Model Output Discussion - 18z - 6th December onward

[lorenzo]

Another set of runs to review this morning and another solution.

Please, please for the sanity of everyone who enjoys this thread engage your brain before posting something.

It's simple - read it back, preview it, ask yourself is this really my best contribution to the thread?

This thread is for discussing the models, NOT, having a dig at each other.

Thank You !

[TEITS]

Well anyone who watched the GFS 18z unfold last night may not be too surprised by this mornings run - the shortwave off the Norwegian coast almost threatened to prevent the HP linking up with the heights around Iceland on that run.

Now on this run the shortwave is that little bit stronger and does prevent the link up, hence the heights are forced to extend South over the UK, so no easterly. Somebody said that easterlies need to come within T72 before they can be 'banked'. We then see a struggle between the Atlantic and the retreating block. GEM supports the initial synoptics from the GFS, and brings the Atlantic in much quicker.

ECM has the shortwave, but makes less of it and the High is able to form to bring an easterly until it then goes down the route of most of the models yesterday by bringing an Atlantic attack from the SW by next weekend.

Hate to admit it but I agree with you IB and im very nervous about the model output this morning.

One trend I have noticed over the years when the models are predicting E,lys is how the models downgrade the duration of the E,ly flow, becomes slacker, less cold. However what then tends to happen is we see last minute upgrades inside +48/+72.

I sincerely hope the GFS/GEM are overreacting to the SW off the Norwegian coast. If not then we are at risk of this turning into a cold spell that consists of being cold, dry at first with only transitional snowfall after.

As much as I like the latest Met O forecast for my region. Based on all todays outputs I already feel as though its null and void because I cannot see the snow shower activity that they are describing in their forecasts.

Edited December 7, 2012 by THE EYE IN THE SKY

[Rollo]

To be fair this mornings charts are a mile from what was on offer a few days ago--- so it looks like more nail biting and prozac is required for yet a while.

[Snowy Easterlies]

Hate to admit it but I agree with you IB and im very nervous about the model output this morning.

One trend I have noticed over the years when the models are predicting E,lys is how the models downgrade the duration of the E,ly flow, becomes slacker, less cold. However what then tends to happen is we see last minute upgrades inside +48/+72.

I sincerely hope the GFS/GEM are overreacting to the SW off the Norwegian coast. If not then we are at risk of this turning into a cold spell that consists of being cold, dry at first with only transitional snowfall after.

As much as I like the latest Met O forecast for my region. Based on all todays outputs I already feel as though its null and void because I cannot see the snow shower activity that they are describing in their forecasts.

yes the met update is good but have they got that from old data ? because the latest UKMO will probably give us fewer showers

tbh i will welcome a return to mild zonal if we get no snow out of this cold spell, i am a fan of snow, not dry cold, heatings costing a fortune anyway thats for another thread

Edited December 7, 2012 by Snowy Easterlies

[TonyH]

Wonder if the models are aware that they can upgrade or downgrade...

[snowmadchrisuk]

The way I see it 4 or 5 days with -10 850's there will be snow showers somewhere , even if it's convective .

[Froze were the Days]

Agreed as we head towards the 'finish' line the models seem to be coming up with small variations which are reducing any decent cold or snowfall, have to say again the models in the medium term haven't handled this very well that's if they carry on the 0z theme. ECM not that great either. Still all to play for.

[IDO]

I can see why the GFS in FI now showing poorer wintry runs. The EC32 also suggesting a breakdown to a milder regime after week 2 (according to Matt Hugo, Twitter). Northern Blocking gone by then. So we have a window of opportunity to get some wintry stuff, a couple of weeks, then a low dominant scenario for Christmas.

[lorenzo]

An update from Matt regarding the outlook from the EC32 from the strat thread sums up the situation very well..

High confidence for the E'ly scenario next week, albeit a weak one, but it still manages to get cold air into place. The breakdown scenario for next weekend is anyone's guess. 'Slider lows' may become involved and from my experience more often than not models breakdown the block/cold air quicker than actually happens when the event in question gets nearer. So that's got high confidence and again 10 out of 10 to the EC32 for picking up this E or NE'ly scenario weeks back.

It keeps N blocking in place with lower pressure to the S or SW until the 23rd (ish) which, to me, suggests that any Atlantic intrusion next weekend is short lived on this model. However, week 3 has changed, Xmas week, which N blocking disappearing and low pressure becoming dominant just to the W or SW of the UK bringing a more unsettled spell, before a weak signal for a Greenland high into early Jan.

Going off recent posts in here this scenario may tally well, with a potential milder/more unsettled/Atlantic influence for a time later in December before a potential 'reload' into January. To be honest after what now looks like being a particularly cold first half of December at least, you would imagine (statistically) that a milder interlude would be likely at some point and if the EC32 is once again correct, unfortunately that may fall over Xmas now, but time will tell.

