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Model Output Discussion - 10th Jan Onwards


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I wouldn't be surprised to see a more zonal outlook simple because it's the default British climate pattern in winter and more likely than cold conditions especially when there is a great deal of uncertainty. On a probabilty basis it is more likely we will see zonal conditions than not and I'm very disinclined to be taken in by fanciful FI charts showing freezing cold even if it isn't what many people 'want' to happen.

 

Quite. The various ensemble means and anomaly maps show a zonal outlook, so high shannon entropy may mean there is lower certainty than average on them being right, but a zonal outlook is more probable than a cold blocked one. The signal may be somewhat confused and noisy but the zonal signal is still the strongest.

 

NAEFS mean Posted Image  ECM ens Posted Image  GEFS Posted Image

(means at day 10)

Edited by Bobby
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  • Location: North Bristol
  • Weather Preferences: Thunderstorms / Sunshine / Snow
  • Location: North Bristol

    Out of interest...has anyone been keeping tabs on the accuracy & verification of these mean outputs, over a period of time this winter?

     

    Genuinely interested to know before I perhaps do a little bit of homework myself, because it all sounds very conflicting here this morning with the ens apparently showing zonal weather is likely...whereas others saying the route to cold is. Such uncertainty!

     

    I guess that is Shannon Entropy at its finest. Although i must admit reading the term is starting to feel like stepping in a dirty cloth on the sidepath.

    Edited by Chris K
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    Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON

    All the models are going nuts at the moment and it is really difficult to pin down any pattern, although the most likely outcome is more atlantic lows and rain, unless the depressions take a different route towards the UK and give us brief northerlies as they clear away.

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  • Location: Weston Super Mare , North Somerset
  • Location: Weston Super Mare , North Somerset

    All the models are going nuts at the moment and it is really difficult to pin down any pattern, although the most likely outcome is more atlantic lows and rain, unless the depressions take a different route towards the UK and give us brief northerlies as they clear away.

    Can't remember a Winter that has had no Cold periods at all, with at least 1 country wide snow event happening per year..If you're talking about odds, I would say odds are were due a Cold period very soon , and at very least a HP settled spell. The Weather likes to even it self out , and I would say were 70-80% likely to see a very Cold Feb and with all the background signals staring us in the face , this makes it even more likely .. The Cluster that is showing the P/V powering up a bit are the runs that want to Split the P/V and take half of it to Siberia. This IMO would then let the Azores fill the gap meet with the Arctic high which by that time will be somewhere around Greenland and there you have it , massive wall of High pressure blocking the Atlantic, P/V energy to our North East in a very Cold air sending low pressure down the North sea setting up a very unstable flow, and any breakdown would likely come from the SW due to the block meaning even more Snow ... May sound silly but this is how I see this whole situation playing out, all with still a brief chance of some kind of Easterly before the PV splits Eastward. Quite enjoying currently watching how events are unfolding . 

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  • Location: uxbridge middlesex(south east england)
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(south east england)

    Ha, I see the shannon Entropy) alluded to much lately. And this is the WHOLE circumstances. The weather (not the models) is on the change northern hemisphericaly, and it is indeed the models coming out of there coma.and awakening from such a rinse and repeat cycle will put any man under immense pressure, let alone cross model perceive. There is mass irregularity at present, and that alone SCREAMS change afoot, and with recent modeled the change if its cold/colder you favour, the pendulum is beginning to swing largely in you favour. Once output gets solid on evolution im sure cold fan sas myself) will be smiling cheek 2 check. The pv (polar vortex) is punching it last punch.

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    Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON

    The Azores high has been trying to link up with heights further north but the link keeps getting snapped by the jet stream. If the jetstream does eventually weaken come February, then the two could finally meet and set up a block.

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    Posted
  • Location: Weston Super Mare , North Somerset
  • Location: Weston Super Mare , North Somerset

    The Azores high has been trying to link up with heights further north but the link keeps getting snapped by the jet stream. If the jetstream does eventually weaken come February, then the two could finally meet and set up a block.

