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Model output discussion - The run up to Christmas


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Posted
  • Location: Broadmayne a few miles north of Weymouth in Dorset
  • Weather Preferences: Snowfall
  • Location: Broadmayne a few miles north of Weymouth in Dorset

    A small adjustment in the track of the low at 264 and it could be southern snowfest.

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    Posted
  • Location: Bury St Edmunds, Suffolk
  • Weather Preferences: Cold, frost and snow
  • Location: Bury St Edmunds, Suffolk

    Feeling a bit more confident tonight for the upcoming cold spell. We're finally seeing that cannon ball of a low from the past few days modelled weaker and slightly shifting just to the east of us for the beginning of next week.

    Uppers as a result also look a bit better as we've lost that washing machine of a low mixing out the cold, and instead we're now drawing in a more northerly component.

    Overall great charts, now we just need to get through the Christmas weekend without any hiccups! 🤞

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    Posted
  • Location: Morecambe
  • Location: Morecambe
    3 minutes ago, NewEra21 said:

    Feeling a bit more confident tonight for the upcoming cold spell. We're finally seeing that cannon ball of a low from the past few days modelled weaker and slightly shifting just to the east of us for the beginning of next week. 

    Uppers as a result also look a bit better as we've lost that washing machine of a low mixing out the cold, and instead we're now drawing in a more northerly component. 

     

    Yet the GFS12z had a touch of milder air mixing in with the low hence the positive upper air temps in Scotland, I don't think uppers are getting any more favourable, if anything they are getting less favourable(we had widespread - 4 uppers now it's down to - 2.

    The set up looks good but the lack of cold air will be a real problems, it's feeding off scraps and why that is the case I do not know but it's something I expect too see more of as the planet keeps on warming up. 

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    GFS 12z, jet stream at start of run:

    82EC7628-2ABE-4036-AA3B-072FFC004FF1.thumb.png.2d7b7f41e9141dd650111bb2e054106d.png

    and at end of run:

    9FAC408A-2156-4A38-B3DD-742079B10795.thumb.png.17b2c3b2025f1f57745267e268a1fd58.png

    Just look how weak (and therefore meridional) it is upstream - there is nothing forcing it.  Total absence of vortex in the usual place.  

    This shows why without a major pattern change of some sort the Atlantic ridge will just keep reamplifying.  

    Edited by Mike Poole
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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    image.thumb.png.230879c28fa26e8bb8c53b774f5fc4a8.png

    That’s an Easterly Blast (not the beast but it’s beastish).......I’m claiming it! 🥸

     

    BFTP

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    Posted
  • Location: Essex, UK
  • Location: Essex, UK
    17 minutes ago, Beanz said:

    I don't suppose they're too worried about one run of the GFS at 354hrs to be honest... 

    it’s not one run though. It’s several and on 3 BIG models. None showing what they “think” come New year.

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    Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
    4 minutes ago, BLAST FROM THE PAST said:

    image.thumb.png.230879c28fa26e8bb8c53b774f5fc4a8.png

    That’s an Easterly Blast (not the beast but it’s beastish).......I’m claiming it! 🥸

     

    BFTP

    HAHA that’s made my day 🤣 it doesn’t even last for 6hrs! You can’t claim a ‘beast from the east ‘ on the back of veering wind 🙈 we are looking at a northerly flow. Hopefully we get a beast from the east in the new year but you need to build a bridge and get over this one 😉

    37848114-4537-4CAB-B08F-6A0674C2E2D2.png

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    Posted
  • Location: Morecambe
  • Location: Morecambe
    Just now, Blessed Weather said:

    Thank you. So the chart was showing the 850hPa temperature anomaly on the 7th January versus the 1981 to 2010 long-term average. Very misleading and totally out of context.

    How is it misleading? The poster says its showing the lack of cold air and clearly there is a lack of cold if Scandinavia is running at above average upper air temperature wise. Perhaps posting a chart for the 7th January is not the best idea but I just looked at the GFS 12Z run upto 200 hours  and not once is there pool of - 20 air in Scandinavia and the uppers in general are between - 8 and - 12 so warmer than average. 

    The only snow risk I can see in the short to medium term is when the low heads over the UK and the winds are slack with very low thicknesses. After that, too much wind so too much mixing and the air not really cold enough for most. 

    It feels like daylight robbery that such a great set up is failing to deliver uppers of - 10 and lower. 

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    Posted
  • Location: Brighton, East Sussex
  • Location: Brighton, East Sussex
    2 minutes ago, Geordiesnow said:

    How is it misleading? The poster says its showing the lack of cold air and clearly there is a lack of cold if Scandinavia is running at above average upper air temperature wise. Perhaps posting a chart for the 7th January is not the best idea but I just looked at the GFS 12Z run upto 200 hours  and not once is there pool of - 20 air in Scandinavia and the uppers in general are between - 8 and - 12 so warmer than average. 

