In Depth Model Discussion, Analysis and Summaries

[Zenarcher]

Looking at what the models say between 96 to 168 hours using the GFS, JMA, ECM, NOGAPS, UKMO and GEM.

96 hours,

Russian High - The GFS brings it in further West than any other model the ECM and GEM both have it more West as well and agree with the GFS. We then have the JMA, UKMO and NOGAPS that have it further East,

I've marked out where the models place 1025mb so the image below is from the GFS as you can see it places it much further West than the other models which have been marked out further behind it where they place 1025mb.

Atlantic Lows - A real lot of difference between the models here but the GFS looks the odd one out, all the other models show a low around 985 to 990mb crossing the Atlantic meanwhile the GFS goes for a flat weak 990mb.

Here I have marked out where the models place the center of the low pressure systems. This goes to show the disagreement we have at just 96 hours.

Azores High - The GFS brings it closer to us than any other model the rest have a 1020mb isobar over Spain but the GFS brings it much further North into the Bay of Biscay.

120 hours,

Russian High - The ECM, GEM, JMA and GFS all have it about the same position. The UKMO and NOGAPS have it further East a lot further this is because the UKMO develops another high to our East and the NOGAPS has a shortwave holding it back.

Atlantic Lows - We have three different idea's here the ECM, GEM and JMA show two lows one that sits in the Southern Atlantic and the other one to the West of the UK like this,

The UKMO and NOGAPS go for something different they just keep it as one low and further South and also weak as well. Once again the GFS is on it's own here it has two lows in the Atlantic like the ECM etc but a lot further West and weaker then it has shortwaves crossing over the UK going under the Russian high which it places right over us.

144 hours,

Despite their large differences at 120 hours we end up with two idea's looking alike, we have the GEM and JMA putting a low over the North of Scotland and still have the other low in the Southern Atlantic. Then we have ECM, UKMO, NOGAPS and for the first time yet GFS agreeing they all show a low sitting out just to the West of the UK the strength of it differs but they all come across the same idea.

168 hours and beyond AKA FI WILL CHANGE - JMA shows low pressure sitting over the UK, NOGAPS gets high pressure in over the pole and tries to get a Atlantic ridging set up for a cold plunge in time for Christmas, ECM also gives us a tease by splitting PV and gives us a good chance for cold weather and the GFS mainly shows the Atlantic weather roll in.

Overall the models are clearly struggling with a lot of things at the moment firstly the Russian high they don't seem to really know how strong or how West it is going to push in, the Atlantic lows as well have really big differences between the models they don't seem to have much of a idea yet of what will happen. It is an interesting time for model watching with the talk about a strat warming towards the end of the month and into the start of the new year it will be interesting to watch how the models handle this.

Edited December 17, 2012 by weathermaster

[johnholmes]

re my promise to update today-sorry due to other commitments I have not been able to do other than save the data needed to make comment. I will try to do this tomorrow sometime

[phil nw.]

Realistically a real push back from the East was never a likely development this week..

What we are seeing are the Atlantic troughs disrupting as they hit the edges of the cold block.It`s not so easy for the models to calculate exact placement of these hence the reason for differences in the modelling of the smaller features through this week.

The upstream flow will push the Iberian ridge ahead of it and the tilt of the jet from the south west looks like having enough forcing to push the milder air across all of the UK by this time next week.

The 12z mean charts at T192hrs.

show us in a westerly type of flow for Christmas week with temps. around average and these have been pretty consistent over the past few days,

What we can take comfort from is the continual modelling of the main core of the vortex displaced towards Siberia in later mean outputs.It creates chances for heights to rise on the Atlantic side which would bode well for a high anomaly somewhere in the N.Atlantic or Greenland.

These are at T240hrs from the 12z mean outputs

We need the Uk trough a little further east to benefit so that`s where the demise of the block to our east would help in the long run.

Edited December 17, 2012 by phil n.warks.

[Gibby]

Good morning. Here is my take on the 00zs from GFS, UKMO, GEM and ECM for today Tuesday December 15th 2012.

