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Model output discussion - Jan 3rd onwards


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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
    5 minutes ago, Cavehill Snow said:

    Just trying to learn, a few questions if I may:-

    Has the trop been uncoupled from the strat so far this year, or has the trop been leading the strat?

    If the stat is not leading the trop at time the time of SSW occurence, can the trop lead the response on this?

    TIA

    I am no expert but once the strat imprints on the trop which it should do with a SSWE then the trop will be guided by the strat within reason. How long for the coupling is difficult, Twittersphere talking from a qtr to Feb. 

    No strat-trop connect this winter so far; so we have avoided that zonal spell that kills our winters.

    The trop has certainly affected the strat with up-welling of waves (Ural) and that is arguably the main effect the trop can inflict on the strat; that being the causal link for the SSWE.

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    A seasonal absentee by-stander in all this - but a one-off offering from me. Its a pity that this post is getting taken apart in some quarters, because hypothetically it *could* promote some inte

    LOL, the only time I tend to interact with SL is to offer a different point of view, so I definitely would not report on his thoughts. Jeez he was still at school when I was monitoring the strat. 

    Been very busy but wasn’t a bad time to be away for a couple of days. Call a spade a spade - got next week wrong. Thought amplification would see off the impact of the displacing vortex given such wea

    Posted Images

    Posted
  • Location: Glasshouses HG3
  • Weather Preferences: Snow upon snow upon SNOW!!!
  • Location: Glasshouses HG3

    Once you pop n all that!...😂

    tentertive signs of a 2018 magnitude SSW event being hinted at now by some of the weather wise big dogs...

    my present puzzlement...

    if back in 2018

    SSW was modelled around 13th Feb...

    BFTE Pounced 25th/26th Feb...

    this would have been back end of winter...

    so...

    if SSW is picked up (maybe gfs?) in the next couple of days say 6th/7th Jan...

    Would BFTE pounce around 15th-20th Jan?...

    more mid winter perhaps?...

    colder average temps etc= BIGGER BFTE???

    again lots of ifs and buts...

    if it’s anything to go by I was based in Leeds during 2018 and yes it was great and lengthy but very choppy off and on affair that didn’t seem overly magical at the time...

    was still great though 🤘🏻☃️🤘🏻

     

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    Posted
  • Location: Ponteland
  • Location: Ponteland
    22 minutes ago, MATTWOLVES said:

    Interesting early developments..could be some wintry showers focused towards the SE and the NE on Tuesday...some of these could get well inland also,so a few surprises in some areas for sure.. I would say areas to the far SW And West more likely to stay dry..But perhaps it would be best to focus on the Radar tomorrow.

    Bit of an update regarding SSW..Temps have now increased a further 44C during the last couple of days..we now have the effects percolating downwards,we now await for wind reversal to percolate down. GFS 6Z seems to be hinting at a MAJOR warming event and it could be declared later today. And according to Judah Cohen it looks on a similar magnitude to the 2018 event....fingers crossed.

    Eq4jy-GXMAA9Eoo.jpeg

    Eq4jzSBXAAAtAah.jpeg

    Eq4n3hjXUAACGfq.jpeg

    Thanks Matt, I enjoy reading your balanced posts, we will all have to hold our breath so to speak and hope the dice fall in our favour.

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    Posted
  • Location: st albans
  • Location: st albans
    50 minutes ago, bluearmy said:

    Maybe at 10hpa (marked 1) 

    bit the reversal clear downwells into the polar field though the area marked 2 shows a small area of positive flow around 12/15 m/s 75N which persists right out until the end of the run 
     

    image.thumb.png.137551b7f2ac97aae10d09e5224666dd.png

     

    The charts for the 06z show way more reversed flow in the lower strat/upper trop polar field days 5-13 

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    Posted
  • Location: Rotherham, East Dene
  • Location: Rotherham, East Dene
    33 minutes ago, bluearmy said:

    Answer to question 1 is ‘yes’

    answer to question 2 is ‘mainly yes’

    answer to question 3 is unknown but with a reversal ongoing and working its way down, the trop will do well do maintain its prevalence...... it could be that the downwelling does not affect the trop over the next six weeks but given the current set up, that looks unlikely 

     

    2018 we had the same questions.

