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Model output discussion - Jan 3rd onwards


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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire
    22 minutes ago, IDO said:

    The gfs goes full on zonal after d10 with a strong westerly flow. This does not tie in with what we have been told to expect so not sure what to make of it:

    anim_wze5.gif

    Absolutely feasible. Though I wouldn’t place much confidence in it. 
     

    With the ensuing SSW you’d hope for a more amplified pattern. 
     

    We will of course find out as the month progresses:) 

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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

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    Posted
  • Location: Aberporth S W Wales
  • Location: Aberporth S W Wales

    Some odd comments about zonality, there is nothing zonal about the ukmo 144 chart, yes, a relaxation of the colder uppers, but its not sinking any further, its waiting for a chance to ridge north again, habbit makes it hard not to factor into local preferences, so I speak for those in the west, and we will definately take this after the days on end of rain.

     

    UKMOPEU12_144_1-7.png

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    Posted
  • Location: Lucan Co Dublin
  • Location: Lucan Co Dublin
    1 minute ago, KTtom said:

    Some odd comments about zonality, there is nothing zonal about the ukmo 144 chart, yes, a relaxation of the colder uppers, but its not sinking any further, its waiting for a chance to ridge north again, habbit makes it hard not to factor into local preferences, so I speak for those in the west, and we will definately take this after the days on end of rain.

     

    UKMOPEU12_144_1-7.png

     

    yes you would think its the end of the world and of winter by some of the comments

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    Posted
  • Location: County end Oldham 202 m Above sea level
  • Location: County end Oldham 202 m Above sea level
    17 minutes ago, Harsh Climate said:

    Fair play you went against the grain and called what the ECM and UKMO are now showing. At least you still have your house 😂 

    I felt bad this morning saying as much mate.

    Hoping as many as possible see some snow this week though ...

    UKMO 850s keep the majority cold out to 144 so a solid colder phase nailed on..

    Let's see where we are in a few days, I have a feeling IDO s zonal express will be on a short journey but we will see...

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    Posted
  • Location: frogmore south devon
  • Location: frogmore south devon
    4 minutes ago, jacke said:

    An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

    you may be a lurker 

    but a talk a lot of sense which the doom mongers on this site should take heed 

     

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

    An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

    Yes I was there too but as much as I enjoy those memories they should be discussed elsewhere. 

    Just so we don't derail the thread. 

    Cheers. 

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    Posted
  • Location: Windsor
  • Weather Preferences: Snow and cold
  • Location: Windsor

    How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

    Anyone?

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    Posted
  • Location: SE London
  • Location: SE London
    1 minute ago, northwestsnow said:

    I felt bad this morning saying as much mate.

    Hoping as many as possible see some snow this week though ...

    UKMO 850s keep the majority cold out to 144 so a solid colder phase nailed on..

    Let's see where we are in a few days, I have a feeling IDO s zonal express will be on a short journey but we will see...

    We must take into account the warming of the surface easterly flow over the North sea. None of the medium term charts quantify this so I would take seemingly low 850s with a pinch of salt.

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    Posted
  • Location: County end Oldham 202 m Above sea level
  • Location: County end Oldham 202 m Above sea level
    1 minute ago, prolongedSnowLover said:

    How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

    Anyone?

    Above my Pay grade but I suspect there is no specific timeframe ...

     

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    Posted
  • Location: Irlam
  • Location: Irlam

     

    11 minutes ago, northwestsnow said:

     

     I have a feeling IDO s zonal express will be on a short journey but we will see...

    The GFS 12z op run looks an unsettled outlier amongst its ensembles, anyway at that stage

    GFSAVGEU12_276_1.png

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    Posted
  • Location: Whitefield, Manchester @ 100m
  • Location: Whitefield, Manchester @ 100m

    I actually like the UKMO. It dispenses with the messy scenario of the low coming down in the wrong location. It shunts it so far east that it will probably push a lot of cold down into Europe and leaves space for our high to build behind, handily supported by low heights to our south.

    Edited by Alexis
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    Posted
  • Location: Ventnor, Isle of Wight
  • Weather Preferences: Anything other than drizzle
  • Location: Ventnor, Isle of Wight

    The GFS is actually following all other models now with regards to showing a flatter more westerly flow in the latter stages. I know there is excitement re the SSW, but it was never guaranteed to go in our favour. Its easy to lose focus on the output and to get excited about events that haven't happened. Its really important to stay impartial and level headed in these types of setup. For the newer members, please look for consistency between models.  