    That's what I see happening , when the P/V splits the Jet will weaken and head South as HLB comes more of a player to the North, By that time Energy to our NW should be pushed back Weston Canada and like I said in my previous post I see Wall of High pressure filling the gap. But let's just wait and watch the story unfold . 

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    Posted
  • Location: leicester
  • Location: leicester

    All set for the 12zs!!!hopefully we see things back west a little bit around the 120 to 144 hour mark so we at least stand a chance of maybe seeing some battleground events!!

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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    This has been such a frustrating winter thus far for cold weather fans and the current set up just adds to that frustration.

    Looking at the 48h charts in isolation you would feel pretty confident of seeing an Easterly develop but the steadfast refusal to clear energy SE scuppers our chances.

    There is little coming off the Atlantic and what there is takes a southerly track but with our perpetual UK trough holding high pressure too far East without the needed undercut our Scandinavian high can only sink away SE.

    Given a quite strong signal for increased blocking into the Arctic by day 8 this is a real shame because if it had held on it would of been nigh on impossible for even the UK snowshield to hold out if they had linked up.

    Still, at least we are still being promised jam tomorrow and the signs are good that Feb will at least be the coldest month of this winter and if we are very good boys and girld we may even get to see a flake or two of snow yet.

    Edited by Mucka
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    Posted
  • Location: Birmingham (Solihull), West Midlands
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Birmingham (Solihull), West Midlands

    The models mostly agree with the next few days carrying on the generally unsettled theme as Low Pressure systems, along with trough disturbances, stay close by to the United Kingdom. The UK will become ravaged by further spells of rain and showers as a result with temperatures probably generally around average, and maybe a little bit cooler further North with the flow backing a little bit more South-Easterly. Some drier and brighter interludes look likely between the rainy spells. This is just an example from the 06Z GFS for 3pm tomorrow:

     

    (The South-West of England look as though they could get quite an intense spell of wet weather)

    post-10703-0-50980700-1389969634_thumb.p

     

    (What the Sea Level Pressure and H500's look like for that day - Low Pressure very close by to the West)

    post-10703-0-42665600-1389969656_thumb.p

     

     

     

    This then looks to move further Northwards towards Scotland, but weakening as it does so. It could perhaps also be cold enough for some of the precipitation over the next few days to fall as sleet or snow over higher areas in the North.

     

    Monday could see a drier day for many places as models, such as the GFS, shows a little ridge of High Pressure trying to track Eastwards through the South of the UK (although the odd shower probably can't be ruled out, especially towards the North-Western areas of the UK):

     

    post-10703-0-60330700-1389971223_thumb.p

     

    What happens later in the week and beyond is not terribly certain. A number of solutions possible as mentioned by some of the great posts above (such as the one from Tamara), where we may see the Atlantic trying to put more pressure against the Scandinavian block to our East, with the possibility of Lows out West trying to make more progress further East. It could still be possible that the models are still underestimating the powers the block to our North-East could have. Otherwise, that idea we'll see an amplified High Pressure out in the Atlantic or something attempting to plug up the flatter, Westerly flow (if it does materialise) seems more possible. And with the help of the other ridges and other High Pressure systems across other areas of the world, such as the one over the Artic/Pole, we could quite easily see the cold coming down from our North eventually. The GFS seems to have somewhat played about with this idea of a High out West linking up with heights further North on some of it's last few runs (example for the 06Z run underneath): 

     

    post-10703-0-12867500-1389972747_thumb.p

     

    I suppose those after the snow and chilly weather would have to be careful that not too much of that energy or pieces of that Vortex remains over to our North-West as it could still usher a string of Lows towards us from the West (although if it backs away far enough North-West then it might not cause too much trouble for the wintry weather fans.

     

    The 00Z Super Murr Ensemble suite (a set of ensembles I had made up along with the Steve Murr model, which was also admittedly made up, so don't take these ensembles seriously if you're a new model reader) continues to go for a very serious cool down around February 1st, although sadly, the coldness of the 850 hPa temperatures for the East of the UK have downgraded. Only -19.9*C 850 hPa's expected for the East, when looking at the very highly detailed SME suite, rather than -20*C. ;-(

    Edited by DiagonalRedLine
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    Posted
  • Location: London, UK
  • Location: London, UK

    CFS till end of February on both 1 and 9 monthly for the daily outputs are not showing anything remotely interesting for the foreseeable. Looks as if the mobile westerly pattern is set to continue till at least end of February. With a Polar Vortex where it is now, I cannot see the end to this relentless run of very wet weather. 

