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


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Posted
  • Location: st albans
  • Location: st albans

    day 8 on the gefs mean and this chart of run to run change gives you a heads up that it’s not moving in the right direction. The rise in heights over Iberia evident on the ec spread and mean on and off days 7/10 probably going to be on the gefs too with a flatter mean solution that the 00z suite 
     

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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: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany
    3 minutes ago, Griff said:

    Much appreciated, especially the eye test at the end 😉 

    Regarding strat effects being an ongoing process, I'd almost suggest taking a step away for a few days, otherwise you'll find yourself repeating yourself over and over here. 

    We seem to be in a discussion loop. 

    FYI I share your pov, just not sure others with an opposing view are listening or receptive to consider the possibility. But that's OK. 

    👍

     

    Thanks Griff. Others may see things diffrent, but for me this is one of the first signs in our heights (off the ssw)

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    Posted
  • Location: st albans
  • Location: st albans
    3 minutes ago, Scandinavian High. said:

    Is there any chance of high pressure setting up over Scandinavia put us in a proper freezer I say this because have seen 0 snow this winter 

    some very tentative ones for me but a long way off and too tentative to go into any detail .....

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
    9 minutes ago, Scandinavian High. said:

    Is there any chance of high pressure setting up over Scandinavia put us in a proper freezer I say this because have seen 0 snow this winter 

    Not in the next three weeks anyway.

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    Posted
  • Location: Coventry
  • Location: Coventry
    2 minutes ago, Griff said:

    Much appreciated, especially the eye test at the end 😉 

    Regarding strat effects being an ongoing process, I'd almost suggest taking a step away for a few days, otherwise you'll find yourself repeating yourself over and over here. 

    We seem to be in a discussion loop. 

    FYI I share your pov, just not sure others with an opposing view are listening or receptive to consider the possibility. But that's OK. 

    👍

     

    I agree with this, and not a dig at anyone, but it seems that milder options in FI are generally more accepted to verify over colder ones. 

    You could use  climatology statistics to say that there is a 75% chance of a flow from SW, which makes this argument valid, but I would say this is only true in a winter where there hasn't been 2 warmings already by mid January. As BA has pointed out there is signs then flow will reverse in the higher lats, is it inconceivable that we can't get this over our latitude in the next 6 weeks?

    Much to play for still and look for the 2nd warming to further increase Arctic heights in the mid term. judah Cohen is really bullish on this happening. I am also keeping a close on eye on the MJO

     

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    Posted
  • Location: County end Oldham 202 m Above sea level
  • Location: County end Oldham 202 m Above sea level
    13 minutes ago, bluearmy said:

    day 8 on the gefs mean and this chart of run to run change gives you a heads up that it’s not moving in the right direction. The rise in heights over Iberia evident on the ec spread and mean on and off days 7/10 probably going to be on the gefs too with a flatter mean solution that the 00z suite 
     

    image.thumb.png.59206c11f7fe7a82885c06fe87249f77.png

    Hence my post suggesting Exeter may revisit the more protracted wintry updates recently.

    We need a flip , but its looking unlikely...

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    Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
    Just now, Battleground Snow said:

    I agree with this, and not a dig at anyone, but it seems that milder options in FI are generally more accepted to verify over colder ones. 

    You could use  climatology statistics to say that there is a 75% chance of a flow from SW, which makes this argument valid, but I would say this is only true in a winter where there hasn't been 2 warmings already by mid January. As BA has pointed out there is signs then flow will reverse in the higher lats, is it inconceivable that we can't get this over our latitude in the next 6 weeks?

    Much to play for still and look for the 2nd warming to further increase Arctic heights in the mid term. judah Cohen is really bullish on this happening. I am also keeping a close on eye on the MJO

     

    The few pros I've had any chat with (the usual suspects) refuse to bow to pressure and give an answer, popular or otherwise. Fence sitting seems to be the name of the game, and you can't blame them. 

    Give it a week or two and things should be clearer? 

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    Posted
  • Location: st albans
  • Location: st albans
    7 minutes ago, Vikos said:

    Thanks for your answer.