    Look back at the thread people were questioning the downwelling response. After 15 days we got our response and the rest was history.

    I think theres an element of undue worry atm but they dont all come to the surface on the flipside

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    Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.
    12 minutes ago, bluearmy said:

    The charts for the 06z show way more reversed flow in the lower strat/upper trop polar field days 5-13 

    Interesting. Any thoughts on why that might be? Are the models now starting to pick up actual starting data as the SSW kicks in, rather than forecasted starting data.

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

    To anyone who is interested in the differences of 06z/18z and MAIN runs 00z/12z  I strongly suggest to have a look here

     

    WWW.METCHECK.COM

    Metcheck.com - GFS GDAS Information - How much observation data went into this GFS run? Latest run and archive information. Updated every 6 hours.

     

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

    Interesting. Any thoughts on why that might be? Are the models now starting to pick up actual starting data as the SSW kicks in, rather than forecasted starting data.

    06z/18z GFS runs have between 80-90% less (newest/fresh) air probe (weather ballon) data in their runs, but those are one of the main input data to have for proper trop/strat. prospects. They mainly use the data from previous runs wich is then kinda outdated and often leads to some furious outcomes the further the model is rendering.

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

    As await further developments on the effects of the ssw we are still looking quite cold over the next week.

    A glance here at the UKMO latest fax at T84 and raw T96 both off the 00z runs.We can see the cold front heading down the country with cold upper air either side.


    fax84s.thumb.gif.31faf093060f90b9a43c2ad2922bfe9e.gifUW96-7.thumb.gif.11eb5fb2375c7768d6f3a2636d366419.gif

    A decent chance of quite a few seeing snowfall especially further north before it starts to weaken on it's journey south.It looks like remaining quite cold after this into the week end as the high starts to ridge in.This would extend the cold spell to around 2 weeks so a decent period these days although i am fully aware many are still to see snow fall.Hopefully a few more get lucky by the end of this week.

    The warks gefs   

    graphe6_10000_270_95___.thumb.gif.f00c799217b74aa037e9d1b2f805a767.gif

    Currently gefs then show a trend upwards in temperatures next week as the Arctic air supply is cut off under high pressure.Indications of a quiet spell with  surface temps looking to head closer to normal and little precipitation in week 2.

     

     

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    Posted
  • Location: Netherlands
  • Location: Netherlands
    1 hour ago, TSNWK said:

    Interesting. Any thoughts on why that might be? Are the models now starting to pick up actual starting data as the SSW kicks in, rather than forecasted starting data.

    Perhaps it has to do with the number of vertical layers. When things come closer, that's less relevant. Just a guess.

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

    My own take on what seems likely to happen beyond the next 4-5 days or so. As ever using the 500 mb anomaly charts

    Monday 4 January 2021

    Monday 4 January 2021

    Ec-gfs and both fairly similar to 24 h ago, again no -/+ shown

    Noaa and it is fairly similar in eastern half but very similar in western half. One difference with ec and gfs is the trough-ridge in far west is a bit more pronounced

    From another source re ecmwf and its 10 day charts, see link below, and there is no doubt that it favours a backing of the 500 flow to a shade s of west over its 10 day period, moving slightly less cold 850 mb air towards the uk. At first glance this seems against the 6-10 day Noaa, however if we look at its 10-14 day chart it in fact fits quite well with this suggestion.

    http://www2.wetter3.de/Fax/00_ECMWF_ENS_p0_500hPa+144_240.gif

    So overall I would favour a lessening of the cold, such as it is currently, in the 10-14 day period. Beyond that, for me, it is wait and see, how these models develop over the next 5-10 days.

    Re 850 mb T, I would estimate from about -2 C now to perhaps +2 by 8-14 days?

