Winter Model Discussion - The Hunt For Cold -18z 17/12/12

[PubliusEnigma]

Please can you point out the 'displaced' Bartlett in these ECM charts from this evening, PE.

Granted, we have raised heights towards the end of the run and temporary ridging between days 3-4 but that is hardly consistency!

I mentioned on the following post that it moves off temporarily around Christmas day before reasserting it self on the run. Its even more prevalent on the

GFS. The finer detail can be argued over however the trend remains out to T 384 on the GFS and is there for almost all of the ECM.

[chionomaniac]

Just looking through todays CPC discussions and the forecasters state only 2/5 low confidence in the forthcoming pattern over the next 2 weeks.

Full text here http://www.cpc.ncep....day/fxus06.html

Some snippets of interest.

THIS SUGGESTS THAT THE WEEK-2 PATTERN MIGHT BE TRANSIENT, WITH A POTENTIAL

REALIGNMENT TOWARD A MORE CANONICALLY NEGATIVE AO PATTERN THEREAFTER. WITH A PERSISTENTLY NEGATIVE AO, THE OBSERVED SURFACE HYDROCLIMATE THIS MONTH REMAINS UNUSUAL, PERHAPS UNPRECEDENTED. FURTHER COMPLICATING THE EXTENDED RANGE

FORECAST IS THE LACK OF ROBUST TROPICAL CONVECTION ASSOCIATED WITH THE MJO,

WHICH HAS BEEN LARGELY INACTIVE FOR THE PAST MONTH, AND IS ONLY NOW SHOWING

POTENTIAL SIGNS OF WEAK REORGANIZATION.

The way i read it is the current modelling full of uncertainty.

The upstream jet pattern over NA not yet agreed amongst the Op.runs

Some adjustment to the current wavelengths in week 2 with a change to a lower AO index.

Hopefully the build of polar heights will become extensive enough to impact the UK.eventually.

Being a bit thick, Phil, I had to look up what they meant by canonically! I have never seen that word used in a forecast before. Anyway, we don't have to pray just yet - rather they are suggesting that the -ve AO will become more orthodox after its stint over the north of America.

So now I just have to work out what an orthodox -ve AO pattern looks like!

[Bristawl Si]

What exactly is a 'displaced' Bartlett?

A HP cell off the coast of Iberia that has 'wandered' from a true bartlett position, but it doesnt know it's called a bartlett until a NW member calls it a bartlett that's been displaced.....apparently!

Or to put it simply a HP and someone decides to add the word "bartlett" to wind others up!

[Cloud 10]

It suprises me that nobody has mentioned the JMA at T192.

Anyone got a link to the 12z ECM ensembles. Where did the op sit in relation to other runs?

A better than normal chance of that JMA chart verifying with the polar vortex on our side of

the hemisphere,and certainly one to watch.

ECM ensembles....Ensembles - GFS / ECMWF--

[PubliusEnigma]

What exactly is a 'displaced' Bartlett?

The clue is in the word displaced.. In the same way one can have a displaced Azores HP, which is often referred to when it retreats SW towards

Bermuda. In this instance the high has displaced SW towards Iberia, has the stubborn characteristics, and a similar effect on weather across the UK.

A more othodox Bartlett tends to deliver highest rainfall totals across the NW especially Western Scotland, the displaced variety allows for the rainfall

trajectory to bring higher totals into SW approaches and S Wales in particular.

[No Balls Like Snow Balls]

A displaced bartlett can go in the same silly bin as faux zonal, oh and faux cold, I swear people make things up to appear clever lol

Edited December 19, 2012 by No balls like Snow Balls

[chionomaniac]

I mentioned on the following post that it moves off temporarily around Christmas day before reasserting it self on the run. Its even more prevalent on the

GFS. The finer detail can be argued over however the trend remains out to T 384 on the GFS and is there for almost all of the ECM.

Well, now that we have worked out that a 'displaced' Bartlett is any other high pressure that isn't a Bartlett, then I dare say that you are right!

[nick sussex]

Looking at the ECM De Bilt ensembles good agreement for the high to head away east, initial scatter disappears as the ensembles are rock solid for that outcome.

Thereafter more scatter as the ensembles remain split on how far south and east troughing will get.

There is some uncertainty with how far south the jet will run and the influence of the Azores high, but any eastwards or south correction in the outputs within 144hrs are going to be important before the next low heading out of the USA phases with troughing over the UK.