     

    Posted Image

     

     

    Although the GFS has sparked some interest for me, Chunk of polar vortex over Newfoundland and the rest is Scandinnavia in this part of the N.Hem.  High pressure over Azores sending warm air advection towards Greenland and thus a 1060hPA high.   First signs of the SSW coming into the modelling systems.

     

    post-15369-0-47047400-1389972746_thumb.p

     

    I think that the only route to cold now is of a Sudden Stratospheric Warming, doesn't look likely that synoptics will play a part in changing the weather pattern and thus the overall picture. Read what Matt Hugo has posted on his twitter.

     

    Posted Image

     

     

    NCEP Ensembles paint a picture of some sort of changes.

     

    TODAY

     

    Posted Image

     

    NEXT Thursday

     

    Posted Image

     

     

    EARLY FEB, things looking blocked...

     

    Posted Image

    Edited by Robbie Garrett
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    Posted
  • Location: Darton, Barnsley south yorkshire, 102 M ASL
  • Location: Darton, Barnsley south yorkshire, 102 M ASL

    I've been meaning to ask for a while... What in the name of Greek touchery is Shannon Entrophy?

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    Posted
  • Location: Preston, 19m ASL when tide out :(
  • Location: Preston, 19m ASL when tide out :(

    God knows where it originated from but it means level of certainty or uncertainty in met office talk, high shannon entrophy = high uncertainty 

    Edited by Nicholas B
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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    I've been meaning to ask for a while... What in the name of Greek touchery is Shannon Entrophy?

     

    What in the name of Shannon entropy is Greek touchery?

     

    Edit.

    He he I put empathy after the seed was sown the other day.

    Edited by Mucka
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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

    The far north east has a chance of wintry ppn later next week which suggests cold air will be flirting with the ne of the uk and northern uk has a higher chance of hill snow as time goes on. Looking further ahead, a better chance of sharp cold incursions, especially between weather systems with snow showers and frosty nights probably becoming more of a feature of february. So I think a change in pattern is eventually on the way with short bursts of potentially Arctic conditions as we go through the final third of winter with some large temperature contrasts.

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    Hard to see an easterly from here in the near future, the critical time is well within the reliable timeframe now, unlikely the models are wrong. Possibly further down the line, beyond day 10 something may evolve but not this time it would seem. T+90

     

    Posted Image

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    Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON

    Hard to see an easterly from here in the near future, the critical time is well within the reliable timeframe now, unlikely the models are wrong. Possibly further down the line, beyond day 10 something may evolve but not this time it would seem. T+90

     

    Posted Image

    We are probably most likely to get a northerly rather than an easterly accorrding to the latest model runs, although it may be brief.  Regarding stratospheric warming, if the warming is weak on our side of the pole, does that mean it won't affect the weather patterns so much here.

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    Posted
  • Location: leicester
  • Location: leicester

    Ukmo 12z at 96 hours doesn't look too bad!!maybe an undercut and a snow to rain event maybe across england!!see what the 120 hours shows when it comes out!!

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    Posted
  • Location: leicester
  • Location: leicester

    Ukmo 120 hours looks good!!battleground over the uk and it looks better than this mornings with the scandi high slightly further west and more robust!!

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

    Some posts have been removed.

    Please keep on topic folks.

    The evening runs are coming out -saves cluttering the thread- and the team extra work.

    Cheers all.

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    Posted
  • Location: Addington
  • Weather Preferences: Love a bit of snow
  • Location: Addington

    Far better ukmo than this morning

    Showing the low digging south east

    What the 12z was hinting yesterday

    Undercut anyone ?

    Hoping the ECM will back this up later early in the run

    Edited by snowbob
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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    Oh it got removed before I edited it with something actually on topic.

    Never mind, the gist was both UKMO and GFS are poor with the jet riding over the block by the mid term. 

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