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Model output discussion 25th Jan - The final third of winter beckons..


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Posted
  • Location: st albans
  • Location: st albans
    1 minute ago, TEITS said:

    Reason why im not paying too much attention to the 0Z ECM at the moment is because of the lack of support from the other models. The key difference with the ECM is from +144 onwards when the high descends from the Arctic.

    Also I noticed someone mentioned a Scandi HP. There is a massive difference between an E,ly that develops from a developing high pressure over Scandi, than a high pressure that descends S from the Arctic into Scandinavia. The latter tends to be much colder as it pulls much colder uppers from the Arctic.

    And usually, Dave, dislodges a lobe of the vortex with it on its eastern flank which descends into the mid lats with it. generally stays over Russia/Ukraine but if lower heights can be pushed into the med then these can be advected west . Talking of lower heights into w Europe, the eps continue to deliver an envelope which covers most bases. 

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    Posted
  • Location: Cambridge, UK
  • Weather Preferences: Anything out of the ordinary!
  • Location: Cambridge, UK

    No sign of anything cold on the gfs ensembles yet....just alternating between cooler and milder with rain. ECM much more promising.

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

    ECM with a hint of potential this morning, as has been mentioned. 

    Also a split in mid strat developing at 150hpa 

    IMG_1827.GIF

    now I'm not sure if this is a result of the trophespheric pattern effecting the higher levels or a case of the disturbances higher up influencing the mid Strat which in turn is effecting the Troph. (Or it may just be a coincidence?) 

    But you can see the correlation with the ridge developing on both the mid strat and troph.

    IMG_1828.PNG

    IMG_1829.PNG

     

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    Posted
  • Location: st albans
  • Location: st albans
    7 minutes ago, chris55 said:

    ECM with a hint of potential this morning, as has been mentioned. 

    Also a split in mid strat developing at 150hpa 

    IMG_1827.GIF

    now I'm not sure if this is a result of the trophespheric pattern effecting the higher levels or a case of the disturbances higher up influencing the mid Strat which in turn is effecting the Troph. (Or it may just be a coincidence?) 

    But you can see the correlation with the ridge developing on both the mid strat and troph.

    IMG_1828.PNG

    IMG_1829.PNG

     

    Chris - 150hpa is very low in the strat and I can't recall when it didn't reflect what the 500 hpa trop output is showing 

    this mornings ec op shows a splitting trend  as high as 50 hpa by the end which is more notable and probably reflects trop wave 2 working up through the strat 

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    Posted
  • Location: Truro
  • Weather Preferences: winter and summer
  • Location: Truro

    GFS could be headed toward the ECM of hinting a scandi ridge at 138.  Certainly a step in the right direction.

    IMG_0989.PNG

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    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire
    1 minute ago, bluearmy said:

    Chris - 150hpa is very low in the strat and will always reflect what the 500 hpa trop output is showing 

    this mornings ec op shows a splitting trend  as high as 50 hpa by the end which is more notable and probably reflects trop wave 2 working up through the strat 

    Ok thanks for that nick, I'm still getting my head around how the strat/troph interact and still learning.

     

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
    20 minutes ago, bluearmy said:

    Chris - 150hpa is very low in the strat and I can't recall when it didn't reflect what the 500 hpa trop output is showing 

    this mornings ec op shows a splitting trend  as high as 50 hpa by the end which is more notable and probably reflects trop wave 2 working up through the strat 

    The wave 2 split goes higher than that Nick - look at 30 hPa

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    Posted
  • Location: st albans
  • Location: st albans
    1 minute ago, chionomaniac said:

    The wave 2 split goes higher than that Nick - look at 30 hPa

    I did see that but I'm a little concerned that the run in general may be a bit iffy - not sure another warmjng sub 30 c at 10 hpa post day 10 is due. Gfs less strong on that 

    however, the potential for a wave 2 induced lower and mid strat split is definitely growing 

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    Posted
  • Location: Erith. SE London/kent 40m asl
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Erith. SE London/kent 40m asl

    Here comes our Scandi high again.:)

    gfseu-0-264.png

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
    Just now, bluearmy said:

    I did see that but I'm a little concerned that the run in general may be a bit iffy - not sure another warmjng sub 30 c at 10 hpa post day 10 is due. Gfs less strong on that 

    however, the potential for a wave 2 induced lower and mid strat split is definitely growing 

    I am tracking the 6ZGFS (out to day 9 so far) and it is definitely heading the same way so perhaps the ECM is not an iffy run. A split here will give the best potential for something really cold later down the line imo. But all ifs and buts. 

