Model Output Discussion 25/11/2012 12Z onwards

[LomondSnowstorm]

so to put everyones mind at rest, even if ecm is on the right track, the end result will be an even weaker canadian vortex. short term pain for long term gain. (and the scottish ski resorts will be well happy anyway).

Oh undoubtedly, the ECM is a fine run for Scottish hill snow:

The margin for error for uppers here seems a lot greater than for the south, so I don't suppose I personally have all that much of an stake in the UKMO over the ECM, but of course the GFS/UKMO remains the more wintry solution in the shorter term for pretty much all of the country, but as I think about five of us has posted now if the ECM came along in the middle of a bog standard spell of zonality we'd be waxing lyrical about its potential.

[Frosty.]

Does anyone see any potential in the following chart?

I do.

This chart smacks of Greenland height rises and a west based negative NAO.

One could be forgiven for thinking that this chart is poor given the state of affairs - but looking at the bigger picture, any Atlantic interlude could be quite brief with the background signals coming back into play.

Yes chio I see massive potential, better than the rot we had for 80% of last winter, a colder trend then less cold followed by very cold, looking at the bigger picture it would just mean a slight delay to snowmagheddon, this evening's chaos was sparked by a few silly comments but hopefully sanity can now be restored.

[nick sussex]

means can be deceiving but it has to be said that ECM ensemble mean is pretty poor at 192h

http://www.wetterzen...s/Reem1921.html

In these situations the mean value isn't a great guide as you have a large split, there will be generally two outcomes only and nothing in between.

One cluster of ensembles will have energy running over the top, the other underneath the block hence when you try and get a mean it shows a skewed picture.

[Bobby]

The ECM mean at day 7 looks much like the OP, has some support in the GFS ensembles too

[johnholmes]

At the moment I'd say the ships taking on water but we still might plug the leak!

If the worse happens then its a case of yet another shortwave drama to add to the many!

For newer members this is a great link and explains longwaves/shortwaves and loads of other very useful info:

http://www.wxonline....pics/waves.html

Nick if the ECMWF is correct how on earth do you refer to that as a shortwave for goodness sake?

[Bobby]

In these situations the mean value isn't a great guide as you have a large split, there will be generally two outcomes only and nothing in between.

One cluster of ensembles will have energy running over the top, the other underneath the block hence when you try and get a mean it shows a skewed picture.

Yes there does seem to be some clustering, things are still quite uncertain for sure. Not a good trend appearing though.

Edited November 25, 2012 by Barb-

[swfc]

Just a quick one from me.Last week during one or two gfs runs and ecm i was"told"not to follow each run but the trends?The 500mb charts were the ones to focus on.Have they suddenly changed because after one ecm run and an average set of ens it seems like everything is imploding!!!!!I realise the lesser models have jumped ship but some of the goal post moving on here is staggering

[Frosty.]

The ECM mean at day 7 looks much like the OP, has some support in the GFS ensembles too

cool/cold zoneality, could be worse!

[Tony Beets]

Panic posts are causing panic reposts and this place is in meltdown! Wait until at least tomorrows evening output for any firming up of new trends and analyse them with a level head! What will be will be, we can't change the weather. I believe we will go down the ukmo route personally.

[Iceberg]

I think if you look at the last 3 sets of ECM ensemble maps at 168hrs you can see how more energy has spilled east from the Atlantic, the problem isnt so much the energy but where its being directed, with ensembles you will get sudden shifts because theres no halfway house with this situation , you either get energy under the block or its game over.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2012112512!!/

I think given the timeframes involved if the GFS 18hrs shows a shift to the ECM then I would take that as a bad sign.

Bear in mind that the differences are starting within 96hrs and that eastern seaboard doesn't suffer from a lack of observational data like the region in which we see the Arctic high.

If the GFS 18hrs holds firm then that would certainly be very welcome!

Yes ens means can be very misleading if you look at the t120 it has the low to the tip of Greenland on the ops 25mb lower than mean.

You only need a couple of outliers like the ops to give a very misleading mean, much better to disregard the outliers from the ens mean and you realise how that the ECM s has the low 30mb lower than it should be. Ie it wildly out at t120 even on the major drivers

[Snowfan50]

Oh undoubtedly, the ECM is a fine run for Scottish hill snow:

The margin for error for uppers here seems a lot greater than for the south, so I don't suppose I personally have all that much of an stake in the UKMO over the ECM, but of course the GFS/UKMO remains the more wintry solution in the shorter term for pretty much all of the country, but as I think about five of us has posted now if the ECM came along in the middle of a bog standard spell of zonality we'd be waxing lyrical about its potential.

Is the ridge of warmer uppers on this chart going across the Uk a shortwave, i have seen this on many charts when viewing before.

[Catacol]

I tend not to bother to look at operational runs at all anymore - they are a waste of time for accurate trends beyond 96/120 hours, but one observation from the ECM ensembles tonight is that they seem to indicate quite a swift reforming of the vortex after 120h with polar heights collapsing. I do not have GP's knowledge at all - but my understanding of the background signals is that this is unlikely, with the vortex under quite severe pressure. This is rather at odds with the GFS ensembles that maintain higher pressure over the pole and a split vortex.

