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Model thread discussion - cold spell looming


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Posted
  • Location: Essex, Southend-On-Sea
  • Weather Preferences: Warm, bright summers and Cold, snowy winters
  • Location: Essex, Southend-On-Sea
    Just now, frosty ground said:

    High is already collapsing at day 5 by day 6 its done

    Not if you're after a wedge towards Greenland its not.

    Scandi high boat has sailed. I still think a wedge of heights North somewhere is best bet.

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    Whilst some are looking W at the low pressure for a possible snowy breakdown. Im looking in the other direction. Could it be that no fronts will get anywhere near at the end of the week (except S

    Wow, it only took GFS one suite to catch up! Wasn't expecting that. This has to be the best period of model watching in the 15 years I've been doing it.

    This is the moment for me when the action really begins. The cold pattern was secured days ago, but only now are we close enough to start forecasting the snow with any confidence. 5 or 6 days with pot

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    Posted
  • Location: bingley,west yorks.81 absl
  • Location: bingley,west yorks.81 absl
    1 minute ago, Battleground Snow said:

    UKMO at 144, better for sure than earlier.

     

    UN144-21 (1) (15).gif

    Looks like the high will collapse on  that.

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    5 hours ago, IDO said:

    Looking at the T138 gefs the op sits in the middle and is similar to the mean with where the 0c isotherm sits:

    gens_panel_opu6.png

    There is a cluster like the UKMO which are more progressive and a cluster holding onto the best case scenario, and a cluster in support of the op. So as we were, a new signal and gfs is trying to resolve the forcing even at this range. As for what follows, a holding pattern looks the call, trough to the west -v- mid-lat HP to the east, UK caught in the middle?

    Thanks for the update.

    It's a pity the ensembles & clusters are not released at the same time as the operational model, as all being available together would provide a more rounded picture of probable ways forward (like your post above). Many people view the Operational only and make judgements on it alone and do not see the later released clusters / ensembles. I know the hardcore do view all the data, but many others like me do not. It would maybe help moderate some of the wild mood swings in here after each run.

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    Posted
  • Location: Leicester
  • Location: Leicester

    Might look mild on that gfs 150 chart but am pretty sure its gona be the complete opposite and theres an improvement on this run with uk still in continental air at 150 hours!!

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    Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth

    T144 gfs 12 z T150 06z look where the low in the Atlantic is trying to go. Remember this day 6. Small changes and further changes and later charts will look very different. T162 12z T168 06z high not being pushed east.

    FA07C7D2-7A35-40F2-A88C-7544DDF45AD0.png

    A8AAAD67-BB2A-4AE2-8B54-A4BA48A56ADF.png

    3A655907-88B4-49B5-9CDD-97B9F15566F2.png

    B929682E-6F0F-4482-8E29-800D4D7489EA.png

    Edited by That ECM
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    Posted
  • Location: Kildare, Ireland
  • Location: Kildare, Ireland

    From my novice point of view, I am intrigued about how the 850 temps translate to what is going on at the surface. In the run up to this cold spell, -10/-12 uppers were frequently mentioned as putting us well clear of any marginal issues for (lying) snow. However, these uppers which are occurring right now, are definitely marginal for lying snow, with surface temps hovering around +1/+2 in many places.  Makes me wonder what sort of uppers we need to be looking at in the longer term forecasts?

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    Posted
  • Location: Nottingham
  • Location: Nottingham
    2 minutes ago, sheikhy said:

    Might look mild on that gfs 150 chart but am pretty sure its gona be the complete opposite and theres an improvement on this run with uk still in continental air at 150 hours!!

    156 an even bigger difference in freezing level.

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    Posted
  • Location: Essex, Southend-On-Sea
  • Weather Preferences: Warm, bright summers and Cold, snowy winters
  • Location: Essex, Southend-On-Sea

    GFS won't make it this run, but it's not overly far off.

    The low which was trying to go under heads back NW. If that sank we would likely have a different a picture.

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    Posted
  • Location: Sible Hedingham, North Essex
  • Location: Sible Hedingham, North Essex
    2 minutes ago, Weather vane said:

    From my novice point of view, I am intrigued about how the 850 temps translate to what is going on at the surface. In the run up to this cold spell, -10/-12 uppers were frequently mentioned as putting us well clear of any marginal issues for (lying) snow. However, these uppers which are occurring right now, are definitely marginal for lying snow, with surface temps hovering around +1/+2 in many places.  Makes me wonder what sort of uppers we need to be looking at in the longer term forecasts?

    I think it's a bit of a lesson in meteorology for some folk on here. There is a lot more to it than sub "-10 uppers over a warm sea will see copious amounts of snow." That theory has been blown out of the water, but I hope that people remember it next time we get a potential easterly (they won't though).

