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Model Output Discussion - The Start Of Winter


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A few of you have asked today about rationale for the (tail-end of) UKMO latest 30-day outlook. There is, of course, a dedicated thread elsewhere for this but I'll just confirm that GloSea5 output rem

Thanks for this Barry   You are however wrong on both counts you suggest :   1) I have explained in extended detail, as much as I am able, the progress of the patterns thus far from autumn (see firs

Hopefully a timely interjection, but UKMO caution (again) that medium range NWP may not be adequately reflecting ultimate broadscale outcome. First tentative signs emerging, they suggest, of *possible

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Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

    Not much cheer in GFS ensembles for those who want a white Christmas but still a long way out. I have been saying that I fancied some blocking to start showing up in the <10 day charts (so by Christmas day) by mid month but starting to look like that will be bust at the moment. (reverse psyche?  :pardon: )

    I still see a window of opportunity for a more amplified pattern to reestablish itself last 3rd Dec even if GFS doesn't but then I may be more bias than GFS:clapping:

     

    Edit:

     

    Just read Fergies post, that should keep spirits up for now.

     

    The control run would deliver for parts of Scotland...

     

     

    ...but ensemble 20 is where the real action is. :D

     

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    Posted
  • Location: Burton-on-Trent
  • Location: Burton-on-Trent

    Yes - We don't know what the ECM strat output ENS longer range are showing but i can't believe that it is too dissimilar to this.

     

     

    attachicon.gifNH_TMP_1mb_384.gif

     

    Not an SSW and not even at day 10 but the way that this warming has been modeled and is reeling in it has the hallmarks of previous SSW's stamped all over it.

     

    My only concern is the displacement type and whether the vortex will be totally crushed but if any one saw the tweet I made yesterday about EN post SSW NAO and NH average temps it is definitely something we want to see.

     

    There's always time for a split though right that could possibly occur after this first warming and displacement? Back in Dec 2012 we only saw the first signs of a second warming producing a split in the FI of the December 25th outputs.

    Edited by Snowy L
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    Posted
  • Location: bingley,west yorks.81 absl
  • Location: bingley,west yorks.81 absl

    Dont know know if you want to answer this @fergieweather,but here goes.Did the GloSea5 pick up on the nov/dec 2010 episode the same distance out and also %wise confidence?.

    Regards.

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    Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

    The million pound question is how much faith we can have in this

    ECH1-240.GIF?10-0

    Good agreement in the Azores high to shift towards Iberia which will probably lift the temperatures a little after this weekend, but nothing to say that it will take up permanent residence. Looks like your usual December weather, some wind, some rain, some sunshine, frost and a little snow thrown in. Temperatures overall near average overall.

    Edited by Captain shortwave
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    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    fergie could you give us anymore information on the potential snow event for north midlands northern england Friday morning!! Gfs has that low crossing through the midlands tomorrow night and now ukmo/ecm have it crossing the same path aswell!!

     

    The ECM initiated HiRLAM has some snow for the area you refer to - the band crosses betwen 00Z and 06Z.

     

    Source courtesy of Weeronline.  http://www.weeronline.nl/vakman-index/130/0

     

    201412101200-201412120400.png

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

    fergie could you give us anymore information on the potential snow event for north midlands northern england Friday morning!! Gfs has that low crossing through the midlands tomorrow night and now ukmo/ecm have it crossing the same path aswell!!

     

    when you have two main models giving such similar tracks then the odds are that the additional data available via GFS will be much the same as UK Met will have from their own sources. The models must be fairly coincident through the whole atmosphere for the surface plots to look very similar.

    So using the data that Net Wx show either in the free are or on Extra you should be able to feed in the relevant parameters literally for your own backyard, use this as a guide to give a decent idea of rain/sleet/snow etc and the timing.

    link below 

    https://forum.netweather.tv/topic/27989-how-to-try-and-forecast-snow/

    be a forecaster, good fun as well

    Edited by johnholmes
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    Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

    Tonight's GEFS 12z mean is dominated by rather cold or at least just below average temperatures for the next few weeks with the airflow from just north of west for much of the time drawing air with origins in canada / greenland rather than any tropical influences, there is very little to indicate anything mild as such, indeed, there is scope for a decent cold plunge again next week from the arctic as seen on some of tonight's 12z perturbations...so what we have here is good support from the latest gefs mean for the rather chilly and very unsettled met office update with continuing frequent polar maritime / borderline arctic incursions bringing blustery and thundery wintry showers with snow at times, especially on hills, overnight frosts and icy patches during the pm incursions, and a few fleeting milder intrusions associated with occasional bouts of wet and very windy weather, low heights to the northwest / north / northeast and the azores high thankfully kept out of harms way with no sign of any mild, benign conditions in the run up to christmas. :)

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    Posted
  • Location: ipswich <east near the a14> east weather watch
  • Location: ipswich <east near the a14> east weather watch

    http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

     

    i know the  models are all over  the  place but looking in to fantasy world some places just might see some of the white stuff on Xmas day  , 

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    Posted
  • Location: Hampton, Evesham, Worcestershire. 27m asl.
  • Weather Preferences: Extreme and Exciting weather, hate stratus clouds and drizzile
  • Location: Hampton, Evesham, Worcestershire. 27m asl.

    Little change in our weather in the days ahead, with frequent spells of Polar Maritime air with some little mild spells. There will be some wintry weather perhaps further south during late Thursday into Friday, but overall feeling very seasonal with the Scottish Ski Industry clapping there hands in snow!!! :cold:

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    It would be nice if the ECM could go with one of the colder options rather than one of the mildest solutions:

     

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    The spreads do show low pressure heading se through the UK, hopefully the ECM will enter the festive spirit tomorrow.

