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Captain Shortwave

Model Output Discussion - The final stretch to Christmas

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Hi IDO

The GEFS have been dire for several days so nothing much has changed there tbh. Just look how the opp run goes zonal as soon as it hits low res again (just like last night).

I use GEFS a lot tbh, but I think right now they are and will be largely useless for a day or so. They could still be right of course, but it will be luck rather than judgement in this instance.

Hi yes I agree that the trend has been zonal for the GEFS for a few runs, but there were still a cluster showing potential in the Pacific region. This morning that is now noise with that baton seemingly dropped. Of course it could all change later and we need 2-3 runs with that signal before we get too worried. but with the CFS churning out consistent zonal means for January it is worth noting.

As for cold without an SSW, that is possible, but a sustained block without one would be a long shot.

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Boxing days looking beautiful and seasonal though

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Morning all,

 

It seems our chance of a pressure rise circa Greenland has now passed,even with the trop vortex relaxing around Baffin low heights have still scuppered any WAA from Atlantic ridging.Indeed current NWP are now pointing towards a rejuvenated trop vortex emerging in the Greenland area around the new year, with current output I would think our best chance of achieving heights that will bring cold to the UK would now be from our N/E,as I think this can be achieved whilst we have a strong trop vortex to the N/W.We have also seen heights low around the Alutians so far this winter and  the snow advancement over Russia we saw in October would I think correlate to us seeing the return of the Russian high at some point this winter.

 

ECM tries to rise pressure into Scandi  around the 29th and we see a link up with the Russian high,

npsh500.168.png

Its something I'll be looking out for wether it materializes is a different matter.

Merry Christmas to you all,

Wolvesfan

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Quite a lot of difference this morning between the model output's and once again a bit more flip flopping around. 

 

The UKMO at +120 has the low centered closer to Iceland than the UK

UW120-21.GIF?22-06

By + 144 is all but game over for cold fans, the Extreme North and NE / NW facing coasts would fair well for a time, but the Atlantic waits in the wings and the finger is on the reset button...

UW144-21.GIF?22-06

 

The GFS OP offers hope and is a step closer to prolonging the cold and offers something to work with. 

Here show blows at + 120 with the Low centered MUCH further south than the UKMO output about to enter Scotland

gfs_0_120_png_0.png

Again the Low dives SE but with the GFS at + 144 there's a better link up between the Azores high and the Greenland High.

gfs_0_144_png_0.png

Which leads to this at +192 on the GFS OP,  an extension of the cold(er) weather and it keeps things interesting. 

gfs_0_192_png_0.png

 

The Parallel is also a very interesting run, reminiscent of the ECM a few days ago, with the Low flattened out and another secondary Low spawning to our West..

gfs-0-120.png?0

Leading to this at + 144

gfs_0_144_png_0.png

the Parallel run then goes on into FI and develops and Easterly from this at + 192

gfs-0-192.png?0

To a Scandi high of sorts later on and a long fetch Easterly

gfs_0_300_png_0.png

What about the Control run ??

 

The control run shows yet another different output to all of the above, stalling the progression of the Low, at +120 it's barely made in roads to the UK, but once again is MUCH further south than no the UKMO

gens-0-1-120.png?0

Once again it is diverted E, or SE fills up, leading this at + 144

gens-0-1-144.png?0

pretty windy along the S.Cost on this run !!

 

The Control run goes on to show a return to Westerly's but it's not a million miles off the Parallel..

 

as you can see at + 228, 

gens-0-1-228.png?0

 

Leading us onto this mornings ECM

 

Here's she blows at 120 on the ECM, Very stormy for the NE and windy along the South, once more modeled MUCH further south than the UKMO

ECM1-120.GIF?22-12

I find the ECM evolution, however hard to believe as the low seems to travel directly south from it's 120 position, to end up here just 24 hours later

ECM1-144.GIF?22-12

Those in the SE must be excited about that !!

