Winter Model Discussion 12Z 22/1/13 onwards.

[Catacol]

Can I add before I shoot back to work that I have never learned as much regarding model/teleconnective/means/ops and all the other bits of the jigsaw that contribute to our weather as I have learned over the last 2 months. This is all down to the learned posters on here, but especially Chio who has a wonderfully balanced and technically accurate perception of various factors. I'm learning and I'm loving it. I think I may even start to frequent this place in spring and summer and see if a fascination with winter can be turned into a fascination with the weather year round. Thanks to all - keep up the great work.

[Jason M]

The MET update seems logical to me. As i said the other night I do feel that people are almost expecting that because of the SSW that we have an almost nailed on Greenland High and that because this isn't being modelled that the models are wrong.

They may well be wrong as they were around new year, but looking at the ouput at the moment it looks like high pressure will dominate to our south rather than north. When I look through the ensembles i'm seeing displaced Azures high's, high pressure to our SE etc, not really Greenland or Scandi Heights. The trend in the output is strongly for heights our south with low pressure to our north and northwest. A couple of ensembles show heights over Greenland but they are very much outriders in terms of the overall output.

The MET outlook is demonstrably correct based on what we see at this point of time and for it to indicate cold weather where none is shown or likely in the medium term would be wrong.

The SSW clearly (or so it seems) had a rapid impact on the atmosphere however that impact seems to be waning very quickly. I also think the level of entropy within the output has started to return to more normal levels. We are starting to see cross model and inter run agreement out at days 4 and 5. Sure detail changes, but the broadscale is fairly similar and within what one would normaly expect. Would be interested to see what Fergie's view is on the entropy levels according to the METO.

I suspect normal winter fare from here. We may get a cold spell in Feb or not but my own view is that the SSW won't be the major driver of our weather in Feb. Also worth considering that the PV would normally be expected to weaken into Feb anyway as the normal way of things. Feb is generally a blocked month, but it looks like the Azures high will be to the fore to me, which given the constant presence of thev PV over Greenland /Mid Atlantic is entirely logical.

Jason

[cheeky_monkey]

We have been talking about the Canadian vortex all winter, right back to Chio's correct call of a CW episode in the threads in November. I think winter 2012/13 may go down as the year we all learned how significant conditions over Canada can be for our chances in winter (those of use who, like me, hadnt really appreciated that before!)

It amazes me that people often dont look at what is happening over North America and the north western Pacific when model watching for Europe.

[bluearmy]

sorry tamara but i just looked through NH charts for jan '85 and this jan is certainly no jan '85. however, your general point is a reasonable one. infact the recent trend for dumbelling mid atlantic ridge in gfs fi is not far away from the early dec pattern only 7 weeks ago.

[Tamara]

sorry tamara but i just looked through NH charts for jan '85 and this jan is certainly no jan '85. however, your general point is a reasonable one. infact the recent trend for dumbelling mid atlantic ridge in gfs fi is not far away from the early dec pattern only 7 weeks ago.

It wasn't meant to be a direct comparison of the severity of the synoptics - clearly Jan 85 was much colder overall just a comparison in terms of weather pattern sequences in general and how we can often see a period of lower pressure to the north and phase of westerlies between cold spells. These dictated by changing polar vortex movements as it adjusts and changes to the different downwelling profiles.

Edited January 23, 2013 by Tamara Road

[phil nw.]

There`s a good chance that the upcoming westerly burst will not last too long and there are indications of this from various outputs.

Starting above in the Stratosphere mean zonal winds are still decreasing at lower and mid-levels and this will continue to keep the vortex under pressure and in a weakened state.

Looking at the 500hPa levels the last 2 operational runs around day 10 suggest that pressure will rise around mid-Atlantic and ridge north.

This develops from the regressing of the Euro high which is modeled for next week.The Atlantic train breaks as the Canadian vortex weakens and more energy comes down through Scandinavia.

We can see the trend in the 00z mean height anomalies for day10 reflecting the pattern in those latest op.runs.

One thing i noticed on the 00z NAEFs -they are different but this looks like it`s because the GEM Ens Hts are flatter and therefore skewing the combined output from that suite.

Certainly the GFS Ens anomls have been trending towards those Atlantic heights for a few runs now and with this change now just coming into the 10 day range the ECM ens are starting to pick this up too..