    The only snow risk I can see in the short to medium term is when the low heads over the UK and the winds are slack with very low thicknesses. After that, too much wind so too much mixing and the air not really cold enough for most. 

    It feels like daylight robbery that such a great set up is failing to deliver uppers of - 10 and lower. 

    This is at day 8-10 range, there is only one way that chart is heading and the GFS has been reliably producing the same thing run after run, it’s not like we are just chasing a rainbow.

     

    Looking at historic snowfalls from the past, yes many have had -16 uppers coming from Siberia but a lot have also had more like -5/-6 uppers sometimes even higher, depending on conditions.

    Sometimes it’s better for snow FALL to have marginal conditions and the moisture associated with ‘warmer’ systems. We will see, but I think somewhere between day 7-10 is going to see a proper dumping. (M4 north 😉)

     

     

     

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    Posted
  • Location: Morecambe
  • Location: Morecambe
    1 minute ago, Weathizard said:

    This is at day 8-10 range, there is only one way that chart is heading and the GFS has been reliably producing the same thing run after run, it’s not like we are just chasing a rainbow.

     

    Looking at historic snowfalls from the past, yes many have had -16 uppers coming from Siberia but a lot have also had more like -5/-6 uppers sometimes even higher, depending on conditions.

    Sometimes it’s better for snow FALL to have marginal conditions and the moisture associated with ‘warmer’ systems. We will see, but I think somewhere between day 7-10 is going to see a proper dumping. (M4 north 😉)

     

     

     

    Realisitially in a northerly situation you need uppers of around - 8 or lower to get snowfall, the GFS run does not fully deliver that despite the low moving away, on the face of it its a fantastic chart but cold wise, then less so. 

    Less cold uppers with wind can work out if you got a continental influence but I'm not seeing that either in the outputs.

    As i say, unless something changes massively, any snowfall people may see is likely to be transient in nature.

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    Posted
  • Location: Kirklees, West Yorks
  • Weather Preferences: Winter
  • Location: Kirklees, West Yorks

    P1 for example shows how easy it is to get the colder uppers stuck in the flow and this is sunday. Not looked at other runs, but the small features and kinks in the flow just show how the cold can ebb its way into the system properly. We end up with -5 uppers across much of country and the main centre of the low. One to watch.

    GFSP01EU12_96_2.png

    GFSP01EU12_102_2.png

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    Posted
  • Location: Central Beds
  • Location: Central Beds
    2 minutes ago, Anthony Burden said:

    GFS still trending some serious wintery weather over the U.K. for a sustained period.

    Although we know not to 

    I have a gut feeling this might turn out to be the crowing period for GfS 

    Typically I’m collecting my new car on Tuesday, for once I really don’t want this to be true - clear skies and dry would suit me fine...

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

    I know this is the snow thread so please move if it's in the wrong place 😉 but I am so drawn to the pressure charts atm - this is the UKMO, usually the king of understanding low pressure - look at that, central pressure below 955mb and much of the country under 970mb. If your pressure gauge is not at the far left, it will need binning!

    Screenshot_20201223-175702.thumb.png.6bad977a2defb8692517f46f6079ef53.png

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    Posted
  • Location: Cambridge
  • Weather Preferences: Cold, snow, heat, sunshine and thunderstorms. Anything severe.
  • Location: Cambridge

    Blatant cherry picking but perturbation 24 is insane with a deep area of low pressure diving south with -12C uppers tucked in with it as it would bring memorable blizzards for many. Would cause absolute chaos!😱

    016A09B0-718A-465A-93A9-2F739CDBDE94.png

    68E332CF-76F2-4DB6-9BE2-4B2F4BD8B64B.png

    Edited by Frosty Winter
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    Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

    Just in case you missed earlier requests, could discussions about the latest Met Office Outlook please be made in the appropriate thread. A number of posts have been moved there. Thanks.

     

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    Posted
  • Location: Exile from Argyll
  • Location: Exile from Argyll

    Day 10  http://brunnur.vedur.is/kort/ec-ens/2020/12/23/00/ec-ens_nat_z500scenarios_2020122300_240.png

    Day 15  http://brunnur.vedur.is/kort/ec-ens/2020/12/23/00/ec-ens_nat_z500scenarios_2020122300_360.png

    Scenarios we would have given our eye teeth for in years past. The strength and longevity of the Greenland heights anomaly.

     

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    1 minute ago, Gael_Force said:

    Day 10  http://brunnur.vedur.is/kort/ec-ens/2020/12/23/00/ec-ens_nat_z500scenarios_2020122300_240.png

    Day 15  http://brunnur.vedur.is/kort/ec-ens/2020/12/23/00/ec-ens_nat_z500scenarios_2020122300_360.png

    Scenarios we would have given our eye teeth for in years past. The strength and longevity of the Greenland heights anomaly.

     

    Wow!

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