     

     

     

     

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    Posted
  • Location: Netherlands
  • Location: Netherlands
    1 hour ago, snowking said:

    The answer really is, much as with tropospheric modelling at the moment, anything beyond T+120 should be taken with a huge great big snow shovel's worth of salt. The next two weeks, stratospherically, will involve models trying to resolve dynamics in an area of the atmosphere in which they don't necessarily have as good coverage as they would do in the troposphere (and we know how fragile tropospheric modelling can be at the best of times), trying to handle one of the more complex stratospheric events that I can recall seeing. We're already seeing that at less than 24 hours out even the model with the best stratospheric coverage, the ECMWF, has been underestimating the scale of the reversal at the top of the stratosphere and has been doing so consistently for some days now. So we are likely to see many twists and turns in the stratospheric modelling of our soon-to-be-declared SSW for many days yet.

    Ditto (and consequently) in the troposphere - we're likely to start seeing some pretty stark arctic heights modelled in the coming days and weeks and tropospheric modelling does not handle this particularly well either.

    I wonder how important is the difference  at 1 hPa -5 hPa.? 

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
    Just now, sebastiaan1973 said:

    Perhaps it has to do with the number of vertical layers. When things come closer, that's less relevant. Just a guess.

    All models start with actual data, there is then the ensemble output which gives the range of outputs. But no forecast data as such is input. Obviously the more vertical layers a model has then the more likely it may be to see what the actual data at the boundary between Troposphere and Stratosphere the more accurate the starting data is.

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    Posted
  • Location: Cardiff
  • Weather Preferences: Day 10
  • Location: Cardiff
    2 hours ago, Timmytour said:

    Regarding the SSW, is there any memory out here among the members of how dramatically the models shift in the event of one?   Or is it more a drip feed effect?  I can  imagine 10 day modelling changing quite a bit but then again it tends to do that on a frequent basis without any SSW  (especially when Narnia is in sight!). But has there been for example an instance of a Day Five view, with a broad agreement across all models, being shifted to such a degree that, by the day before it materialized, the models were in agreement of a completely different outcome for the same day ?

    The last one I followed went all over the shop and got it completely wrong

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    Posted
  • Location: Coventry
  • Location: Coventry

    Better amplification here from the icon early doors, allows the cold in from the North faster too. Could we see a spectacular last minute turn around? Probably unlikely, but let's see

     

    iconnh-0-90.png

    iconnh-1-90.png

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    Posted
  • Location: frogmore south devon
  • Location: frogmore south devon
    1 minute ago, Battleground Snow said:

    Better amplification here from the icon early doors, allows the cold in from the North faster too. Could we see a spectacular last minute turn around? Probably unlikely, but let's see

     

    iconnh-0-90.png

    iconnh-1-90.png

    looking good lets hope it picks up on a SSW

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    Posted
  • Location: Coventry
  • Location: Coventry
    1 minute ago, BARRY said:

    looking good lets hope it picks up on a SSW

    It blows the low up again further on but the Arctic heights are getting better in the earlier timeframe now. Intriguing stuff.

     

    iconnh-0-114 (1).png

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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
    50 minutes ago, johnholmes said:

    All models start with actual data, there is then the ensemble output which gives the range of outputs. But no forecast data as such is input. Obviously the more vertical layers a model has then the more likely it may be to see what the actual data at the boundary between Troposphere and Stratosphere the more accurate the starting data is.

    Well, only the starting data is actual data. +0h is actual data.
    However as the model progresses, the forecasted previous step will be the input for the next step and so on. Every development we see at +96, +144, +240 is the result not only of actual data, but actual data + forecasted 'data' in previous steps.

    So, having the reversal of zonal winds available as a measured phenomenon (and not only at the 'technical' SSW, but across the layers) instead of a forecast, should intuitively make the model outcome more reliable, right?

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    Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.
    4 minutes ago, Battleground Snow said:

    It blows the low up again further on but the Arctic heights are getting better in the earlier timeframe now. Intriguing stuff.