All models shows a very unsettled and turbulent spell of weather between now and Christmas with a block of cold High pressure maintained over Europe and the UK being the battleground between the mild Atlantic, pumping disturbance after disturbance into the UK from tomorrow on. Details are vague but the message for the remainder of the week and weekend after today is that there will be plenty of rain moving into the South and West of the UK with flooding issues a real possibility for some here. Further North and East the rain will be slower to arrive and lighter with colder air brought in from Europe in the SE flow, especially to the far North and East where the rain could occasionally fall as snow. Temperatures will range from above normal in the SW and below for much of the time in the far NE.

GFS then shows a deep Low over NE England over Christmas Eve with rain and gales for many Southern areas while Scotland on the cold side of the Low may see some snow in a strong East wind. Christmas Day shows the cold air over Scotland sweep South as the Low stays out in the North Sea with wintry showers driven SE on the strong NNW wind. Boxing Day shows rather chilly and wet conditions as further disturbances run into the UK from the North Atlantic with the chance of further wintriness on Northern hills and mountains. FI this morning shows a trend to drier conditions for a while in the South as High pressure ridges in before a return to windy and stormy conditions arrive as we move into the first few days of the New Year.

The GFS Ensembles show a sine wave pattern within the individual members indicating very changeable and often wet conditions as a succession of Low pressures bring various air masses across the UK from time to time. A lot of spread is shown between the members again from mid run with the Christmas period showing normal 850's. Using the ensembles as a guide the events of Christmas explained above are shown as a cold outlier within the group so chances of a white Christmas are slim with rain the more likely outcome.

The Jet Stream shows a continuation of a strong flow across the Atlantic undulating North and South between 45 and 55 deg North over the Atlantic the UK and Europe.

UKMO for midnight on Christmas Eve shows Low pressure close to SW Ireland with a strong South or SSW flow over the UK with troughs moving NE over the UK delivering spells of rain and showers in relatively mild conditions, especially in the SW.

GEM for Christmas Eve shows a similar synopses at Christmas Eve as UKMO moving the Low NE through Christmas Eve and Christmas Day to the NE pulling rain and strong winds to all areas followed by a NW wind and showers for Boxing Day in fresher conditions. Then towards the New Year things are shown to become milder as winds back West and a North/South split develops with the wettest weather reverting to the NW in fresh SW or west winds.

ECM for Christmas Eve shows deep Low pressure out in the Atlantic with a strong South to SW breeze bringing rain and showers NE over Britain. Christmas Day and Boxing Day sees the Low drift over Northern areas with further very unsettled and wet weather for many in strong to gale SW or West winds by then. By the end of the run the Low has made its way out to the North Sea bringing rather colder and showery conditions steadily across the UK with some wintry showers then on high ground in the North.

In Summary there is a lot of very unsettled weather to come as we move up to and over the Christmas period. There is a strong possibility of more flooding over South-western Britain as a succession of fronts bring freqent spells of heavy rainfall here with some strong winds at times. Further North and East will see rain at times too but with winds in the SE here there is colder air not far away over Europe and at times this may spread across from Europe to NE areas with rain turning to snow at times in the far NE. A white Christmas is unlikely for many as things stand currently away from the aforementioned high Northern elevations with widespread frost and fog unlikely too as winds will be too strong and cloud amounts too large for much of the time. As we look towards the New Year there are a variety of options shown this morning between the operationals but none of them show anything dramatically wintry as things stand so travelling over the Christmas period will probably not be disrupted by meteorological factors away from the very wet and potentially flooded parts of the SW.

[johnholmes]

A look at what ‘Might’ happen over the Christmas week from the anomaly charts etc

I showed the 30mb temperature trend and suggested that there was evidence that the type of spike shown on the link below, it started 1 December, had in the past led to cold spells in the UK, 2008/9 and 2009/10 were examples.

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html

Judging from the anomaly charts, both NOAA and ECMWF-GFS there is nothing to support this idea. There was one brief blip, chiefly on the GFS output that did suggest there might be something developing around the Christmas period but it lasted just one day and then disappeared. This could mean that there would be a cold blip sometime over the Christmas period but it would be a 24-36 hour shot only IF that.

