Jump to content
Cold?
Local
Radar
Snow?

Model Output Discussion - cold spell to end Autumn


Recommended Posts

Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

    06z GFS keeps the secondary low dropping SE on Sunday completely separate from the parent low wallowing around the Norwegian Sea further north, hence it has its 'freedom' to wander further south on this run. Look at the frames on the EC and UKMO det. run and Sunday's slider low merges with the low to the north (which loses its identity eventually) - perhaps this merger with the other low tending to pull it on a more northerly track than GFS.

    The tracking of this low wouldn't normally be so fixating if there wasn't cold air entrenched before it arrives! My money's on a more northerly track like the 00z, but I would love to be proved wrong!

    Edited by Nick F
    • Like 6
    Link to post
    Share on other sites
    Spotted a post you think may be an issue? Please help the team by reporting it.
    • Replies 5.7k
    • Created
    • Last Reply

    Top Posters In This Topic

    Top Posters In This Topic

    Popular Posts

    You know what - I havent seen 1 hopecast on here. People have put all their points of view across in a pretty good mannor- infact its been pretty good debate. The only post that sticks out a mile

    Still coming slowly off a cautious fence Long term total global atmospheric angular momentum trends can tell you a lot about pattern changes due to the effects the rises and falls in global wind-

    Afternoon All - A frantic few days on here with pages & pages of posts flying through in a matter of hours- I think we have 2 main discussion points at the moment-  1) The short to

    Posted Images

    Posted
  • Location: Horwich, Bolton
  • Weather Preferences: Heavy snow.. frost. Freezing fog
  • Location: Horwich, Bolton
    8 minutes ago, Singularity said:

    Alright, no need to scream :laugh:

     

    gfsnh-0-174.png?6 gfsnh-0-180.png

    At this range the details are of little concern but it is of note how the Pacific ridge is not as sharp on this run (left chart) which increases the risk of the Canadian trough breaking loose. On the other hand, the seed for the deep trough is shallower and more stretched out which makes me wonder if that will evolve into such a 'pushy' system.

    Given the 00z ECM this is just speculation with respect to this particular run (for the fun of it, if I'm honest!).

    PV looking very angry over Eastern Canada & Western Greenland 

    Link to post
    Share on other sites
    Posted
  • Location: Wombwell, South Yorkshire (75m / 246ft ASL)
  • Weather Preferences: Summer Sunshine / Winter Snow
  • Location: Wombwell, South Yorkshire (75m / 246ft ASL)
    10 minutes ago, bluearmy said:

    We are now within the timeframe (T120) where the ops verify better than the ens mean on heights. 

    But the eps running at 14km are a very good tool compared to a few years ago 

    i am intrigued by the second feature which is now consistently modelled to approach on a more west to east basis rather than sliding or diving 

    I take it that is not such good news in terms of prolonging this cold spell?

    Link to post
    Share on other sites
    Posted
  • Location: HILL OF TARA IRELAND
  • Weather Preferences: SNOW ICE
  • Location: HILL OF TARA IRELAND
    2 minutes ago, Steve Murr said:

    Morning -  I see yer more drama on the 06z ... Time after time its 'South west'... yet   Some members still question why some of us document in advance the reasons why-

    The models are now 'resolving' the visibility of the ridge that sits to the south of iceland at T96 that little 'sausage' is becoming more & more apparent which is in turn increasing the trough disruption & track-

    The low is elongating so much that we are now also beginning to lose the onshore flow that for the S/SW & SE is the killer

    here side by side is the 18z V 06z

    IMG_2188.thumb.PNG.ad871859e66c30d1da4a7c904b942654.PNGIMG_2187.thumb.PNG.bf37390bf3d38c72cc8603b55f05561b.PNG

    you will now the negative tilt & south Easterly flow on the 06z v the more positive 18z ...

    Its all getting rather interesting... 

    Wales > Cotswolds in the £££ seat or just the hills in Devon if it holds true to form & history!!

