12 days for effect, which is different to what others suggest, but works for me)

    The most likely phase is COD from now, and anyones guess from there. It is a complete mess with as much uncertainty there as in the 500mb charts and Surface pressure charts. All data beyond 5 days is up in the air. If any one of these is wrong then down stream everything else will to some extent be wrong.

    The trend 00z run v 00Z Run etc  is not going our way at the moment, but we saw this in 2018. If we just view the run in comparison with previous run of same time we can figure out the minor changes early on that give such a different outcome. Then you can see if its feasible and likely.

    What i will say, is getting precipitation here in UK has never been an issue, getting cold air in has. That cold air over the medium term has a very good chance of making progress towards the UK. Not shown consistently by models but hinted at  by them. 

    Please see the latest phases and forecasted phases of MJO

     

    combphase_noCFSfull.gif

    ECMF_phase_51m_full.gif

    ensplume_full-2.gif

    rmm.phase.Last40days.gif.small-2.gif

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    Posted
  • Location: West/East/Sussex Surrey border
  • Location: West/East/Sussex Surrey border
    33 minutes ago, carinthian said:

    Ok, I have a bit of an update. Looks like the correction westward for today got the predicted snowfall about right . Nowcasting really comes into its own for this weekend. The team think another correction westward on the frontal system moving into The British Isles on Saturday. Perhaps not as advanced as shown on the models or UKMO fax. So a slowing up or disruption of the trough could give a more prolonged spell of snow. The  outer parameter of the snow computer flag up up the East of England with a moderate fall in places , especially East Anglia. That would indicate a wedge of cold still very close to the British Isles. The front is expected to move through by the end of Saturday .  Long term very uncertain but likely to stay cold for many, how  cold ? not sure but there is now some sort of thinking of undercut scenario to develop  around the last 1/3rd of the month with Southern Britain trending to a snowy outlook ( more southerly tracking low pressure systems )

    Hope that helps.

     C

    I love you x

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    Posted
  • Location: Ashbourne,County Meath,about 6 miles northwest of dublin airport. 74m ASL
  • Weather Preferences: Cold weather - frost or snow
  • Location: Ashbourne,County Meath,about 6 miles northwest of dublin airport. 74m ASL
    52 minutes ago, MJB said:

    We have another 17 days this month , that's a huge amount of time to set up a wintry February .

    We rarely get  a cold snowy January , maybe this is the "set up" month for February ?

    Post of optimism 

    Personally it's been feb that I have always thought  of  when the cold will come not last third of Jan. 

    Perhaps the last week of Jan the models will firm up properly on a cold spell ,that will strike first week of feb. Hopecasting perhaps but that's my thoughts. 

    Edited by sundog
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    Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

    The loss in modeling of a solid GH showing only a couple of days ago was certainly a set back in driving the cold down from the ne.In spite of that though we can see how close we are to bedding in some cold after the disruption of today's front across the UK.

    T24

    UW24-7.thumb.gif.e40c4b057f61c4d57b4abe8fb6d17f31.gif

    Looking upstream and currently the jet coming across the Atlantic is splitting around 80/20 in favour of tracking south.GFS 06z T96

    1157689163_gfsnh-5-96(1).thumb.png.2b168290fd5efeb592ce06d202be1049.png

    The problem is the leakage across Greenland keeping a lid on further ridging north,so we remain in a flatter pattern with the real cold not able to come far enough south but we do see more modest bouts of cold still mixed in to the pattern.

    Looking at the ecm mean 850's days 5/10 and this shows we mostly remain north/colder side of the jet 

    EDM0-120.thumb.gif.1a2e8394f5af689efe91d68689d0a7a1.gifEDM0-240.thumb.gif.b080e0bf52bf350c3fecb93bfc326c90.gif

    I think it's worth keeping positive in spite of recent setbacks.With this setup we can't rule out a southerly tracking low creating a snowy battleground situation.If we look at the gefs day 8 ht anomalies

    EDE101-192.thumb.gif.cf7d2eb463b26e71e32078c1410ba90a.gif

    The basic outlook remains heights favoured to our nw and the lows across our latitude.If the pattern develops even a modest amount of extra ridging then one of those lows could well deliver as it meets more resistance to the cold further north.Seeing so much chopping and changing in the short term we shouldn't rule this out. 

     

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    Posted
  • Location: Cwmbran. South East Wales 300ft ASL
  • Location: Cwmbran. South East Wales 300ft ASL
    3 minutes ago, phil nw. said:

    The loss in modeling of a solid GH showing only a couple of days ago was certainly a set back in driving the cold down from the ne.In spite of that though we can see how close we are to bedding in some cold after the disruption of today's front across the UK.

    T24

    UW24-7.thumb.gif.e40c4b057f61c4d57b4abe8fb6d17f31.gif

    Looking upstream and currently the jet coming across the Atlantic is splitting around 80/20 in favour of tracking south.GFS 06z T96

    1157689163_gfsnh-5-96(1).thumb.png.2b168290fd5efeb592ce06d202be1049.png

    The problem is the leakage across Greenland keeping a lid on further ridging north,so we remain in a flatter pattern with the real cold not able to come far enough south but we do see more modest bouts of cold still mixed in to the pattern.

    Looking at the ecm mean 850's days 5/10 and this shows we mostly remain north/colder side of the jet 

    EDM0-120.thumb.gif.1a2e8394f5af689efe91d68689d0a7a1.gifEDM0-240.thumb.gif.b080e0bf52bf350c3fecb93bfc326c90.gif

    I think it's worth keeping positive in spite of recent setbacks.With this setup we can't rule out a southerly tracking low creating a snowy battleground situation.If we look at the gefs day 8 ht anomalies

    EDE101-192.thumb.gif.cf7d2eb463b26e71e32078c1410ba90a.gif

    The basic outlook remains heights favoured to our nw and the lows across our latitude.If the pattern develops even a modest amount of extra ridging then one of those lows could well deliver as it meets more resistance to the cold further north.Seeing so much chopping and changing in the short term we shouldn't rule this out. 

     

    Hi...when we talk about about the possibility of a southerly tracking jet creating a snowy battleground....would this still favour more northern areas or bring say midlands south in to play? Sorry if it’s a dumb question 

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    Posted
  • Location: Whitefield, Manchester @ 100m
  • Location: Whitefield, Manchester @ 100m
    9 minutes ago, WINTRY WALES said:

    Hi...when we talk about about the possibility of a southerly tracking jet creating a snowy battleground....would this still favour more northern areas or bring say midlands south in to play? Sorry if it’s a dumb question 

    Both! (or neither) 🙂

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    Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl
    2 minutes ago, WINTRY WALES said:

    Hi...when we talk about about the possibility of a southerly tracking jet creating a snowy battleground....would this still favour more northern areas or bring say midlands south in to play? Sorry if it’s a dumb question 

    Hi WW,

    It just depends on the angle and track of an approaching low WW.We really can't say where this may be is the honest answer.

    For snow further south in the uk a track along the channel would be better especially if it elongated west to east.If you have a look at some of the chart archives ,say Jan 63.Feb 47 and 78/9 you should see some examples.Iirc even in the great Winter of 63 some of the uppers were very modest but the south saw some heavy snow at times. 

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