I think discussions of a short wave flattening out the atlantic pattern are a bit of a red herring therefore. They mask the fact that if the ECM is modelling the polar heights incorrectly then the zonal solution offered by the operational run tonight simply wont happen.

The question therefore becomes: why is the ECM lowering polar heights and reforming the vortex when teleconnections say no, and the GFS ensembles say no too.

I dont have the answer to this - GP is certain to know better than me... but it makes me rather dubious of the ECM solution at present.

An even bigger question would be whether any of these models have a proper grasp of stratospheric factors. We know that the UKMO now incorporates these into its thinking, and they are staying with a blocked atlantic. At present, therefore, I am not too worried by the ECM flip, though I would be very glad if the more knowledgeable posters on here could provide a more hemispheric analysis and offer a reason why the ECM ensembles are lowering polar heights and reforming the vortex within the next 10 days. Is it just off on one?

Edited November 25, 2012 by Catacol_Highlander

[swfc]

Yes chio I see massive potential, better than the rot we had for 80% of last winter, a colder trend then less cold followed by very cold, looking at the bigger picture it would just mean a slight delay to snowmagheddon, this evening's chaos was sparked by a few silly comments but hopefully sanity can now be restored.

Yes there is potential but seeing as the last week or so has been given such a build up only to be talking about potential is in its self a downgrade.forecasting up to 2 days on the runs seems impossible at moment so 240hrs seems a lifetime away.

[nick sussex]

The very latest breaking news from our correspondent based in Maine!

Dramatic developments re the upstream low which throws big doubts into the ECM upstream:

A STORM SYSTEM MOVING OFF THE MID ATLANTIC COAST DURING THE MID WEEK

PERIOD NOW APPEARS MOST LIKELY TO PASS WELL SOUTH AND EAST OF THE

AREA SPARING THE REGION FROM SIGNIFICANT PRECIPITATION. HOWEVER...AS

THE SYSTEM INTENSIFIES SOUTH AND EAST OF NOVA SCOTIA WEDNESDAY NIGHT

AN INVERTED TROUGH WILL EXTEND BACK FROM THE SYSTEM SUPPORTED BY

ADDITIONAL JET ENERGY COMING IN FROM THE GREAT LAKES. THIS INVERTED

TROUGH MAY SUPPORT A SMALL AREA OF LIGHT SNOW OR SNOW SHOWERS ALONG

THE DOWNEAST COAST WEDNESDAY NIGHT

Inverted in this case means negatively tilted, look at the timeline and what the ECM does between Wednesday and Thursday!

[tcc]

Didn't GP allude to the possible idea of the segment of PV moving from Canada to Scandi? I can't find the post now but I thought he had mentioned this a few days ago?

Anyway if ECM is on to something then fair enough, we'll see what happens next however what cannot be denied is that there is not much of a Vortex so we know that we're not heading for a long zonal spell.

Let's see what the fax says tonight (whether it follows the ECM) and what tomorrow morning brings, it'll be interesting to see if UKMO and ECM are still different!

[SnowObsessor90]

So bigger picture is that we could now very well be back to looking for the slightest hint of potential in deep FI, oh joy

Edited November 25, 2012 by Anonymous21

[LomondSnowstorm]

Is the ridge of warmer uppers on this chart going across the Uk a shortwave, i have seen this on many charts when viewing before.

In this instance it's just warm air being advected northwards on southerly winds at the east of a low pressure system:

Not hard to see though how a middle ground between this and the GFS could be quite promising in the medium term.

[nick sussex]

Nick if the ECMWF is correct how on earth do you refer to that as a shortwave for goodness sake?

I was talking about longwaves/shortwaves in general its a great link I thought.

And I'm fully aware of what a shortwave is in relation to the current set up thanks!

Take a chill pill and stop being so grumpy!

[Isolated Frost]

The very latest breaking news from our correspondent based in Maine!

Dramatic developments re the upstream low which throws big doubts into the ECM upstream:

A STORM SYSTEM MOVING OFF THE MID ATLANTIC COAST DURING THE MID WEEK

PERIOD NOW APPEARS MOST LIKELY TO PASS WELL SOUTH AND EAST OF THE

AREA SPARING THE REGION FROM SIGNIFICANT PRECIPITATION. HOWEVER...AS

THE SYSTEM INTENSIFIES SOUTH AND EAST OF NOVA SCOTIA WEDNESDAY NIGHT

AN INVERTED TROUGH WILL EXTEND BACK FROM THE SYSTEM SUPPORTED BY

ADDITIONAL JET ENERGY COMING IN FROM THE GREAT LAKES. THIS INVERTED

TROUGH MAY SUPPORT A SMALL AREA OF LIGHT SNOW OR SNOW SHOWERS ALONG

THE DOWNEAST COAST WEDNESDAY NIGHT

Inverted in this case means negatively tilted, look at the timeline and what the ECM does between Wednesday and Thursday!

