WInter Model Output Discussion 12z- 28/01/2013

[winterof79]

Wouldn't normally consider an ESTOFEX forecast for inclusion here, but they had some interesting comments in their latest output:

http://www.estofex.org/

You could say this chart fitted that bill http://www.meteociel.fr/modeles/ecmwf/runs/2013020100/ECH1-240.GIF?01-12

But its cold.

[TEITS]

As others have highlighted an excellent ECM with a very snowy +240 chart with plenty of potential thereafter. However as much as I would like to see the ECM being correct we must be cautious. As I highlighted last night W,lys could easily occur instead as the GFS & GEM suggest.

http://modeles.meteo...em-0-240.png?00

Thankfully its the ECM that is showing the E,ly rather than the other way round.

So yet again our nerves are going to be put to the test with yet another chase of an E,ly and lets hope this time around we get lucky!

Edited February 1, 2013 by THE EYE IN THE SKY

[Frosty.]

As others have highlighted an excellent ECM with a very snowy +240 chart with plenty of potential thereafter. However as much as I would like to see the ECM being correct we must be cautious. As I highlighted last night W,lys could easily occur instead as the GFS & GEM suggest.

http://modeles.meteo...em-0-240.png?00

Thankfully its the ECM that is showing the E,ly rather than the other way round.

So yet again our nerves are going to be put to the test with yet another chase of an E,ly and lets hope this time around we get lucky!

The Ecm 00z is epic enough at T+240 but that undercut would probably bring strengthening ESEly winds had it run further with widespread blizzards and much more to come, what it potentially shows is what RJS/BFTP and GP/CHIO have been expecting to come and it would be even better than the recent freeze.

PS...I read a post from Gibby overnight, just to say, gibby, you don't speculate, you give a detailed but easy to understand unbiased view of the models which I hope you will continue to do for a long time to come, I rarely disagree with you and I rate you as a highly valued expert poster:) don't stop.

[nick sussex]

Lets hope the GFS does what it did yesterday, it woke up in a flattish mood and then improved during the day.

The later ECM brings a battle ground over the UK with pressure rising to the ne. Those low heights to the nw though are still troublesome and we'd want to see some of that energy held further back over Canada.

There is a better looking cold pool to the east and I do think if we're going to see deep cold and the chance of ice days for the UK then it really has to happen now.

If the high to the ne wins the battle then theres a good chance of that , if not then we'd perhaps have to lower our expectations for the rest of February.

[MR EXTREMES]

nick sussex would u say this does not bode well if its correct>>>>>

The polar vortex remains somewhat disturbed with roughly 20 K temperature anomalies still present at 30 hPa. However, some gradual re-organization of the vortex is anticipated with AO ensemble members tightly clustered although this strengthening might be only on a temporal basis. However, despite those trends in the upper troposphere/lower stratosphere, the European weather remains influenced by an healthy looking branch of the split polar vortex, which moves north towards the Greenland Sea. This pattern is reflected in the maps of the 500 hPa height anomalies, which show a strong negative signal south of Iceland and a NE-ward building positive anomaly over far SW Europe.

because my translation would be that its looking like the gfs type setup am i right ?

[bradymk]

Modelling seems to be following a very similar path to early December: a deepening Euro trough, shortwaves cutting NW-SE across the UK.

I wonder how soon before models begin to develop heights to the NE, and what if any will the fate of any attempted easterly ? Will it share the same fate of the mid December one ?

The sun has been spokily quiet of late.

This was GP's last post a couple of days. ECM this morning starting to show this with heights building to our NE and a deepening euro trough.

[lorenzo]

GFS MJO forecasts explain it's reluctance to shift onboard with the ECM, UKMO the most progressive out of the Big 3.

GEFS and GFS go for a huge loop the loop in phase 8 the MJO tracking regressing before moving on round to phase 1 and 2, the CPC said the signal wanes and becomes incoherent towards the end of their last bulletin. You could argue it has been completely incoherent however in terms of the predicted pattern being erased completely by travelling vortex.

ECM mean at 216 is a great place to be, that was the one that caught the eye this morning for me anyway.

