Model Output Discussion 1200 hrs 15/11/14

[Timmytour]

A little diigging around in the archives of the MJO to see if any years matched current forecast - it produced three matches - '75 - '84 and '93.

 

I suspect the winter that would most appeal among those three is 84/85 so a quick recap of the state of play on the first of December of that year.

 

http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phasediag/pd.1984.12.1.gif

 

 

Looking very familiar? .....thought so.....

 

The archive - to have a look at the other options:-

 

http://www.meteociel.fr/modeles/archives/archives.php?mode=2&month=12&day=1&year=1984&map=0&hour=0

 

The MJO archive.   http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phasediag.list.htm

That was a notable winter in the US..... "The Winter 1985 Cold Wave" that started off with the US having unseasonably high temperatures in the preceding December. I wonder if that could translate a month earlier and a a couple of thousand miles east into something for us this winter

Certainly as you say though, there would appear to be a lot of similarities with this year

Edited November 21, 2014 by Timmytour

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY FRIDAY NOVEMBER 21ST 2014.

NEXT UPDATE SATURDAY NOVEMBER 22ND 08:00

THE CURRENT GENERAL SITUATION A complex series of troughs will move slowly NE across the UK today and become slow moving near to SE Britain from tomorrow morning with wave disturbances running North along it at times over the weekend. Pressure rises strongly across the North from tomorrow.

MODELS-2 WEEK HEADLINE Slowly becoming windier and more changeable next week and beyond with rain or showers and strong winds at times moving down from the NW. Temperatures near or a little below average.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the disrupted flow to the West of the UK continuing over the next week with something of a split flow over Europe-one arm high over the Arctic and another one well South over the Med or North Africa. The pattern simplifies in Week 2 as the pattern flattens and a strong flow crosses the Atlantic and Southern Britain later in the period.

GFS OPERATIONAL The GFS operational this morning shows asteady trend towards a more unsettled spell as Low pressure develops and moves down from the NW later next week. There will be spells of rain and showers as a result in temperatures close to or slightly below the seasonal average in increasingly blustery winds. Through Week 2 the winds remain strong and from the West with further spells of rain with temperatures recovering to average or somewhat above in the South as the pattern flattens to a more traditional West to East flow of Low ressure to the North of the UK.

THE GFS PARALLEL RUN The GFS Parallel run is basically similar in trend and sequence of events with the unsettled and breezy weather revolving around deepening Low pressure over the UK later next week gradually simplifying as pressure rises from the South with Low pressure then to the North carrying wind and rain to more especially Northern areas later while the South sees longer drier phases when temperatures will reach and exceed normal values at times.

THE GFS ENSEMBLES The GFS Ensembles agree with the first half of the partner runs in as much as deep Low pressure develops close to Southern Britain later next week with much wind and rain for all as a result. It then diverges away from the operational and parallel runs in as much as it maintains deep Low pressure sweeping East over the UK rather than to the North with potentially quite stormy conditions at times in periods of rain and showers and temperatures close to average overall.

UKMO UKMO today shows very benign conditions under a slack pressure area from Days 4 to 6 with variable conditions as a result with a mix of sunshine, mist, fog, frost and a little rain all possible with a little sunshine too for the lucky few. Conditions do look like deteriorating from the NW soon after close of the run.

THE FAX CHARTS The Fax Charts continue to show a complex pressure pattern under basically High pressure over the weekend and start to the new week. Complex frontal activity will prevail near the SE of the UK for the next 72 hours and again by 120hours as well as new versions approaching from the West at the end of the Fax period.

GEM GEM this morning shows the UK remaining the battleground between a block of High pressure over Europe and repetitive Low pressure moving in off the Atlantic and disrupting SE while filling over the UK. This means that after a quiet period early next week more wind and rain is likely thereafter in temperatures close to average but feeling chilly in blustery winds at times.

NAVGEM NAVGEM also shows the theme of Low pressure developing and sliding down towards the UK from the NW later next week with rain and wind increasing in intensity and extent with time in blustery winds too but average temperatures overall.