[Paul]

When I first clicked into this thread this morning I thought I'd made a mistake and landed in the moaning thread or even the lounge as it's been a struggle to delve through and actually find the posts which have any relation to the models.

So just to clarify - discussing the models means just that, not bickering, not moaning that the models are bad, not posting to moan about off topic posts (does no-one ever find an irony alert going off in their heads when they do that?!), so please make an effort for the sake of all the other members who want to enjoy this thread.

As a team we can only do so much tidying in here, and we don't want to be blocking anyone from posting into this thread but there comes a point when some people just don't want to show some consideration for others that we end up with no choice - please don't let it get to that point.

[Alex95]

Obviously the GFS is a big downgrade as the easterly doesn't happen, leaving us dry and cold for next week. Of course there is some possibility of frontal snow in FI, but it's pretty silly to be talking about that since those type of events never seem to be nailed until +48.

The ECM would still give significant snow to the east coast for anyone north of East Anglia, and the UKMO might do as well, though the showers wouldn't get very far inland. What worries me though is the GFS is usually better than the ECM when it comes to modelling shortwaves in the short term. Sometimes it makes a meal out of them at around +96, so we can only hope that this has happened.

Fingers crossed for an upgrade later, but don't hold your breath.

Edited December 7, 2012 by Alza

[johnholmes]

I can see why the GFS in FI now showing poorer wintry runs. The EC32 also suggesting a breakdown to a milder regime after week 2 (according to Matt Hugo, Twitter). Northern Blocking gone by then. So we have a window of opportunity to get some wintry stuff, a couple of weeks, then a low dominant scenario for Christmas.

best read the actual quote by Matt posted by Lorenzo?

[Met4Cast]

I think we have to be realistic.

The 00z GFS is a massive downgrade with little in the way of significant blocking and a weak Northerly with high pressure stuck over us, the cold still gets into place but widespread snow and interesting, it's not. The ECM is a little better with stronger blocking but still no where near what we were being offered a couple of days ago or even this time yesterday morning.

Lets hope we see things upgrade come the 06z, if not, I fear this'll be yet another missed Easterly.

[sunnijim]

UKMO view remains much as I hinted yesterday evening: we expect likelihood of breakdown/partial breakdown into next weekend with associated increasing threat of significant snow event as a consequence, but detail of course still impossible:

" 3. Days 8-10 - Friday to Sunday : WEATHER: E’ern and some central areas are most likely to continue to see a mix of bright spells and wintry showers at first. However, signs are that temperatures may start to recover a little from the SW, with an increasing chance of more unsettled conditions starting to edge N and E across parts of the UK through this period. This may also lead to further significant snowfall on the boundary between the two. Mostly light or moderate winds at first, but perhaps turning windier at times from the SW. Temperatures widely below normal initially with widespread frost, and icy patches, but perhaps a gradual recovery towards nearer-normal temperatures from the SW. EXTREMES COMPARED TO CLIMATOLOGY: Moderate prob of staying significantly colder than normal in the NE. Lower probs elsewhere. CONFIDENCE: High for the initially cold theme, but much lower for a gradual upward trend in temperatures and also detail of any more unsettled conditions spreading N and E."....

"5. Discussion : Good agreement between models for much colder-than-average conditions to dominate, at least through the first half of this period, bringing further wintry showers. GFS and EC are in general agreement for pressure to fall from Wednesday onwards, bringing a threat of wintry showers/precip to areas other than just E’ern coasts. From Friday, models diverge more significantly, with GFS deterministic preferring to bring low pressure and much more unsettled conditions quite quickly NE, whilst EC maintains a colder showery scenario. Ensembles signal increasing probs of precip through this period, but what remains unclear is how quickly temperatures start to rise. There is a significant threat, if more unsettled weather spreads NE, of snowfall, especially on the boundary between the two. Overall, both MOGREPS and EC EPS show a cyclonic bias with generally SE’erly flow veering more SW with time, bringing low pressure and more unsettled conditions from the W."

A tease for some next week then,just who sees snow is still differing wildly run to run so speculating and ranting is pointless.It may just turn out a 48hr "snow window" for the faivored and cold/dry either side of that,before turning milder around the 14th,15th for most. I can see a reload just ahead of Christmas and maybe that will be the real mcoy.

[TEITS]

On a more positive note the latest fax for Monday does suggest snow showers moving into E areas.

http://cdn.nwstatic..../fax/PPVL89.png

Really can't make my mind up this morning because i've been there, got the T shirt. What is in our favour is time because we still have plenty of time for upgrades. I think back to Dec 2005 when for around 48hrs the models completely backed off the idea of an E,ly only for it to return at the last minute.