    Models seemed to have dropped the Scandi high now, and we have to rely on other things now.

    20 days to get something decent before Spring!

     

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

    Well really by day 6 it looks a bit of a stalemate.Both gfs/ukmp show the block is not giving enough to let the Atlantic right into the UK.

    It is more than likely the west will see something milder at least for a spell but a look at the gfs jet pattern at t144 shows the difficulty modeling is having in calculating the pathway forward.

    gfsnh-5-144.thumb.png.ec672b31ae60660b74224c8d7d0dd0b2.png

    The northern arm of the jet has no coherent pathway but does limited resistance to the ridge getting further north.The main energy in the jet is still running south so that Atlantic push remains quite indecisive up to there.

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    Posted
  • Location: Croydon. South London. 286 ft asl
  • Weather Preferences: Thunderstorms, snow, Ice days, warm sunny days.
  • Location: Croydon. South London. 286 ft asl

    The NH view looks promising - will the arctic high link up with the one over scandi?

    image.thumb.png.e0a639e16f1a790accea9a821d870ca0.png

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    Posted
  • Location: South Essex
  • Location: South Essex
    9 minutes ago, Weather vane said:

    From my novice point of view, I am intrigued about how the 850 temps translate to what is going on at the surface. In the run up to this cold spell, -10/-12 uppers were frequently mentioned as putting us well clear of any marginal issues for (lying) snow. However, these uppers which are occurring right now, are definitely marginal for lying snow, with surface temps hovering around +1/+2 in many places.  Makes me wonder what sort of uppers we need to be looking at in the longer term forecasts?

    It was a combination of factors and a large dose of bad luck. Main issue was that it was a fairly quick transition from mild wet weather to snow. Had we managed one frosty night or even a few hours under clear skies the outcome would have been different. The bad luck also manifested itself in the fact that the transition to snow took place after dawn for most in the south. Had the snow been very heavy it probably wouldn’t have mattered but you had moderate snow, warm ground temps and a bad time of day. the uppers were fine as was demonstrated by the strange mix of wet pavements and dry blowing snow on surfaces that were not in direct contact with the soil. In essence it was the mild weather of last week that caused the issue. 
     

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    Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
    19 minutes ago, Weather vane said:

    From my novice point of view, I am intrigued about how the 850 temps translate to what is going on at the surface. In the run up to this cold spell, -10/-12 uppers were frequently mentioned as putting us well clear of any marginal issues for (lying) snow. However, these uppers which are occurring right now, are definitely marginal for lying snow, with surface temps hovering around +1/+2 in many places.  Makes me wonder what sort of uppers we need to be looking at in the longer term forecasts?

    One word.. Sun.   Yesterday it was snowing moderately, -8 uppers, -2c air temp, -4 DP and sun 528 Dam thickness. Despite all of this the snow was melting quicker than it was falling. If you looked at the sun you could just about make it out behind the clouds so the light was enough to warm the black pavements etc.  Today was sub zero with below zero DP but one sunny spell and all the snow has gone. It’s approaching mid feb so it takes something very special to deliver long lasting snow. Unfortunately no models are showing this now. Perhaps as GFS shows we can get one last proper snow fall in Sunday or Monday (icon also does Amy his further west on Sat) but no model shows anything near to what is needed for a proper snowy spell in mid Feb. 

    21FBFE1F-4C82-4155-8954-E710207BFC1B.png

    50D3D403-D6D3-4218-B4ED-FC14005EB51B.jpeg

    Edited by Tim Bland
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    Posted
  • Location: Maidstone, 230ft ASL
  • Location: Maidstone, 230ft ASL
    10 minutes ago, Djdazzle said:

    I think it's a bit of a lesson in meteorology for some folk on here. There is a lot more to it than sub "-10 uppers over a warm sea will see copious amounts of snow." That theory has been blown out of the water, but I hope that people remember it next time we get a potential easterly (they won't though).

    Models seemed to have dropped the Scandi high now, and we have to rely on other things now.

    20 days to get something decent before Spring!

     

    I think there is other stuff coming into play here such as:

    - the underlying warmth of the ground from last week which is still not that cold

    - solar heating in the day from when the clouds clear in the afternoon.  I think even under colder uppers such as minus 20 you can still get partial melting in the day due to solar activity.   Someone please correct me if I am wrong?

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    Posted
  • Location: Kildare, Ireland
  • Location: Kildare, Ireland
    3 minutes ago, Djdazzle said:

    I think it's a bit of a lesson in meteorology for some folk on here. There is a lot more to it than sub "-10 uppers over a warm sea will see copious amounts of snow." That theory has been blown out of the water, but I hope that people remember it next time we get a potential easterly (they won't though).