GP posted the GWO orbit this week giving it two distinct options and outcomes. Tiny steps but edging towards opening the door to winter again..

From 7 days ago you could argue we are moving away from the heavy zonal outlook where the huge low piled in on the block. Lots of Northerly North Easterly incursions piling in now.. Any bets on That ECM part 2 this weekend..

[Dexter29]

Welcome to frozen snowfest britain..enjoy your stay

I think the Ecm is handling the evolving pattern much better than the woeful gfs.

I agree.

The ECM handled the last cold spell much better than the GFS

[Gibby]

Good morning folks. Here is my take on the 00z outputs from GFS, UKMO, GEM and ECM for the first day of the new month (where has January gone?) Friday February 1st 2013.

All models show an agreed pattern of events over the next 4-5 days. Low pressure lies to the East of the UK with a temporary Northerly flow developing over the British Isles. Residual overnight rain will exit SE Britain this morning leaving a brighter day to develop with sunny spells later. It will feel colder with a chilly Northerly breeze developing bringing some wintry showers down the Eastern coast through the day with some rain showers too elsewhere. Tomorrow shows a Northerly flow too with a cold day in prospect with some snow showers near Eastern Coasts while most places have a dry and sunny day with a frost possible early and late. On Sunday a frontal system moves in from the West turning things less cold for a time with rain moving SE across the UK through the day. Early next week sees all models developing a chilly and strong WNW flow over the UK with rainfall and cloud slowly being replaced by sunshine and showers, these turning steadily wintry from the North with time with all areas becoming cold or rather cold by midweek in a keen Northerly wind.

GFS then gradually brings less cold conditions in from the West albeit slowly and complex with several bands of rain and sleet moving in from the West. Winds are then shown to strengthen from the West in association with deep Low pressure crossing East to the North of the UK with rain and strong winds followed by showers for all. this unsettled and windy phase then takes us out to the end of FI.

The GFS Ensembles show a rather cold spell to come under winds from a Northerly quarter. The trend is for uppers to rise to nearer the normal levels for early February in line with the operational along with an increase in rainfall.

The Jet Flow continues to track across the Atlantic over the Atlantic High and down across the UK to Southern Europe over the coming week or so.

UKMO's chart for midnight on Thursday shows Low pressure centred over Denmark with a cold Northerly flow over the UK. There would be cold weather for all in widespread snow showers for all Northern and Eastern areas in particular as well as close to Western Coastal extremities with many inland areas staying largely dry especially in the sheltered South.

GEM shows a slider Low next Thursday on the back of a Northerly flow with rain and possible snow crossing SE over the UK followed by another brief Northerly. Towards the end of it's run GEM flattens the pattern to bring milder Westerly winds in with rain and strong winds to end the run.

ECM shows a cold Northerly too through the middle of next week, weakening slowly towards the weekend as disrupting Low pressure slides SE over Britain enhancing the risk of more general rain and snow next weekend, the snow fall being totally dependant on where the Low tracks SE across the UK.

In Summary today it looks like the emphasis next week will be on rather cold and showery Northerly winds. There could be snow showers almost anywhere through the middle of the week before a slow return to something rather less cold develops later in the runs, particularly from GFS & GEM , supported by the GFS ensembles but less so from ECM. Despite these cold synoptics it's ECM's closing days pattern which could develop into a more noteworthy cold spell further down the line if pressure is shown to continue to rise over Scandinavia.

[chionomaniac]

I agree.

The ECM handled the last cold spell much better than the GFS

And the UKMO beat them both hands down. I would agree with SM, keep to the UKMO up to T+144 and then the ECM and ensembles and then look at the GFS and its ensembles for fun.

[nick sussex]

nick sussex would u say this does not bode well if its correct>>>>>

The polar vortex remains somewhat disturbed with roughly 20 K temperature anomalies still present at 30 hPa. However, some gradual re-organization of the vortex is anticipated with AO ensemble members tightly clustered although this strengthening might be only on a temporal basis. However, despite those trends in the upper troposphere/lower stratosphere, the European weather remains influenced by an healthy looking branch of the split polar vortex, which moves north towards the Greenland Sea. This pattern is reflected in the maps of the 500 hPa height anomalies, which show a strong negative signal south of Iceland and a NE-ward building positive anomaly over far SW Europe.

because my translation would be that its looking like the gfs type setup am i right ?