6-10 day NOAA link

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

and the 8-14 day outlook

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

As you can see none of them suggest anything but a fairly strong westerly flow across the Atlantic into the country, probably mostly below average temperatures, quite likely windy at times as lows track close by. Snow unlikely except on the higher parts in Scotland-the ski areas may do quite well. Just that small chance of a 24-36 hour blip sometime over the festive period but impossible to give any dates. If this did occur then a chance of some sleet or snow further south to lower levels but not lasting even if it did occur.

Enjoy the walk in a green countryside on Christmas morning for most of us!

and copied into the model thread

[lorenzo]

FWIW, Larger ensemble MJO prediction from ECM, GFS one seems to be offline at present, moves things through to the pre-cursor phases for positive NAO . Although GFS off line the weekly update 17/12 indicates enhanced maritime continent convection at the New Year, also the OLR projections cite the MJO cycling more quickly through phases than the plots show.

One thing this does map out is the potential of leading us back to a Scandi Block later on, Phase 6>7 being the pre cursor here, not sure if we can take the excitement of will it won'tr it again.

Some ghastly looking analogs to get through first..but here is Jan phase 7 if the MJO as suggested by the CPC update gets kicked up a gear. January phases 5 and 6 here if you want to punish yourself.

.

Although not as influential when in a low trajectory it would appear that much of the EC32 after day 10 is built on a loading pattern specific to the MJO action - maybe a reflection on the updates provided by the later weeks in this longer range model.

Just one part of the puzzle but worth keeping an eye on..

[SMU]

Just a question, how come you dont do a winter forcaste steve? I respect your knowledge on this subject and enjoy reading your posts in the MOD thread etc but im getting a sense that your enjoying questioning others forcasts but im yet to see one from you.

HI WM- Because there is a simple answer that people wont like.

Been there & done it- & realised for this little plot of land its a waste of time.

THe short answer is

PPN totals- unforecastable- It would be better to try & estimate rain DAYS V Norm as I believe that then moves away from the amount but gives you a feel for the amount of times it will rain V the norm.

Temp- Broadly forecastable but open to a LOT of volatility that unless there is an over whelming signal for ONE particular feature that effects over a sustained period of time then our weather then you are basically forecasting the norm within 1 degree up or down -

The long answer- hum...

It depends what you want / expect- its a bit like supply & demand- there is a huge demand for as much detail as possible, however you cannot go supply such details at long range ESPECIALLY for the UK as our country is to small.

Building a forecast up is about layers of information, the very top layer being high level factors that influence the globe- The Pacific water temps for El nino / La nino, The stratosphere,Arctic sea ice loss, Snow cover-

Then another overlay of teleconnection indices- QBO, PDO, Solar flux - & so on-

After that possible local factors- of which for us the atlantic is still the MAIN driver of our weather-

Every factor will influence the global pattern in some way shape or form- its the weighting to determine whats the leader, whats not so important that becomes the important analysis-

The BEST day to release any sort of data is the last day of November as its the most up to date source of information you have- as Autumn especially late Autumn builds the picture for Early winter- especially around the stratosphere-

By Nov 30th you should have enough date to forecast what you may THINK there will be Rossby wave wise across the NH & how long they may last, Rossby waves are how many standing waves / Eddies you will get along the jet in the NH, the max really is 4, but even 1 can deliver sustained cold for the UK ( greenland high)

THe more blocked the pattern you forecast the higher the probability of cold conditions entering the UK , & more often than not you would be forecasting Less rain days in a blocked pattern-

However its not that straight forward & this is why forecasting for the UK becomes a lottery & or requires a large element of luck to land.-

If you examine the size of a high pressure- pick say a Greenland high- possibly as big as 8-10 times the size of the UK- however look at how the parcel of advection that comes from these high pressures, the core of sub -10c air is usually as wide as 500 miles- with the -5c line maybe 250 miles either side, so the allignment from Greenland or Russia of this parcel of cold air advection that decreases in size as its modified away from source will need to be alligned towards the UK at the right angle for at LEAST 36 hours to reach us-

That doesnt sound long but to get a cold source Easterly ( usually 48 hours at least) the high pressure over scandi has to be held in situ for that amount of time- where as usually by day 2 its moving or reshaping.

Greenland pressure is usually more reliable.

