Model Output Discussion - 1st - 7th January

[phil nw.]

The overall picture shows little change for the next 10days at least.

High pressure moving in and remaining close to the south for the reliable timeframe.

Mainly dry and raather mild for much of next week,perhaps a little more cloud and light rain for the far north and west at times in the westerly breeze up there.

Going into week two it`s still looks like a zonal picture but the ECM shows the jet further south bringing some colder conditons whereas the GFS continues to favour High pressure closer to the south and a flatter pattern-however the GFS Operational shows up very much as a mild run at this timeframe on the GEFs ENs.Graph.

For comparison at T240hrs.

ECM GFS

The GFS Ens.

Finally a look at the latest NAO med.term ht.anomal.500hPa pattern.

Nothing in the way of deep cold on the horizon yet then,as far as current modelling shows but a trend towards a somewhat colder regime in week 2 seems likely with the High pressure easing more north west into the Atlantic and the troughing extending south east into europe.This would favour the flow turning more north west and introducing colder polar air into the mix.

[Tom Montalbano]

I've seen these charts posted before but could someone explain what these are showing and specifically from the 00z ECM what do they mean for the UK.

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=2

Thanks.

Regards,

Tom

[nick sussex]

I've seen these charts posted before but could someone explain what these are showing and specifically from the 00z ECM what do they mean for the UK.

http://www.meteociel...=1&map=0&type=2

Thanks.

Regards,

Tom

Its basically the dispersion or spread from the mean value, in this instance how the ensembles bunch around the mean value. Or not as the case maybe, the brighter the colours the more dispersion from the mean value.

This translation seems ok. Thats in relation to the GFS spread but means the same for the ECM ensembles.

Ecart-Type/Spread cards are used to assess the confidence of all GEFS for a given period, and a parameter (or 850hPa temp GEOPA z500). Less value is important (to purple), more confidence is important. The value represents the dispersion of the 15 scenarios for this parameter

[bluearmy]

More confusion. The ECM op brings the trough closer to us (remember the spreads I posted last night?) . However its shallower and has no proper cold uppers in there as no decent low uppers have penetrated into the circulation. Maybe this is why we have seen few really cold options showing on the london ens. More importantly, the upstream flow is much flatter than yesterday's 12z showed. What is more significant for me is the gfs in high res. Forget the dross post t192. However, the desire of the ncep modelling to retain high heights close to the south of the uk pre T192 is a major concern for those wanting to see cold before the 20th.

Let's see if its a one run job or if high res continues to prog the mid lat high and keeps the euro trough further east.

Btw, the gem at day 10 isn't a bad tool and has, on occasion, flagged up a pattern that the others have subsequently latched onto.

[mcweather]

More confusion. The ECM op brings the trough closer to us (remember the spreads I posted last night?) . However its shallower and has no proper cold uppers in there as no decent low uppers have penetrated into the circulation. Maybe this is why we have seen few really cold options showing on the london ens. More importantly, the upstream flow is much flatter than yesterday's 12z showed. What is more significant for me is the gfs in high res. Forget the dross post t192. However, the desire of the ncep modelling to retain high heights close to the south of the uk pre T192 is a major concern for those wanting to see cold before the 20th.

Let's see if its a one run job or if high res continues to prog the mid lat high and keeps the euro trough further east.

Btw, the gem at day 10 isn't a bad tool and has, on occasion, flagged up a pattern that the others have subsequently latched onto.

Your last comment about the GEM is very true blue army especially in relation to cold scenarios . It has occassionally been a trend setter. IIRC it was one of the first to pick up the drop into the cold abyss at 240 last november. The evolution it shows is as likely as any of the others on offer at the moment.

The sucking of the euro high north then east into a scandi has been seen on occassion before and is not that unusual a development.

Edited January 7, 2012 by mcweather

[snowingman]

... Everyone can put as much spin on this as possible - but the 00GFS is a shocker if you are looking for cold or snow, the "worst" winter for snow potential on record continues, I have never seen charts which offer NOTHING right out for 2 weeks..