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    Posted
  • Location: Irlam
  • Location: Irlam
    5 minutes ago, Weather-history said:

     

    The GFS 12z op run looks an unsettled outlier amongst its ensembles, anyway at that stage

    GFSAVGEU12_276_1.png

    Actually it looks as though GFS FI is trending towards anticyclonicity

    Friday 15th Jan on 18z ensemble mean chart

    GFSAVGEU18_300_1.png

    0z ens mean chart

    GFSAVGEU00_294_1.png

    06z ens mean chart

    GFSAVGEU06_288_1.png

    12z en mean chart

    GFSAVGEU12_282_1.png

     

    Maybe something to keep an eye on to see if this trend continues

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    Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth
    8 minutes ago, prolongedSnowLover said:

    How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

    Anyone?

    Happened in mid feb. Have a look in the archive charts for exact detail but from memory about two weeks. But this doesn’t mean this will be the same as all are unique.

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    Posted
  • Location: Cornwall
  • Location: Cornwall
    1 minute ago, Weather-history said:

    Actually it looks as though GFS FI is trending towards anticyclonicity

    Friday 15th Jan on 18z ensemble mean chart

    GFSAVGEU18_300_1.png

    0z ens mean chart

    GFSAVGEU00_294_1.png

    06z ens mean chart

    GFSAVGEU06_288_1.png

    12z en mean chart

    GFSAVGEU12_282_1.png

     

    Maybe something to keep an eye on to see if this trend continues

    What would this mean? Especially with the SSW going on?

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
    4 minutes ago, prolongedSnowLover said:

    How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

    Anyone?

    The SSW doesn’t have any direct impact on the 850s.  It has an impact on wind flows and positions of blocking patterns etc, which will in turn allow the normal weather in the troposphere to impact on the 850s.  That’s why it is uncertain whether we will go cold after a SSW, it depends where the dice fall.  But usually 2/3 of the time we do - and that is for any SSW.  With what we know about the state of the atmosphere at all levels coming into this, we can probably use Bayesian updating to modify this to 7/8.  I’m not going any further.  

    This chart explains why I think that, the NAM plot that shows the equivalent of the AO at all levels of the atmosphere.  It is negative everywhere from the SSW onwards.  This is why there won’t be ‘flushing down of the westerlies’ because there aren’t any.  

    2756A501-06DE-46AF-9DAE-C442D9576F8F.thumb.png.21db0ec2bd0fbed11d1e0e7ae0caa1fc.png

    So it should be quick, really, but just that maybe 1/8 call where yes we get the -AO but the -NAO doesn’t play ball for our small island.  Hope that helps.

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    Posted
  • Location: worcester
  • Weather Preferences: Cold cold cold!!
  • Location: worcester
    24 minutes ago, jacke said:

    An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

    As this is aimed at me I feel I need to reply!! I have changed my text to thaw( don’t know why I put flood)

    it was a 3 day ‘warm up’ which induced a thaw with burst pipes etc!! Circa Jan 25th 1963.

    Goes to show even in the coldest part of winters ‘warm ups’ can happen!! 
     

    Then the beast returned.

    So anything is possible in current output.

    Check Winter Watch!

    MNR

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    21 minutes ago, prolongedSnowLover said:

    How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

    Anyone?

    As someone mentioned above, it was about 2 weeks between SSW and the start of the beast from the east. But as Mike Poole mentioned, there isn't a specific relationship between the SSW and 850s

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    Posted
  • Location: South Croydon
  • Location: South Croydon
    1 hour ago, John88B said:

    Serious question from a complete novice when it comes to reading the models but is it worth even looking at the models for a period of time if a SSW can shuffle the deck so much so to speak? Thanks in advance.

    Yes and no.  My experience has been that initially after the SSW (which still is 2 days out), the models struggle to process how the downwelling will impact the trop.  So you get a lot of volatility between both models and runs.  Then the SSW will take between 2 week and 2 months for the impact to be felt.  In 2018 we had a QTR (quick trop response) and we actually felt that impact within 2 weeks.  The models started to show some consistency again fairly quickly (post event).  I'm not a strat expert but it's been suggested that the response from strat to trop will be quick this time too.  So I'd expect a lot of volatility (people on here like to refer to it as Shannon entropy but don't get me going on that one), between runs and between models.  If the response is quick expect to see the volatility dropping over the next week.  Posters on here correctly state that the models know there is going to be a warming but the main issue is the interaction of the strat and trop and the outcome.  We know reversal of wind is likely as is blocking but exactly where the blocking sets up seems to take longer to resolve.  I think the key to remember is no poster or model has this dialled in.  SSW have only been studied in earnest fairly recently.

    So don't despair if runs flop from ultra cold to mild.  If we are lucky with the SSW (and we seem to be around 2/3rds of the time), then expect to see colder solutions impacting the models some time post 5th of Jan (speed of the propagation being key).

    There are some great posters on here so try to follow them.  It takes a little bit of time to understand how to read a model but once you can you get a better idea of who to pay credence to.  

    Edited by Trom
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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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