Winter Model Discussion - Cold Hunting -23/12/12

[Grimsby Snow Lover]

Looking at the 6z ensembles the word 'average' springs to mind. Unsettled with average to slightly above temperatures as we head through the last few days of Decemeber-early January. At face value these are colder (be it slightly) than what were shown yesterday. My glass is always half full

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

[lorenzo]

From what i gather even for those who have researched/and are researching the connection between Strat warming and the weather, would say they're still learning - it's v much in its infancy in scientific terms.

There are a few on here who are v well researched on it and are way way ahead of the vast majority (chio, recretos, GP to name three)

But i think it's typical of today's internet age that many many more NW posters are simply quoting and re-quoting - chucking in the odd line in their posts referring to the Strat, etc. That means the 'knowledge' effectively gets 'diluted' as more and more posts come from those who don't really know, but are just quoting references from the more 'experienced' Strat posters.Sorry but that's the way i see it.

As for the models it's pretty obvious we're in a v zonal period, with possibly a quieter spell around the new year. If it stays mild then so be it.

Maybe there'll be changes around mid-month but at the mo that's a long way off (in UK weather terms).

Interesting post BB, totally agree that research in the connections are in infancy and I also agree that a whole lot of hope is being pinned on the projected warming, this is understandable, given that folks are looking for a way out of the zonal mush. Am fearful of a backlash if the outcome is not 110% favourable to cold.

The bit highlighted - whilst I get what you are saying, I view this as a positive rather than a negative as more folks are taking interest in this area and more posts are referring to what is happening in the Strat. this is is a good thing, the previous years threads were under visited and also Chiono has done loads of work to make this as accessible as possible. When reading some of the papers it is not the simplest of subjects, ultimately the technical posts and knowledge will still be there for everyone.

Let's hope it works out favourably for cold seekers everywhere..

[nick sussex]

I think I've finally worked out the mystery behind the NAO/PNA forecasts from NCEP and whether they're just a bi product of the GEFS.

This from the ESRL website:

Compare 1-15 day forecasts of teleconnection indices from the PSD Medium-Range Forecast Ensemble (15 members, run daily in Boulder, CO) and the NCEP Medium-Range Forecast Ensemble (12 members, run daily at NCEP in Washington, DC). Typically, the most recent forecast runs available will be from the previous night.

Looking at that the NCEP MRF ensembles must be different from the GEFS as that has 20 members excluding the control run so something just doesn't add up re the operational outputs.

That chart compares the ESRL forecast and the NCEP one, either way they don't correlate with the operationals we're currently seeing.

I'm waiting for the latest update which should be out soon but if that stays the same then either the operationals are wrong or these ensembles are .

If those ensemble forecasts are close to the truth then we should see changes in the output and the ECM in particular with that large PV to the north at day ten is rubbish.

Edited December 24, 2012 by nick sussex

[UV-RAY]

Interesting post BB, totally agree that research in the connections are in infancy and I also agree that a whole lot of hope is being pinned on the projected warming, this is understandable, given that folks are looking for a way out of the zonal mush. Am fearful of a backlash if the outcome is not 110% favourable to cold.

The bit highlighted - whilst I get what you are saying, I view this as a positive rather than a negative as more folks are taking interest in this area and more posts are referring to what is happening in the Strat. this is is a good thing, the previous years threads were under visited and also Chiono has done loads of work to make this as accessible as possible. When reading some of the papers it is not the simplest of subjects, ultimately the technical posts and knowledge will still be there for everyone.

Let's hope it works out favourably for cold seekers everywhere..

Agree Lorenzo, although I've said GP's winter forecast is bust I still think that teleconnections are the future of metrology. Also I feel that there are too many with limited knowledge on this subject who keep posting that cold is coming because x says this or y says that and it's this that causes friction in the MO when posters only comment on what is actually showing in the models. If it ain't showing cold we can't really comment on it really and the MO thread does what it says on the tin, so maybe some need to relax and just discuss whats showing in the output and not what other people say may happen.

[polarlow2]

UK Outlook for Tuesday 8 Jan 2013 to Tuesday 22 Jan 2013:

Rather unsettled weather is likely to persist during the first half of January, with low pressure expected to be dominant near the British Isles, bringing further spells of wet and windy weather to most regions. Rainfall amounts are expected to remain above average for most parts of England and Wales, while temperatures are likely to often be close to or perhaps a little above average. Later in this forecast period there is greater than average uncertainty, though some marked changes of weather-type are possible and the risk of spells of colder than average conditions increases.

Not model-related I know, but interesting, no? What do people make of the last couple of lines...?

[nick sussex]

UK Outlook for Tuesday 8 Jan 2013 to Tuesday 22 Jan 2013:

Rather unsettled weather is likely to persist during the first half of January, with low pressure expected to be dominant near the British Isles, bringing further spells of wet and windy weather to most regions. Rainfall amounts are expected to remain above average for most parts of England and Wales, while temperatures are likely to often be close to or perhaps a little above average. Later in this forecast period there is greater than average uncertainty, though some marked changes of weather-type are possible and the risk of spells of colder than average conditions increases.