ECM ECM this morning remains in the habit of being somewhat different to the majority, this morning making rather less of the disrupted Low pressure pattern of later next week before pulling Low pressure further towards a position North of the UK and subsequently taking a lot of it's rain with it while the majority of the UK remain bathed in a relatively mild and Westerly pattern.

THE ECM ENSEMBLES The Ensemble run continues to show a deep trough lying from Southern Greenland through the West of the UK to the Meditteranean with cyclonic South or SW winds across the UK with spells of rain and showers for all likely in average tmperatures overall.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend still is relatively one of Atlantic Low pressure gradually taking control of the weather with some disagreement on the positioning and resulting surface conditions in what remains a largely wintry free run.

MY THOUGHTS The output remains very mixed in detail between the models but the general message from them all is similar in that all areas are going to see rain at times across the period. For a time with Low pressure predicted to lie close to or indeed over the UK later next week some very wet weather is likely in places with winds occasionally strong but variable in direction. At this time temperatures may be held back close to or a little below average at times. Thereafter the general trend with exceptions is for Low pressure and the Jet Stream to move North and flatten. There is some evidence that Low pressure will go far enough North in Week 2 to bring drier air across Southern areas from High pressure developing to the South which of course means mild Westerly winds as a result. However there remains enough support too for very unsettled and windy and at times wet weather to persist for all under deep Low pressure lying close to the UK. The High pressure block to the East remains in situ but has shifted away from supplying too much influence to the UK later as the barrage of Atlantic Low pressure overrides it and displaces any chance of cold from a Continental source reaching the UK on this occasion. A more worrying trend is the rise of pressure to the South which is shown on several outputs this morning which coupled with High pressure over Eastern Europe could form an unwelcome Euro High block to the SE of the UK with a mobile Atlantic setup developing delivering most wind and rain to the North and West later. Once this pattern has formed it can prove stubborn to shift and delay a shift towards a more seasonal pattern while maintaining the string of warmer than average months that have occurred this year. However, there is a lot of water to pass under the bridge before we reach that stage and we still have the ECM Ensemble data this morning showing more support for a more entrenched and deep UK trough keeping things volatile and unsettled for all.

[Weather Boy]

Another set of model output, same old stalemate

That is quite a southerly we are getting, shame it's late November and that would probably just squeeze temperatures into double figures for some. Rainfall could potentially become an issue if active fronts stall over areas of the country from time to time, though you would favour eastern areas to receive little rainfall during this period. The ECM overpowers the block by day 9 and 10, will that verify though?

GEM

The GFS and parallel offer some more widespread rain though as low pressure makes it closer to the UK

 

Given these model outputs, can any more educated participants explain why the temperatures forecast for tomorrow are so ordinary?

 

Given the draw from north Africa, I would expect at least a 14C if not a 16C but they're saying more like 11 or 12?

[Man With Beard]

ECM mean D8-D10: Unlike the op, the centre of the PV never makes it to Greenland, Scandi heights remain strong throughout and consequently the Atlantic almost doesn't make it to the UK. It's a real game of cat and mouse ATM between heights to the east and lows to the west and we're the piggy in the middle. The stalemate means endless southerly sourced winds for now...

[IDO]

A few days ago when the plume for this weekend was predicted for the south, which now looks like verifying, GFS were predicting very mild temps. They have been very consistent since then. ECM were also showing this plume but were suggesting below average temps (some members were kind enough to post the metrograms for these).  Now ECM is fully on board for about 14c for London for Saturday:

 

 

I do keep an eye on their 2m temp forecasts and they are usually consistently 2c out compared to GFS for forecasts. Yet another ECM question mark to add to the list. I noticed the Express headline, where I think it was Madden again, basing his three months of Arctic weather on the upcoming Sunday night, as it was going (forecast by ECM) to be very cold. ECM was showing a sharp frost at that time; now it's showing just an average 5c; the GEFS around the same:

 

 

With the GEFS now looking to show good confidence, the Express hyperbole of yesterday, shows the unwise judgement of taking one op run in an uncertain setup even just 5 days away.

 

Looking at Sunday we have two cold fronts crossing from the west. The first one stalls in the east against the block and starts to edge back west as a warm front. However the second cold front catches up and helps it return back east as a cold front again! Rain for the SE/E looking a good bet for Sunday then.