[TEITS]

As others have said the GEM is the pick of the bunch this morning and in my opinion perfectly possible hence why I said a few days ago my beast from the east sig may return, What also struck me this morning is the dip in the ensembles around the 15th with quiet a few members dropping below -5C.

http://hw.nwstatic.co.uk/ensimages/ens.20120107/00/t850Cambridgeshire.png

Having said all of this I do feel as though the model output is farcical at the moment. Last night I read the Accu weather blogs for the USA and their outlooks for the rest of Jan were completely opposite from each other. One of the forecasters said this though.

"The model has clearly made some changes to its forecast since last week, but I am still far from sold with what it is showing for the pattern through the end of the month right now. There are a lot of changes going on in the stratosphere right now and it may take another week before several of these models have a good handle on what is actually going to happen over the next few weeks."

http://www.accuweather.com/en/weather-blogs/anderson/long-range-computer-model-forecast-update-1/59941

[Cecil Hogmanay Melchett]

And so the mind numbing +NAO signal continues.

ECM/GFS/UKMO all flat as a pancake with nothing of interest for cold lovers.

Starting to look like Jan is going to be a dogs dinner for cold lovers.

Events in the stratosphere may well provide hope for Feb,and im happy to clutch at any straw after weeks and weeks of wind and rain but i'd be far from suprised if the time lag assosiated with SSW's provides us with a cold wet Spring.

[SP1986]

I'm not so willing to accept the GEM's hypothesis, whether or not it is an improved model, it still has a lot to prove.

As far as I'm concerned the models are a mess in terms of any agreement (intra-model) on what will happen in the later stages, although there is good agreement for the near term, which is encouraging at least.

Like has been said above, it will be maybe a week before we have any idea.

The 6z should, nevertheless, be fairly interesting.

[nick sussex]

... Everyone can put as much spin on this as possible - but the 00GFS is a shocker if you are looking for cold or snow, the "worst" winter for snow potential on record continues, I have never seen charts which offer NOTHING right out for 2 weeks..

So you don't like its output very much today then!!!

Yes apparently all the rest of the models have ceased to operate, and the GFS is now the global king of all it surveys, all hail Emperor GFS!

It's the model discussion thread not the lets all obsess over just the GFS operational output. Theres a reason that the models keep chopping and changing, just wait for things to calm down and then lets see what they show then.

[suxer]

Where can i view the GEM ? Thanks in advance.

[Liam J]

Where can i view the GEM ? Thanks in advance.

Here you go

http://www.meteociel.fr/modeles/geme_cartes.php

[wolvesfan]

Morning all,

Most fellow posters now agreeing a change is on it's way,the models flip flopping at the moment indicative of this.we should start to see some good synoptics being modeled shortly as the mods get a better handle of the good background signals that are developing,especially the continuing warming to the stratosphere.

[UV-RAY]

I mentioned yesterday how it may take until midweek before we start to see some model consistency regarding a pattern change. Reading the latest in the Strat thread, may help those who are puzzled by some posts on here.

[Frosty.]

What on earth has happened to the gfs (00z) overnight? I have never seen such an anticyclonic run before, it somehow manages to keep high pressure in control for the next 384 hours! firstly by pushing high pressure northwards into the uk, then sending for reinforcements with the azores high coming to the rescue when the first high is about to leave, the 2 highs then merge to form a super high which then sets up home over the whole of the uk until late january. The Ecm 00z eventually becomes unsettled after next week but no -5 T850's on the entire ecm run out to T+240 hours, at least the gfs 00z would bring some fog and frost but the ecm would just bring a return to average zonal weather from next weekend, I hope the models show something more wintry soon.

Edited January 7, 2012 by Frosty039

[ICETAB]

Subtle improvments showing on the 06z GFS. It should develop into something more interesting down the line. High pressure looks a little more robust further north

It would be nice to see the GFS start to back the GEM.

Is the GEM a German model?