It's inevitable that you'll get some reformation of the PV, its where it sets up thats important, if it elongates running sw/ne further to the west of the UK you can still get a cold pattern.

The GFS briefly builds a ridge ne then flattens it, even if you have a negative anomaly in the Greenland Sea it could still be just far enough north to have a decent high over the UK with colder air especially for more southern and eastern areas.

I think MR its just a wait and see because of the model disagreements.

[chionomaniac]

Strat wise I know that some have been asking. The 10 day trend is for a lower split - more pronounced on the GFS - but the main axis is for one segment of energy based towards the west of Greenland (The Canadian Vortex segment!) with the other based over Kosomolsk-on-Amur (look it up!) as can be seen on this 100 hPa chart

The ECM is less distinct with this set up but the trend is there.

This type of split is favourable to NE height rises - as ever though this depends upon the Canadian segment backing far enough west to see the really cold air coming our way. In January we were undone by the third strat warming that displaced the tropospheric Canadian vortex segment eastwards, (when the really cold air had amassed to our east and was ready to strike). And with that, the end of Jan forecast went with it!

Hopefully with this set up we won't be undone again.

Edited February 1, 2013 by chionomaniac

[Katiewombat]

Good morning folks. Here is my take on the 00z outputs from GFS, UKMO, GEM and ECM for the first day of the new month (where has January gone?) Friday February 1st 2013.

All models show an agreed pattern of events over the next 4-5 days. Low pressure lies to the East of the UK with a temporary Northerly flow developing over the British Isles. Residual overnight rain will exit SE Britain this morning leaving a brighter day to develop with sunny spells later. It will feel colder with a chilly Northerly breeze developing bringing some wintry showers down the Eastern coast through the day with some rain showers too elsewhere. Tomorrow shows a Northerly flow too with a cold day in prospect with some snow showers near Eastern Coasts while most places have a dry and sunny day with a frost possible early and late. On Sunday a frontal system moves in from the West turning things less cold for a time with rain moving SE across the UK through the day. Early next week sees all models developing a chilly and strong WNW flow over the UK with rainfall and cloud slowly being replaced by sunshine and showers, these turning steadily wintry from the North with time with all areas becoming cold or rather cold by midweek in a keen Northerly wind.

GFS then gradually brings less cold conditions in from the West albeit slowly and complex with several bands of rain and sleet moving in from the West. Winds are then shown to strengthen from the West in association with deep Low pressure crossing East to the North of the UK with rain and strong winds followed by showers for all. this unsettled and windy phase then takes us out to the end of FI.

The GFS Ensembles show a rather cold spell to come under winds from a Northerly quarter. The trend is for uppers to rise to nearer the normal levels for early February in line with the operational along with an increase in rainfall.

The Jet Flow continues to track across the Atlantic over the Atlantic High and down across the UK to Southern Europe over the coming week or so.

UKMO's chart for midnight on Thursday shows Low pressure centred over Denmark with a cold Northerly flow over the UK. There would be cold weather for all in widespread snow showers for all Northern and Eastern areas in particular as well as close to Western Coastal extremities with many inland areas staying largely dry especially in the sheltered South.

GEM shows a slider Low next Thursday on the back of a Northerly flow with rain and possible snow crossing SE over the UK followed by another brief Northerly. Towards the end of it's run GEM flattens the pattern to bring milder Westerly winds in with rain and strong winds to end the run.

ECM shows a cold Northerly too through the middle of next week, weakening slowly towards the weekend as disrupting Low pressure slides SE over Britain enhancing the risk of more general rain and snow next weekend, the snow fall being totally dependant on where the Low tracks SE across the UK.