Just a quick word about tonights JMA that shows the importance of splitting the energy to the west and not having an elongated trough running through the UK.

This really is the only chance to get some colder air to dig further south, unless you get the jet much further south with troughing located to the south of the UK.

The JMA is worth a look, its really the best of the operational outputs this evening.

Edited December 19, 2012 by nick sussex

[IDO]

"However, in recent years (this written in autumn, 2005), these situations have been notable by their absence. What 'high' blocks there have been stay teasingly just too far east and more often than not, a broad band of high pressure extends from the Azores area, east-north-eastwards towards the Biscay / English Channel region - perhaps now & thendisplacedtowards the Alps, as storm upon storm sweeps in from the North Atlantic, hurried along by an often powerful upper jet (see "What are jetstreams?"). Rain, gales and above average temperatures prevail, with any 'wintry' weather confined to brief incursions of Polar Maritime west or WNW'lies, or perhaps a temporary Arctic Maritime blast from the north - which is shunted away as the next surge of mild air hurries in from the west. The apparently semi-permanent belt of high pressure in the 'wrong' place has been christened ... "The Bartlett High", in honour of Paul Bartlett, a luminary of this ng, who used to put his experience of forecasting to the test by publishing a reasoned winter forecast for all to see. As Les Crossan has noted (also a stalwart of this ng), this has come to be regarded as a 'slug' - nothing moves it, not even extracting a pair of dividers and skewering the said beast as it sits dominating any particular synoptic chart!" (http://weatherfaqs.org.uk/node/117)

As PE implied. Its on the GFS from T180 to T384 and has barely moved:

http://modeles.meteo...fs-0-180.png?12

http://modeles.meteo...fs-0-384.png?12

And looks like it has found a home for Winter.

Edited December 19, 2012 by i'm dreaming of...

[johnholmes]

for those who may want to see will it be cold Christmas and beyond

make your own mind up please?

[blueballs]

My first post(its like doing a bungee jump but here goes).

Even though the models have teased us and let us down in recent weeks i think we have been very lucky to have been in with a shout of something akin to 2010 considering the fact that were currently reaching solar max which usally lends itself to a more westerly regime, the blocking has been there and the jet has tracked well south at times which are generally sypnotics of low solar activity. currently solar activity is at very low levels for a solar max(more akin to a solar minimum) which is why i belive we have had so much northern blocking so early this year even though it hasn`t delivered the good as yet.

with the imminent ssw being forecast were in with another good chance of some propa cold in jan so basically everyone needs to be patient and wait for the dice to roll in our favour...which they will at some point! btw if it was a snowmageddon every day of winter we`d soon get p****d off, 3 weeks of mayhem would be fine.

[PubliusEnigma]

My first post(its like doing a bungee jump but here goes).

Even though the models have teased us and let us down in recent weeks i think we have been very lucky to have been in with a shout of something akin to 2010 considering the fact that were currently reaching solar max which usally lends itself to a more westerly regime, the blocking has been there and the jet has tracked well south at times which are generally sypnotics of low solar activity. currently solar activity is at very low levels for a solar max(more akin to a solar minimum) which is why i belive we have had so much northern blocking so early this year even though it hasn`t delivered the good as yet.

with the imminent ssw being forecast were in with another good chance of some propa cold in jan so basically everyone needs to be patient and wait for the dice to roll in our favour...which they will at some point! btw if it was a snowmageddon every day of winter we`d soon get p****d off, 3 weeks of mayhem would be fine.

Welcome to NW ! Blue Balls

[johnholmes]

welcome bb enjoy the ride in here, remember there are other outlets on here, forecasts, data galore, so enjoy

[nick sussex]

My first post(its like doing a bungee jump but here goes).

Even though the models have teased us and let us down in recent weeks i think we have been very lucky to have been in with a shout of something akin to 2010 considering the fact that were currently reaching solar max which usally lends itself to a more westerly regime, the blocking has been there and the jet has tracked well south at times which are generally sypnotics of low solar activity. currently solar activity is at very low levels for a solar max(more akin to a solar minimum) which is why i belive we have had so much northern blocking so early this year even though it hasn`t delivered the good as yet.

with the imminent ssw being forecast were in with another good chance of some propa cold in jan so basically everyone needs to be patient and wait for the dice to roll in our favour...which they will at some point! btw if it was a snowmageddon every day of winter we`d soon get p****d off, 3 weeks of mayhem would be fine.