Big spanner in the ECMWF 'maniac' run, which has no H5 support-

compared to

and

Upstream modifications change the story a lot for those who mindlessly follow the latest NWP- so thanks for these Nick

[JP1972]

Panic posts are causing panic reposts and this place is in meltdown! Wait until at least tomorrows evening output for any firming up of new trends and analyse them with a level head! What will be will be, we can't change the weather. I believe we will go down the ukmo route personally.

While the Meto keep their long ranger as it is, I'm happy to believe we're still on course.

During the cold spells of 2009 and 2010 we had model drama before the evolution was cemented.

But I can't believe the amount of doom mongering tonight over what the weather may or may not do

[Catacol]

... I would add that the CPC update today is this:

Notice the very strong heights retained at the pole, and substantially low pressure predictions over Europe. The ECM run at present has the Azores high regaining strength and a flat pattern dominating to the north, this within the context of collapsing polar heights. It just doesnt fit. Something is wrong there.

EDIT: to be fair ECM at 240 is not flat at all. The pattern is still very blocked and meridional... so it has not lost total sight of the cpc predicition... but its modelling of the low pressure exiting Canada in midweek seems very aggressive. I suggest that it is putting too much energy into this, and that tomorrow it will pick up on this and reverse the ensemble picture of today. We will see.

Edited November 25, 2012 by Catacol_Highlander

[The Northern Ramper]

The very latest breaking news from our correspondent based in Maine!

Dramatic developments re the upstream low which throws big doubts into the ECM upstream:

A STORM SYSTEM MOVING OFF THE MID ATLANTIC COAST DURING THE MID WEEK

PERIOD NOW APPEARS MOST LIKELY TO PASS WELL SOUTH AND EAST OF THE

AREA SPARING THE REGION FROM SIGNIFICANT PRECIPITATION. HOWEVER...AS

THE SYSTEM INTENSIFIES SOUTH AND EAST OF NOVA SCOTIA WEDNESDAY NIGHT

AN INVERTED TROUGH WILL EXTEND BACK FROM THE SYSTEM SUPPORTED BY

ADDITIONAL JET ENERGY COMING IN FROM THE GREAT LAKES. THIS INVERTED

TROUGH MAY SUPPORT A SMALL AREA OF LIGHT SNOW OR SNOW SHOWERS ALONG

THE DOWNEAST COAST WEDNESDAY NIGHT

Inverted in this case means negatively tilted, look at the timeline and what the ECM does between Wednesday and Thursday!

What does this mean Nick?

[Snowman31]

The very latest breaking news from our correspondent based in Maine!

Dramatic developments re the upstream low which throws big doubts into the ECM upstream:

A STORM SYSTEM MOVING OFF THE MID ATLANTIC COAST DURING THE MID WEEK

PERIOD NOW APPEARS MOST LIKELY TO PASS WELL SOUTH AND EAST OF THE

AREA SPARING THE REGION FROM SIGNIFICANT PRECIPITATION. HOWEVER...AS

THE SYSTEM INTENSIFIES SOUTH AND EAST OF NOVA SCOTIA WEDNESDAY NIGHT

AN INVERTED TROUGH WILL EXTEND BACK FROM THE SYSTEM SUPPORTED BY

ADDITIONAL JET ENERGY COMING IN FROM THE GREAT LAKES. THIS INVERTED

TROUGH MAY SUPPORT A SMALL AREA OF LIGHT SNOW OR SNOW SHOWERS ALONG

THE DOWNEAST COAST WEDNESDAY NIGHT

Inverted in this case means negatively tilted, look at the timeline and what the ECM does between Wednesday and Thursday!

Sorry nick, is this good or bad news, and what does it mean? thanks

[Isolated Frost]

... I would add that the CPC update today is this:

Notice the very strong heights retained at the pole, and substantially low pressure predictions over Europe. The ECM run at present has the Azores high regaining strength and a flat pattern dominating to the north, this within the context of collapsing polar heights. It just doesnt fit. Something is wrong there.

That was yesterday's, they don't do it on Sundays- but your point remains.

[bradymk]

The very latest breaking news from our correspondent based in Maine!

Dramatic developments re the upstream low which throws big doubts into the ECM upstream:

A STORM SYSTEM MOVING OFF THE MID ATLANTIC COAST DURING THE MID WEEK

PERIOD NOW APPEARS MOST LIKELY TO PASS WELL SOUTH AND EAST OF THE

AREA SPARING THE REGION FROM SIGNIFICANT PRECIPITATION. HOWEVER...AS

THE SYSTEM INTENSIFIES SOUTH AND EAST OF NOVA SCOTIA WEDNESDAY NIGHT

AN INVERTED TROUGH WILL EXTEND BACK FROM THE SYSTEM SUPPORTED BY

ADDITIONAL JET ENERGY COMING IN FROM THE GREAT LAKES. THIS INVERTED

TROUGH MAY SUPPORT A SMALL AREA OF LIGHT SNOW OR SNOW SHOWERS ALONG

THE DOWNEAST COAST WEDNESDAY NIGHT

Inverted in this case means negatively tilted, look at the timeline and what the ECM does between Wednesday and Thursday!

I didnt think NOAA did any updates on sunday Nick but some welcome news indeed. A manic 18z coming up. Matthew