Not model-related I know, but interesting, no? What do people make of the last couple of lines...?

Basically hedging their bets regarding the effects of any strat warming. Until you know whether its just a displacement or a split of the PV, also where this would be located.

[EML Network]

And so the remainder of 2012 looks set to remain much the same as it is now, with yet more Atlantic systems rolling in, we had the Russian High combo...that didn't work in getting cold and snow to us, and it's only now that we see it bowing down to the more powerful Atlantic.

Now we have yet another High pressure system to content with, the all too familiar Azores, which as we know from years gone by can ruin an entire Winter from a cold and snow lovers perspective, there's nothing I can see on the horizon that suggests we are going to find a way out of this pattern for at least a few weeks now, happy Xmas and New year to one and all, I'll see you all on the 'Flip side'

J

[latitude]

All I want for Christmas is a Greenland High!!!

[lorenzo]

Spotted that reforecast product before, looks like a ghost of GFS Xmas past.. MRF. http://www.esrl.noaa...sts/reforecast/

I liked this claim, seems to indicate that some of the white noise would get eradicated.

Among the advantages associated with this long reforecast dataset is that model forecast errors can be diagnosed from the past forecasts and corrected, thereby dramatically increasing the forecast skill.

You can make some nice charts on the 6-10 and 10-14 selection, although the ones visible today aren't particularly appealing !

[A.J]

UK Outlook for Tuesday 8 Jan 2013 to Tuesday 22 Jan 2013:

Rather unsettled weather is likely to persist during the first half of January, with low pressure expected to be dominant near the British Isles, bringing further spells of wet and windy weather to most regions. Rainfall amounts are expected to remain above average for most parts of England and Wales, while temperatures are likely to often be close to or perhaps a little above average. Later in this forecast period there is greater than average uncertainty, though some marked changes of weather-type are possible and the risk of spells of colder than average conditions increases.

Not model-related I know, but interesting, no? What do people make of the last couple of lines...?

It ties in with a post Ian Fergusson made a couple or so days ago hinting that there are signals for a possible pattern change early to mid January....just to side track a moment, it's been rather frustrating reading this thread the past few days, and I understand that the majority of posters want to see cold synoptics and current model output is thus frustrating to those, but from what I've read earlier this winter, from the likes of GP (with his excellent winter forecast) Ed, Phil, Lorenzo to name a few, this winter so far seems to be going to plan.....a mild, wet push mid to late December was forecasted with an above average chance of a pattern change to colder synoptics into January.....To those members, keep up the good work!

[nick sussex]

Spotted that reforecast product before, looks like a ghost of GFS Xmas past.. MRF. http://www.esrl.noaa...sts/reforecast/

I liked this claim, seems to indicate that some of the white noise would get eradicated.

Among the advantages associated with this long reforecast dataset is that model forecast errors can be diagnosed from the past forecasts and corrected, thereby dramatically increasing the forecast skill.

You can make some nice charts on the 6-10 and 10-14 selection, although the ones visible today aren't particularly appealing !

Looking at the PSD ensembles they obviously use a different system hence we get those different PNA/NAO forecasts.

The Physical Sciences Division (PSD) "downloads" these forecasts from NCEP computers on a daily basis and produces the plots shown on the page. Currently, there are 11 predictions that are run at 12z and another 12 that are run at 00z. PSD transfers these results to Boulder, CO overnight, after the 00z runs have been completed. Results are usually displayed by the next morning. Thus what you see today was derived from initial atmospheric conditions from last night (the 00z runs) and from yesterday morning (the 12z runs). These 23 members represent the current best estimate of the distribution of states expected in the atmosphere out to lead or forecast times of 15 days.

I haven't found yet whether the PSD is more accurate but you would think because they combine 00hrs and 12hrs data that this would perhaps give a less volatile picture.

As for the MRF ensemble I cant find any more info at the moment but the info in my previous post would suggest it has to be different from the GEFS as that runs four times a day with more members..

[Bobby]

It seems you can get the ECM ensemble anomaly maps on Meteociel now. At ~240 the ECM ensemble mean shows more of a mid-Atlantic ridge than the NAEFS mean.

Pressure anomalies

NAEFS +240

ECM +240

Interesting??

I wonder if the ECM would blast the ridge away if it went further or if it would establish, should be interesting to see the 12z runs.

[Grimsby Snow Lover]

It seems you can get the ECM ensemble anomaly maps on Meteociel now. At ~240 the ECM ensemble mean shows more of a mid-Atlantic ridge than the NAEFS mean.

Pressure anomalies

NAEFS +240

ECM +240

Interesting??

I wonder if the ECM would blast the ridge away if it went further or if it would establish, should be interesting to see the 12z runs.

That ecm chart is a defo straw to clutch at the minute both for cold prospects and perhaps more importantly one that might stop the conveyor of low pressure systems steaming off the Atlantic. Something which need watching I believe, thanks for posting.

Edited December 24, 2012 by Grimsby Snow Lover

[nick sussex]

It seems you can get the ECM ensemble anomaly maps on Meteociel now. At ~240 the ECM ensemble mean shows more of a mid-Atlantic ridge than the NAEFS mean.