So you see forecasting at 1 tier in terms of possible anomlies over the NH is as far as you ideally want to go, as if you get them right- IE greenland high or scandi high fore example almost guarentee cold for Europe- however for the UK that cold is subject to attack from almost any pressure to our south, so even with the right anomlies pitched it could all be meaningless-

The pressure to paint a detailed picture for the UK & be held to account for it is why the METO probably gave up because they realised that with the tools we have the would be under to much scrutiny if they got it wrong- they were even scrutinised for being to vague- when actually vague is best fit.

I believe stuart has based the forecast on a lot of analogue data- the QBO, Snow build up, Arctic Seasonal melt, OLR, Flux etc etc- & its lead to X forecast which the analogues say drive greenland high pressure & scandi high pressure for December-

However thus far it isnt right - Especially for Greenland- The stratosphere has been Very cold - so the Signal for atlantic & greenland blocking has been slowley overwhelmed by the Jet which over December has acceleraed & reduced the blocking & Rossby waves.

This is why people that follow the strat are geting very excited at the warming because it should signifcantly decelerate the jet again once it propergates down- ~ early- mid Jan, then with the other favourable factors the forecast probability of cold will go up again.

Would I have forecast a cold Winter- even Decemeber,?-Yes initially - especially around Arctic ice loss & the snow advance-

but I would have say high the probabilty of it sustaining cold was LOW- with the strat taking over at some point.

Also for Dec-

* because of the stratospheric profile over Late Nov- at some point that would propergate to the zonal mean

* You cannot forecast Stratospheric warming with any degree of accuracy- especially for subsequent H5 Anomalies

* The norm here isnt cold

* Not enough of an overwhelming signal for greenland blocking-

I believe one flaw in the NW forecast- All Best fits were used against Top 10 Neg AO winters & some of the teleconnections signalled a high correlation- however IF we had data for the top 10 coldest November Stratospheres then the H5 anomalies for December would have significantly muted any cold signal-

As for Jan, I think the atmosphere is looking like working backwards- Primed for no High lattitude blocking ( or at least minimal) But if this warming event delivers then it will slow the jet down to a weak zonal Mean-

* remember this couldnt be forecast in advance though *

I think we have been very lucky for December cold so far, its a pity though for most it didnt deliver much snow- jan hopefully will be better-

As for Winter forecasts until you can get a refined H5 anomaly pattern for a season then you have no chance for the UK- when will that come about - NEVER until the parameters that are being used stabilise- Which in itself is unlikely to happen-

What would i do.

Scrap Winter forecasts- & stick with a monthly as you have real time infor infront of you for support to the H5 anomaly.-

S

Edited December 18, 2012 by Steve Murr

[lorenzo]

IF we had data for the top 10 coldest November Stratospheres then the H5 anomalies for December would have significantly muted any cold signal-

Scrap Winter forecasts- & stick with a monthly as you have real time infor infront of you for support to the H5 anomaly.

Well reasoned post Steve, the UKMO cite the problem of forecasting for a wee dot of land that is the UK on this blue marble as being one of the reasons they respect the JMA model highly.

Any chance of you cooking up a monthly forecast for January?

[SylvainTV]

Edit:sylvain - can you give a full answer on the meteociel v wz gem run issue?

What is exactly the problem ? Both don't show the same data ?

Well first no 12z run on WZ, hard to compare tonight.

Could you pinpoint on what run the problem appeared in the archives ?

Thanks

[UV-RAY]

Good post Steve, I wholeheartedly agree with your view on LRF for this little part of the world, it's all well and good getting the NH profile right to some degree, but it's the little unforeseen things that scupper the output 9/10 for us. Best to keep things simplistic and look no further than a month at a time, even that's not foolproof by any stretch of the imagination, still if we only use LRF as a just for fun guide then people won't get as hung up when they go the way of the pear.

[SMU]

Well reasoned post Steve, the UKMO cite the problem of forecasting for a wee dot of land that is the UK on this blue marble as being one of the reasons they respect the JMA model highly.

Any chance of you cooking up a monthly forecast for January?

I think you have just asked me to do what I said nobody could do lol-

What do I THINK.

A game of 2 halves- a Backward version of December with the jet slowing. With such a big warming projected there is a CHANCE of the blocking being in situ long enough for the UK to become significantly cold- however we all know thats a tough cookie to crack.

