Model output discussion - cold proper on the way?

[MR EXTREMES]

17 minutes ago, johnholmes said:

Well the models are having fun with everyone, up down, roller coaster covers it. But in the quieter world up aloft what has been happening?

Obviously it is the 500 mb anomaly charts. They are means so do tend to be less up/down compared to the synoptic 6 or 12 hourly outputs. Indeed I would suggest it might be a better idea to simply look at the synoptic 500 mb chart run to run or better still to compare like runs, you may have heard that somewhere else before!

Anyway

The ECMWF-GFS this morning

Not surprisingly they are not that different to what they have predicted over the past 4 or 5 days, see below

Atlantic ridging towards Greenland and EC still with GFS now showing a building of ridging over Scandinavia with an extension west towards Greenland. Something that the occasional run on the 6 hours outputs has suggested. Marked troughing on both remains into Europe.

The configuration on these two shows lower contour heights on EC compared to GFS. However on both the upper flow shows the cold will persist over the next 6-10 days. Okay it may wax and wane but no signal showing for any mild air for the UK.

So what about NOAA and it has a chart that covers 8-14 days out.

The 6-10 last evening, largely between the UK and Scandinavia well north with the flow dropping into the European trough. About a week ago the contour flow had the slightest hint of this. The actual +ve height anomaly is show away from any of this, just off the American coast. With such a meridional flow obviously the contour heights over the UK area are higher than the other two. This has little effect ob surface temperatures, indeed if there is any surface ridging in between weather systems might create lower values at the surface. To me the strong flow out of America does leave a question mark for day to day. Will any deepening systems move NE or SE once into the eastern Atlantic?  With the deep trough east of the UK one would expect them to steer SE or ESE, which may provide some excitement if they get close to the UK. Looking at their 8-14 day chart and perhaps the most interesting change from the 6-10 is the increase in –ve heights over NW Europe. Again little signal for any mild air. That is unless we get a flow not easterly but SE/or worse SSE with air originating from the Med. Nothing to be concerned about in the next 6-10 days but a possibility beyond that.

So, overall the cold will continue, the synoptic models will come and go so to speak on its depth and ideas on where/when any ppn will occur. Up to 24 hours out forget what the models may predict, they are right a few times at longer time scales but not often. Just think back to summer set ups and how often they get the rainfall correct? In winter there are another 8 or so additional variables to get right.

Hope this summary helps calm the nerves a little.

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Excellent level headed post.

[BLAST FROM THE PAST]

Not liking the GFS....t90 to t96 we see the slug nudge east, it’s going to flatten?

 

BFTP

[Deep Snow please]

Seems okay for Tuesday at least. Nationwide snow event.

 

[Summer Sun]

Quite a drop in temps Tuesday morning once the mix of rain, sleet and snow clears away

[kold weather]

1 minute ago, BLAST FROM THE PAST said:

Not liking the GFS....t90 to t96 we see the slug nudge east, it’s going to flatten?

 

BFTP

Looks just about ok to me, the Arctic high is there, not as strong as on the 00z but then again that went bombastic. However evolution is broadly the same as per 00z, so got a bit of a Mexican stand off here...

[MKN]

Seems to be heading in the direction of the ECM by 108.

[swfc]

Gfs 6z doesn't really amplify tbh and leaves things a bit flat.fi hopefully brings better synoptics and 850s

[northwestsnow]

1 minute ago, MKN said:

Seems to be heading in the direction of the ECM by 108.

Its nothing like EC really..

GFS 120

EC 120-

[frosty ground]

Just now, northwestsnow said:

Its nothing like EC really..

GFS 120

EC 120-

But the high is collapsing 

[snowangel32]

Well our Eastern promise might have gone but at least Tuesday shows Nationwide snow and a brutally cold day. Gfs is collapsing the high. Now it's over to you UKMO.

Edited January 19, 2019 by snowangel32

[ItNeverSnowsInWindsor]

1 minute ago, frosty ground said:

But the high is collapsing 

Not with the Arctic high nearby it’s not and the European low.

[karyo]

2 minutes ago, northwestsnow said:

Its nothing like EC really..

GFS 120

EC 120-

Sadly the low west of Iceland is deeper on the 6z gfs than the earlier run. This run is going in the wrong direction.