    S

    I see from 06z could big a big surprise over here:)

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

    Looks like a whole week characterised by 'marginality' - which, lo-and-behold, is an actual word...So why 'zonailty' isn't is a bit of a mystery: 

     

    h850t850eu.png

    Link to post
    Share on other sites
    Posted
  • Location: HILL OF TARA IRELAND
  • Weather Preferences: SNOW ICE
  • Location: HILL OF TARA IRELAND

    It's the north westerly train not the zonal 

    South westerly.:)

    Link to post
    Share on other sites
    Posted
  • Location: leicester
  • Location: leicester
    13 minutes ago, Nick F said:

    06z GFS keeps the secondary low dropping SE on Sunday completely separate from the parent low wallowing around the Norwegian Sea further north, hence it has its 'freedom' to wander further south on this run. Look at the frames on the EC and UKMO det. run and Sunday's slider low merges with the low to the north (which loses its identity eventually) - perhaps this merger with the other low tending to pull it on a more northerly track than GFS.

    The tracking of this low wouldn't normally be so fixating if there wasn't cold air entrenched before it arrives! My money's on a more northerly track like the 00z, but I would love to be proved wrong!

    Nick everything has moved south!!this is what i mentioned last night!!even the midlands could get lucky at this rate to even get any snow at all!!

    Link to post
    Share on other sites
    Posted
  • Location: .
  • Location: .
    22 minutes ago, snowray said:

    Big shift south on the ICON 06z, not as far south as GFS but close. ICON tends to follow the ECM idea by the way. Here are the two PPN charts, 00z and 06z for comparison.

    icon-0-120.png

    icon-2-120.png

    icon-2-126.png

     

    Indeed. It's worth bearing in mind that whilst marginality is nail-biting, it's also historically the setup that produces the heaviest snowfalls.

    I'll wager that many of us on here would prefer to see boundary snow events, which occasionally over step the mark only to re-load from the north than endlessly bone dry cold days like February 1986? The winter which stands out for me is 1978/9 when we had prodigious snowfalls from occasionally precarious setups.

    • Like 6
    Link to post
    Share on other sites
    Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

    Morning

    Seems "slider gate" has kept the headlines again today!So not seen much comment on the gulf between gfs and ecm be it at 240hrs? ?? Looks huge imo and ecm looks unlike the 6z gfs keeping the colder theme going

    Sorry if I seem off topic:hi:

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Weston-Super-Mare, North Somerset
  • Weather Preferences: Thunderstorms in the summer, frost fog & snow in winter.
  • Location: Weston-Super-Mare, North Somerset
    33 minutes ago, ICE COLD said:

    I'm liking the 6z moving the snow boundary south . Means I'm gonna get some snow in Hertfordshire. Like people have said it will probably miss all together . 

    IMG_0725.PNG

    Beautiful chart that, just a little more correction south and west would be even better although  as others have mentored on here these 'sliding' lows often do correct sw nearer the time.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
    14 minutes ago, Steve Murr said:

    Morning -  I see yer more drama on the 06z ... Time after time its 'South west'... yet   Some members still question why some of us document in advance the reasons why-

    The models are now 'resolving' the visibility of the ridge that sits to the south of iceland at T96 that little 'sausage' is becoming more & more apparent which is in turn increasing the trough disruption & track-

    The low is elongating so much that we are now also beginning to lose the onshore flow that for the S/SW & SE is the killer

    here side by side is the 18z V 06z

    IMG_2188.thumb.PNG.ad871859e66c30d1da4a7c904b942654.PNGIMG_2187.thumb.PNG.bf37390bf3d38c72cc8603b55f05561b.PNG

    you will now the negative tilt & south Easterly flow on the 06z v the more positive 18z ...

    Its all getting rather interesting... 

    Wales > Cotswolds in the £££ seat or just the hills in Devon if it holds true to form & history!!

    S

    Brings back memories of the Jan 2013 'wedge' which I seem to recall you were expecting to become more influential and with good success :)

    This cut-off ridge in this case is so closely entwined with the way the trough shapes up in the first place, though, that I'm not sure which is leading the other. One could side with the upstream dictating the downstream but I have see these ridges also be influenced by Arctic Highs (and a strong one is in the frame on this occasion...) plus lower-stratospheric patterns (not sure about this one - anyone got charts at 100 hPa? TIA).