    I will say, that once the easterly flow is developed, with that snow and ice coverage to the east and a rather neg AO/NAO (westerlies will have to fight hard against cold ground air masses and flows), it will just strengthen up. So while I am not living at the pole, I am very happy with this signal (snow in garden tralala), and as I mentioned in strat thread, EC Outputs are quite reliable on that timeframe.

    this chart from the gfs 00 op so not to be analysed low down too far into the distance.  It’s specifically at 60N.  The ssw reverse flow showing at 10hpa out to around the 25th - obviously you can see from the ec chart you showed for the whole globe that above 60N the reversal gains traction right down trop (the neg AO the solid response)  

    the flow must be a global return at 60N which makes it tough to over analyse. We dont know where the positive and negative flows will establish. I have ringed two areas where surface flows are negative and these reach up into the 500hpa area where we need to see them.  The overall global flow at 500hpa is not reversed but it very weak. That’s likely to give us a better chance but I just think it’s more a case of pot luck without decent amplification establishing in the right place and sustaining for a period ..
     

    image.thumb.png.6da5b03ce4e1473d00cfb770bead6023.png

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    Posted
  • Location: st albans
  • Location: st albans
    4 minutes ago, northwestsnow said:

    Hence my post suggesting Exeter may revisit the more protracted wintry updates recently.

    We need a flip , but its looking unlikely...

    They’ve been pretty vague re the snowline - I doubt that will change.  I currently have the Scots safe and also a line n of around Carlisle to Newcastle.  we’re not talking 2010 freeze conditions but I am expecting anywhere n of this line to be seeing way more white than wet (potentially no wet) once we get past the back end of this week.  

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
    12 minutes ago, bluearmy said:

    this chart from the gfs 00 op so not to be analysed low down too far into the distance.  It’s specifically at 60N.  The ssw reverse flow showing at 10hpa out to around the 25th - obviously you can see from the ec chart you showed for the whole globe that above 60N the reversal gains traction right down trop (the neg AO the solid response)  

    the flow must be a global return at 60N which makes it tough to over analyse. We dont know where the positive and negative flows will establish. I have ringed two areas where surface flows are negative and these reach up into the 500hpa area where we need to see them.  The overall global flow at 500hpa is not reversed but it very weak. That’s likely to give us a better chance but I just think it’s more a case of pot luck without decent amplification establishing in the right place and sustaining for a period ..
     

    image.thumb.png.6da5b03ce4e1473d00cfb770bead6023.png

     

    image (2).png

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    Posted
  • Location: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany
    11 minutes ago, bluearmy said:

    this chart from the gfs 00 op so not to be analysed low down too far into the distance.  It’s specifically at 60N.  The ssw reverse flow showing at 10hpa out to around the 25th - obviously you can see from the ec chart you showed for the whole globe that above 60N the reversal gains traction right down trop (the neg AO the solid response)  

    the flow must be a global return at 60N which makes it tough to over analyse. We dont know where the positive and negative flows will establish. I have ringed two areas where surface flows are negative and these reach up into the 500hpa area where we need to see them.  The overall global flow at 500hpa is not reversed but it very weak. That’s likely to give us a better chance but I just think it’s more a case of pot luck without decent amplification establishing in the right place and sustaining for a period ..
     

    image.thumb.png.6da5b03ce4e1473d00cfb770bead6023.png

    And thanks again, BA.

    What more to say than a classical: "More runs needed" 🙂

    The only thing you and me are shownig at long last are the uncertainties of mid-term (not to speak about mid-to-long-term) predictions atm.

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    Posted
  • Location: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany
    6 minutes ago, feb1991blizzard said:

     

    image (2).png

    Well, it can't last forver, though. That's just plain physics of reaction and counterreaction I would say.

    Lets just wait and see, M-R-N 🙂

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    Posted
  • Location: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany

    EC 00z Scenarios

    spacer.png  spacer.png  spacer.png  spacer.png

     

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    Edited by Vikos
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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
    15 minutes ago, Vikos said:

    And thanks again, BA.

