Model output discussion 25th Jan - The final third of winter beckons..

[iapennell]

17 hours ago, Harsh Climate said:

Im sorry guys but this is why I tend to stay away from the model thread now, too many unfounded knee jerk reactions every single run, sometimes before a run has even fully come out.. O when will you learn :/

@Harsh Climate; Indeed, chart-watchers can tie themselves in knots looking a depressions crossing the North Atlantic and high-pressure cells over Spain: This is part of the prevailing climate of NW Europe with a prevailing wind from the south-west! Current and predicted developments in the Arctic Stratosphere (and predicted up to a week into the future with considerable reliability nowadays), and which take two to three weeks to fully manifest at the surface give a better general outlook for two or more weeks out.

Beyond that, the state of the Quasi Biennial Oscillation (the alternating pattern of east then westerly winds high up above the Equator), the state of the Sun, El Ninó/La Niná and patterns of sea-surface temperature in the North Atlantic and Arctic pack-ice extent are the parameters I use in making seasonal forecasts- with some measure of reliability.

I know from bitter experience not to look at weather charts predicted more than a fortnight out. One is liable to be disappointed!

[iapennell]

12 minutes ago, Man With Beard said:

Much respect to you Ian as you completely ignore the hype and trust in your methods (very often correctly).

But I will very slightly contest the bit in bold. If you're speaking about long-range models e.g. ECM 46 - then yes, agreed.

But the shorter term models - on balance, I think many of them have actually underestimated eastern blocking in the D8-D15 range. End of December looked like a zonal-fest at first - but just a few days in, the easterly block was back. The past two weeks have been endless attempts by the models to send storms towards Scandinavia in the mid-term - it's in reality been two weeks of constant set-backs and although we're getting a few storms now, we are the very end of the line. 

What I'm saying is, if the models are now going for even stronger north-eastern blocking and disrupted Atlantic lows at D8, I am very much inclined to believe them. Paticularly the GEM, which has not shown any HLB at all in FI until now - and now it's really putting the foot to the floor!

Must comment on the GEFS as they are trending, trending, trending towards the NE block winning out.

that's not bad at this stage, not bad at all.

@Man With Beard; I do actually hope that this Scandinavian blocking-pattern comes off because for where I live, at over 400 metres' elevation in the North Pennines (a location where in a typical winter we would expect extreme minima down to -8C and over thirty days of snow-cover) it has been a thoroughly naff winter! Even on the highest part of the North Pennines (Cross Fell at almost 900 metres' elevation) there is scarcely any snow lying at present and tomorrow is 1st February!

We could well do with some proper winter weather-excitement for a change. Real snow and low temperatures. The developments aloft high over the Arctic do in that regard offer some grounds for optimism (though not massively so, the mean wind-speed at 10 mb and 60N is still-just- westerly at its weakest)!

[nick sussex]

7 minutes ago, Johnp said:

Thanks @nick sussex although when reading that, I assumed the IDO was related to how often he posts ie the fewer posts = more chance of cold weather 

Lol! IDO I think does like cold weather. But anyway I apologize to the thread for bringing in yet another pretentious sounding met term! As everyone knows I'm rather obsessed with the MJO and anything that effects that.

[Man With Beard]

13 minutes ago, Luke Attwood said:

Hmm don't really agree,no strong block to the east and the UK left in southerly to southeasterly wind.not particularly cold!

If verified like that, then yes agreed - but the things which are interesting me: 1. increased signal for heights pushing a long way up into Scandi and beyond / 2. increased signal for troughing to be diverted south rather than north. 

The sort of signal that won't be nailed down for specifics until even D5, but that allows for potential cold development

[Seasonality]

Good news from the GFS ensembles further east everyone. And this is the direction the UK needs to be looking for the potential colder spell. Last couple of runs were massive outliers. Now the op and later on the control are at the bottom of the ensemble suite yes, but crucially not so wildly out of sync and showing increasing support with the mean trending colder as a result. In fact the op has the mildest uppers later on with the rest of the suite colder! Small steps towards the outcome UK cold fans would like if the cold can get far enough west, but of course nowhere near anything being certain… Just wanted to take a glass half full approach and show that things are starting to brew out east.

