Model Output Discussion 1st Nov.2013

[Purga]

Deep in FI, but theres that thing called WAA gathering momentum 

Wild Assumptions Abound!

[essexweather]

Todays 12Z ECM ensembles starting to show the trend downwards in temperature towards the end of next week:

 

http://www.essexweather.com/outlook.html

 

There were around 15% of members going for below average temps from 17th November onwards

[SMU]

I don,t wish to be a wet blanket but whilst those purples and deep blues remain solidly modeled over the Arctic any cold incursions will be brief.

The vortex is still cooling and what we are seeing is the ebb and flow of it,s shape as it spirals around the Pole.

As CC inferred in a post earlier we are seeing reactions to the Jet running over the top of the NE Pacific block which is inducing some upstream buckling of the jet.

 

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-3-144.png?12

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013110612/ECH1-144.GIF?06-0

 

There's no forecasted warmings to slow the zonal winds currently so these ridges will be transient and mid-latitude blocking is more likely at the moment.

The ens graph for C.England says it all.Just your typical mobile November pattern.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=262&ext=1&y=97&run=12&runpara=0

 

Not to say we wont see some short bursts of polar air behind the passing rain bands of course.

 

 

HI Phil - I disagree with the assumptions you are making in this post- almost Ian Brown esque-

 

 

What you are intimating is that due to the fact that the stratosphere is cooling that vis a vee there cannot be any cold or any polar blocking, & because the models aren't modelling any warming or any abate of the zonal wind there cannot be any cold either-

 

Well, that is why annoyed me with the stratosphere thread from last year - Everyone has gone stratosphere mad, sure is part of the system, however it doesn't have total control of the weather-

 

For example take the stratospheric profile for November 2010

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/50mb9065_2010.gif

 

Below the norm getting close to getting to the bottom of the range-

 

but what chart do we see in that month?

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-25-0-0.png

 

 

The stratosphere will indeed continue to have its periods of cooling & hopefully as we head into Winter we will see a warming like last year where the temp anomaly goes off the scale-  we can of course then take some confidence into a cold -AO forecast.

 

There is however nothing to assert though that because there is no blocking now there can be no blocking in say 10-15 days time.

 

We should be keeping the options open looking at how things develop- & no one can say with confidence that there will be no blocking in 10 days, just because the stratosphere doesn't seem to be playing ball or because we currently have a period of zonal conditions....

 

I notice Ian piped up- his zonal forecast for more than 10 days of zonal conditions have finally come to fruition- hes only been forecasting them since 2008-

 

S

Edited November 6, 2013 by Steve Murr

[BlueHedgehog074]

The latest 8 to 14 day NOAA anomaly chart doesn't really show anything particularly cold - higher than average heights expected to our South, with areas of lower than average heights expected to be concentrated to the North and North-West of the UK. The general flow, over the UK, still seems to be from the West. Clearly, this chart isn't a 100% guarantee of what will evolve as the NOAA anomaly chart from the 5th November had shown higher than average heights generally more concentrated over the UK, rather than to the South just like shown on this current chart. That chart from 5th November, though, would have delivered something more settled on the whole. We could possibly see the current 8 to 14 day NOAA chart reverting back to something a little more settled for the UK if higher pressure can migrate further North. Either way it does, at least, look as though High Pressure may hang about close by to us, but again with the general flow likely to be from some sort of Westerly direction.

 

The current anomaly chart does also show the possibility of some amplification occuring from the higher than average heights to the South-West of Greenland (so could quite possibly lead to something more chillier further down the line if we see this sort of outlook come off).

 

8 to 14 day NOAA anomaly chart

 

I suppose the GFS, with some of its blocking ideas in Fantasy Island, probably shouldn't be totally ignored (plus some do mention ECMWF's outlook could lead to something more favourable for blocking and/or cold potential), although the GFS's FI outlook is probably only really worth taking seriously if its cold blocked outlook can reach the much earlier time-frames on future runs. (Even though I don't know much about the Pacific High Pressure ridge, I suppose it could still help become a friend for the Irish and British cold/snow fans).

 

I do agree that some cool Polar Maritime airflow's do look likely to occur in the next few days helped by some ridges of High Pressure tracking Eastwards sometimes turning the less-cold Westerly or South-Westerly flow to something more North-Westerly. Although any sleet or snow is likely to fall over the hilly areas to the North, one or two of the Polar Maritime airflow's could possibly become potent enough for sleet or snow to fall to some lower levels in the North.