There`s no avoiding the warm up next week as we get that burst of energy from the Atlantic but there are definite signs in this mornings mid-range outputs that this Atlantic pattern will be relatively brief.

Edited January 23, 2013 by phil nw.

[Catacol]

Interesting point regarding the MetO - may or may not have any relevance I suppose... Anyway I work now with a guy whose wife works at the MetO in the media section - publicity basically. When she got the job there was a welcoming party and a lot of the big wigs down there came out for a meal as part of the welcome. He is a mathematician and was telling me this week how amazed he was at the people he met because, as far as he could work out, they were almost all mathematicians and statisticians and computer experts. He said there didnt seem to be a "forecaster" amongst them. When he asked them about up and coming weather they didnt have a clue really - all they did was interpret data.

Might this suggest that the MetO respond much more directly to computer model output than some of our own more teleconnective and "gut" forecasters here? In one regard it gives them a massive head start as I am sure that the modelling they work with down there is state of the art and possibly second to none globally... but it may also leave them vulnerable to processes that require a bit more human interpretation and input.

I think GP and RJS are still quite bullish about cold in February...

Edited January 23, 2013 by Catacol_Highlander

[latitude]

There`s a good chance that the upcoming westerly burst will not last too long and there are indications of this from various outputs.

Starting above in the Stratosphere mean zonal winds are still decreasing at lower and mid-levels and this will continue to keep the vortex under pressure and in a weakened state.

Looking at the 500hPa levels the last 2 operational runs around day 10 suggest that pressure will rise around mid-Atlantic and ridge north.

This develops from the regressing of the Euro high which is modeled for next week.The Atlantic train breaks as the Canadian vortex weakens and more energy comes down through Scandinavia.

We can see the trend in the 00z mean height anomalies for day10 reflecting the pattern in those latest op.runs.

One thing i noticed on the 00z NAEFs -they are different but this looks like it`s because the GEM Ens Hts are flatter and therefore skewing the combined output from that suite.

Certainly the GFS Ens anomls have been trending towards those Atlantic heights for a few runs now and with this change now just coming into the 10 day range the ECM ens are starting to pick this up too..

There`s no avoiding the warm up next week as we get that burst of energy from the Atlantic but there are definite signs in this mornings mid-range outputs that this Atlantic pattern will be relatively brief.

Height anomolys have been showing high pressure in the Atlantic towards greenland all winter. Havent seen it in the models yet!

[jimben]

may interest some in here http://www.metoffice.gov.uk/about-us/jobs/current-vacancies/002653

[TEITS]

Only just catching up and looks like our final straw to clutch i.e Met O outlook has been removed. Still on a positive note the 12Zs should be better because frankly they can't be much worse.

A mean of 1000mb in Iceland doesn't really suggest a GH developing in the near future.

http://cdn.nwstatic.co.uk/ensimages/ens.20130123/06/prmslReyjavic.png

My faith in long range forecasting is hitting an all time low. I can't help but wonder with internet forecasts that are we so focused on looking for signs of cold that we miss the signs that point to mild? I say this because I often follow a forecaster on another website who forecasts for the NE of the US and he is often wrong because he is such a cold ramper. In my opinion its incredibly difficult to not allow your bias to affect your judgement and this forecaster im referring to in the US is a professional!

[phil nw.]

Height anomalies have been showing high pressure in the Atlantic towards Greenland all winter. Havent seen it in the models yet!

The anomalies are not to be read the same as the actual heights though Latitude.

They are a guide to where the weaknesses or strengths are in the mean 500hPa pattern and need to viewed against the rest of the outputs.

A strong anomaly usually reflects where the highs and lows are likely to go-here for example at t96hrs

which shows nicely the Atlantic lows heading our way showing in the operational runs.

Agreed we havent had a solid Greenland High yet but we have had enough height anomalies to our north to drive the jet south with the undercutting lows and a cold block the UK have been and are currently experiencing.

Edited January 23, 2013 by phil nw.

[SnowBallz]

Interesting point regarding the MetO - may or may not have any relevance I suppose... Anyway I work now with a guy whose wife works at the MetO in the media section - publicity basically. When she got the job there was a welcoming party and a lot of the big wigs down there came out for a meal as part of the welcome. He is a mathematician and was telling me this week how amazed he was at the people he met because, as far as he could work out, they were almost all mathematicians and statisticians and computer experts. He said there didnt seem to be a "forecaster" amongst them. When he asked them about up and coming weather they didnt have a clue really - all they did was interpret data.