 

[Weather Boy]

25 minutes ago, Luke Attwood said:

Hmm don't really agree,no strong block to the east and the UK left in southerly to southeasterly wind.not particularly cold!

I'm very far from an expert, but I think that you are reading to much into a mean chart.  Because mean charts, by their nature, are an ensemble, you can't really deduce such small detail as wind direction from them.  That chart shows NE Europe high, Atlantic high and Portuguese trough.  All you can do is to infer that that is generally a favourable set up for UK cold.  You can't go to such detail as to deduce a SE wind, as it's not intended for such detail.

I think....

[snowfish1]

6 minutes ago, Weather Boy said:

I'm very far from an expert, but I think that you are reading to much into a mean chart.  Because mean charts, by their nature, are an ensemble, you can't really deduce such small detail as wind direction from them.  That chart shows NE Europe high, Atlantic high and Portuguese trough.  All you can do is to infer that that is generally a favourable set up for UK cold.  You can't go to such detail as to deduce a SE wind, as it's not intended for such detail.

I think....

Looking at the latest gfs run that ridge of high pressure just keeps the worst of the wind and rain away from the SE corner. That

second low looks nasty though with gale force winds and it's just outside 192 hours 

[snowfish1]

From a novice point of view the Scandinavian high is something of beauty to behold and holds the key to something distinctly wintry especially for eastern districts. This trend has been showing for a few days an with ukmo also showing it GFS is not on its own let's hope it delivers ....

[Ali1977]

Still nothing on the METO medium or long range suggesting an Easterly feed other than maybe very late Feb and March.  If the 12z and evening runs gather traction and were correct I'd say watch for a marked change in their wording - however I think the fact we are seeing some cold synoptics by late next week in some models, and they aren't mentioning any type of cold weather says that we shouldn't yet be too confident of anything in the next 10 days or even more.

They of course could be holding back as so far their predictions haven't exactly been great, they may want to nail this one before putting pen to paper etc....they do say largly mild with colder spells, this is fence sitting in my book.

Edited January 31, 2017 by Ali1977

[mb018538]

50 minutes ago, Summer Sun said:

9th to around the 14th the 06z Op is very much on the cold side of the mean and control

Not really a surprise at all. I guess the good thing is there are actually properly cold members appearing now, whereas a couple of days ago we had nothing.

[chionomaniac]

There is also a growing trend by day 10 on both the EPS and last two runs of the GEFS to introduce a more amplified pattern across the Atlantic, with a very southerly aligned jet.

 Chart weather bell

 

The ECM anomaly is fairly similar. As any block wanes this could serve as a reinforcement and positionally encourage further westward drift. No sign of a long term raging Atlantic on any ensembles days 10-15.

[SMU]

Afternoon All -

ive not really read the MOD in any depth this morning however the mood should be 'positive' today-

The GEM / GFS blend are fast on an Easterly flow across europe hitting the UK at 192, UKMO appears a bit slower however without the real clarity of the 168 - 192 evolution its very hard to call

ECM - whilst most would still take it, the model takes us out to 240-264 to see cold filtering west-

It has been noticable that the ECM has been on the back foot a bit here - not the 'trendsetter' as it once was- The UKMO has really been thus far solid with its runs-

Ive seen some comments re the Ensembles :

Heres 2 very clear obsevations relating to the ENS from 16 years of model watching

* When a decent easterly does varify which of course is rare as hens teeth- so 2005,2009, etc - the ENS suite is ALWAYS 1 day behind the ops trend setter- to put this into context where we are now-

yesterday 12z GFS had one sub -10 run for london now the 06z has 3 / 4

same as ECM yesterday only having one cobra run- now the 00z has many more plus the control -

So ensemble means charts poinless in isolation, only good if your comparing trends along a time - say GFS 00z 156 V GFS 06z 150- your looking for incremental movements of the ENS towards the Ops - its been shown time & time again this winter than at this current time in resolution accuarcy that when there os significant change - the ENS cant handle it-

* The second point is for all the failed Easterly attempts - & sadly this is the total inverse of the point above in as much as the ops jump on the easerly band wagon the ENS because of there slow reactions often phase / blend out the ops reaction to the potential change being different displayed - so when the ops go pete tong everyone says the ENS werent on board anyway they must have been correct -...