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    An interesting trend developing in both the ECM and GFS 06hrs run but theres one thing getting a high to the e/ne and another for that to get far enough west to effect the UK. That PV lobe in Canada needs to move further nw otherwise its likely to be another close but no cigar outcome.

    We've had enough of those this winter so need to see westwards corrections if this trend remains.

     

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    Posted
  • Location: Erith. SE London/kent 40m asl
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Erith. SE London/kent 40m asl

    All upgrades in the last 24hrs, trend?

    gfseu-0-324.png

    gfseu-1-324.png

    gfseu-2-324.png

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    Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl
    3 minutes ago, snowray said:

    All upgrades in the last 24hrs, trend?

    gfseu-0-324.png

    gfseu-1-324.png

    gfseu-2-324.png

    Who needs a cigar?

    I'll settle for that.

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    Posted
  • Location: Erith. SE London/kent 40m asl
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Erith. SE London/kent 40m asl

    Yes I would almost be ready to say bank, short cold spell and country wide snow event looking possible there. But is there more to come I wonder?

    Upgrades around day 7/8 would be nice, closest we get to the split PV is around that time on this run.

    gfsnh-0-192.png

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    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire
    38 minutes ago, chionomaniac said:

    The wave 2 split goes higher than that Nick - look at 30 hPa

    Hey chino 

    what is the difference between a wave 1 and wave 2 break, is it simply geographical location? 

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    Posted
  • Location: Chessington, Surrey
  • Weather Preferences: Snow, Hot and Sunny but not opressive
  • Location: Chessington, Surrey
    28 minutes ago, snowray said:

    All upgrades in the last 24hrs, trend?

    gfseu-0-324.png

    gfseu-1-324.png

    gfseu-2-324.png

    Here we go again , buckle in folks . We may win the raffle this time . Let's face it everyone else has a prize it's about time we have one too.

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    Posted
  • Location: Cyprus and North east Swindon. 104 ASL
  • Location: Cyprus and North east Swindon. 104 ASL
    3 minutes ago, chris55 said:

    Hey chino 

    what is the difference between a wave 1 and wave 2 break, is it simply geographical location? 

    I thought it was 2nd bite of the cherry, second warming causes wave 2 break? 

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    Posted
  • Location: st albans
  • Location: st albans
    6 minutes ago, chris55 said:

    Hey chino 

    what is the difference between a wave 1 and wave 2 break, is it simply geographical location? 

    There must be something on the nw site re this chris - perhaps the first page of the strat thread?

    anyway, wave 1 will be driven by one wave  (usually from one big ridge ) whereas wave 2 requires two ridges ( see upcoming trop pattern with big n Pacific and scandi ridges into the polar field) 

    these waves can be driven from the trop upwards or the strat down 

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    Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

    After a few days not looking at the models, sure enough I've come back to find a few chinks of interest among this rather boring pattern we now find ourselves in.

    First point of interest on the GFS 06Z showing little lows going increasingly south, this one along the channel. Probably too mild for snow in the south but maybe where winds are lighter further north, room for snow from evaporative cooling with uppers around -2/-3.

    Then, after another unseasonal low passed around the 7th/8th, a final budge down into Europe with easterlies coming in over the top. Uppers aren't particularly impressive, and the later this happens into February the colder the uppers will need to be, but it's a good start and much more like what I'd expect at this time of year.

    h850t850eu.png h850t850eu.png

    Then there's this chart from the ECM which I quite like as it shows us sandwiched between a polar blast to the west or a continental blast to the east. One will eventually give as that low over the UK peters out.

    ecmt850.240.png

    So the models aren't completely devoid of interest in my relatively amateur eyes however it does seem we will unfortunately have to endure a rather autumnal and some times mild damp/wet and windy week before something more interesting is likely to verify.

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
    10 hours ago, chris55 said:

    Hey chino 

    what is the difference between a wave 1 and wave 2 break, is it simply geographical location? 