    What more to say than a classical: "More runs needed" 🙂

    The only thing you and me are shownig at long last are the uncertainties of mid-term (not to speak about mid-to-long-term) predictions atm.

    I disagree. We can look at the models and decipher them even if it is only to rule out options. For instance the d12 gefs and mean:

    gens_panel_zcp8.png 1594213058_gensnh-31-1-288(2).thumb.png.190520b21ef5a076cf03584cc9268837.png

    We can look at the mean and see there is nominal chance of upstream amplification for the UK's benefit. Check the gefs to confirm that is a sufficiently high cluster (100%) and be relatively confident that by d12 we will not be seeing any Atlantic amplification.

    What does that leave us? Likely a flatter pattern as the mean suggests? So I would surmise that from d8-d12 there is a block and we are sitting within a westerly regime confined within those "invisible walls" waiting for the theme to change? That is as far as I would go, though I suspect that even if at d12 the pattern relents, it will take a few days for a worthwhile improvement for our regime.

    Edited by IDO
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    Posted
  • Location: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany
    18 minutes ago, IDO said:

    I disagree. We can look at the models and decipher them even if it is only to rule out options. For instance the d12 gefs and mean:

    gens_panel_zcp8.png 1594213058_gensnh-31-1-288(2).thumb.png.190520b21ef5a076cf03584cc9268837.png

    We can look at the mean and see there is nominal chance of upstream amplification for the UK's benefit. Check the gefs to confirm that is a sufficiently high cluster (100%) and be relatively confident that by d12 we will not be seeing any Atlantic amplification.

    What does that leave us? Likely a flatter pattern as the mean suggests? So I would surmise that from d8-d12 there is a block and we are sitting within a westerly regime confined within those "invisible walls" waiting for the theme to change? That is as farb as I would go, though I suspect that even if at d12 the pattern relents, it will take a few days for a worthwhile improvement for our regime.

    I personally am against mean charts after d4 as the get too diffuse. I will try to specify why:

    The advantage of the ENS mean is purely statistical and must be understood as such. From a synoptic point of view, however, averaged maps show unreal situations. This becomes immediately clear to you when you imagine a bifurcation (and every deviation, no matter how small, is in principle the beginning of a bifurcation). Both branches develop on the basis of calculations of physical driving forces and reflect physically real scenarios in the calculated state space. But if one determines a mean from both, this yields points (in the state space) that have a physically indeterminate or non-evident history and in principle can even be impossible themselves. This also corresponds to the effect that averaged maps seem somehow unreal (for the synoptically trained eye). And then there is another very nasty effect: in error calculations, quadratic error sums are evaluated. Large differences are therefore particularly pronounced. It is similar with correlation. However, the averaging irons out these differences. In terms of quantity, the pretense of a forecast quality that is not even given because the averaged maps only reproduce the spatial details with low accuracy.

     

    Main run + control + ens = low variance -> rel. reliable prediction or fundamental error in the model

    Main run + control same; ens scatter heavily -> ens are negligible (however sensitive weather conditions) main / control show direction unless fundamental errors

    Main run sole runaway control + ens together -> either anticipation of the main run ) or problem in a higher resolution ("mother of all outliers")

    As a result, the Ens can never (apart from the resolution errors) come close to the main run in terms of quality, because disturbed initial conditions and worse resolved. You can only test the main run for quality and safety (if you disregard fundamental model errors). If an Ens applies, it is usually a coincidence (exception: disturbed initial condition is not irrelevant in the actual in the model) This also applies to the mean value as well as the Ens mean value. One can only speak of a "trend" here if everyone agrees. Only then can the Ens mean value be used.

    Hope you get my point... 🙂

    Edited by Vikos
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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

    The mean is a determination of certainty and uncertainty so they are indeed very useful.

    We will agree to disagree.

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    Posted
  • Location: Leicester
  • Location: Leicester

    Horribe terrible mean at 240 hours and after!!!we are in a westerly flow across the uk and pure boredom!!!!!wake me up when something interesting turns up😴!!!