 

The ECM goes on to something of a half way ground between the GFS Control and GFS Parallel not far from an Easterly 

 

this at + 216

ECM1_216_GIF_22_12.gif

 

Interesting developments this morning and a step away from an Atlantic takeover (except for the UKMO, which should never be discounted) 

 

Hopefully we can see further moves toward Height Rises over Scandinavia in the coming days...the roller coaster ride continues !!

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Looks like the razor blades can be put under lock and key again, some exciting times ahead

A very snowy weekend if (when) the GFS (P) verifies and then various models showing some excitement from the east

Game on

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Looks like the razor blades can be put under lock and key again, some exciting times ahead

A very snowy weekend if (when) the GFS (P) verifies and then various models showing some excitement from the east

Game on

 

Yes John, All is not lost this morning with some promising signs further into the out-put. The bumpy ride continues  :)

Edited by Polar Maritime

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The model fiasco continues!

 

The ECM has made a huge backtrack, the UKMO still doesn't have the shortwave upstream, the GEM well last night comments like " out to lunch" by NCEP was hardly a ringing endorsement!

 

The GFS P probably the best of the bunch for cold, the ECM has some scope, the UKMO not quite as underwhelming as yesterday evening but still poor relative to the GFS P.

 

Overall no sign of the uncertainty letting up just yet.

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Yes John, All is not lost this morning with some promising signs further into the out-put. The bumpy ride continues  :)

GEFS panel is interesting

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=0&ech=240

1,3,6,7,8  i will stop there but i could go on as many suggest our weather could be coming from the east come New Year :cold:

http://modeles.meteociel.fr/modeles/gens/run/gens-12-0-240.png

 

EDIT i see SK has posted .

 

Just as an add on the met maybe hinting at the above.

UK Outlook for Friday 26 Dec 2014 to Sunday 4 Jan 2015:

A cold and largely fine start to Boxing Day with a widespread frost likely. Remaining dry for most of the day, but unsettled conditions pushing eastwards later, with rain, perhaps transient hill snow, and strong winds developing, with a risk of gales, most likely in north and west. During the weekend, unsettled, slightly milder and windy conditions are most likely across the UK, with periods of rain or showers. Into the following week, more settled conditions may push into western parts, and outbreaks of rain and showers will then primarily affect northern and eastern areas, with snow possible to lower levels in the north. Thereafter, the most likely solution is for periods of frontal rain and milder temperatures, but also some good spells of dry weather, especially in the south.

Edited by winterof79

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You can see the varying positions of the low at T120hrs on the ECM postage stamps, having looked at these last night there has been a marked shift in terms of the amount of members who bring the low in further south:

 

post-1206-0-93416500-1419237155_thumb.gi

 

The ECM spread though grows rapidly from T144hrs onwards with the mean likely diluted out by conflicting solutions.

 

It's evident from those ensemble members in the stamps that some keep a trail of shortwave energy running ne/sw to the north these will likely be the milder solutions. So today its really down to whether you get that split or not.

 

And then how much amplitude is left upstream so I'd be a bit wary of using the mean as a guide until these early differences are agreed on.

Edited by nick sussex

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HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY DECEMBER 22ND 2014.

NEXT UPDATE TUESDAY DECEMBER 23RD 08:00

THE CURRENT GENERAL SITUATION
A mild SW flow will continue to affect England and Wales with a slow moving trough near to the borders between England and Scotland slow moving. A colder westerly flow will affect the far North of Britain.

MODELS-2 WEEK HEADLINE Changeable weather with rain at times and wintry showers at others. It will be cold and windy at times with some overnight frosts.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Foreecast is for the flow to continue it's undulating pattern over the next week or so with the longer term trend still indicative of a relatively flat pattern across the UK between High pressure near the Azores and Low pressure to the NW and North.