 

So in a nutshell- ENS means & 850 ENS are chocolate teapots today other than to observe trends of block locations & overall changes in amounts of cold runs-

The GFS/GEM/UKMO blend for me looks slightly the form horse over the ECM purely based on whats happened so far this winter which is eastward progression of low pressures has always been over estimated-

Can we get the deep cold with just 1 cycle a la GFS.... hum... it usually takes 2 cycles / 2 trigger lows to usher the beast in via the garden of englands back door....

S

Edited January 31, 2017 by Steve Murr

[Daniel*]

48 minutes ago, Luke Attwood said:

SE'ly winds would be cold It's a mean - pretty good. Last Thursday which brought an ice day to the City of London - the flow was essentially a southerly. However, by February it isn't easy, GFS 06Z is certainly plausible. I don't agree with Pennell, not that I know much but the upcoming period looks to differentiate itself to anything we've seen so far this winter and the last few arguably, something more concrete for coldies.

 

 

[bluearmy]

Only three or four eps members bring deepish cold to Belgium/holland/uk 

whilst i understand steve's point, I'm struggling with those odds 

[Panayiotis]

1 hour ago, Luke Attwood said:

Hmm don't really agree,no strong block to the east and the UK left in southerly to southeasterly wind.not particularly cold!

Although yes the chart does show a southerly/south-easterly wind, you have to take into account thats it's an ensemble mean. Climatology, as stated countless times this winter, will skew any signals of easterly winds. Looking +8 days into an ensemble mean will (most of the time) have a west-east flow bias. 

Edited January 31, 2017 by Panayiotis

[Luke Attwood]

7 minutes ago, Panayiotis said:

Although yes the chart does show a southerly/south-easterly wind, you have to take into account thats it's an ensemble mean. Climatology, as stated countless times this winter, will skew any signals of easterly winds. Looking +8 days into an ensemble mean will (most of the time) have a west-east flow bias. 

I suppose its not such a bad mean,could be better of course. I have a feeling that the coldest weather will remain to our east.Romania turkey being the favoured areas.I hope I am wrong though

[Scandinavian High.]

Lots of copping and changes to come will this come of no one knows yet but if it does this could bring blizzard to the south east england and southern England and then pushing to other parts of uk let's see where we are at the weekend with this trends. And I did not see 6z this is very interesting. Tonight's  runs I think there going to be a Steve murr boom .

Edited January 31, 2017 by abbie123

[MattTarrant]

12 minutes ago, abbie123 said:

Lots of copping and changes to come will this come of no one knows yet but if it does this could bring blizzard to the south east england and southern England and then pushing to other parts of uk let's see where we are at the weekend with this trends.

That is an 0z chart but yes it would, what I like from the 6z development is that the Azores high is displaced out into the Atlantic allowing low heights to remain across Southern Europe. It would  be even better if the high could just ridge a little up towards Greenland.  

Jet Stream backs the continuation of the feed of low heights into Southern Europe

 

Edited January 31, 2017 by MattTarrant

[Nouska]

Well, there are some historic cold February months in the NOAA upstream analogues derived from the GFS 06Z run!

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/model_guidance.php?dayin=11

Why do those conundrums always feature on the last day of the month - when CET competition requires an entry.....decisions, decisions....  the ECM not buying it as yet and remembering sudden swing on cusp of the last two months.

[TEITS]

Story of the winter so far.

4 days ago GFS wanting to blast mild W,lys into Europe on the 6th Feb.

Today a very different story.

Point is all winter long the operationals have been too progressive in sending low pressure systems east. The ensembles have been even more useless and don't even get me started on the ensemble means!

I will remember this winter as the unforcastable winter. A winter when even the ECM has been woefully wrong many times.

[Paul]

Matt's latest synoptic guidance blog is online. It's a bumper edition this week, with plenty going on...

http://www.netweather.tv/index.cgi?action=news;storyid=7936;sess=

[Nick F]

3 hours ago, iapennell said:

The Quasi Biennial Oscillation, that pattern of alternate easterly and westerly winds high up in the Equatorial Stratosphere has been in a record Westerly phase for three months now, this is not conducive to weak westerlies and more blocking patterns in higher latitudes. It does offer an explanation as to why some promising potential cold-weather patterns for the UK have failed to materialise over the last couple of months. Had the Quasi Biennial Oscillation been strongly easterly we could well have had much more blocked colder weather affecting the entire country.

