Model Output Discussion - 05/01/2016 18z onwards

[JOPRO]

People at it again! Assuming charts post 120hrs are set in stone, think we have plenty more mileage left in this yet. Our man from the met office (Ian f)is still saying it's all to play for and he has access to the much hyped  MOGREPS model and that has been almost rock solid with its output over the last few winters. Last time I think it struggled was Jan 2013 then what happend. I would treat any output post 120  with extreme caution and avoid absolute statements with regards to next week. Short term cold is on the way, after that all is up for grabs. Fascinating times!! Makes me think of the opion poll cock up during the last election, looks like it's going to take the exit poll to tell us where we are going!! Anyone for another GFS flip later?? 

 

[Eastwoods]

What's really cool about that 3d model is you can roll the globe around to see all aspects, well on android anyway not sure about PC. I guess some of you will already know that but new to me. Thanks for the link Cloud 10

[Day 10]

49 minutes ago, Greenland1080 said:

Cloud10 I'm reeling out the big guns,my secret weapon.....The CPTEC....

No panic MAJOR support from 2 ensembles

[blizzard81]

I guess Nick is not having much luck in his quest to find support for the ukmo state side

[Kentish Snowman in Yorks]

Regardless of the fact the models seem to be showing a fairly swift return of the Atlantic next week, I am very sceptical of such a development.

I have seen many a cold spell get extended day by day over the years simply because the models underestimate the strength of the blocking and cold.

I just cannot see the Atlantic sweeping through as modelled at present.  I fully expect trough disruption next week and maybe even an Easterly, but definitely not a return to Westerlies as easily as shown.

In the meantime, we have some snow and increasingly sharp frosts to look forward to over the coming days and nights (if you are into that sort of thing!)

[BM4PM]

 

21 minutes ago, Minus 10 said:

No panic MAJOR support from 2 ensembles

It wouldn`t suprise me if the 18z supports this, then shortly after ushers in spring! These blooming models are sending me bonkers. 

Edited January 11, 2016 by BM4PM

[karlos1983]

If I'm reading this correctly, this would suggest that there is a lot of uncertainty at +144 in the N ATLANTIC?

Tell us something we don't know

Edited January 11, 2016 by karlos1983

[Stuie]

There is a fine effort to the East/NE on the ECM of a holding block. Maybe retrogression of the cold isn`t there yet.

 

Edit: wrong terminology

 

Edited January 11, 2016 by SaffW

[feb1991blizzard]

1 minute ago, karlos1983 said:

If I'm reading this correctly, this would suggest that there is a lot of uncertainty at +144 in the N ATLANTIC?

Yes, that's quite a spread at that range. that's usually the sort of spread that only appears after 200hrs. It could just be one loan big outlier causing that though, you don't really know unless you see the full suite.

Edited January 11, 2016 by feb1991blizzard

[grca]

ECM short ensemble for De Bilt - op following the warmer breakaway group

[Lukesluckybunch]

4 minutes ago, grca said:

SorrhECM short ensemble for De Bilt - op following the warmer breaka

 

[chrisbell-nottheweatherman]

1 minute ago, grca said:

ECM short ensemble for De Bilt - op following the warmer breakaway group

Clusters appearing in the temperatures around the 17th, and the operational appears to jump from the colder cluster to the warmer one.  What stands-out to me, though, is the rate of temperature increase that the operational run shows - I can't see any ensemble members that jump that rapidly.

[Kentish Snowman in Yorks]

10 minutes ago, grca said:

ECM short ensemble for De Bilt - op following the warmer breakaway group

Two distinct and fairly equal (in number) clusters starting to diverge around the 18th there.  The colder cluster look to sustain if not intensify the cold after that date.

Very interesting indeed...

[chionomaniac]

One of the main reasons that I can see that we are having a tightening of the vortex and increase in AO and NAO is stratropherically based. And we can travel right up to the top of the vortex to demonstrate this.

As a warming gathers momentum there will be a 'squeeze' on the vortex as the warmer air moves around the surf zone. This squeeze can be seen quite clearly on the ensembles right up at 60N 10 hPA. If we use Recretos lego ensemble chart then we can see this demonstrated quite clearly at around days 8-9 before reducing as the warming takes hold. The vortex is not totally destroyed at 10hPa by the end of the run - merely displaced from the pole - so will have some strength but not centrally positioned.

Recretos has kindly reproduced his wonderful  graphic for me for lower down in the strat so that I can demonstrate how this tightening of the vortex is just not limited to the upper levels. And below is the same diagram but for 50hPa and we can see the tightening up and increase in mean speed for at the same time. The ECM is demonstrating the same as these GFS charts.

But the one thing to note is that this is most certainly a temporary affair - it is the final throw of the dice of a vortex living on borrowed time. Look what happens after. And once its time is up stratospherically then it is only a matter of time for the tropospheric vortex to also collapse once again. I think GP's torpedo has definitely been fired!

Thanks to @Recretos - I hope that everyone is following his wonderful charts in the strat thread or on twitter!

[Timmytour]

This 18z is the one chaps and chapesses....  energy going under or over.....it's finely balanced and the distribution early on determines the outcomes later on.