GFS OPERATIONAL The GFS operational this morning maintains it's prediction of rapid deepening of a storm system post Christmas as it winds it's way from the North of the UK to Europe. After a quiet and chilly Christmas with frost a period of strong winds and gales become replaced by cold North winds and snow or wintry showers  on the western flank of the Low. As this moves away winds decrease under rising pressure with bright days and sharp frosts and perhaps a little sleet or snow in the SW for a time as a small disturbance bumps into High pressure over the UK. Then as we move into the New Year the default pattern of High to the SW and Low to the NW with mild and strong Westerly winds prevail.

THE GFS PARALLEL RUN The Parallel run makes much less of the storm system with regard to the UK post Christmas but still potent enough to bring strong winds and cold weather under Northerly winds with wintry showers in the North and East. The cold winds then die away as pressure becomes High over the UK with cold and frosty weather prevailing over and into the New Year. Pressure then transfers East to become High over Northern Europe and brings a blast of cold East winds across the Uk towards the end of the run with snow showers in places as a result.

THE GFS CONTROL The GFS control run appears to be fairly similar in storm development to the North of the UK post Christmas with rain and strong winds for all before cold Northerly winds and eventual High pressure take over with frosty night and wintry showers in places for a time. Then the UK High cell drifts South later to set a regular pattern of strong and milder west winds and rain at times late in the run.

THE GEFS ENSEMBLES The GFS Ensembles do show the temporary chance of cold weather from quite a few members post Christmas with the overlying trend thereafter for the cold to lift out in preference to milder Westerly winds between High to the South and Low to the North into the New Year.

UKMO UKMO's development of the storm is more muted with it being just a standard deep Winter depression held well up to the North of Scotland bringing the strongest winds and rain to the North and NE with all areas seeing some rain before chilly NW winds and wintry showers take over by the end of next weekend.

THE FAX CHARTS The Fax Charts today show slow progress SE oof troughs across NW Britain replacing the mild and windy weather with quieter High pressure weather over Christmas with frost and night and light winds. Further fronts and increasing SW winds reach the NW by Day 5.

GEM GEM today shows the UK coming under a very mobile westerly pattern following Christmas with rain and strong winds alternating with colder and brighter periods with some wintry showers in places. The storm system after Christmas looks not at all threatening now blending instead with the overall pattern under strong Westerly winds and average temperatures.

NAVGEM NAVGEM's does show a more direct hit from the storm after Christmas as it drifts down the North sea enhancing a cold north flow for a time with sleet and snow showers quite widesly in the North and East following the rain and gales of previous days. High pressure then feed across Britain with fine and frosty weather developing as we move towards the end of 2014.

ECM ECM this morning shows probably the most direct hit from the storm after christmas this morning sending it SE down across the UK and on into the Meditteranean by the end of the run. This would bring rain and gales followed by cold North or NE winds and wintry showers post Christmas and then a shift of emphasis towards fine and cold, frosty weather develops for many with pressure holding High across Germany to the UK on Day 10.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart is made up of a varity of options but with a bias towards the default pattern of Low near Greenland and High south of the Azores with changeable weather with rain at times under average temperatures the most likely poitn the UK wll find itself in at day 10.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS While the trend towards the severest risk of a marked storm post Christmas has receded for now the new trend appears to focus on the greater persistence of High pressure close to the UK thereafter slowing the breakdown from the West which still holds the greatest trend longer term.

MY THOUGHTS While the overall trend in the short to mid term remains as before the focus on the main storm event post Christmas have taken a more relaxed view on it's positioning and severity in the way it affects the UK. It is still shown though to give all areas a good blow with rain followed by colder conditions with wintry showers as the wind swings Northerly on the exiting East of the depression. The new theme appears to be a greater reluctance to bring the Atlantic back in as quickly with a strong surge of High pressure over the UK towards the New Year. What's more interesting is that this High pressure extends into Europe and with lower pressure held over the Med it is shown far enough North by a few models to allow a cold East flow across the South of the UK in particular with some further wintry or snow showers in the East and more importantly keeping things cold and the Atlantic at bay for a time. This is specifically shown by the GFS Parallel run but is hinted at by ECM too at the Day 10 point with cold frosty weather maintainedover the UK should it verify. However, having said all that there is also a lot of support for a flattening of the pattern into a mobile Westerly flow between Low pressure near Iceland and Greenland and High pressure over the Azores with strong winds across the UK delivering rain at times under mild conditions overall. In my opinion the period post Christmas remains a very fluid situation and the behaviour of the deep Low expected at that time could have major repercussions on the emphasis of pattern resulting thereafter. If it's final resting place lies to the SE or over the Meditteranean then High pressure could hold cold and frosty weather in situ over the UK ala GFS(p) or ECM or if it floats away further East over mainland Europe the pattern will quickly flatten to one of zonal West winds and rain at times and temperatures close to average if not a little above in the South. All should be revealed over the coming days as we near the event and the models hopefully get a more conclusive handle on the timing, depth and positioning of the Low.