I would say: ( based on the notion of a decelerated jet propergating week 2 of Jan. )

High prob >60% that jan will not be +1c over the 71-00 Mean.

High prob> 75% that jan second half will be colder than first half ( or better still in the warmest third at the start )

Higher than average chance of a CET -1c below the 71-00 Mean.

cheers

Edited December 18, 2012 by Steve Murr

[lorenzo]

Good to get your thoughts Steve, glad you accepted the impossible challenge!

I only asked after you wrote indicating that monthly would be better than a LRF. I hope the jet decides to calm down, another month of being at it's mercy will make for unpleasant if not boring model viewing.

[SMU]

Best Day for a Jan forecast-

Dec 31st-

We can see where the warming is going- what the propergation rate is & where the likely H5 blocking is going to be-

So maybe an update then... maybe things will be a little quicker than planned which then hopefully would distort the trend to colder quicker.

S

[lorenzo]

With the potential for warming within the first fortnight of the New Year would think a January forecast is already massively difficult to work out.

I wouldn't dream of attempting to write a January forecast. Even less so on Hogmanay..

[Severe Siberian icy blast]

I think you have just asked me to do what I said nobody could do lol-

What do I THINK.

A game of 2 halves- a Backward version of December with the jet slowing. With such a big warming projected there is a CHANCE of the blocking being in situ long enough for the UK to become significantly cold- however we all know thats a tough cookie to crack.

I would say: ( based on the notion of a decelerated jet propergating week 2 of Jan. )

High prob >60% that jan will not be +1c over the 71-00 Mean.

High prob> 75% that jan second half will be colder than first half ( or better still in the warmest third at the start )

Higher than average chance of a CET -1c below the 71-00 Mean.

cheers

Evening Steve ,

Can I just say that firstly I find your posts fascinatingly knowledgeable , and I always read and take note of your posts, I would agree with your summary there regarding jan, I think the last episode of what's happened these last few weeks have been a big learning curv for many, and it certainly has made me much more reserved about my belief in stratesphere warming/displacement of the vortex = cold for uk, I was naive to think that, but I really got took in and as you say I was borderline obsessive with it , but lessons learnt all round I think.

It's fair to say the jet street is a massive massive player in our weather hear, and in my eyes that has the power to override all other signals, northern blocking really increases our chances of cold in the uk, and obviously we cannot deny the stratospherer and the vortex are also very very big players in our weather, I think though in order for cold in this country we need a combination of a week and southerly jet , a vortex displacement with no residual energy over Greenland , along with many many other factors but if we can demolish the vortex and remove the residual energy from Greenland then we have a good chance.

It's very clear to see we have much better prospects this winter than last, we have constant wave one and two into the vortex, and 2 warmings forecast in the strat, that's a fantastic position, obviously that's not a done deal for us though but it seems favourable to say the least .

On a personal note though I think we should all show the likes of chionomainiac and glacier point huge respect for the time and effort they put into this site and feel privileged to be part of such a site, I put them two up there with the very best, and I feel for Gp hugely because as you say he got all the big things right, as he always does, the amount of work he puts in to this thred along with ed in the strat thred is much appreciated by me and should be by EVERYBODY ELSE .

I feel In the new year we will be on the crusp of a freeze, that's not a hope cast that's an honest thought Iv got , I know things can go wrong but with longer signals pointing to a greeny high and with the jet streem slowing in jan and feb I think things look good.

[Gibby]

Good evening. Here is the latest report on the 12z output from GFS, UKMO and ECM for this evening Tuesday December 18th 2012.

All models continue to show a very complex pattern which continues all the way to Christmas. Todays ridge and fine weather is soon to become a distant memory as a vigorous Atlantic depression throws a series of troughs North and East into the UK over the coming 24-48 hours. The weather will see rain move into the SW tonight and other areas tomorrow. A very vigorous area of rain then spins North across SW Britain tomorrow night and on North through the Midlands and North. Amounts of rain will cause concerns for some as flooding is renewed in the SW especially. Elsewhere the rain will be less troublesome but will be falling in rather colder air than in the SW with some snow expected over Northern hills and mountains. With the block of cold air holding to the NE further pulses of wind and rain will occur over the weekend with the same NE/SW split in temperature remaining. Things then start to change between the models on Christmas Eve.