Might this suggest that the MetO respond much more directly to computer model output than some of our own more teleconnective and "gut" forecasters here? In one regard it gives them a massive head start as I am sure that the modelling they work with down there is state of the art and possibly second to none globally... but it may also leave them vulnerable to processes that require a bit more human interpretation and input.

I think GP and RJS are still quite bullish about cold in February...

With respect, you can only "interpret data" if you know the principles by which to interpret it against.

It's always been true, that a robust mathematical grounding will always serve you in good stead in meteorology - indeed, in just about all sciences. Further, and a natural dove-tail, is a deep understanding of physics to a fairly respectable level. To a lay person, I'm sure such people would appear to be merely mathematicians, whereas - in actual fact - they're professionals who use their understanding of applied physics and mathematics to abstract an understanding of meteorology.

With regard to computer experts (probably core programmers) you're naturally going to encounter such people, when you're developing thousands of lines of raw code which must be overlaid onto a multimillion pound supercomputer. For what it's worth, a programmer doesn't need to be a meteorology; he/she merely needs to be able to write code which instructs an algorithm to calculate in-line with meteorological principles, the majority of which - at their core - rely on mathematics.

Media people are very airy-fairy; they like to consider themselves to be lifes great creatives; they don't understand physics, in the same way that they don't understand finance. In truth, they don't understand anything vaguely intellectual or remotely tangible. Hate for that to sound like a slight on your friends wife, but as she sees fit to cast doubt on the credibility of professional forecasters who work for the Met Office, I think it's fair game. She should stick to difficult things, like designing pretty leaflets or having several meetings over font size.

[polarlow2]

Only just catching up and looks like our final straw to clutch i.e Met O outlook has been removed. Still on a positive note the 12Zs should be better because frankly they can't be much worse.

A mean of 1000mb in Iceland doesn't really suggest a GH developing in the near future.

http://cdn.nwstatic....mslReyjavic.png

My faith in long range forecasting is hitting an all time low. I can't help but wonder with internet forecasts that are we so focused on looking for signs of cold that we miss the signs that point to mild? I say this because I often follow a forecaster on another website who forecasts for the NE of the US and he is often wrong because he is such a cold ramper. In my opinion its incredibly difficult to not allow your bias to affect your judgement and this forecaster im referring to in the US is a professional!

But TEITS, you're questioning long-range forecasting, yet in your assertion that the models 'can't get much worse', you are putting your faith in a long-range forecast?!

[phil nw.]

Can we confine anymore views related to the MO -it`s latest LR outputs or indeed it`s workings- to the relevant thread please.

The 12Zs are out soon so let`s keep the thread on topic now.

Thanks all.

[nick sussex]

Still differences at short range between the GFS and UKMO regarding the breakdown.

The UKMO raw output looks much better for snow for more favoured areas as the low pivots sufficiently to draw some lower dew points in from northern France, once the snow to rain event occurs enough of a lull before the next low that might see any clearer skies help to slow any thaw so a chance some of this will hang around into Saturday.

[High Altitude]

With respect, you can only "interpret data" if you know the principles by which to interpret it against.

It's always been true, that a robust mathematical grounding will always serve you in good stead in meteorology - indeed, in just about all sciences. Further, and a natural dove-tail, is a deep understanding of physics to a fairly respectable level. To a lay person, I'm sure such people would appear to be merely mathematicians, whereas - in actual fact - they're professionals who use their understanding of applied physics and mathematics to abstract an understanding of meteorology.

The irony however is that having said all of that they're still unable to forecast with any great degree of accuracy beyond 4 days at best. In the 1950's the accuracy was at 2 days.

The question is, if you take away the computer model can a forecaster forecast. If they are presented with a chart at 12z today and asked to provide a forecast for 1,2,3 days ahead without the use of a computer can they do it. Half the people in here can interpret the models to provide a forecast and how many of those are expert mathematicians, physicists etc.

All the lay person wants to know is will it be wet, warm, dry or cold, not be baffled with b******t. It's about the end product - an accurate weather forecast; from what I can see, all these advancements in technology, the sciences etc and for what...........to extend the forecasting accuracy by 2 days!