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ECM ENS mean is pretty flat after T144hrs.. Not good for coldies

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This post will not be popular with the cold fans but for beyond 6 days it is to me what seems the most probable unless the MJO begins to show some definite support over the next few days?

 

Mon 22dec

Ec-gfs

Changes again with ec showing ridge with sw flow today, totally opposite to last issue

Gfs shows trough is in charge and flow is from n of west but with ridge edging in from west

No reliability here and gfs most like noaa 6-10 from last evening

As to what MAY happen to the upper flow then certainly less reliability than I can usually give. Probably the noaa-gfs is the most likely but neither suggest any marked cold plunge, certainly not of any lasting cariety. Within the 6 day or so time frame then a fairly brief one is possible, beyond that the  a mainly westerly flow at 500mb seems the most probable. That takes us into the first third of January possibly?

MJO currently in very low phase 3 and predicted to stay very low into phase 5-I am not sure if any guidance is really available from this to change the predicted 500mb flow.

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The model fiasco continues!

The ECM has made a huge backtrack, the UKMO still doesn't have the shortwave upstream, the GEM well last night comments like " out to lunch" by NCEP was hardly a ringing endorsement!

The GFS P probably the best of the bunch for cold, the ECM has some scope, the UKMO not quite as underwhelming as yesterday evening but still poor relative to the GFS P.

Overall no sign of the uncertainty letting up just yet.

I no Nick , we all knew the models would struggle with a pattern change , Tamara's post illustrated the volatility of the models as they get to grips with the drivers behind the scenes , but I don't think we/me realised how much they would struggle , big swings at relatively early frames . Which is why I really think it's completely pointless in posting endless charts of d16 mean charts buts that's another debate I really can't be arsed to get into again !

After my negative annalysis yesterday I'm feeling slighltly more positive going forward , mainly because there's a fairily significant warming happening high above our heads starting now and continuing for the next 10 days+? Models really haven't got a clue at the minute and signs are now starting to appear in the form of hights to our North east , not quite sure what's happeneds to the neg PDO does seem to have waned somewhat ?

But purely looking at analogues of past years , with a strong aluetian low in place that normally correlates with the siberian high , so maybe the excpected winter pattern getting its act together ?

Edited by Severe Siberian icy blast

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ECM ENS mean is pretty flat after T144hrs.. Not good for coldies

I think you're better of looking at the spreads:

 

post-1206-0-48242400-1419237846_thumb.gi

 

It's impossible with that spread to look at the mean as a guide, the solutions at that point are split widely.

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Well the ECM ens favour a north/south split developing with pressure rising across central/southern Europe

EDM1-192.GIF?22-12

 

This reflects well in the metoffice update with longer drier spells developing for southern areas as the influence of the heights to our south strengthen somewhat. Nick L's post below pretty much says it all, the major clustering goes for a milder south westerly flow.

 

So that is the more rational part of my post.....

 

Snowking you had to mention January 2013 didn't you :p I was actually thinking something similar based on this mornings output. I would add at the moment this type of solution will not show on the ens very well given that the majority will push the northern arm of the jet straight through from west to east. The Scandi high or even a wedge will be our most likely route to cold if it does occur as we head into 2015. 