Edited January 7, 2012 by ICETAB

[shedhead]

What on earth has happened to the gfs (00z) overnight? I have never seen such an anticyclonic run before, it somehow manages to keep high pressure in control for the next 384 hours! firstly by pushing high pressure northwards into the uk, then sending for reinforcements with the azores high coming to the rescue when the first high is about to leave, the 2 highs then merge to form a super high which then sets up home over the whole of the uk until late january. The Ecm 00z eventually becomes unsettled after next week but no -5 T850's on the entire ecm run out to T+240 hours, at least the gfs 00z would bring some fog and frost but the ecm would just bring a return to average zonal weather from next weekend, I hope the models show something more wintry soon.

i'd be surprised if the 06 keeps such anticyclonic conditions in place throughout the run, indeed I think we'll be back to colder (all relative of course) zonality by this time next week.

Edited January 7, 2012 by shedhead

[SP1986]

In the near terms I think I've spotted the reason why the PV is staying strong in the forecast, and it might be down to the Azores High. As far as the 'Atmsopheric Mechanics' go, the High pressure stalls over the UK, allowing the low pressures to developing over Canada and they keep on moving eastwards, but because the high pressure is stagnant they pile up on it, giving more time for the PV to strengthen again. I suspect if the Euro High moved eastwards quicker, then there would be a much better chance for the Greenland High to set up in a nearer timeframe.

Interesting high developing over Svalbard on the 6z run, not sure it'll do much, but there's an outside chance it'll result in a northeasterly into the lower resolution part of the run.

[SMU]

The GEM is the canadianModel-

Here we are at 174 with the GFS having massive changes to the NE- a lot closer to the GEM FWIW

http://176.31.229.22...706-0-174.png?6

S

http://176.31.229.22...706-1-186.png?6

Cold building to the NE at 186

s

Even though I hate the 06z I will take that run- We need more like that we the atlantic conveyor getting shunted -

That low sliding into Europe with Pressure rising towards Svalbard is the route to true cold other than a GH- & well worth noting that its appeared this morning-

Interest remains in the 12z's- other than that a pleasent mildish week-

S

Edited January 7, 2012 by Steve Murr

[TEITS]

Sorry but I can't resist.

http://www.wetterzentrale.de/archive/ra/1987/Rrea00119870109.gif

http://www.wetterzentrale.de/pics/Rtavn1921.png

Fair enough the 06Z doesn't come off but based on my experiences of how the models handle these situations I wouldn't rule out an E,ly. Have to say the difference between the 0Z/06Z is comical.

[SP1986]

It won't occur in reality, but look at the angle the colder air is coming from around western Greenland at around 240 hours, pretty impressive to see, regardless or not of whether it would effect the UK. It's an interesting FI, synoptically!

[The PIT]

No sign of Armageddon cold in either the GFS or the ECM this morning although a hint of a return to mobile Atlantic and storms once again with returning pm air. The quieter spell of weather starting now but the weather here hasn't read the script so far.

[shedhead]

As expected a very different looking FI on the 06GFS, but one that is much more in line with what is likely to happen from mid month onwards imo, i.e increasingly cold zonality and then eventually a pressure rise over Greenland.

[SMU]

Sorry but I can't resist.

http://www.wetterzen...00119870109.gif

http://www.wetterzen...s/Rtavn1921.png

Fair enough the 06Z doesn't come off but based on my experiences of how the models handle these situations I wouldn't rule out an E,ly. Have to say the difference between the 0Z/06Z is comical.

TEITS pulling out the big guns-

lol-

2 things to look for at the 12's- T 120 the low in the atlantic being slower & further NW - compare 120 V 126 06z V 120 12z

& more of a wedge of high pressure between the 2 systems at 168-

To get an Easterly you are actually going to need that low ( the firsty one at 130) to head to greenland then stall as the jet piles south & pressure builds to the NE, the 06z has the next wave off the states rushing through before any pressure to the NE can take a hold- but its a start!

S

[kev238]

Well, I think there are definite signs of a change in pattern, but whether it will produce cold for the uk is another matter. We could end up with cold zonal weather like at the start of December.

However, if the cold doesn't arrive we could end up with a very westerly and mild January. Incidentally on accuweather they were saying snow cover in the states is the lowest since 2007, which is an interesting point, when that was also a pretty mild winter in this neck of the woods.