Model Output Discussion 19th January 2014-18z onwards.

[karlos1983]

pretty good agreement from the GEFS

 

Can't post images for the min

[ukpaul]

The benchmark I suggested I was looking for in the ensembles of blocking within the timeframe of 27th-29th-ish shows that around 55-60% of members have blocking to our west whichcould help to bring colder uppers our way (from north or east). That's not as good as the 75% on yesterday's 18z but a clear improvement on today's 12z, which was at around 25-33%..

 

Game on, as they say......

 

The mean at 180h shows this clearly, much further west than the 06z for the same timeframe.

 

Edited January 22, 2014 by ukpaul

[Mucka]

GFS ensembles

 

NW England

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=233&y=38

 

SE England

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=291&y=125

[Purga]

http://www.wetterzentrale.de/pics/Rukm1441.html

Looks good to me

Only for the NE otherwise you're snookered. Cold rain and an Azores ridge wafting in to dumb everthing down again.

[The Eagle]

Yep. Solid agreement across all models on the jet stream going over the top after the LP sinks SE and reintroducing the mobile westerly regime. It's only a timing issue but by 192 no model has any easterly still in place. Will the ECM show any different?

 

It looks like it will be a case of how far west the cold air comes before the setup sinks away. 

Edited January 22, 2014 by The Eagle

[Summer Sun]

GFS ensembles

 

NW England

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=233&y=38

 

SE England

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=291&y=125

 

40% chance of snow on the 27th and 29th on the SE short term ensemble

 

60% chance of snow on the 27th on the NW short term ensemble

 

50% chance of snow on the 29th on the NW short term ensemble

[Troubleatmill]

The benchmark I suggested I was looking for in the ensembles of blocking within the timeframe of 27th-29th-ish shows that around 55-60% of members have blocking to our west whichcould help to bring colder uppers our way (from north or east). That's not as good as the 75% on yesterday's 18z but a clear improvement on today's 12z, which was at around 25-33%..

Game on, as they say......

The mean at 180h shows this clearly, much further west than the 06z for the same timeframe.

Sorry Ukpaul is that supposed to blocking to the east or the block to our east getting further west, and improvement on 00z or 06's?. Lost me a bit pal Edited January 22, 2014 by Nicholas B

[The Post-modern Winter]

Only for the NE otherwise you're snookered. Cold rain and an Azores ridge wafting in to dumb everthing down again.

 Considering the number of posts stating that it is difficult to call what would occur beyond this and the absolute certainty with which you state this outcome, you really should be working for the Met office Purga. Ally this with the confidence you place on the zonal FI outcomes you often post in here, I'm surprised you haven't already been head-hunted by them. 

Edited January 22, 2014 by The Post-modern Winter

[swfc]

Transient easterly looks on the cards as they low eventually pulls away on ukmo with possible wintry precipitation around the 144 hour mark.Thereafter things look rather slack imo and with no great heights to the north east ete the atlantic low looks favourite to push east.Obv any correction westward would change things but as would things pushing east.Unsttled,cool and wet would sum things up for me

[Panayiotis]

Nice NAVGEM tonight, and the charts at the end is what could happen if you get enough WAA northwards @144hrs, for this we need to look at the low the exiting the US. But details on that should be looked for later next week.....

Edited January 22, 2014 by Panayiotis

[fergieweather]

 Considering the number of posts stating that it is difficult to call what would occur beyond this and the absolute certainty with which you state this outcome, you really should be working for the Met office Purga. Ally this with the confidence you place on the zonal FI outcomes you often post in here, I'm surprised you haven't already been head-hunted by them. 

 

As of a few minutes ago (!) the consensus opinion from UKMO colleagues does remain one of Atlantic superiority returning at some stage next week (intense cold leaking ad-infinitum from Canada ensures that likelihood), but we shall see.

[ukpaul]

Sorry Ukpaul is that supposed to blocking to the east or the block to our east getting further west, and improvement on 00z or 06's?. Lost me a bit pal

 

An improvement; better blocking = greater chance of colder air moving in.

[SE Blizzards]

I wouldn't be so cock sure Purga.

GEFS suite looking nice...

 

Yep, GEFS suite out to 240 now, and they look nice and pretty cold to me 

 

They do go a little pear-shaped after that though.

Edited January 22, 2014 by SE Blizzards

[Bobby]

The GEFS 12z ensembles are pretty interesting around 168hrs to 192hrs - quite a bit more support for some kind of easterly flow than the 06z and previous ensembles, quite a shift really. Means:

 

 

Quite a few petrubations pull in a cold easterly feed. Does look temporary though as it's back to normal after that, 216hrs:

 

 

Will be interesting to see if the ECM and its ensembles back this up later

Edited January 22, 2014 by Bobby

[sunnijim]

Only for the NE otherwise you're snookered. Cold rain and an Azores ridge wafting in to dumb everthing down again.

Disagree,if we had a 168hrs chart it would surely show the low further SE still and many other parts of the uk in the freezer with wintry potential.Certainly looks more likely than the azores high and cold rain taking over at that juncture. Perhaps a short lived window for widespread uk cold this, before the azores high/ cold rain or any other option toyed with in the last few days takes hold post 168hrs. Edited January 22, 2014 by sunnijim

[Purga]

 Considering the number of posts stating that it is difficult to call what would occur beyond this and the absolute certainty with which you state this outcome, you really should be working for the Met office Purga. Ally this with the confidence you place on the zonal FI outcomes you often post in here, I'm surprised you haven't already been head-hunted by them. 

See the post from Ian F..........