In Summary today it looks like the emphasis next week will be on rather cold and showery Northerly winds. There could be snow showers almost anywhere through the middle of the week before a slow return to something rather less cold develops later in the runs, particularly from GFS & GEM , supported by the GFS ensembles but less so from ECM. Despite these cold synoptics it's ECM's closing days pattern which could develop into a more noteworthy cold spell further down the line if pressure is shown to continue to rise over Scandinavia.

Excellent clear summary Gibby, especially for us dumbo's who can't actually read models :-)

[mulzy]

Just a note of caution, it's very likely that the ECM operational solution this morning is one of the colder runs. The day 8 ensemble mean chart looks a lot flatter than the operational. The DeBilt ensembles confirms that the operational was on the cold side of the ensembles.

Operational:

Ensemble Mean

DeBilt ensembles

Edited February 1, 2013 by mulzy

[nick sussex]

Given Mulzy's post I think we should still view the GFS as a plausible scenario, you can see two separate clusters opening up at days 8 to 10.

If the elongated PV sets up too far east then its unlikely we'll hang onto the cold, further west and the UK will probably be the battle ground so some areas seeing some snow, much further west and we see that high to the ne play a bigger role.

The elongation of that PV is aligned for something from the ne but we do need some luck here with where it sets up.

[Guest bjaykent]

Hi guys. I know it's a bit late and not many people may still be awake but I do appreciate your comments of earlier this evening. I wish I had more time to join in with your excellent discussion between the 00zs and 12zs but life can be very time restrictive at times. However, if anybody has any suggestion good or bad in ways that I can improve or dumb down my reports to you even if you think I should not do them at all I am quite open to suggestions either through the forum or via the email link via my website. I guarantee I will reply to all emails providing they are constructive in their criticism and will endeavour to adjust the reports to make them a more pleasurable experience for all. Once more I thank you for those that have complimented me in the past, it is much appreciated and as long as you enjoy reading them I will continue to compile them.

Hi have just caught up with your post from last night and can I say I love your forecasts, you just say it as you see it and I like many who are trying to learn how to read the models will look at your forecast and then go back and relate it to the models. Please don't change a thing!

[Hotspur62]

Note to Gibby-Your posts are always informative,simple and you just say it as the models see it.Keep up the good work!!

Onto the models and i did think by last night things would be a bit clearer for the medium/long term but still things are nicely balanced with the big 2(GFS and ECM) still at odds with each other.The pessimist in me says GFS will be right in the Longer Term,but i hope that ECM is right and then we may be in for a final cold spell which would please most members on here.I agree with what most senior members say in that we need the energy of Vortex off NE Canadian coast to stay as far West of possible and that would i feel allow us more chance of Heights building from NE and eventually allow a North Easterly/Easterly flow to establish and give the POTENTIAL for snow across UK.Come on GFS,jump on board with the ECM!!

[TEITS]

And the UKMO beat them both hands down. I would agree with SM, keep to the UKMO up to T+144 and then the ECM and ensembles and then look at the GFS and its ensembles for fun.

Does anyone know if the UKMO has recently been upgraded. I ask because as CH says this model has been the star performer this winter. Take for example today when the GFS/ECM/NAE all predicted an intense LP system and yet the UKMO never was interested and proved correct. I find it a shame the UKMO only goes to +144 at the moment.

At the moment this is reminding me of our last cold spell where I had no interest in following the GFS. Have to be honest I don't feel as though the ECM has performed that well this winter.

[nick sussex]

The GFS 06hrs run is even flatter than the earlier 00hrs and with those low heights stuck to the nw you'd need a miracle to hang onto the cold.

The PV looks really reluctant to give us a break and even though the ECM 00hrs is much better than recent GFS runs that still has too much energy east.

Unless the PV gets shunted much further to the nw then any cold is always going to be under alot of pressure to hang on.

[Tamara]

The models this morning I think depict quite well that February crossroads I mentioned yesterday evening. Clearly we are edging back to a situation where pressure is looking to rise to the NE whilst at the same time the polar vortex continues to nestle in its seasonal home to the west of Greenland and Canada. ECM shows the recent January cold pattern set up once more by day 10, which would give us another bite of the apple before the days get too much longer. UKMO supports this greater amplification on its medium term limit output. GFS has the emphasis clearly on energy from the eastern seaboard flattening the pattern and with greater eastward progression of the pattern.