 

 

...maybe along with the possibility of this taking place on the hills... (or perhaps not that extreme)...

 

 

 

 

 

[syed2878]

also the mets 16-30day forecast becoming uncertan towards mid month some of thos gfs and ecmf charts might be on to somethink.

[damianslaw]

Looking at the jet stream forecasts there is a strong signal emerging of mid atlantic heights building through middle of November and consequently a northerly could very easily emerge - not surprised to see GFS latch onto this idea, whilst I don't rate GFS particularly well, it is in my book the best model when it comes to forecasting northerlies.

 

This November has certainly started on a very seasonal traditional note and I wouldn't call the outlook particularly mild, recent 'westerly' winds over the northern half of the country have had a notable feed of cold air embedded within them - so I wouldn't call westerly winds necessarily mild. Indeed temps over Scotland struggled to hit much above 6 degrees for much of the week so far - Aviemore saw a max of 1 degree recently for instance and Glasgow only 2 degrees - very cold for early November under a supposedly 'mild' spell as some are describing... there really has been a notable north-south difference in recent days.

 

The first half of November in particular is not a period when the atlantic is easily beaten. Indeed not since 1987 have we seen the atlantic tamed for more than a few days in the first half of November and on many occasion it has been in full flow. Looking for deep cold ito establish itself for any great length of time in early to mid November is a bit of a fruitless task - a shortlived notable northerly blast is the best we can ask for.

 

On a personal note I am enjoying the start to this November a bit of everything - rain, showers, first snows for the hills, air frosts and decent sunshine - now looking for some gales and fog and hopefully first snows for low ground before month is out. (I know many in the south of the country won't relate to this).

[Cheshire Freeze]

It's clear to see what that ridging (Pacific side) does to the NH flow. It's a bit like sticking a brick in a shallow stream- disrupts the flow around it. From there, the knock on effect (in recent GFS FIs) has been to amplify the N Atlantic flow too

 

 

Which eventually leads to this...

 

 

and then this....

 

 

The cessation of the zonal train. All VERY interesting even though firmly in FI (Although the Pacific side ridging seems to be a strong signal).

 

 

[East_England_Stormchaser91]

Greeny high is there on GFS!! Albeit FI, but still it could well become a trend in the near future.

[Purga]

18z NH profile doesn't look too bad at the end of FI

 

PV moves away from Greenland to Siberia.

[UV-RAY]

HI Phil - I disagree with the assumptions you are making in this post- almost Ian Brown esque-What you are intimating is that due to the fact that the stratosphere is cooling that vis a vee there cannot be any cold or any polar blocking, & because the models aren't modelling any warming or any abate of the zonal wind there cannot be any cold either-Well, that is why annoyed me with the stratosphere thread from last year - Everyone has gone stratosphere mad, sure is part of the system, however it doesn't have total control of the weather-For example take the stratospheric profile for November 2010http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/50mb9065_2010.gifBelow the norm getting close to getting to the bottom of the range-but what chart do we see in that month?http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-25-0-0.pngThe stratosphere will indeed continue to have its periods of cooling & hopefully as we head into Winter we will see a warming like last year where the temp anomaly goes off the scale- we can of course then take some confidence into a cold -AO forecast.There is however nothing to assert though that because there is no blocking now there can be no blocking in say 10-15 days time.We should be keeping the options open looking at how things develop- & no one can say with confidence that there will be no blocking in 10 days, just because the stratosphere doesn't seem to be playing ball or because we currently have a period of zonal conditions....I notice Ian piped up- his zonal forecast for more than 10 days of zonal conditions have finally come to fruition- hes only been forecasting them since 2008-S

Here here Steve, far too much preference given to the Strat by too many who don't really understand its workings. We don't need any warming of the stratosphere for a lengthy cold spell for these shores, yes it certainly helps but other factors are just as important. Back to the models and the thing that is quite striking is how cold this protracted mildish spell as actually been with a fairly cool/cold westerly flow. The next 7 days look like seeing a continuation of the current pattern but there are now tentative signs of a mid Atlantic ridge possibly extending into Greenland in the next 10+ days. Edited November 6, 2013 by Sceptical Inquirer

[phil nw.]