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire
    16 minutes ago, Steve Murr said:

    Morning -  I see yer more drama on the 06z ... Time after time its 'South west'... yet   Some members still question why some of us document in advance the reasons why-

    The models are now 'resolving' the visibility of the ridge that sits to the south of iceland at T96 that little 'sausage' is becoming more & more apparent which is in turn increasing the trough disruption & track-

    The low is elongating so much that we are now also beginning to lose the onshore flow that for the S/SW & SE is the killer

    here side by side is the 18z V 06z

    IMG_2188.thumb.PNG.ad871859e66c30d1da4a7c904b942654.PNGIMG_2187.thumb.PNG.bf37390bf3d38c72cc8603b55f05561b.PNG

    you will now the negative tilt & south Easterly flow on the 06z v the more positive 18z ...

    Its all getting rather interesting... 

    Wales > Cotswolds in the £££ seat or just the hills in Devon if it holds true to form & history!!

    S

    Yes Steve :)

    its key to keep it cut off from the trough to the eas with that little wedge of high pressure more apparent on the 6z, keep it clean and you lose the warmer flow, and bring the snowrisk further south.

    IMG_2953.thumb.GIF.662073d107c005662ad0c655ded11418.GIF

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: st albans
  • Location: st albans
    1 minute ago, Kentish Snowman said:

    I take it that is not such good news in terms of prolonging this cold spell?

    Given the eps appetite to amplify the jet again I’m not convinced re the transition period at the moment on any model !!

     

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: New Ash green 150M / 500 FT
  • Location: New Ash green 150M / 500 FT
    18 minutes ago, chris55 said:

    Yes Steve :)

    its key to keep it cut off from the trough to the eas with that little wedge of high pressure more apparent on the 6z, keep it clean and you lose the warmer flow, and bring the snowrisk further south.

    IMG_2953.thumb.GIF.662073d107c005662ad0c655ded11418.GIF

    Yep happy with the local elevation here as well - 

    certainly not nailed yet- Just waiting for the 06z JMA etc not for definitive tracks but for all models to be making adjustments...

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    I see the slider continues to cause major drama!

    As Nick F just mentioned phase timing or no phasing with the trough to the east is critical, the normal effect of phasing is to pull the upstream system further north and east so no phasing or later phasing will alter the track.

    I wouldn't trust any output until the slider is within T72hrs range  because of that.

    Later on the GFS tries to flatten the pattern but  its view upstream isn't what NOAA expect, a blended solution with the ECM to address both biases should see the cold continue for longer.

     

     

    • Like 4
    Link to post
    Share on other sites
    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

    Rather surprised to see the GFS revert to a SW slider!!

    I also note that the latest JMA/ARGEPE, though not fully out yet, have adjusted by D3 slightly in favour of a more SWly slider.

    Steve M - I'm not sure the models always get the sliders wrong in this kind of set-up - I think they get them wrong more often when there is a better block directly to the E or NE. I thinking the outcome is more to do with whether the low to the E will phase with the slider low to the W, and if so, when. The ECM op phases them, the GFS 06Z doesn't. We'll probably see this resolved in the next 24 hours.

    Link to post
    Share on other sites
    Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

    To give some credibility to the 06z more southerly track for Sunday's low, the 00z GEFS stamps had a fair few southerly tracks for the low too

    gefs_stamps.thumb.png.effe9680635786518aee2e6b4bdcc48c.png

    Be interesting to see what the 06z GEFS stamps show too, though as others have said, the high res runs should be a better guide than the ens mean or clusters at only 5 days out. Though there are six EPS clusters as early as 00z Monday:

    ec-ens_nat_z500scenarios_2017120600_120.thumb.png.604a78d18bda91441fab3c21f393940b.png

     

    Edited by Nick F
    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Morecambe
  • Location: Morecambe

    Very nice too see the slider modeled further south and west, slightly surprised by that but this gives more room for error that at least somewhere across the UK will see some frontal snow on Sunday but its still far too early to nail down the details thats for sure.

    I don't think the ECM is that bad regarding the slider, very low thicknesses and a slack flow which results at least some places seeing some snow I feel despite the uppers looking a little underwhelming but all in all positive runs this morning imo.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: st albans
  • Location: st albans

    The number of eps clusters early on tells us that it’s pretty pointless second  guessing this 

    on the extended, the clusters reveal a binary evolution between a fairly zonal solution and more amplified with the more amplified cluster ending up with a distinct  ridge to our north and euro trough maintained (as much as one can see on the Icelandic output)

    • Like 3
    Link to post
    Share on other sites
    Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

    Ensembles have the first slider hitting pretty much anywhere in the British Isles, no pattern at all yet defined. One even misses the south completely while the rest have snowfests to marginal further south, west, east and north!