 

Out in FI I did notice that the 500hPa PV lobe over Greenland/NE Canada is gaining strength as a variable. The mean at D16:

 

 

Also the mean 850's lobe of cold moves some of its energy from Canada to Greenland through the GEFS runs. This would indicate the potential for a cooler flow from the Atlantic as we head through early December, depending on how far south the polar jet slips (Azores still in play at D16 on the GEFS):

 

 

Not much to say with regard to the medium range, as we continue to wait for the next undercut possibility to resolve amongst the models.

 

 

 

 

 

 

[knocker]

The ECM monthliy update for your delectation.

 

Much of the same really. The first couple of weeks the persistent trough Greenland SE to UK remains in situ then basically a westerly unsettled airflow.

Thus some vigorous trough first couple of weeks and then a low./HP split within the unstable westerly regime in the Atlantic. Perhaps more influence from the HP in the south later in the run. Temps around average.

[Duane S.]

I would have to concur, hopes of am early December cold spell are fast diminishing but it can't still be ruled out quite yet. Optimism runs rife though.

The 1984/85 analogue is a very good one IMO.Viewer discretion advised if viewing the archive charts, December was, on the face of it, pretty awful, this place would have been awash with winter's over rhetoric no doubt!Then came the turn of the year, 1985, and it was certainly worth the wait.

1984 saw strong wave1 activity through November (sound familiar?) and then a very big wave2 event mid-late December which no doubt did the trick with the vortex split straight down the middle. 84/85 was also an E-QBO season and it ties in very well indeed with the OPI. 84/85 perhaps slightly better in respect that it was further ahead in descending solar activity. So yes the ECM monthlies may well be on the ball in terms of weather on the ground but expect a big uptick in wave2 in the coming weeks and then it will just be case of when...

[Tamara]

I would have to concur, hopes of am early December cold spell are fast diminishing but it can't still be ruled out quite yet. Optimism runs rife though.

The 1984/85 analogue is a very good one IMO.Viewer discretion advised if viewing the archive charts, December was, on the face of it, pretty awful, this place would have been awash with winter's over rhetoric no doubt!Then came the turn of the year, 1985, and it was certainly worth the wait.

1984 saw strong wave1 activity through November (sound familiar?) and then a very big wave2 event mid-late December which no doubt did the trick with the vortex split straight down the middle. 84/85 was also an E-QBO season and it ties in very well indeed with the OPI. 84/85 perhaps slightly better in respect that it was further ahead in descending solar activity. So yes the ECM monthlies may well be on the ball in terms of weather on the ground but expect a big uptick in wave2 in the coming weeks and then it will just be case of when...

Based on my recent apparently bullish posts including the one last night I completely agree with this. In my own mind, the first half of December (at the least) has always been unlikely to provide much interest (at least on the ground). That is the very important caveat...

 

It is important to differentiate between the face value tropospheric modelling which might not suggest much for some time (in MOD terms) and what is going on in the bigger picture and way up above us that can have much bigger impacts further down the line.

 

This thread gets that type of crossover insight. Those of us who appear upbeat in the face of bland and uninspiring weather closer to the present are sitting and waiting  based on the fact that what is driving the future weather patterns is looking much more promising than anything the foreseeable future offers on the ground.

 

Never any guarantees it will come to anything for the UK. But that applied in winters like 84/85, as it does at this time

[nick sussex]

Theres no point trying to spin the ECM this morning, its a horror show of epic proportions for coldies.

 

A role reversal from yesterday with the operational as flat as  pancake upstream and a bigger cluster of easterly winds in the ensembles, last night the ECM run was not supported by its ensembles .The main clustering from the 28th to the 1st December is at odds with the operational.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

If you're a coldie start praying the ECM has just thrown out a rogue progressive flat pattern upstream and hopefully moves towards the main ensemble cluster tonight!

[nick sussex]

In a nutshell this says it all !!!!!!

 

 

Oh dear the GFS 06hrs run now follows the ECM trend, the GFS P less awful. When it rains it pours!

Edited November 21, 2014 by nick sussex

[IDO]

In a nutshell this says it all !!!!!!