HI Phil - I disagree with the assumptions you are making in this post- almost Ian Brown esque-

 

 

What you are intimating is that due to the fact that the stratosphere is cooling that vis a vee there cannot be any cold or any polar blocking, & because the models aren't modelling any warming or any abate of the zonal wind there cannot be any cold either-

 

Well, that is why annoyed me with the stratosphere thread from last year - Everyone has gone stratosphere mad, sure is part of the system, however it doesn't have total control of the weather-

 

For example take the stratospheric profile for November 2010

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/50mb9065_2010.gif

 

Below the norm getting close to getting to the bottom of the range-

 

but what chart do we see in that month?

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-25-0-0.png

 

 

The stratosphere will indeed continue to have its periods of cooling & hopefully as we head into Winter we will see a warming like last year where the temp anomaly goes off the scale-  we can of course then take some confidence into a cold -AO forecast.

 

There is however nothing to assert though that because there is no blocking now there can be no blocking in say 10-15 days time.

 

We should be keeping the options open looking at how things develop- & no one can say with confidence that there will be no blocking in 10 days, just because the stratosphere doesn't seem to be playing ball or because we currently have a period of zonal conditions....

 

I notice Ian piped up- his zonal forecast for more than 10 days of zonal conditions have finally come to fruition- hes only been forecasting them since 2008-

 

S

 

Come on Steve you should know by now that i say what i see and i stand by my earlier post on the 12's.

It could well be some reaction from the trophospheric pattern will show up soon to induce heights into the Arctic but it does not show yet-it may tomorrow or next week etc.

Believe me i will be one of the first to point to a cold setup if it shows up-but there,s nothing in the way of sustainable HLB on the 12;s imo.

I know you like to discuss possibilities on what could evolve from current outputs-nowt wrong with that but i just stick to what's before me.

[Tom Jarvis]

from what i'm seeing. the key part of changing the pattern is the ridging on the pacific side of the vortex which is causing the disruption in the PV. once this happens as pointed out by CC the knock on effects lead to the uk becoming cold. so this ridging is now in the 240H timeframe which we hope will continue to be modelled until 0h once that ridging happens it set off a chin reaction which causes the uk to become cold. so the key part for getting the uk cold isn't that far into FI and hopefully it will get closer.

[SMU]

Cheers ^

 

The most notable thing on the ECM is the big high driving into the pole from the very East of Russia at 240- that's a proper cross polar arctic high if it indeed does develop

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013110612/ECH1-240.GIF?06-0

 

S

[Cheshire Freeze]

Oh and latest CFS wants in on some potential Greenland blocking too....

 

 

 

 

Cheers ^

 

The most notable thing on the ECM is the big high driving into the pole from the very East of Russia at 240- that's a proper cross polar arctic high if it indeed does develop

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013110612/ECH1-240.GIF?06-0

 

S

 

Yep all very interesting around the day 10 juncture at this very early stage Steve.

[Tom Jarvis]

Cheers ^

 

The most notable thing on the ECM is the big high driving into the pole from the very East of Russia at 240- that's a proper cross polar arctic high if it indeed does develop

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013110612/ECH1-240.GIF?06-0

 

S

just like that failed easterly last year where the highs needed to touch but a shortwave stopped it from happening. but in this case it is the heights disrupting the PV over the pacific that is needed to get cold to the UK

[Cheshire Freeze]

just like that failed easterly last year where the highs needed to touch but a shortwave stopped it from happening. but in this case it is the heights disrupting the PV over the pacific that is needed to get cold to the UK

 

It's not always that straight forward Tom. Though it certainly gives us more of a chance to free ourselves of the zonal flow. The next few days could be interesting as to whether we see the signal strengthened and carried forward.

[Snowy L]

HI Phil - I disagree with the assumptions you are making in this post- almost Ian Brown esque-

 

 

What you are intimating is that due to the fact that the stratosphere is cooling that vis a vee there cannot be any cold or any polar blocking, & because the models aren't modelling any warming or any abate of the zonal wind there cannot be any cold either-

 

Well, that is why annoyed me with the stratosphere thread from last year - Everyone has gone stratosphere mad, sure is part of the system, however it doesn't have total control of the weather-

 

For example take the stratospheric profile for November 2010

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/50mb9065_2010.gif

 

Below the norm getting close to getting to the bottom of the range-

 

but what chart do we see in that month?

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-25-0-0.png

 

 

The stratosphere will indeed continue to have its periods of cooling & hopefully as we head into Winter we will see a warming like last year where the temp anomaly goes off the scale-  we can of course then take some confidence into a cold -AO forecast.

 

There is however nothing to assert though that because there is no blocking now there can be no blocking in say 10-15 days time.