[kiddydaz]

Anyone willing to enlighten the uninitiated what might happen during the breakdown Friday ?

Sorry for disturbing the slumber

[TEITS]

I was wrong this is even worse.

Very odd because historically Feb is the most blocked months out of all the winter months and yet despite the SSW the models are predicting a zonal even possibly stormy spell of weather at the moment.

Again Deja Vu as this is looking like a repeat of what happened last year. Really does make you think back to how extraordinary those Greenland HP's were in Dec 2009, 2010 without the aid of a SSW!

[Weather-history]

Very odd because historically Feb is the most blocked months out of all the winter months and yet despite the SSW the models are predicting a zonal even possibly stormy spell of weather at the moment.

Why is it very odd? The weather does not have a memory, it will do what it will do due to the circumstances at the time. It does not look at the calendar and say its February, turn the zonality down.

And doesn't it depend what model you look at? ECM 0z at 240hr doesn't look stormy or especially zonal at that. Infact hints at possible further blocking but we shall see what ECM 12Z comes up with.

Edited January 23, 2013 by Weather-history

[lord stratus]

Anyone willing to enlighten the uninitiated what might happen during the breakdown Friday ?

Sorry for disturbing the slumber

Friday, rain turning to snow mainly in north and east, turning back to rain by Saturday evening over all of the UK. Sunday, milder damp and breezy everywhere!

[Weather-history]

Again Deja Vu as this is looking like a repeat of what happened last year. Really does make you think back to how extraordinary those Greenland HP's were in Dec 2009, 2010 without the aid of a SSW!

Wasn't the first two weeks of February last year cold in the CET area?

[lord stratus]

Why is it very odd? The weather does not have a memory, it will do what it will do due to the circumstances at the time. It does not look at the calendar and say its February, turn the zonality down.

And doesn't it depend what model you look at? ECM 0z at 240hr doesn't look stormy or especially zonal at that. Infact hints at possible further blocking but we shall see what ECM 12Z comes up with.

Quite right, saying the weather should be cold in February is like saying August should be hot. It just doesn't work like that!

[phil nw.]

Friday, rain turning to snow mainly in north and east, turning back to rain by Saturday evening over all of the UK. Sunday, milder damp and breezy everywhere!

Yes it`s the second system on Sunday that really brings the Atlantic in with some strength.

After that it looks a period of typical Westerly type conditions with temperatures up and down between the mild and cooler sectors of the lows with rain or showers at times crossing the UK.

Any snowfall next week looks likely to be confined to the high ground in Scotland.

[TEITS]

Why is it very odd? The weather does not have a memory, it will do what it will do due to the circumstances at the time. It does not look at the calendar and say its February, turn the zonality down.

Very surprised you of all people have said.

Its very simple really. Why do you think its commonly said that snow is more likely during March than Dec? This is because blocking becomes more frequent during late winter than early winter because the strength of the PV & PFJ generally weaken during late winter compared to early. This is why synoptically Dec 2009, 2010 were so exceptional because you rarely see such extensive blocking over Greenland during the early winter months.

So all im saying is combined with the above and the SSW im very surprised at some of the output that is being currently modelled. Very little sign of any HLB, and the NAO continues to be progged as positive.

Whatever any positive spin anyone tries to put on the model output the 12Z GEFS ensemble mean at +180 is crap from a coldies perspective!

http://modeles.meteo...21-1-180.png?12

Wasn't the first two weeks of February last year cold in the CET area?

No I was referring to last Feb when we we're supposed to see some excellent blocking appear at the end of Feb due to Stratospheric conditions and the complete reverse occured. (See below).

http://www.wetterzentrale.de/archive/ra/2012/Rrea00120120228.gif

Edited January 23, 2013 by THE EYE IN THE SKY

[TEITS]

Quite right, saying the weather should be cold in February is like saying August should be hot. It just doesn't work like that!

Did I say it should be cold??

No I said blocking is historically more frequent during Feb than Dec. You will also find the frequency of E,lys is greatest during March, April. Lastly gales and deep Atlantic LP systems are also more frequent during late Autumn, early winter. This all ties in with the fact that during late winter the PV weakens and so does the PFJ because the thermal gradient becomes less in late winter.