     

     

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    Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk

    Oldmetman certainly see this as well and from a purely amateur point of view the only model that pushes the Azores heights to our South is the gem and even that's back tracked.

    All the models broadly keep the Azores to out sw and some even pushing North into the mid high Atlantic.

    Maintains a west northwest flow northerly even North East flow also possible.

    A far cry from this mornings drama of a south southwest flow so far more wintry plus brief milder air that's it.

    More changes to come winter is truly with us now colder end to dec into jan looking far more likely than not and the models lean towards this to slowly but surely were getting there snow buddies

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    Posted
  • Location: Hampton, Evesham, Worcestershire. 27m asl.
  • Weather Preferences: Extreme and Exciting weather, hate stratus clouds and drizzile
  • Location: Hampton, Evesham, Worcestershire. 27m asl.

    I've been studying model output on and off all day, and for the life of me I cannot make much sense of anything shown beyond about 3-4 days. The sticking point for me has been the insistence of maintaining progression (except for the GEM earlier, but even that has now backtracked) when, to me, the whole situation right now is shouting "amplification"

    So, in such cases, I take a look at what is actually going on right now, that is, current analyses and satellite imagery.

    First, the current surface analysis:

    attachicon.gif2014121019_eur_full.gif

    So what do we have? A strong PM airstream, LP to the N, a good solid looking HP over Canada, stretching SE towards the Azores and LP heading NW into the E USA. Developing from this is a northern stream wave heading E, engaging the cold air and deepening. So far so good. But after that, we have a) maybe another such wave, b) maybe the polar front meandering across the Atlantic, c) a flat W flow with a series of LP, taking us in and out of the cold air. In other words, quite a confusing mixture.

    So, why progression? Why not a solid blast of cold northerlies, lasting more than a few hours, maybe with short-wave features heading SE from the S Greenland/Iceland area?

    The hemispheric WV loop is interesting.

    http://mp1.met.psu.edu/~fxg1/SAT_NHEM/animweur.html

    This shows the extending upper trough off the US. the same off the W US coast. Even some extension of a trough towards the Med. Amplifying long waves.

    All of which suggests to me ridging in mid-Atlantic and a more long-lasting cold northerly outbreak.

    I may be way off here of course! Maybe the last GFS today might look a bit more realistic!

    BTW, who else is sick of hearing this silly "weather bomb" expression?!

    Indeed, the "Weather Bomb" With the "Polar Vortex" and along with other sayings  has become tiresome  in the media in recent years... :closedeyes:

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

    The million pound question is how much faith we can have in this

    ECH1-240.GIF?10-0

    Good agreement in the Azores high to shift towards Iberia which will probably lift the temperatures a little after this weekend, but nothing to say that it will take up permanent residence. Looks like your usual December weather, some wind, some rain, some sunshine, frost and a little snow thrown in. Temperatures overall near average overall.

    Just looking at this chart again Cap'n, actually it's a very interesting one I feel, it puts us on the thin line between westerlies sourced from the Azores (temps in the teens if that happens) and on the other hand a cold blast sourced somewhere near Greenland. I also note that the vortex has slightly relented over Greenland and we're not a million miles from a Greenland High splitting the N Atlantic pattern. Could it trend that way? Probably not quite but getting closer.

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    Posted
  • Location: Ripon , North Yorkshire 34m/112ft ASL
  • Weather Preferences: heat and cold, storms and blizzards...zonal a no no
  • Location: Ripon , North Yorkshire 34m/112ft ASL

    The current synoptic set-up for our part of the world doesn't seem too far away from mid-January 1965:

    attachicon.gif12z+0.png attachicon.gif17-1-65.gif

     

    Fast forward to 48 hours out and still fairly similar, but you can see that the base of the trough is allowed to progress further east in 1965:

    attachicon.gif12z +48.png attachicon.gif19-1-65.gif

     

    96 hours out, and you can see how the 1965 evolution allows the cut-off low to sink south, bringing an easterly flow.

    attachicon.gif12z+96.png attachicon.gif21-1-65.gif

     

    The difference here is that the trough over the UK is allowed to sink further SE in 1965, linking up with the lower pressure over southern Europe, while in the current GFS modelling shown this doesn't occur.

     

    An additional caveat is that the 1965 pattern wasn't particularly remarkable as far as I'm aware (Jan '65 CET 3.3, Feb 3.1) but the change in pattern does allow the lows to track south and the blocking from the east to back west over and to the north of the UK, which is similar to what some have suggested as a possible evolution in the longer term this month.  So this could be an example of how such an evolution may be able to play out if the current pattern persists, probably not this time around as those who have studied the 500mb charts have suggested, but there may be further opportunities as the set-up seems to continue for a while to come, e.g.:

     

    attachicon.gif12z +132.png

     

    Unfortunately I can't seem to find northern hemisphere archive charts so I can't see how similar the overall pattern is - which is likely to be driving developments here.

    Here you go VS ... http://www.meteociel.fr/modeles/archives/archives.php?day=21&month=1&year=1965&hour=0&map=0&mode=0

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    Posted
  • Location: winscombe north somerset
  • Weather Preferences: action weather
  • Location: winscombe north somerset

    Some realy good posts today and great to be a part of a brilliant weather forum .charts still showing plenty of interest and we dont seem to be stuck in a rut ,great start to our winter and some hints of plenty of variation in the longer outlook models ,thats what im looking for variation ,just getting it right for cold sometimes comes when we have some uncertainty ,and its only early days  :cold: cheers gang 

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