Pressure anomalies

NAEFS +240

ECM +240

Interesting??

I wonder if the ECM would blast the ridge away if it went further or if it would establish, should be interesting to see the 12z runs.

Yes and that looks a bit more like that chart posted by Lorenzo.

It's all a bit confusing because the operationals seem adamant about flattening the pattern out with a negative PNA but yet the teleconnections suggest it should be a plus PNA with negative NAO at that timeframe!

[Summer Sun]

It seems you can get the ECM ensemble anomaly maps on Meteociel now. At ~240 the ECM ensemble mean shows more of a mid-Atlantic ridge than the NAEFS mean.

Pressure anomalies

NAEFS +240

ECM +240

Interesting??

I wonder if the ECM would blast the ridge away if it went further or if it would establish, should be interesting to see the 12z runs.

I'm still learning some of these charts, does the red indicate high pressure and blue low pressure?

Latest IRI model has updated for December and covers the period of January to March

[Bobby]

I'm still learning some of these charts, does the red indicate high pressure and blue low pressure?

Latest IRI model has updated for December and covers the period of January to March

The red is above average pressure and the blues are below average pressure.

[Summer Sun]

The red is above average pressure and the blues are below average pressure.

Thanks well at least the ECM t240 would be an end to this relentless cloud and rain then

[Summer Sun]

GFS is also showing above average pressure as 2013 begins

Before lower pressure rolls back in

Before high pressure has another go

Maybe a new trend will establish during the first few weeks of 2013 lets face it this pattern of relentless low pressure systems won't last for ever it will end at some point its just a matter of when and not if. By the law of averages another dry period will develop but 2013 will be drought free unless we get an exceptionally hot and dry spring and summer

[HotCuppa]

I think really, people need to keep a lid on strat warming until the actual evidence is in. Right now there is nothing, because it is in it's infancy. And yet people cling to the strat warming theory as if it's gospel. There in lies the problem.

Also I have read a few posts, regarding using things like fantasy island charts way off into the distance for trends. The only trends I see that can be reasonably reliable in the 300 mark is during the summer months in general.

During the winter, the fact is, people do it clinging at straws because there is little else to do.

It surprises me quite a bit, when said people then cry about FI not coming off. The time frame at this time of year is 96 hours, with a max of 144 hours.

We have the exact same thing every year, and yes it's fun to model watch, but be careful what you say, I have seen a lot of people cling to things they

clearly have no idea what they are talking about, just parroting other people.

Still, it's no surprise that this year is turing out to be 'almost' a carbon copy of last year.

It is very sad indeed we have to now look to middle and back end January for anything of note for England. Scotland will always get it's snow over the mountains

but this is the first year where not 1 flake as fallen over my home in 17 years, inside 12 months. Global Warming? hahahaha sorry

[nick sussex]

I'm still learning some of these charts, does the red indicate high pressure and blue low pressure?

Latest IRI model has updated for December and covers the period of January to March

That IRI model looks bizarre, its very unlikely the whole of that region could possibly all be above normal, above normal in one area would tend to lead to below average in another.

So for Greenland to be above normal you'd tend to find the synoptics would deliver colder conditions further east, cold winters in Europe tend to equate with blocking and warmer conditions up there so I don't see how you have both.

I think that IRI model is as bad as the CFS, basically cat litter!

[PJG_Redditch]

Hi everyone, my first post on this forum. The hunt for cold continues to be a frustrating one but also one which is very familiar !.

The only crumb of comfort I can find in the output after yet another wet morning is that at least we are moving into a more mobile pattern for a few days. So heavy rainfall events will move through a bit quicker and we'll see some strong winds to help dry things at least a little in between.

To be honest, I don't so much want cold weather at the moment, just some dry weather....pleeeease !!

Have a very Merry Christmas everyone.

[bluearmy]

the ecm anomaly makes a lot more sense looking at the spreads (especially 850's). London temps show a pretty even chance of some cool/cold conditions. Presumable, MOGREPS doesnt see this, judging by todays 10/15 dayer. Naefs also not seeing such a mid atlantic ridge so i suspect ecm will trend flatter.

[Ian Brown]

the ecm anomaly makes a lot more sense looking at the spreads (especially 850's). London temps show a pretty even chance of some cool/cold conditions. Presumable, MOGREPS doesnt see this, judging by todays 10/15 dayer. Naefs also not seeing such a mid atlantic ridge so i suspect ecm will trend flatter.

It looks progressively zonal with the HP to the South coming more into play; I was a little surprised by the 6-15 dayer talking about 'average to below average' in the North, I would be thinking 'average to above average' in the North and potentially much above average in the South.

[karyo]

It looks progressively zonal with the HP to the South coming more into play; I was a little surprised by the 6-15 dayer talking about 'average to below average' in the North, I would be thinking 'average to above average' in the North and potentially much above average in the South.

The Met Office 6-15 dayer is identical to yesterday's so they haven't bothered to change anything.

The same applies to the 16-30 dayer.

Karyo

[Katiewombat]

I haven't got time to read thread today. So someone please please do me a quick summary

Happy Christmas

Katie