    Models seemed to have dropped the Scandi high now, and we have to rely on other things now.

    20 days to get something decent before Spring!

     

    Although for many this cold spell has been a bit disappointing, I for one have learned lots about chart interpretation, and the pitfalls of making conclusions based on a limited set of considerations. Thanks to you and all the other learned on here for that.

    Now back to what's happening out there - hoping the clash of atlantic and cold brings something interesting for Thurs/Friday. However, not sure at all if there will be sufficient cold left at the boundary for a very significant snow (ie, that which falls and stays on the ground for at least a day so we can have some fun !). Chart below is 850 uppers for Thursday afternoon.

    ARPOPUK12_48_2.png

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    Posted
  • Location: bingley,west yorks.81 absl
  • Location: bingley,west yorks.81 absl
    Just now, D.V.R said:

    The NH view looks promising - will the arctic high link up with the one over scandi?

    image.thumb.png.e0a639e16f1a790accea9a821d870ca0.png

    Promising for far east Europe. Not us if it's cold you're after.

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    Posted
  • Location: Midlands
  • Weather Preferences: Very Cold, Very Snowy
  • Location: Midlands

    There are some good baby steps on GFS and Meto. Particularly like wedge to our North at day 6 on Meto. Potential....

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    Posted
  • Location: Croydon. South London. 286 ft asl
  • Weather Preferences: Thunderstorms, snow, Ice days, warm sunny days.
  • Location: Croydon. South London. 286 ft asl
    2 minutes ago, joggs said:

    Promising for far east Europe. Not us if it's cold you're after.

    We'll see how this run finishes but it's working it's way down towards us.

    image.thumb.png.94d4788516539dafc27550be7fa6c095.png

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    Posted
  • Location: Camborne
  • Location: Camborne
    22 minutes ago, Weather vane said:

    From my novice point of view, I am intrigued about how the 850 temps translate to what is going on at the surface. In the run up to this cold spell, -10/-12 uppers were frequently mentioned as putting us well clear of any marginal issues for (lying) snow. However, these uppers which are occurring right now, are definitely marginal for lying snow, with surface temps hovering around +1/+2 in many places.  Makes me wonder what sort of uppers we need to be looking at in the longer term forecasts?

    Once again and you can do no better

    https://www.netweather.tv/forum/topic/23729-will-it-snow/

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    Posted
  • Location: Cardiff, Wales
  • Weather Preferences: Snow, Thunder & Lightning, Thundersnow, Storms, Heatwave
  • Location: Cardiff, Wales

    GEFS certainly an improvement up to 120 hours and probably best to leave it there for now given the potential for more changes before that timeframe.

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    Posted
  • Location: Harrogate, Pannal Ash, 179m
  • Location: Harrogate, Pannal Ash, 179m
    1 minute ago, James Maidstone said:

    I think there is other stuff coming into play here such as:

    - the underlying warmth of the ground from last week which is still not that cold

    - solar heating in the day from when the clouds clear in the afternoon.  I think even under colder uppers such as minus 20 you can still get partial melting in the day due to solar activity.   Someone please correct me if I am wrong?

    Yes you can still have a thaw under February's sun exposure but the underlying warmth of the ground has nothing to do with it. It all depends on continuous ppn intensity. For example eastern Greece next week will possibly have 50cm+ in places and they've been under 20C+ at 2m T for 2 weeks. On/off showers with variable intensity never provide significant snow depth unless there is a proper lake effect snow with severe mm/h. 

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

    GFS 12z still quite cold for most of the UK until around day 6 with many central and eastern areas especially keeping a bit of a south/south easterly wind. Inevitably as the cold uppers retreat east the near continental flow would become milder too.

    What coldies wouldn't wish for i guess is a protracted standoff with little happening for a number of days as the block and Atlantic go nowhere.The UK possibly stuck in the middle and with little interesting weather other than perhaps a little front edge snow that dries out along a weakening frontal system.Added to that we would gradually warm at the surface without the block pushing back.

    It's probably wise in this finely balanced evolution not to focus too much on detail beyond the weekend at this stage.

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    Posted
  • Location: Coventry
  • Location: Coventry
    5 minutes ago, bradymk said:

    GEFS certainly an improvement up to 120 hours and probably best to leave it there for now given the potential for more changes before that timeframe.

    Yes a couple more have joined the colder cluster at 144, the OP one of the milder options in the pack.

    gfs-london-gb-515n-0e (1) (20).jpeg

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    Message added by Paul,

    It's busy right now, so please ensure you only post about the model output in this thread. 
    For local snow discussion and will it snow posts, please use the regional threads
    And for more general chat please use the chat, moans and ramps thread.
    There's now also a cold spell chat and discusison thread.

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