     

    iconnh-0-114 (1).png

    That still looks darn cold at surface for the bottom 2 3rd of our island and the NH profile is ripe for picking 🙂

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    Posted
  • Location: Buckinghamshire
  • Location: Buckinghamshire

    The showery rain falling in the southeast will continue until Wednesday as much as 25-30mm accumulating in a few places here, some of this may fall as a wintry mix at times over higher ground.. particularly the northwestern edge of this which may fall occasionally as a wintry mix to some lower levels possibly wet snow occasionally on higher ground such as the Chilterns most likely tomorrow but depending on how northwest some of that showery rain gets.

    EUROPE_PRMSL_12.thumb.jpg.4cc52b4cee7dfd887191c2fe9fddadd0.jpg

    EUROPE_PRMSL_54.thumb.jpg.4398a6f44cb88186fa5ff42076de6ab1.jpg

    EUROPE_PRMSL_102.thumb.jpg.43b1230999e5b030ab7c1883509dbfde.jpg

    Rainfall..

    1269471650_EUROPE_PRMSL_RAIN_12(2).thumb.jpg.c5b21e2d35fff14f962954599833e65e.jpg

    2087158945_EUROPE_PRMSL_RAIN_30(2).thumb.jpg.9dc0ec2a7caedd0588f6bd255db5f667.jpg

    335124531_EUROPE_PRMSL_RAIN_72(4).thumb.jpg.cd47e0a89a4922da694945ee3aab77cc.jpg

    Arpege..

    06_12_ukpreciptype.thumb.png.8c2b606d8e34c068544369177773d37f.png

    06_28_ukpreciptype.thumb.png.a75bfdf94e02abc4a051b518eea7844b.png

    06_41_ukpreciptype.thumb.png.e57da59e81c43b8d50f33974b628cd3b.png

    06_54_ukpreciptype.thumb.png.b3e9a62f0cfe6a61e07bd31d9ca03cd1.png

     

    Wintry showers in mainly Northeastern areas continue.. then by Wednesday night into Thursday a band of rain moves southeast into northern ireland and scotland perhaps falling as snow to lower levels here with a few cm's possibly accumulating and over hills in scotland as much as 10-15cm is possible too.. some of this may reach down into more Central parts of England later Thursday.. but weakening giving patchy light sleet and snow also patchy outbreaks of rain and sleet may move into Eastern England briefly too on Thursday but mostly dry elsewhere but cold.

    06_70_ukpreciptype.thumb.png.e52944693ee947d57ed14e1d1a19cd1a.png

    Winds from a northerly at the end of the week then turning northwesterly by the end of the weekend and becoming less cold although still the chance of wintry showers, some weather systems may bring milder air and bands of rain west to east next week particularly for the north but high pressure to the west of the uk with another probably short lived northerly wind too seems likely atm at some point next week for most with further wintry showers.

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    Posted
  • Location: Brighton, East Sussex
  • Location: Brighton, East Sussex

    Whoever decided to release the ICON before all the other models is a marketing genius 😂 

    Certainly some differences between this morning and this afternoons ICON, more forcing on the Low and an increase in pressure around southern GL, most important those low heights over Europe might serve to stop the high sinking back over us.

    5863A8C4-294C-4831-8B8E-B27B7C8BAD3C.png

    73B6AF2B-5DA8-4692-8EE2-7B544677AF2C.png

    Edited by Weathizard
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    Posted
  • Location: oldham
  • Location: oldham
    2 minutes ago, Weathizard said:

    Whoever decided to release the ICON before all the other models is a marketing genius 😂 

    Certainly some differences between this morning and this afternoons ICON, more forcing on the Low and an increase in pressure around southern GL, most important those low heights over Europe might serve to stop the high sinking back over us.

    5863A8C4-294C-4831-8B8E-B27B7C8BAD3C.png

    73B6AF2B-5DA8-4692-8EE2-7B544677AF2C.png

    Big changes 

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    Message added by Paul,

    Please stick to discussing the model output in this thread. For more general chat , please use the winter/cold weather/snow chat, banter, moans and ramps thread

    For local cold/snow and weather related chat, please head over to the Regional Area.

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