 

eps_pluim_dd_06260.png

 

 

ECM are churning out different charts on a bi-daily basis and this is to be expected; if you take the last undercut as a basis for model uncertainty. At D5 on the ECM 0z there are three clusters of similar size so we can expect at least three variations on the theme at D7+. The GFS 06z highlights this with the P and Op offering different takes at D8:

 

Op:  P:

 

I suspect that like the last time we will just get the continued repeating pattern maintained, similar to the P...

Edited November 21, 2014 by i'm dreaming of...

[BLAST FROM THE PAST]

In a nutshell this says it all !!!!!!

 

eps_pluim_dd_06260.png

Still a week + away so hope is appropriate for whichever angle one looks at.  I think there is still a lot of resolving to come ahead.   I agree the overnighters are not good for cold but lets see what consistency we get over next 4 days

 

BFTP  

[nick sussex]

Still a week + away so hope is appropriate for whichever angle one looks at.  I think there is still a lot of resolving to come ahead.   I agree the overnighters are not good for cold but lets see what consistency we get over next 4 days

 

BFTP  

It actually starts unravelling pretty early, the ECM phases several shortwaves before T144hrs with the incoming trough which spills a lot of energy over the top.

 

This already means that the pattern is further east than the UKMO which makes less of those shortwaves, this then makes it a hard slog already.

 

The ECM postage stamps do have quite a few options at T120hrs:

 

 

I remember the ECM threw out one progressive run a few days back which it then dropped the next morning and we have to hope that the same applies here.

[fergieweather]

ECM mean D8-D10: Unlike the op, the centre of the PV never makes it to Greenland, Scandi heights remain strong throughout and consequently the Atlantic almost doesn't make it to the UK. It's a real game of cat and mouse ATM between heights to the east and lows to the west and we're the piggy in the middle. The stalemate means endless southerly sourced winds for now...

Indeed so. In fact, UKMO Medium Range forecaster has been at pains to emphasise exactly this issue in this morning's briefing, and the high likelihood that the sort of day-to-day forecast headaches we currently face will probably prevail through at least the next 10-15 days and quite possible beyond that. EC-EPS time series plot for next 30 days of 500hPa GPH anomalies has a strong signal for the UK to remain at the disjunction between positive anomalies to the east and negative ones to the west. This signal persists through the bulk of the time series dataset (to 22 Dec), with no real hint of waning until a more mixed (but not definitive either way) signal apparent circa 2nd week December. Thus meridional pattern remains strongly implied, with slow progressive attempts incoming periodically from west, but no strong indication of any significant cold weather into forseeable (predominantly southerly-quarter flow). So, a tricky forecast period in terms of nationwide detail. What a mare...!

Edited November 21, 2014 by fergieweather

[Gael_Force]

Well, well, well!

We've finally got a global model showing something cool/colder for winter. Shame it is only the BCC but it has had flashes of correct insight before.

 

[Hocus Pocus]

Well, well, well!

We've finally got a global model showing something cool/colder for winter. Shame it is only the BCC but it has had flashes of correct insight before.

 

I rate this model actually, not like any of them are that good anyway.

[bluearmy]

Indeed so. In fact, UKMO Medium Range forecaster has been at pains to emphasise exactly this issue in this morning's briefing, and the high likelihood that the sort of day-to-day forecast headaches we currently face will probably prevail through at least the next 10-15 days and quite possible beyond that. EC-EPS time series plot for next 30 days of 500hPa GPH anomalies has a strong signal for the UK to remain at the disjunction between positive anomalies to the east and negative ones to the west. This signal persists through the bulk of the time series dataset (to 22 Dec), with no real hint of waning until a more mixed (but not definitive either way) signal apparent circa 2nd week December. Thus meridional pattern remains strongly implied, with slow progressive attempts incoming periodically from west, but no strong indication of any significant cold weather into forseeable (predominantly southerly-quarter flow). So, a tricky forecast period in terms of nationwide detail. What a mare...!