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Bedford, 30m asl
  • Location: Bedford, 30m asl

    gens-0-1-108.pnggfs-0-108.png?6

    Just to show the minute variance which makes all the difference, the low on the 6z control is about 5mb deeper, which helps to pull it a little further north and merge somewhat with the low to the north - net result is pretty good continuity with the median position of the potential snowfall from the 0z EPS (Wales, Midlands primarily, most of it to the north of the M4)

    Link to post
    Share on other sites
    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    22 minutes ago, Nick F said:

    To give some credibility to the 06z more southerly track for Sunday's low, the 00z GEFS stamps had a fair few southerly tracks for the low too

    gefs_stamps.thumb.png.effe9680635786518aee2e6b4bdcc48c.png

    Be interesting to see what the 06z GEFS stamps show too, though as others have said, the high res runs should be a better guide than the ens mean or clusters at only 5 days out. Though there are six EPS clusters as early as 00z Monday:

    ec-ens_nat_z500scenarios_2017120600_120.thumb.png.604a78d18bda91441fab3c21f393940b.png

     

    And look at just how evenly spread the ECM clusters are - only 10 in the biggest cluster, 6 in the smallest. All with different interactions between the lows to the NW and SW!

    This slider is absolutely not call-able yet.

    One thing in my mind though - troughs to the NE are often correcting a little further NE nearer T0 - such a trend might favour the SW route?

    Regarding longer term, there continues to be excellent continuity for 15-16 December with two-thirds of clusters a renewed Atlantic ridge by the 16th:

    ec-ens_nat_z500scenarios_2017120600_240.

    however, as BA alluded to, the less blocked solution becoming more evident between D12 and D15, up from 30% yesterday to 50% this morning. Still a very large cluster with a ridge to the north and potentially east ( @ShortWaveHell yes, this latter theme has been the most evident one in the past few ensemble runs, and interesting to hear Glossea going this way too)

    ec-ens_nat_z500scenarios_2017120600_288.  ec-ens_nat_z500scenarios_2017120600_360.

     

    Edited by Man With Beard
    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Mile Oak, 3 miles West of Brighton UK, 130 Meters above sea level
  • Weather Preferences: Anything Extreme
  • Location: Mile Oak, 3 miles West of Brighton UK, 130 Meters above sea level

    The same posters on here always trying to see what they want to and hopecast. 

    I have to chuckle when I see so much attention on one LP system, of course it's path is going to be modelled differently from run to run and I understand why so many people are interested, but the path is more or less clear..this will move pretty much straight across the UK from NE to SE cutting a thin sausage shaped wedge, Snow more likely from Wales in the West drawing a line to Lincoln in the East and anywhere North of that is in the firing line. 

     

    Those like me in the South really aren't going to get much out of this from Sunday onwards...those in the South and South West...your best chances of seeing snow is prior to Sunday, with Friday being your best opportunity and this has been consistently modelled for some time now. 

     

    prectypeuktopo.png

     

    If you like cold zonality and lots of rain then you're in for a treat next week, I really can't see how anyone see's it any differently ?

     

    prectypeuktopo.png

    As it usual from cold Zonality, N.Ireland, Scotland or NW England coastal areas are where you want to be. 

    If you want a UK wide snow event then you need an Easterly or a North Easterly and until that happens the majority of us on here are going to be in for a let down...personally I can't stand nothing worse than cold, strong winds and rain...and that's what most of us are going to see from this set up AFTER the weekend. 

     

    So enjoy what is to come from Thursday through until Monday IMO, but by all means feel fee to see what you want to and ignore what is actually being modelled

    • Like 2
    • Thanks 1
    Link to post
    Share on other sites
    Message added by Paul

    Please only post model discussion in this thread. 

    For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
    https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

    For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
    https://www.netweather.tv/forum/forum/142-regional-discussions/

    Thank you!

    Guest
    This topic is now closed to further replies.
    ×
    ×
    • Create New...