At the moment I see 4 options.

1. Cold, dry at first before we see a short spell of snow followed by rain and turning milder.

2. Cold, dry at first before we see a LP approach the SW bringing a spell of snow, remaining cold afterwards.

3. Cold with snow showers followed by a short spell of snow followed by rain and turning milder.

4. cold with snow showers before we see a LP approach the SW bringing a spell of snow, remaining cold afterwards.

Edited December 7, 2012 by THE EYE IN THE SKY

[Methuselah]

Although the models may 'upgrade', 'downgrade', or whatever, the weather will just do what it's going to do...Weather cannot be 'downgraded'!

[Snowmadsam]

On a more positive note the latest fax for Monday does suggest snow showers moving into E areas.

http://cdn.nwstatic..../fax/PPVL89.png

Really can't make my mind up this morning because i've been there, got the T shirt. What is in our favour is time because we still have plenty of time for upgrades. I think back to Dec 2005 when for around 48hrs the models completely backed off the idea of an E,ly only for it to return at the last minute.

At the moment I see 3 options.

1. Cold, dry at first before we see a short spell of snow followed by rain and turning milder.

2. Cold, dry at first before we see a LP approach the SW bringing a spell of snow, remaining cold afterwards.

3. Cold with snow showers followed by a short spell of snow followed by rain and turning milder.

4. cold with snow showers before we see a LP approach the SW bringing a spell of snow, remaining cold afterwards.

I will take option 2 or 4....

Lets wait and see what the 6z says...lets not have this Winter is over thing again

Edited December 7, 2012 by Snowmadsam

[Severe Siberian icy blast]

Hate to admit it but I agree with you IB and im very nervous about the model output this morning.

One trend I have noticed over the years when the models are predicting E,lys is how the models downgrade the duration of the E,ly flow, becomes slacker, less cold. However what then tends to happen is we see last minute upgrades inside +48/+72.

I sincerely hope the GFS/GEM are overreacting to the SW off the Norwegian coast. If not then we are at risk of this turning into a cold spell that consists of being cold, dry at first with only transitional snowfall after.

As much as I like the latest Met O forecast for my region. Based on all todays outputs I already feel as though its null and void because I cannot see the snow shower activity that they are describing in their forecasts.

I understand your nerves I feel the same, although I feel once the models come to terms with this attempted breakdown , and also get to realise the strength of the block , which remember has been showing very strongly in the models for some time, then they will fall back into line some what.

Remember when the models pick up on a signal, they over-react to that signal,because its new, it over emphasises to it, as they do when they initially pick up on northerly or easterly, gp , chiono , John Holmes , matt Hugo , the ECM 32 dayer, the strat conditions , need I go on? They all agree that this will not be blown away by first wkend, I feel we will get failed attempts , bringing snow events, sliders , which can be amazing, followed by reloads.

Also gp just the othe day , gave a detailed explanation of the long term signals, and mentioned there will be a false dawn from the Atlantic?? As they come to grips with the vortex moving to Siberia. So come on guys pls look at the bigger picture.

[Roadrunner]

Hate to admit it but I agree with you IB and im very nervous about the model output this morning.

One trend I have noticed over the years when the models are predicting E,lys is how the models downgrade the duration of the E,ly flow, becomes slacker, less cold. However what then tends to happen is we see last minute upgrades inside +48/+72.

I sincerely hope the GFS/GEM are overreacting to the SW off the Norwegian coast. If not then we are at risk of this turning into a cold spell that consists of being cold, dry at first with only transitional snowfall after.

As much as I like the latest Met O forecast for my region. Based on all todays outputs I already feel as though its null and void because I cannot see the snow shower activity that they are describing in their forecasts.

Dave, I bow to your superior knowledge of easterly's but as another poster recently said, didn't the models do a similar backtrack for the 2010 snow event only to bring it back within a day or so of it actually happening?

I may be wrong and the synoptics may have been different but I distinctly remember this place going into meltdown for a few runs before the models got a grasp on things.

[Heisenberg]

How many times have we been here before. The models do and will chop and change. Yes there has been a downgrade from the snow fests that have been showing but it always happens and models wobble the same as they always do with these changes.

I find it so frustrating that when cold is showing everyone says its in FI dont worry. But when it IS cold and they show mild out to 240 its not FI and its a dead cert its going to happen.

Come on guys, no need for wrist slitting just yet. Lets see what happens in the next few runs......then we can slit our wrists

[Timmytour]

Have to admit I've been pretty disappointed wrt some of the comments on here won't say which ones but it was an effort at times to read through some posts that were only really interested in wind ups. Hope the mods can do something about it.

