Model output discussion - proper cold spell inbound?

[Gowon]

1 hour ago, Quicksilver1989 said:

Background

So, first some context…. The UK winter is moderated by the Gulf Stream, warm ocean currents move north from the tropics and help prevent the UK from being as cold as somewhere like Moscow. The diagram below shows a picture of the ocean currents.

 Warm air directed to the UK from Gulf stream

Now interestingly there is evidence to suggest this is slowing down which generally should mean a negative feedback in the northern hemisphere due to a decrease in heat transport. Just one problem… the strengthening of mid latitude highs and deepening of polar lows means the Eurasian continent has warmed substantially during the winter.

 

 

 

So, the moral of the story is.. our winters will progressively get worse?

[Seasonality]

12 minutes ago, Faronstream said:

I might be wrong but a SSW can actually change the current situation in the atmosphere and strengthen the upper winds in the polar vortex so we get mild SW winds for a  long time. I think that happened winter 2011/12

Still looks pretty mild in both GFS and ECM, anyway it's getting too late for any proper cold and the sun angle is high.

 

I looked it up and the record low for February in Orebro is actually marginally colder than for January, and for March only slightly warmer. Jan = -29.6, Feb = -30, Mar = -28. That data comes from SMHI, so a reliable source. Not true that it is too late.

[Scandinavian High.]

Looking like trend for high pressure over uk and just to east  southerly south easterly breeze we may go in to something colder later if high can push north  it might not show what you want snowy easterly I think trend is good get us in to  southerly south-east  Easterly..

[Singularity]

Worth noting what IF says (see Model Tweets thread) this morning; key period of model divergence starting 18th i.e this coming Sunday, and "Still a way to go before we can be more bullish on the outcomes after this weekend".

So it's not the best of practice to infer from the current model output that we'll likely be looking at next week day X or later for a colder flow returning... end of this coming week is the limit.

Could be a properly pleasant Friday and weekend beforehand for many, perhaps best to make the most of it if you can? Cue exciting model output gluing us to our screens 

Edited February 12, 2018 by Singularity
My keyboard is a twit

[Daniel*]

Very strange chart ECM T+240 not far away from a good chart vortex looks as strong as it now to NW dubious. I think height rises to north east will come sooner than we think. 

Both ECM and GFS are interested in MLB doesn’t necessarily mean this is certain but presently more likely, just past day 10 GFS 06Z has a 1947 vibe - started in a similar way.

[Weather-history]

GFS 06z ensembles are looking very anticyclonic 

Mean at 198hrs

[bluearmy]

11 minutes ago, Singularity said:

Worth noting what IF says (see Model Tweets thread) this morning; key period of model divergence starting 18th i.e this coming Sunday, and "Still a way to go before we can be more bullish on the outcomes after this weekend".

So it's not the best of practice to infer from the current model output that we'll likely be looking at next week day X or later for a colder flow returning... end of this coming week is the limit.

Could be a properly pleasant Friday and weekend beforehand for many, perhaps best to make the most of it if you can? Cue exciting model output gluing us to our screens 

I think it’s all coming together now. Whether we get a cold flow setting in pre day 10 is the question. I would say currently unlikely but not out of the question depending on the pattern as the ridge pushes north. Also, uncertain whether it stays nnw or settles Scandi.  

Edited February 12, 2018 by bluearmy

[karlos1983]

looking through the individual GEFS purbs at +276, an awful lot show an easterly of sorts, hardly any are what I would call mild! and some corkers in there too. I would expect a colder set of ens in graph format to follow. 

Here's the mean for the same time which is a pretty good representation after studying the set. 

 EDIT: Here they are

Edited February 12, 2018 by karlos1983
said cold meant Mild D'oh - Monday morning grhh

[Daniel*]

4 minutes ago, Weather-history said:

GFS 06z ensembles are looking very anticyclonic 

Mean at 198hrs

Scandi looks inviting for height rises it’s quite possible models will suddenly pick up on it as EPS has showed more ‘delayed’ it isn’t really, time is sadly not on our side I wouldn’t be fretting if it was mid winter. Possibly we won’t see a turnaround come as soon as we hoped before or at 20th however not as long. 

[SLEETY]

18 minutes ago, Singularity said:

Worth noting what IF says (see Model Tweets thread) this morning; key period of model divergence starting 18th i.e this coming Sunday, and "Still a way to go before we can be more bullish on the outcomes after this weekend".

So it's not the best of practice to infer from the current model output that we'll likely be looking at next week day X or later for a colder flow returning... end of this coming week is the limit.

Could be a properly pleasant Friday and weekend beforehand for many, perhaps best to make the most of it if you can? Cue exciting model output gluing us to our screens 

Think it’s been obvious for ages  it’s too early to say what going to be eventual outcome of this SSW,let’s hope for once we can hit the jackpot ,seem to be chasing Easterly on the model thread all winter now 

[Daniel*]

4 minutes ago, karlos1983 said:

looking through the individual GEFS purbs at +276, an awful lot show an easterly of sorts, hardly any are what I would call mild! and some corkers in there too. I would expect a colder set of ens in graph format to follow. 

Here's the mean for the same time which is a pretty good representation after studying the set. 

That’s not far off being a very good mean we need more northern latitude not a huge push. 

[karlos1983]

Just now, Daniel* said:

That’s not far off being a very good mean we need more northern latitude not a huge push. 

Yes, that should prevent the Acorns growing 

[Summer Sun]

06z ens looking colder than the 00z run with the mean on this run heading down to around -5

[Daniel*]

GFS ens have trended colder mean flatlines at -5C 850hPa for the foreseeable which is quite decent interesting the disparity going on between OP well GFS 06Z does have a go.