 

No real sign that this is changing at the moment ian. within the broad envelope, as the continent cools, the eastern half of the uk could well end up quite chilly (overall)  whereas the westwern side could well record above av mean.  as i said last evening - where's your money? the siberian high or the east canadian/west greenland vortex ? given the background picture, i know where i am on this though a very slow drift in general without something unexpected to break the pattern (ie. another ex TD)

[throwoff]

So reminds me of 2010 at the moment, the models all over the place, some hints of cold, PV falling to bits..

 

Who knows what is coming.

[Methuselah]

 

Who knows what is coming.

Nobody does. Not man, not beast, not model??

[Barry12]

I think the position we are currently in is actually not bad at all, within the reliable time frame we still have a strong block, the Atlantic is clearly struggling and we also pick up a slight Continental influence. The GFS P 06z, is an example of this at day 4. If we had a similar flow in a month's time, when the continent has cooled down, it would actually be pretty cold, maybe even cold enough for snow. We have seen time and time again from the models, that as long as we have this block there is definitely a chance of getting an Easterly flow, it's just at the moment we've been unlucky that the continent is relatively mild for the time of year. We could be in far worse positions at this time of the year when the Atlantic is at it's most strongest, the fact that the Atlantic is struggling is a massively positive thing to see as we head into Winter. Combine that with a struggling Polar Vortex and I would be very confident that eventually, probably sometime in December we will see a cold spell, cold enough for snow.

 

 

GFS 06z P at day 4:

 

 

A cool continental flow at day 4, also look at the Polar Vortex, it's not particularly weak but it's in a good position, a large chunk of it is to our East. Which is a good place for it to be if we are wanting the Continent to cool down. It is not sat over it's usual place in Greenland. For people worrying this Winter will be a repeat of last year, (which I know is not many) it is nothing like last year, as Tamara and many others have been saying. Below is a chart showing this time last year, you can obviously see straight away that the Polar Vortex is far more stronger and organized, especially to the NW which is one of the worst positions it can be in, if you're looking for cold weather.

 

 

That chart is pure awful, a very strong organized Polar Vortex, and a mild south westerly. Last year when we were constantly seeing charts like this I think many of us would have given an arm and a leg to instead be in the position we are in right now. So theirs definitely no need for doom and gloom, it could be an awful lot worse. Look at the chart below and you will see instantly just how much of a better position we are in this year:

 

 

Fair enough, it's a pretty mild flow we are in now, but now we are in a position of potential as we head into December, last year there was only potential of less stormy conditions.

2 weeks from now (5th December) I am very confident that we will be in a much better position than we are now, and may even of had our first proper cold spell already.

Edited November 21, 2014 by Barry95

[MR EXTREMES]

gfs is following the same trend as the earlier model run dont look like there be any joy from tonights 12zs looks like a major waiting game for anything cold.

although starting above average looking likely to drop to dec averages.

 

could well become stormy and very wet.

 

high presuure to our south very slightly futher north eastern block retreating looking likely now the alantic is back.

Edited November 21, 2014 by emotional rollercoaster

[Snowy L]

Well, well, well!

We've finally got a global model showing something cool/colder for winter. Shame it is only the BCC but it has had flashes of correct insight before.

 

Jamstec is also going for a colder than average winter for the UK, the Ma-May one is especially cold, which suggests to me an SSW in late Decembe/early Jan and a lot of high lattitude blocking around throughout Feb, March and April. El Nino years usually do see a warm start to winter and a cold 2nd half, most likely because of the vortex being much weaker and disorganized in El Nino yeas.

 

http://www.jamstec.go.jp/frcgc/research/d1/iod/e/seasonal/outlook.html

Edited November 21, 2014 by Snowy L

[Barry12]

Day 7 is a million times better on the 12z, this block is never going to die!

 

 

GFS P 12z is also looking much better

 

 

Chalk and Cheese from the 06z really, Atlantic dominance is being pushed back further into FI!

Edited November 21, 2014 by Barry95

[swfc]

12z looks better regarding the jet pushing south at 162 hours and also notice the high pushing off the eastern seaboard.Diff so far thats for sure!!!

[MR EXTREMES]

massive difference in the later runs from the gfs the high to our east had moved far east but now is trying to ridge into eastern greenland.

and 192 still there

Edited November 21, 2014 by emotional rollercoaster