[Cecil Hogmanay Melchett]

The GEFS 12z ensembles are pretty interesting around 168hrs to 192hrs - quite a bit more support for some kind of easterly flow than the 06z and previous ensembles, quite a shift really. Means:

 

 

Quite a few petrubations pull in a cold easterly feed. Does look temporary though as it's back to normal after that, 216hrs:

 

 

Will be interesting to see if the ECM and its ensembles back this up later

Yes,momentum building for some kind of cold outbreak as the trough drops to the South east next week.

Fingers crossed..

[The PIT]

Subtle differences between the GFS and UKMO at T96 which get very large by T144. GFS being less progressive for once while the UKMO drags the cold air down as the low pressure powers SE . UKMO out performing the GFS at T120 and T144 off late although that doesn't mean it will definitely this time of course. A t168 chart would be interesting if the next low takes the same path. Either way that block is hanging on.    

[Cecil Hogmanay Melchett]

See the post from Ian F..........

And?

UKMO favour a return to Atlantic regime,they also favoured a barbeque summer in 2007/8?

They get it wrong sometimes Purga,as do we all.

Anyway,GEFS 12Z are looking very good for next week.

[Mucka]

We can't of course take the ensembles at face value at the further ranges, it is all about picking out signals and trends from among the noise.

As such there is a signal in the GFS 12z ensembles for better amplification upstream later which has not existed before.

The signal is fairly muted and certainly not a trend but it is the sort of positive shift we need to see if we want to see a chance of any sort of sustained cold of a few days rather than some blustery cold days among milder ones.

If ECM and JMA are half decent then we will have recovered our ground this evening from this mornings step backwards. 

Onwards and upwards!

 

Edit.

 

I should also mention there is a signal for high pressure to move into the Arctic once more probably through second half of the first week of February - interesting times.

Edited January 22, 2014 by Mucka

[SMU]

I would be careful about making the assumption about the atlantic moving back in so fast-

 

the UKMO 12z & seemingly long lost partner the NAVGEM show the V of high pressure nosing across from Scandi that stops the high sinking-

 

If we look at the UKMO 144 again-

http://www.meteociel.fr/ukmo/runs/2014012212/UN144-21.GIF?22-18

 

You will see almost a perfect pressure balance across the piste with the UK being the midpoint of the symmetry- ( but on the cold side of the polar front)

 

NB:

 

Pressure to the EAST

HIGH 1035 MB  NE

LOW 990 MB   SE

 

Pressure to the West

LOW 990 MB   NW

HIGH 1035 MB SW

 

Perfect equilibrium- meaning that the pattern could well remain stationary.

 

Anyone banking on the GFS to be a trend analysis need only remind themselves of its easterly bias-

 

Remember the GFS & how awful it is - lets remind ourselves-

 

Current 48 chart

http://modeles.meteociel.fr/modeles/gfs/runs/2014012212/gfsnh-0-48.png?12

 

the SAME chart for 168 5 days ago

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014011712-0-168.png?12

 

Whilst theres a chance the atlantic solution is correct you have to go back to teh UKMO & look at how much negative zonal energy is working against the atlantic at 144-

http://www.meteociel.fr/ukmo/runs/2014012212/UW144-21.GIF?22-18

 

Negative zonal winds from the heart of europe all the way across to Southern Greenland ( & Weak higher pressure over Svalbard)

 

this will ensure that the diverted atlantic track will more than likely be SW of greenland SE towards Ireland.

 

There in lies the problem-  if the track is through ireland & the SW then its a UK snowfest. If the track is SE through scotland then it will warm up-

The third solution is more energy is sent North up into Greenland which allows pressure to build more readily from the NE like the persistent NAVGEM shows- again it cannot be discounted & If people remember I used the NAVGEM solutions all week so far ( because of the solution NOT the model)

 

onto the ECM, consistently poor for UK cold over the last few days- ive a feeling that we are going to see a change this evening.-

 

S

PS watch the GFS correct west over teh next 48 hours...

Edited January 22, 2014 by Steve Murr

[Bobby]

And?

UKMO favour a return to Atlantic regime,they also favoured a barbeque summer in 2007/8?

They get it wrong sometimes Purga,as do we all.

Anyway,GEFS 12Z are looking very good for next week.

 

That was a long range seasonal forecast, totally different beast to a medium range weather forecast... come on, be fair!

[Purga]

I wouldn't be so cock sure Purga.

GEFS suite looking nice...

Sorry General but if you look at the GEFS charts sure they look 'good' with low 850 temps but check out the best part of the run

 

 

And a bit later -6C thicknesses 850hPa getting into the NE

 

 

 

But apart from the NE it's cold rain as I suggested - maybe a bit of sleety stuff up North but not significant.

 

 

Thereafter the zonal train progresses

 

Far more significant is the potential rainfest likely to be endured by poor folk in flood areas!!

Edited January 22, 2014 by Purga

[Cecil Hogmanay Melchett]

That was a long range seasonal forecast, totally different beast to a medium range weather forecast... come on, be fair!

The point is,they get it wrong sometimes and have been wrong at short,medium and long range timeframes.

The GEFS 12Z suite and ukmo are looking good for a cold shot.

It may or may not happen,we'll see...

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=187&y=174 (South West England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=307&y=138 (South East England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=269&y=0 (Northern England)

As several have pointed out, the 12z ENS are much better for blocking and, as a consequence, better for cold and snow, reflected in the 850 temps. One thing that is worth pointing out is that you don't need deep cold for snow so many of these members could provide snow quite widely on account of low thicknesses and/or low dewpoints, depending on where the surface flow is coming from and the upper air profile. No certainty yet, but nothing can be ruled out!

Edited January 22, 2014 by Joe Levy