    It's to do with how many planetary waves are affecting the vortex at any one time. If there is only one wave affecting the vortex then we call that wavenumber 1 and this will displace the vortex. Imagine a balloon blown up - if you put 1 finger of pressure on that balloon then you will distort it into a more banana like shape - akin to a wave 1. For wave 2, put 2 fingers of pressure on the balloon on opposite sides and you will achieve an '8' shape - with a split down the middle.

     

    So that is what we are seeing with the strat vortex - here is the classic wave 1 displacement

    gfs_z10a_nh_23-1.png

     

    And late in the run we see the pinching effects that wave 2 brings

     

    gfs_z10a_nh_61.png

    Technically, the waves don't need to be geographically based, but in reality they tend to be Atlantic or Pacific based because of the position of land masses and mountain ranges.

    Charts courtesy of weatherbell

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    Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

    The GFS 6z shows some pretty wild weather for next weekend as a group of Low's wisp in off the Atlantic bringing gales for the South before they track North, Cold enough for sleet/snow showers over the spine of the UK and Scotland.

    a.pngb.pngc.png

    It goes with-out saying there is certainly some cold options cropping up in the models as we head into February as the Strat warming gains momentum , As per last few frames of GFS with a N/E/East flow.

    d.png

     

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    Posted
  • Location: Waddingham, Lincolnshire. (9m asl)
  • Weather Preferences: Anything newsworthy, so long as it's not in the Daily Express
  • Location: Waddingham, Lincolnshire. (9m asl)
    21 minutes ago, chionomaniac said:

    It's to do with how many planetary waves are affecting the vortex at any one time. If there is only one wave affecting the vortex then we call that wavenumber 1 and this will displace the vortex. Imagine a balloon blown up - if you put 1 finger of pressure on that balloon then you will distort it into a more banana like shape - akin to a wave 1. For wave 2, put 2 fingers of pressure on the balloon on opposite sides and you will achieve an '8' shape - with a split down the middle.

     

    So that is what we are seeing with the strat vortex - here is the classic wave 1 displacement

    gfs_z10a_nh_23-1.png

     

    And late in the run we see the pinching effects that wave 2 brings

     

    gfs_z10a_nh_61.png

    Technically, the waves don't need to be geographically based, but in reality they tend to be Atlantic or Pacific based because of the position of land masses and mountain ranges.

    Great, informative post Chiono. Based on that forecast, would be interested to know if and what blocking might prevail thereafter. 

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

    FebruaryPhase5gt1500mb.gif FebruaryPhase6gt1500mb.gif

    Just thinking briefly about how much the more active phase 5 MJO that ECM is going for might be influencing it's wave-2 projections. The composite for that on the left suggests some support for W-Asia height rises and a more disrupted Atlantic jet pattern so there may be something in that. On the other hand, the usual model biases may be at play; GFS too flat and ECM too amplified, with the reality likely to be somewhere in between.

    Any improvement on GFS is noteworthy though given that it already looks quite reasonable at 10 hPa by day 15... it may be far away in time but the seeds are sown much earlier on.

    Regardless of level of impact while in phase 5, continuation to 6 would make for an interesting period if we had a big block to the NE before that time, though all these composites are only loose guides given the potential influence of many other variables.

    These may only be possibilities, but at least they're nicer than some that we've been having to contemplate in recent times :)

     

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    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.
    1 hour ago, bluearmy said:

    There must be something on the nw site re this chris - perhaps the first page of the strat thread?

    anyway, wave 1 will be driven by one wave  (usually from one big ridge ) whereas wave 2 requires two ridges ( see upcoming trop pattern with big n Pacific and scandi ridges into the polar field) 

    these waves can be driven from the trop upwards or the strat down 

    I don't know if it is mentioned in the first page or not but this question asked many times over the years. There is a good explanation in a specific thread in the learners section. Unfortunately some of the visuals are missing. Maybe an idea to link this in the opening post of the strat thread.

     

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    Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire

    It wouldn't surprise me if a block to our north east develops more rapidly than what the models are currently showing. The models are clearly sniffing this out but I have a feeling that they are a little behind the game. Don't be surprised if tonight's 12z runs show a scandi high in the 7 day timeframe :)

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