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    1 hour ago, Scandinavian High. said:

    Is there any chance of high pressure setting up over Scandinavia put us in a proper freezer I say this because have seen 0 snow this winter 

    I believe yes. Many models are hinting at a cold surface high (not a strong upper high) with a flow close to Scotland. Not a big jump to a southerly tracking jet pushing the lows just to our south whilst air over the top is sourced from the east via a surface Scandi High, or Scandi/Russian wedge. Not saying this is the likely way forward but imo it's in the mix.

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    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

    Big three for next Friday, cold air being drawn down from the north, you'd think there would be snow snow showers into Northern island and Scotland with some snow also in England. This sets up the cold airmass over the entire UK. No Beast from the East but cold.

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    Snowfall chances begin Thursday, and on Into the weekend, any Atlantic systems trying to push in would give the risk of frontal boundary snowfall on the northern side.

    (GFS ppn charts, just to give an idea, not to be taken literally)

    Thursday

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    Friday

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    Saturday

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    Long way off still but I have next weekend in the diary for a snowfall "event" in the heart of the uk.

    GEM ...JFF

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    Posted
  • Location: Banbury
  • Weather Preferences: Deep Deep Snow causing chaos
  • Location: Banbury

    I'd take that NOW Chris 

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    8 minutes ago, sheikhy said:

    Horribe terrible mean at 240 hours and after!!!we are in a westerly flow across the uk and pure boredom!!!!!wake me up when something interesting turns up😴!!!

    GEFS seems keen on a pulse of heights between D9-D11 perhaps knocking the jet back north temporarily, but the jet generally returns south D12-D15.

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    Posted
  • Location: Bournville Birmingham
  • Weather Preferences: Hot n cold
  • Location: Bournville Birmingham
    10 minutes ago, sheikhy said:

    Horribe terrible mean at 240 hours and after!!!we are in a westerly flow across the uk and pure boredom!!!!!wake me up when something interesting turns up😴!!!

    See you in April then

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    Afternoon lovely peeps 😊

    Hope everyone is keeping well and safe. Saw a little bit of snow early today here in Walthamstow NE London but it was gone back to rain before you could blink.

    I guess it's back to the drawing board. The models are hinting at a milder interlude this week, more specially for us down south whilst the northern parts stay cooler. Then towards the end of next week looks like a cooler or colder setup is being hinted with a NW airflow ( still chances for wintry precipitation the more north you go).

    from a Londoners point of view I have now discounted the next 2 weeks for getting anything severe or wintry. The writing seems to be on the walls, we down here more often do well in a E or NE wind flow setup and I don't see any hints of that yet.

    That still leaves 4 weeks of February and the first week of March (being really realistic) to still get a good pattern setup) so not is all lost yet.

    I think there has been far too much hype and expectation over these past weeks and say the least there was reason for it. We had a good NH profile with blocking in evidence and we were latching on to the help of the SSW. Up to this point to be blunt non have yet done us any real good in terms of severe cold. Saying this there is still time for change and things could flip all of a sudden, but I am just trying to be realistic. 

    The models are still flipping and  turning as I speak, we have seen this in the past two weeks. Whatever the weather has got in store for us for the remaining winter who knows. I hope we do see signs of some decent wintry setups soon. Time is with us at the moment but as each day from here that goes past now it's shrinking the thread of hope that we still hold on to.

    leaves me to say stay safe all and your families we always will live in that hope that maybe one day the jigsaw will fall in our favour.

    THE SEARCH FOR OUR WINTER ❄️ WONDERLAND CONTINUES 

    stay safe

    regards 😊😊😊😊

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    Posted
  • Location: frogmore south devon
  • Location: frogmore south devon
    16 minutes ago, sheikhy said:

    Horribe terrible mean at 240 hours and after!!!we are in a westerly flow across the uk and pure boredom!!!!!wake me up when something interesting turns up😴!!!

    tomorrow is another day

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    Posted
  • Location: County end Oldham 202 m Above sea level
  • Location: County end Oldham 202 m Above sea level

    Marco Petanga now suggesting model guidance is pointing to a milder second half of winter.

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