A look through the ECM postage stamps at t168 shows a fair amount of support for the greater amplification option with most of the members supporting the operational quite well, and not flat like the GFS. This is encouraging perhaps for how the GFS may trend in future outputs

http://www.ecmwf.int...0100!!chart.gif

[snowmadchrisuk]

Maybe just temporary , but if there is one trend I have noticed over the last few GFS runs is that the P/V seems to be getting much weaker than it has been ,,, +180 below and then current P/V below that,

[SMU]

The UKMO has been updgraded to a higher vertical resolution to incorperate more of the stratosphere-

Also the seasonal model has been updated as well but I cant remember its bloo*dy name-

S

[snowking]

It should be noted that on the 0z's @ day 6:

It goes GFS, then UKMO, then ECMWF

However, at 12z:

Its ECMWF, then UKMO, then GFS, with the 12z's overall verifying slightly better than the 0z's at present.

However, what has been notable for some time now is that out at day 10:

The GFS over a running mean of 31 days has been better verifying than the ECMWF. Now in fairness, I suspect that once we lose the period before the 5th January (the zonal period) from the running 31 day mean the two will become rather more equal in terms of verification stats, however if people will insist on looking at day 10 at the present time then despite the lower resolution, its the GFS 0z that the data insists we should be looking at.

What I need to do is go in search of verification stats for specific locations rather than the N Hemisphere as a whole!

SK

[Cecil Hogmanay Melchett]

Awful 06gfs,flat as can be upstream.

[Catacol]

When this winter is over it will be interesting to hear why the NAO has gone pearshaped along with the lack of a blocking over Greenland. If I remember correctly GP expected the core of blocking to move W over Winter with the NAO becoming a W based negative NAO as the blocking moved over to Canada. The problem is the blocking can't move over to Canada in Feb because it never developed in the first place!

I think we will end up declaring that it has all been about the positioning of the tropospheric vortex, and that all our "usual" teleconnections have been thrown off tack by the pressure the displaced and disrupted stratospheric vortex has put on patterns at a tropospheric level. The debate will then be about why energy has so consistently set up shop in the Canadian sector - is that luck/bad luck or is there something we can learn in terms of predicting the energy transfer over the arctic. As a fascinated watcher of this we have heard our more experienced posters on here consistently mention pressure rises over Greenland in response to movement of the vortex to Siberia - but this has been consistently exaggerated. In reality we keep coming back to vortex positioning in the same place.

This suggests to me that our developing understanding should place stratospheric events at the top of the teleconnection tree - and that all the work Chio and others are doing to understand it more fully is vitally important.

From this angle 2012/13 has been a disappointment so far in terms of product - I cant subscribe to Matt Hugo's vision of a winter of extremes at all... it has been a winter of the unexpected for me: background signals pointing strongly one way but then tropospheric reality ending up somewhere else. This was the case in December when the vortex over rode signals; it is the case currently where we are not seeing the expected composite match for AM and MJO phase (at least not yet...) and to an extent it was the same when we got our cold spell of a week or so because we managed to get that with a pattern that was only just conducive to cold: really it was a zonal pattern driven by gentle height anomalies to our north - a very very marginal winter situation and not severe cold at all. Lying snow and gentle winds gave us the low night time minima. It has certainly been wet, but temperature and pressure extremes? Absolutely not.

There are 4 weeks to go - but I agree that the post winter debrief is going to be fascinating - almost more fascinating than the forecasts and the product itself!

In the meantime I wonder if we can get a second bite at a snow pattern. Amplification is occuring; there is a trend for blocking too in the models, for all the frustraton of energy still firing out of Canada. I'll take a punt and suggest that Canadian energy is long overdue a rest... and so perhaps mid Feb may deliver something genuinely cold. We keep pushing the date back and back, but Feb 15th onwards for me now, a climb down from my previous estimate of Feb 9/10.

Edited February 1, 2013 by Catacol_Highlander