GFS continues to feed troughs into the UK from the SW which disrupt and send there energy ESE into Europe and less push NE. the result is the same mild and wet SW and a colder and possibly wintry NE as cold air brings a risk of the rain turning to snow over the hills in the North and East on Christmas Day and Boxing Day. Thereafter, the block subsides over Europe allowing the trough to make its way over the UK to allow a NW flow to bring a mix of sunshine and wintry showers briefly. towards the New Year and into 2013 High pressure ridges North from the South bringing very welcome drier weather for all as the High sits over the UK eventually bringing quiet and settled conditions with the usual Winter High pressure problems of widespread overnight fog and frost.

The GFS Ensembles show a mixed set of members tonight. There are many disagreements between the indivudual members from a relatively early stage, especially in Northern locations with the milder pack having the upper hand on this run. There are some colder options too but the one common factor between the members are the large precipitation amounts spread about through the run.

The Jet Stream shows a continuation of the undulating flow over the coming week or so either over, near to or to the South of the UK.

UKMO for midday on Christmas Eve shows a deep depression over the Hebrides with a strong SW flow over the UK with showers or longer spells of rain in relatively mild conditions.

ECM shows the Low pressure more to the NW but with an unstable and strong SW flow with the same mix of rain at times in fairly mild conditions. Later in the run the Low fills somewhat but maintains a feed of relatively mild and damp SW winds with further heavy rain at times for all.

In Summary tonight the next 4-5 days could see significant and newsworthy rainfall events for the same areas that were ravaged in November. Frequent troughs moving up from the SW stall and disrupt against the cold block over Europe. The cold does stay for the main part over the other side of the North Sea though some incursions could affect the North and East at times, especially if the GFS operational verifies. Christmas is looking like a relatively mild and wet period though once more the GFS operational would spring a few surprises for a few. Beyond that though the block finally crumbles and the Atlantic winds its way right across the UK with the mix of rain at times, fresh winds and temperatures fairly close to normal for all by then. There doesn't look to be any great chance of many parts of England and Wales at least of seeing a white Christmas this year.

[chionomaniac]

Best Day for a Jan forecast-

Dec 31st-

We can see where the warming is going- what the propergation rate is & where the likely H5 blocking is going to be-

So maybe an update then... maybe things will be a little quicker than planned which then hopefully would distort the trend to colder quicker.

S

Do you not think Steve that it is a tad hypocritical to go out of your way in the model thread to suggest that the stratosphere is being overplayed, and yet when asked for your own forecast for the month ahead, the only variable that you have used for this forecast is the stratosphere?

Why is that?

c

[legritter]

Well just had a look in my clutching box and its nearly empty ,will have to ask Santa for some new straws .i was hoping for a good upgrade from ECM PAST 168hrs but not to be .But last 2 frames does get things moving a little . i do feel [gut feeling ]that modells could give us something soon . i also feel that the jet is a big player in our weather . i know there are other things like P VORTEX and strat temperatures but the jet in my opinion plays a large part . back to now and a look at todays fax charts tells the story very well with some nasty weather again hitting flood prone places .RADAR ALREADY SHOWING FRONT APPROACHING . Gfs rain maps very impressive .all charts and data suggesting copiouse rain for severall days to come .then modells give us possibly cooling temperatures .beyond this i think it could go many ways ,but hoping for the odviouse .

[peterf]

any chance we can get back to the models and their outputs.I'm sure theirs a specific thread somewhere for personal discussion.

[peterf]

only joking,just always wanted to do that lol.

carry on chaps it's all fascinating stuff.

[Zenarcher]

Here are my thoughts and an updated view on the models this evening using the GFS, JMA, ECM, NOGAPS, UKMO and GEM.

72 hours

Russian High - All the models apart from NOGAPS bring it in West and it looks very similar to what the GFS said 24 hours ago it seems the other models have slowly caught up with it. NOGAPS is still a bit behind and doesn't push it West as much.

Atlantic Lows - Yesterday I marked out on a map where the center of the low pressure systems where on the models today the centers are all in a very similar place, so all the models agree on a weak 990mb low to cross over the Atlantic but it's what happens next is where the mystery still lies.