The operationals (GEM excluded) don't seem to be showing a strong jetstream coming across the Atlantic with conditions settling down over Europe and this could definitely allow heights to drift northwards, especially if there is sufficient cold pooling over Southern Europe to support this.

Edited by Captain shortwave

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I know I said not to look at the 00z output but I couldn't resist the ECM ens ... There is a spread cluster to support colder uppers coming in from the east by day 10.

The weekend low has decent spread cluster support to go just about anywhere.

The term 'Murr sausage' may get an outing soon.

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ECM clusters showing a predominantly mild and southwesterly theme as we head into the new year.

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This post will not be popular with the cold fans but for beyond 6 days it is to me what seems the most probable unless the MJO begins to show some definite support over the next few days?

 

Mon 22dec

Ec-gfs

Changes again with ec showing ridge with sw flow today, totally opposite to last issue

Gfs shows trough is in charge and flow is from n of west but with ridge edging in from west

No reliability here and gfs most like noaa 6-10 from last evening

As to what MAY happen to the upper flow then certainly less reliability than I can usually give. Probably the noaa-gfs is the most likely but neither suggest any marked cold plunge, certainly not of any lasting cariety. Within the 6 day or so time frame then a fairly brief one is possible, beyond that the  a mainly westerly flow at 500mb seems the most probable. That takes us into the first third of January possibly?

MJO currently in very low phase 3 and predicted to stay very low into phase 5-I am not sure if any guidance is really available from this to change the predicted 500mb flow.

Does not sound like a confident summary by any stretch of the immagination.So the worst case scenario is we get to the 1st Jan,10 days from now and it has not been very cold.Not the end by any means for cold lovers.

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I think you're better of looking at the spreads:

 

attachicon.gifEEH1-144.gif

 

It's impossible with that spread to look at the mean as a guide, the solutions at that point are split widely.

Hi Nick, I have been viewing the forum for some time but never felt confident enough to post except for a few simple replies. But having seen the spread charts refered to on several occasions. I realised that I do not understand what they are showing, I assume from the name they represent the variance in the output. I have looked at the legend and really I am none the wiser is there an area on the forum which explains what these charts are for, their reliability and how to read them please

Edited by EastAnglian

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There are five clusters for Saturday on the ECM and all pretty much have the same probability:

post-14819-0-63458000-1419237035_thumb.p Spread large at D5: post-14819-0-43197200-1419237605_thumb.g

So uncertainty re track of LP system. The op looks unlikely to bring snow with that Low, as the precipitation coincides with a warmer sector:

post-14819-0-87396800-1419237444_thumb.p

Maybe back edge for hills and snow showers to the north afterwards.

The CFS MJO for early Jan is phase 5 and the corresponding anomaly:

post-14819-0-73690200-1419237871_thumb.g post-14819-0-54609000-1419237872_thumb.p

So likely any height rises will be temporary before it flattens out in our sector. Maybe changes in the second half of Jan or the strat warming can get things moving quicker.

So unlikely anything wintry as we head into Jan. As for a possible easterly, GEM picked this up on the 0z yesterday and it remains a small cluster this morning. A low probability I would have thought; getting everything right for one of them is seemingly as difficult as a GH! The GFS P is great this morning, but it has been great for over a week; it maybe another model, like the ECM op, that has a habit of teasing us with over amplified solutions. So I am wary of this at the moment at least till one of it's blocked solutions actually materialises.

Edited by i'm dreaming of...

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Hi Nick, I have been viewing the forum for some time but never felt confident enough to post. But having seen the spread charts refered to on several occasions. I realised that I do not understand what they are showing, I assume from the n

The ECM spreads show the divergence from the mean. The darker the colour the less the spread of solutions and vice versa. It's quite unusual to see that bigger a spread at that timeframe.

 

And you shouldn't worry about posting everyone is welcome to post, and people are always happy to answer any questions. Welcome to NW I hope you enjoy lots of drama because that's part and parcel of searching for cold!

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