Precip only at 72hrs and below general patterns from 72-144 and only general trends backed up with ens and cross model support t144 and beyond.

Quite why some expected the exact tightness of the isobars on a model run 5 days away to stay the same is beyond me, but they are probably the people who counted the thickness of the snow that they would bring.

Good agreement on the start of the easterly still.

Some differences re the sw and the ability of the low to move westwards, but to counter this a strong high in the reliable medium range.

Generally too model agreement that the cold is still in place to t200 or so and still agreement on the chance of a snowy break down.

As things get more and more into the t72 region I am sure they will change and more chances for snow et will crop up in the cold to very cold air.

Remember its at this time free t72 to t120 that gfs in particular likes to discover a new shortwave/trough and over play it, before down playing it agin in later runs.

I'm sure or at least I hope, a lot of what you say will bear fruit.

But I guess some of the "despair" arises from the fact that the mild stuff is now being shown with the same degree of consistency and the same timeframe as the cold was that got us all excited about it in the first place.

Things as they are, compared to many winters, are excellent. Things as they are compared to what we could expect are excellent. In comparing what we are faced with compared to some individual runs, they ight seem poor, but compared to a lot of other, now-forgotten runs, they remain excellent.

It's been great model watching and remains so. The only disappointed ones will be those who count chickens..

[Jayces]

It's the same every year, why are people chasing the breakdown before the event has occurred?

I also don't understand why people don't read the thoughts from some excellent posters and I think we are also very lucky to have professional meteorologists contributing too, I wonder if these people often wonder why they bother?

The models show a cold spell next week, this is currently a fact, as many others have said it's not yet known how long or how snowy and this fact will change every 6 hours (damn you GFS and your 4 runs a day!).

The UK is not Siberia so we don't get 3 months of cold snowy conditions here, we get wintry spells if we are lucky and the last few years we have been luckier then we have for a long time.

I'd use the ignore feature for all the downbeat posts but then there would only be a handful of posts in here, still that could be a good thing I guess ;-)

[TEITS]

I understand your nerves I feel the same, although I feel once the models come to terms with this attempted breakdown , and also get to realise the strength of the block , which remember has been showing very strongly in the models for some time, then they will fall back into line some what.

Remember when the models pick up on a signal, they over-react to that signal,because its new, it over emphasises to it, as they do when they initially pick up on northerly or easterly, gp , chiono , John Holmes , matt Hugo , the ECM 32 dayer, the strat conditions , need I go on? They all agree that this will not be blown away by first wkend, I feel we will get failed attempts , bringing snow events, sliders , which can be amazing, followed by reloads.

Also gp just the othe day , gave a detailed explanation of the long term signals, and mentioned there will be a false dawn from the Atlantic?? As they come to grips with the vortex moving to Siberia. So come on guys pls look at the bigger picture.

The problem is the signals such as the Strat, teleconnections cannot pick up on the tiny details such as shortwaves and neither can the anomaly charts that John H posts. These shortwaves can have implications because as some of the output suggests today this could prevent the block fully extending W and thus makes the UK more prone from attack from the Atlantic.

I just feel at the moment that members should sit on the fence and not assume anything until we get the closer timeframe resolved because this has implications later on. All those options I posted are possibilities.

Edited December 7, 2012 by THE EYE IN THE SKY

[Heisenberg]

I understand your nerves I feel the same, although I feel once the models come to terms with this attempted breakdown , and also get to realise the strength of the block , which remember has been showing very strongly in the models for some time, then they will fall back into line some what.

Remember when the models pick up on a signal, they over-react to that signal,because its new, it over emphasises to it, as they do when they initially pick up on northerly or easterly, gp , chiono , John Holmes , matt Hugo , the ECM 32 dayer, the strat conditions , need I go on? They all agree that this will not be blown away by first wkend, I feel we will get failed attempts , bringing snow events, sliders , which can be amazing, followed by reloads.

Also gp just the othe day , gave a detailed explanation of the long term signals, and mentioned there will be a false dawn from the Atlantic?? As they come to grips with the vortex moving to Siberia. So come on guys pls look at the bigger picture.

S

Superb post!!

Completely correct. This seems to be the models trying to get to grips with a possible incursion. We know they dont handle new scenarios well and over do them all of the time. I still think the block is too strong to just be blown away at the first hint of the Atlantic trying to smash against it, which as we know can set up some great snowfall.

Chin up guys....lets see what happens.

[Iceberg]

I tend not to believe a breakdown until the models agree on the method for the breakdown, atm we still have a number of different scenarios for it, which when combined with the "too quick to break down the cold" factor the models have that there is very low confidence in the breakdown or timing as yet.