96 hours

Russian High -

It's difficult to make it clear in the image but the lines are where the 6 models place 1025mb as you can see still a large difference and once again the GFS is pushing it the furthest West but the ECM is also not far behind either. It's NOGAPS and the UKMO that have it more East the same two models that under done it yesterday to only end upgrading it today in the early timeframes.

Atlantic Lows - We've got a few things going on here first of all we have 3 pressure systems one is to the South of Greenland another in the South of the Atlantic and the third one is a shortwave that only appears on some models tonight that's trying to go under the blocking to our North. The GFS is good news for those wanting cold weather and the reason why it's a interesting run tonight is because it keeps the Russian high strong and also has a good amount of energy going under it as well, both NOGAPS and JMA do this too the only problem with them is they don't have the Russian high strong enough to make things good enough. The other models don't really send any energy or not enough under the high. So once again we have big disagreements at 96 hours.

120 hours

Russian High - GFS once again leads it further West but the ECM, JMA and GEM do have it around the same strength as the GFS just not as far West. UKMO and NOGAPS have it a lot further East and weaker.

Atlantic Lows -

I have marked out where the center of the lows are,

So they all agree on that a low will sit to our West at the moment by the end of the week, the dot furthest West is the GFS and the two furthest East are the UKMO and NOGAPS it shows if the Russian high is stronger it does push everything West like shown on the GFS. Most models at the moment show this low to be around 975mb again if this low gets downgraded and the Russian high upgraded or pushed West cold lovers would be happy with that.

144 hours - Three different solutions here firstly GFS of course still has everything further West in the Atlantic and the Russian high looking strong. NOGAPS, ECM and JMA are sort of in the middle of everything, things aren't placed too far East or West. Then lastly we have the UKMO and GEM that place a 970mb low over the UK with the Russian high looking fairly weaker than what the rest show.

168 hours and beyond FI Changeable Outlook - For those new to model watching we are down to four models now because two don't go past 144 hours, so GFS breaks up PV in the Northern Hemisphere but we don't see any high pressure building up over Greenland just towards the end of the run high pressure rises from the South, ECM also gives PV a difficult time and places a high pressure over the pole the outlook gives us plenty of potential towards the end of the month and into early January, NOGAPS shows low pressure sitting over the UK so a unsettled outlook from it but in the Northern Hemisphere it also gives PV a hard time and builds high pressure over the pole and now finally the JMA it has low pressure staying with us although it's not as strong like NOGAPS so unsettled weather would be less likely, in the Northern Hemisphere it does bring high pressure over the pole but PV moves in over Eastern Greenland.

Overall - Over the past 24 hours we see better agreement now at 72 hours on the Russian high and the Atlantic lows, once again though it all goes different at 96 hours where some models want to bring in the Russian high and send energy under it meanwhile other models aren't keen on this idea and show a more Atlantic weather type move in instead. It is interesting to see the GFS yesterday estimating the Russian high and being consistent with it then today the models move over to agree with it at 72 hours. If the same thing happens tomorrow we could end up with good looking charts for cold lovers across the models. The next 24 hours are very important indeed.

[SMU]

Do you not think Steve that it is a tad hypocritical to go out of your way in the model thread to suggest that the stratosphere is being overplayed, and yet when asked for your own forecast for the month ahead, the only variable that you have used for this forecast is the stratosphere?

Why is that?

c

Not really beacuse the rest of the indicators this Autumn pointed towards a weaker jet- ..

If you read my post above I said the cold stratosphere is muted out the otherwise good signal........... & its a very general forecast based on back of fag packet probabilites-

S

Edited December 18, 2012 by Steve Murr

[chionomaniac]

Not really beacuse the rest of the indicators this Autumn pointed towards a weaker jet- ..

If you read my post above I said the cold stratosphere is muted out the otherwise good signal........... & its a very general forecast based on back of fag packet probabilites-

S

Ahh I see - so the stratosphere has overridden the good signal............

[SMU]

so what are you saying ---

or is the semi sarcastic tone just how you have orientated the post-

[UV-RAY]

I think that's a tad unfair as Steve has never underplayed the Stratosphere, but merely commented how some have overplayed it's importance as the be all and end all for cold spells.