The QBO is not a make or break factor in whether we see high latitude blocking. There are occasions in the past where the easterly QBO values were not a factor in some of our really cold and blocked winter spells.  For example, the blocked and very cold months of November and December 2010 had a (westerly) QBO value of +12.16 and +10.96 respectively. February 1986 was extremely cold, 2nd coldest Feb of the 20th century, yet had a QBO value of +8.73.

QBO Index: http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index

A westerly QBO regime, a major stratospheric warming is less likely but not impossible. Though a SSW is close but no cigar for now, probably because of the wQBO.  As such, overall, a positive QBO regime would suggest a stronger stratospheric Polar Vortex. However, we know that last autumn that the stratospheric and tropospheric Polar Vortex was actually weak and the QBO had been westerly for some time, November was strongly positive at +14.16.  As such, one has to question just how much of an influence the QBO is having on the stratospheric environment.

As some have pointed out – the blocking showing from the models recently is being trop up (wave 2) lead rather than strat down – MJO moving coherently through 5/6/7/8 will help amplify the flow further as we head towards 2nd week of February. This is the best MJO propagation we've seen all winter.

So the westerly QBO may not be heavily in the equation in terms of getting blocking, we’ve seen a lot of blocking this winter, despite the strongly wQBO, just the blocking thus far has not placed itself favourably to advect deep cold across the UK for more than a day or two.

Edited January 31, 2017 by Nick F

[Weather-history]

28 minutes ago, Nick F said:

The QBO is not a make or break factor in whether we see high latitude blocking. There are occasions in the past where the easterly QBO values were not a factor in some of our really cold and blocked winter spells.  For example, the blocked and very cold months of November and December 2010 had a (westerly) QBO value of +12.16 and +10.96 respectively. February 1986 was extremely cold, 2nd coldest Feb of the 20th century, yet had a QBO value of +8.73.

QBO Index: http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index

 

To give further examples, look at the 4 winters from 1988-89 to 1991-92 in that link 

Out of the 4 winters, which was the best winter for snowfalls and indeed coldest? The only westerly QBO out of the 4, The other 3 were mediocre to almost snowless.

 

Edited January 31, 2017 by Weather-history
.

[IDO]

1 hour ago, TEITS said:

Story of the winter so far.

4 days ago GFS wanting to blast mild W,lys into Europe on the 6th Feb.

Today a very different story.

Point is all winter long the operationals have been too progressive in sending low pressure systems east. The ensembles have been even more useless and don't even get me started on the ensemble means!

I will remember this winter as the unforcastable winter. A winter when even the ECM has been woefully wrong many times.

I think I am missing something as the last three days have been wet and the next 7/8 are forecast to be similar, with about 6 more spells of rain incoming from the west!!!

For the UK it has not really made a difference and I for one never expected full on zonal once the PV to the NW dissipates (in a week or so). So we still would have had the forecast 10 day or so spell of Atlantic, maybe the UK the end of the line rather than Europe, but essentially the same either way! IMO that was a good spot by the models of this westerly flow and as our many years of experience tells us the models probably overplayed the Atlantic viz the stubborness of the block. I could argue that if the block was over run by the Atlantic then any forcing may have been more favourable to the UK re an Atlantic ridge rather than having to rely on the retrogression of the block to our east, which rarely goes to plan?

There remains much uncertainty, with several possible outcomes, from UK high to euro block to maybe a bit higher blocking. The models tend to play around with these possibilities at this range and anybodies guess? What we do need is this downwelling from the warming to favour the UK as for us in the south it may be our last chance of decent snow chances.

My thoughts are that the models are over zealous when a new signal is signposted and that they are more likely than not over doing the heights, as they have all winter, so I expect the models to reflect that in the next day or so (NB. As when a zonal spell is spotted the Atlantic is overdone, when blocking is modelled, they over play the heights).

[Mucka]

GFS would be a throwback to Winters of old with a East/West battle and front stalling and turning to snow.