 

[Daniel*]

Interesting where the spread is at D10 to our north suggestive we could see blocking root further north possible even towards Greenland.

[The Beast From The East]

On 10/02/2018 at 10:04, johnholmes said:

The post above by ba is perhaps the most constructive one I have seen since the anticipated reaction to the 'warming' and how it 'might' affect the UK.

I have to confess to being at odds with a lot of the euphoria on here and not really convinced by my ex colleagues at Exeter over this deep cold possibility from a point east of the UK. Staying colder than normal into the next 2 weeks I quite agree with but to me, most of what I can see from this forum and data we can all pick up from various weather centres suggests that the cold is going to come from a westerly not easterly point, more like NW and at times perhaps N. That is in the 14 day time scale from now. What happens beyond is not my sphere.

The 500 mb anomaly charts are not as solid as needed for a definite take but all 3 I use have consistently shown height rises across much of the northern part of our hemisphere but with not much, to me, to suggest that any upper or indeed surface ridging is going to come from other than the Iceland/Greenland area, again I stress in the next 14 days.

The upper heights from northern Russia all the way across into the far NW of N America mean that the surface lows may well end up being further south than currently. Behind one of these I suspect a burst of polar air is likely. Beyond that then I am uncertain how it may play out. If the expected effect on the Troposphere occurs in our area at such a time then the snowy wonderland so hoped for on here might well happen-I don't know.

Bit coldish, even cold at times is the weather for 2 weeks or so.

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

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

Well done John on this great post. At the time things were still looking great for cold and like you said even Exeter were still going for the real cold option but it looks like you were on the money with what you were seeing.. ?

[ICE COLD]

That is a bloody good set of ensembles from the GFS 6z . A stonking set as @feb1991blizzard would say ?. Not often you see the snow row so high so far out for the London set ?. Well just maybe we're gonna get somewhere as IF tweeted more easterlies showing in the ECM ensembles . 

Edited February 12, 2018 by ICE COLD

[Derecho]

48 minutes ago, D.V.R said:

So, the moral of the story is.. our winters will progressively get worse?

In theory, yes but as anything with UK weather its more complicated then that.

I have no doubt we will see cold snowy winters again but more of the 2010 arctic type rather then those from Scandi highs. If certain factors allign then a fight could be put up against the vortex and deliver a classic winter in the UK but its getting tougher. Low solar activity in the next few years may give a helping hand though but we shall see.

The other alternative is that the AMOC really slows down and we get 2010 style synoptics frequently. UK winters would actually become colder at the expense of rapidly accelerating warming over the arctic and tropics.

So I think the moral is that things like the NAO will get stuck in certain phases for longer with more extreme deviations from the mean, with extreme positive NAOs prevailing over extreme negatives. As mentioned though if the AMOC slows down substantially we could well see fundamental changes to the climate system but lets wait and see.

That spot in the Central North Atlantic is of particular interest though especially when you start looking at global temperature evolution. A very cold year globally on the left and the 2nd warmest on the right (2015):

                           1917                                                            2015


In fact 2015 was by far the coldest year in the Central North Atlantic since 1880. Is this telling us something? Is the answer lurking in the oceans? It's what I find fascinating but from a model output point of view hopefully we can break this trend of the cold blob returning every March....

[dixonoid]

On 10/02/2018 at 20:31, bobbydog said:

It seems to me that after a point the models want to keep the Atlantic flowing and very much struggle with ssw's, as I understand a strong SSW reverses the flow, so our weather comes from the east, been a strange old winter with lots of winter weather from the NW, quite unusual but the USA has had a quite cold winter so far, even Florida experiencing frost :-) . past experience model watching, says a beast from the east might appear closer than day 10 :-)

 

[bluearmy]

12 minutes ago, TheBeastFromTheEAST said:

Well done John on this great post. At the time things were still looking great for cold and like you said even Exeter were still going for the real cold option but it looks like you were on the money with what you were seeing.. ?

Strange Fred - I think the cold signal is now gathering pace for week 2. 

Yesterday I wasn’t convinced how long the MLB would hang around 

[fromey]

2 minutes ago, bluearmy said:

Strange Fred - I think the cold signal is now gathering pace for week 2. 

Yesterday I wasn’t convinced how long the MLB would hang around 

And to back that up a little

[ICE COLD]

4 minutes ago, fromey said:

And to back that up a little

And to back that up GEFS 6z set have trended colder ?

[chrisbell-nottheweatherman]

15 minutes ago, bluearmy said:

Strange Fred - I think the cold signal is now gathering pace for week 2. 

Yesterday I wasn’t convinced how long the MLB would hang around 

As highly as I rate John's analysis (I pay more attention to his posts than those of the majority here), I think the marginal shifts in the ECM output suggest that we cannot be certain that the mild outcome after this week is going to verify, and I suspect that John himself would agree.

Edited February 12, 2018 by chrisbell-nottheweatherman
Edited for clarity.

[bluearmy]

5 minutes ago, chrisbell-nottheweatherman said:

As highly as I rate John's analysis (I pay more attention to his posts than those of the majority here), I think the marginal shifts in the ECM output suggest that we cannot be certain that the mild outcome after this week is going to verify, and I suspect that John himself would agree.

I don’t believe JH was of the opinion that any outcome would verify! And certainly not a mild one !!

i suspect many in here are fed up of the chase and being disappointed- I urge you to get on board this time !!

 

[Purga]

Indeed Nick et al...

 

06z GEFS trending colder but still uncertainty evident.

The wind spreads (for De Bilt) shows that EPS favours a more solid easterly cluster:

The latest GEFS cluster analysis data points to the same:

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=324&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=