 

We should be keeping the options open looking at how things develop- & no one can say with confidence that there will be no blocking in 10 days, just because the stratosphere doesn't seem to be playing ball or because we currently have a period of zonal conditions....

 

I notice Ian piped up- his zonal forecast for more than 10 days of zonal conditions have finally come to fruition- hes only been forecasting them since 2008-

 

S

 

 

I'm quoting Chionomaniac on this but the stratosphere did indeed play a part in that cold spell:

 

"There is still a lot to learn about this subject and on the surface the stratospheric conditions were nothing too out of the ordinary in late autumn in 2010. However, at that time of year, the vortex is yet to gain the kind of strength that a prolonged winter cooling would lead to and so is vulnerable to attack. And this attack came in the form of the rare tropospheric led Greenland wave break, which broke into the lower reaches of the stratosphere creating a split, which in turn reinforced the Greenland high. Later on in the season, these types of tropospheric waves will be suppressed by the vortex if it has cooled and strengthened sufficiently.

 

So enhanced tropospheric wave activity was enough to split the lower stratospheric vortex before the stratospheric vortex had increased to it's full winter strength. Quite rare."

 

In fact it bares a few similarities to what I think is our current situation. The vortex is strengthening and will continue to strenghten with strong zonal winds, however wave breaking is expected to begin next week, which some models, the GFS in particular, are forecasting to affect the lower stratosphere. There was an interesting GFS chart posted in the strat thread which shows a split in the lower vortex, albeit in FI, which if becomes reality we could be looking at some form of Northern blocking. This of course being started by the big height anomaly in the Aleutian Islands in the troposphere. The stratosphere isn't the main contributor to winter weather, but I think the troposphere>stratosphere>troposphere is by far and away the main cause of winter set ups.

[UV-RAY]

from what i'm seeing. the key part of changing the pattern is the ridging on the pacific side of the vortex which is causing the disruption in the PV. once this happens as pointed out by CC the knock on effects lead to the uk becoming cold. so this ridging is now in the 240H timeframe which we hope will continue to be modelled until 0h once that ridging happens it set off a chin reaction which causes the uk to become cold. so the key part for getting the uk cold isn't that far into FI and hopefully it will get closer.

the problem with the Pacific ridge is at the moment it's more of an hinderance than help, also we need to see a lowering of heights in Southern Europe as any cold we may see will be very fleeting if heights remain strong in this area.

[Gael_Force]

the problem with the Pacific ridge is at the moment it's more of an hinderance than help, also we need to see a lowering of heights in Southern Europe as any cold we may see will be very fleeting if heights remain strong in this area.

 

Maybe so - I posted the Nov '10 run in the winter thread yesterday - have a look at the NH pattern, it all started with a sharp Pacific Ridge and the response to it. It runs like a model output, just mouse down the dots.

 

http://www.meteociel.fr/modeles/archives/archives.php?mode=2&month=11&day=16&year=2010&map=4&hour=0

[SMU]

snowy L

All very well producing a hindcast 3 years down the line...... Why wasnt it forecast at the time with the same information at hand as we have now- all what your saying sort of confirms my post-

The assumption that phil made by saying because everything points to cold in the stratosphere it therefor is curtains for any form of blocking is I think a poor assumption-

The type of blocking over the nh can take on many shapes and forms, we can get a scandi block in a predominently zonal flow we can a GH in a cold stratosphere

Remember we can get cold with a neutral AO as well..

I homestly think people put to much faith into the strat thread, its great to use as a guide and even more exciting when there is some explosive warming however that usually spans just a short period of our winter time-

The strat is only just beginning to be discovered, we are only at the tip of the iceberg in terms of its interactions, what we do know is the larger the +ve anomalies do in terms of polar heights, but we would would be better off reanalising what the height profiles were like in the 'normal' periods not just the execptions.

Im sure the strat thread will be busy this winter - however the bottom line is though because the models will model any such warmings they will be onto it before any forecaster on here as we simply dont have the full picture to beat them to it....

S

[Panayiotis]

Another blocked end to the GFS...

[Barry12]

Will the block show in the ECM 240 hour in a couple of days I wonder!?

[Tom Jarvis]

Will the block show in the ECM 240 hour in a couple of days I wonder!?

it was already in the 12z at 240hs

[Sean19]

Where do you find these charts? 

 

 

it was already in the 12z at 240hs

[Tom Jarvis]

Where do you find these charts? 

here click on the model you want on the banner http://www.meteociel.fr/modeles/gfse_cartes.php