[frosty ground]

1 minute ago, snowangel32 said:

Well our Eastern promos might have gone but am least Tuesday shows Nationwide snow and a brutally cold day. Gfs is collapsing the high. Now it's over

Correction 

 

not winter of course just this potential spell

[That ECM]

T120 to far out to call when such small differences make big differences. 

[ItNeverSnowsInWindsor]

1 minute ago, snowangel32 said:

Well our Eastern promos might have gone but am least Tuesday shows Nationwide snow and a brutally cold day. Gfs is collapsing the high. Now it's over to you UKMO.

Not for all low ground, could be sleet or wet snow instead.

[WhiteFox]

18 minutes ago, Steve Murr said:

 

My form horse is the UKMO with others falling into line this eve... A 3/4 way house to the amplified solution & the energy will split in the atlantic with the shortwave spoiler heading towards Portugal..

I think some people are disappointed that Narnia seems to be disappearing from many of the models this morning. Nothing wrong with that as many would love to see the conditions those sorts of charts would bring.

But feet need to be planted on the ground again and emotions untethered from each run.

What Steve says is true; it is unusual for an actual outcome to fully reflect one model's output if there are wide differences at a specific timescale. The most likely outcome would be some sort of blended solution which, it seems to me, has cold written on it albeit not in hundred foot high letters portrayed by all models yesterday for a brief few hours before the ECM came out.

Signals are still there: GFS still says cold. UKMO still says cold. ECM less so. But this is where @johnholmes ever excellent insights into the upper charts provide guidance. The pattern is still cold and there is, currently, no signal in the medium range for that to change.

In conjunction with the unchanged background signal of the SSW and the MJO heading for phase 6, the position will only become more favourable, not less, even if the ECM is correct on its own (which I don't think it is for now).

It is possible that the MJO phase 5 signal is, for now, overriding the SSW effect on blocking to our north. On the other hand, there could be issues with the models handling the SSW impact and the counter-effect of a phase 5 MJO. This is not a position they will have modelled frequently, so there is extra room for uncertainty.

For now, position remains largely the same which is not to let individual runs cloud judgement on the overall pattern which, at the microscale, is certain. To be uncertain .

.

[snowangel32]

1 minute ago, frosty ground said:

Correction 

 

not winter of course just this potential spell

Haha all these early mornings to check out the 00z completely messed up my spelling.

[bluearmy]

12 minutes ago, Deep Snow please said:

Seems okay for Tuesday at least. Nationwide snow event.

 

Impressive ...... especially as these charts tend to overdo it (that’s sarcasm btw)

Edited January 19, 2019 by bluearmy

[edinburgh_1992]

Positive 850s over most of the UK on gfs by next Friday  

+4 850 temps in scotland. Thats supposed to be cold?

Edited January 19, 2019 by edinburgh_1992

[Guest]

1 minute ago, bluearmy said:

Impressive ...... especially as these charts tend to overdo it (that’s sarcasm btw)

Way too marginal down here for snow, which off course means the most dreaded weather of all - 1c and rain! 

[Spah1]

The artic High is being modelled further and further East stopping the link up. 

[frosty ground]

There is a possibility of a slider which would be a longer route to cold

[kold weather]

Just the wrong side of things on this run, think that we will probably see a compromise solution, GFS seems like a good one, especially given we have already seen a lot of anticyclonic spells so far this January and I'm a firm believer in patterns repeating once set-up.

Still fairly chilly as well, especially in the SE part of the country.

[IDO]

The problem we have with nascent wedges is that they are not blocks per se, they flow within the pattern directing traffic. They are incumbent to the upstream flow. The Arctic wedge will get pushed and shoved around if the upstream pattern dictates. In the current trend, we have a high moving west to east at around T114 flattening upstream as the spoiler low off the E US directs the flow.

The GFS moves a step closer the ECM on this run.

Look at that cut off low send the pattern west to east and thus dictating the Canadian PV and pushing any wedges east...

[frosty ground]

Just now, Spah1 said:

The artic High is being modelled further and further East stopping the link up. 

Yes the high was modelled in the wrong place which is why the term spoiler short waves is very misleading