Welcome to netweather , although I think you'd find most members in here would be quite happy with 12 weeks of snow! lol

[Cheshire Freeze]

- anyone forecast this? - no - I thought not.......

Yes, me back at the end of winter last year where I did a brief synopsis of what I expected spring- summer to bring, based mostly on CFS/ECMWF long range and gut instinct. CFS was plugging a wet summer months beforehand.

Then, back in autumn (October time) I was quite blase about how I expected Nov and Dec to be Atlantic driven.....against what many people expected.

It's not that no-one expected it, it's that no-one wanted to entertain the idea.

[East_England_Stormchaser91]

Them charts are looking very good indeed ! This will make places such as NW England, and the classic 'cheshire gap' come into play !

[chris55]

It suprises me that nobody has mentioned the JMA at T192.

Anyone got a link to the 12z ECM ensembles. Where did the op sit in relation to other runs?

Good spot, hadn't look at the JMA today, shows how some eastward moment of the pattern along with some favourable upstream conditions can make a difference.

[PubliusEnigma]

Has all the rain gone on the 18Z?

South East Christmas eve rush hour looks horrendous, could be an absolute deluge with the low tracking bang

over London on the 18z !

Edited December 19, 2012 by chionomaniac
Housekeeping!

[Ruzzi]

On another note, I'm sorry if this offends a few members, but this thread is becoming ridiculous. There's clearly a divide between a lot of members of the "cold side" and "warm side" that persistently nit-pick little snippets of charts, models and data to try to validate a point about writing off the winter for the good or worse. The models are struggling with the details beyond 48-72 hours at the moment so it is laughable at how anyone can say something is definitely going to happen in 8, 10, 14 days time. I also want to make clear I'm not having a go at people's forecasts or predictions, but the people who see one chart and decide that's what is going to happen and commence their doom-mongering for the evening!

It is getting to the stage where I'm going to stop wasting my time on this thread which is a real shame as the more level headed posters (ala Chiono, GP, johnholmes to name a few) provide some really decent analysis and give out some real great learning points. The only problem is that you have to pick it out amongst the endless pages of squabbles and down right ridiculous remarks.

Rant over!

Edited December 19, 2012 by chionomaniac
more housekeeping

[phil nw.]

Being a bit thick, Phil, I had to look up what they meant by canonically! I have never seen that word used in a forecast before. Anyway, we don't have to pray just yet - rather they are suggesting that the -ve AO will become more orthodox after its stint over the north of America.

So now I just have to work out what an orthodox -ve AO pattern looks like!

You`re not the only one Ed-i looked it up too.

In that context i would think more extensive polar heights-more central?Hence my little ramp that the Uk may be impacted later.

Maybe they have a possible SSW in mind?

[Harsh Climate]

High over greenland 10mb stronger but russian high further west (144h)

[Panayiotis]

Amazing similarities between 18z and 12z, could we get a nice northerly for Christmas night, once the low moves west? So far great consistency with moving the Arctic high to the west of Greenland! http://cdn.nwstatic....141/h500slp.png I have been saying this for days, as the Arctic high could be our savior!

Edited December 19, 2012 by Panayiotis

[Robbie Garrett]

Models have a bit of 1978/1979 feel about them, was just having a good look at the model runs. Whilst NO two winters are the same, I am looking at what GP has posted over on the other forums regarding heights and there positioning and have come up with Something Similar.

In 1978, The first cold spell of this winter began in the last week of November. It also did this year, and lasted into December. Over the UK, the weather for mid December was mild and cyclonic. Guess what it is now?? Vigorous lows moved into the SW. This heralded a wet Xmas for most places with fronts straggled across the UK. What's happening now??

Heading into the New Year Period, whilst we are not YET on par with the following scenario, I couldn't ask if we are in a far better position.

Predicted position, however I do think this will move slightly further east with time...

Data for Winter 1978-79

December 1978: 3.9 (-0.5)

January 1979: -0.4 (-3.7)

February 1979: 1.2 (-2.4)

[on the coast]

The High to the West is really becoming annoying now. How long will this stalemate go on for?

[LomondSnowstorm]

I wouldn't call this a Bartlett-type setup by any means, clearly an Azores high is present but heights are low for most of continental Europe too.