Well, much as an 18z run from  (not sure was it friday or saturday...seems ages ago now!)  signalled the beginning of doubt in the intensity and longevity of this upcoming cold snap/spell/one fifth of a year, I believe we are about to see a huge back track from the GFS with heights rising in the Atlantic a couple of hundred miles west of where they have been on runs hitherto and the colder air from our east being dragged over us like a blanket with a lovely looking T168 nurse tucking us in

<crossed fingers>

[Summer Sun]

Tonight's ECM ens shows high pressure starting to build over the UK giving most parts a chance to dry out towards the end of the run Scotland could become more at risk of some rain but else where the high keeps us dry

Temperatures very slowly recover though it could be mid next week before they do

 

After weeks and weeks of rain and floods high pressure is just what's needed

Edited January 11, 2016 by Summer Sun

[reef]

16 minutes ago, Summer Sun said:

After weeks and weeks of rain and floods high pressure is just what's needed

On the contrary Gavin, its exactly the opposite of what is needed. A very mild, moist flow like that would lead to huge amounts of orographic rainfall in north-western areas. It could well lead to huge rainfall totals much as at the beginning of December.

In case anyone wondered, its a textbook 'Bartlett' high pressure. It would be another week at least to anything snowy from there. 

[chionomaniac]

Just to add further to my earlier post - the forecast for the AO increase is far more dramatic on the ECM than the GFS and we can see another view of the u wind (mean zonal mean wind) from the following chart. This demonstrates the positive AO seen throughout most of the winter - the  increased sections between 100 -1000hPA in December. This then gave way to the early January trop/strat disconnect following the Kara ridge formation. The strat then connected back with the trop and  now we see the forecast of the pre warming strengthening and what I expect to occur after.

 

[damianslaw]

Echoing others sentiments, its a very uncertain outlook. What is certain is we are entering a rather cold period, nothing exceptional, perhaps a standard cold spell for the time of year, but it will feel very cold compared to recent weeks. We had a very similar spell exactly this time last year with some snow for some and frosty nights with daytime maxima struggling into the low single digit figures at least around here.

I'm keeping an open mind how things might pan out - if we do see the atlantic crashing back through with a strong SW flow as suggested by GFS and ECM, it by no means a return to conditions of Nov-Dec.. we are in a very different atmospheric state. Another surge of warm air advection over scandi and into the arctic combined with a Polar Vortex weak on its knees could be just what is needed to shake things up finally - trough disruption, heights pulled back out of Europe and into the mid atlantic, whilst all the time those arctic/Russian heights lie in waiting ready to pounce on Greenland.. A very shortlived mild atlantic outburst end result with a marked full stop!..

[bluearmy]

2 hours ago, nick sussex said:

Its turning into the Twilight Zone! So what do you think BA still a big split in the ECM ensembles? Early next week looks impossible to predict. I'm hoping NCEP will become big UKMO fans this evening! Generally though in their State forecasts they don't mention it much, its really the shorter term and WPC ones where it figures.

I'm off now to find any info that backs the UKMO!

I'm thinking pretty well the same as yesterday evening nick.  Why the sudden flip from neg AO/NAO to positive is an interesting question.  If it were a little later, I might be inclined to think it was a reconnection of the trop/strat as the  zonal winds get flushed down ahead of the potential SSW.  

EDIT:. guess I should have read the rest of the thread before answering !

Edited January 11, 2016 by bluearmy

[Grimsby Snow Lover]

3 minutes ago, chionomaniac said:

Just to add further to my earlier post - the forecast for the AO increase is far more dramatic on the ECM than the GFS and we can see another view of the u wind (mean zonal mean wind) from the following chart. This demonstrates the positive AO seen throughout most of the winter - the  increased sections between 100 -1000hPA in December. This then gave way to the early January trop/strat disconnect following the Kara ridge formation. The strat then connected back with the trop and  now we see the forecast of the pre warming strengthening and what I expect to occur after.

 

What exactly could we expect to see in the models over the next few weeks chiono? Sorry to ask but I struggle to understand what you mean lol.

[Radiating Dendrite]

2 minutes ago, Grimsby Snow Lover said:

What exactly could we expect to see in the models over the next few weeks chiono? Sorry to ask but I struggle to understand what you mean lol.

I believe he is saying we should expect a temporary strengthening of the vortex before it significantly weakens / collapses in response to warming. 

[booferking]

Is it not best to compare last nights  GFS 18z with tonights 18z as this gives you a better understanding if there is a trend are does this not make a difference.  Are should you compare with GFS 0Z   GFS 6Z   GFS 12Z sorry if i sound stupid. 

Edited January 11, 2016 by booferking

[Radiating Dendrite]

Just now, booferking said:

Is it not best to compare last nights  GFS 18z with tonights 18z as this gives you a better understanding if there is a trend are does this not make a difference are should you compare with GFS 0Z   GFS 6Z   GFS 12Z sorry if i sound stupid. 

That is certainly what JH is always telling us. Pick one run a day and stick with that. 

[booferking]

1 minute ago, Radiating Dendrite said:

That is certainly what JH is always telling us. Pick one run a day and stick with that. 

Thanks for confirming,