Model Output Discussion; into 2015

[Mucka]

Hi

 

I don't have access to the ECM extended ensembles, clusters or otherwise. I would therefore be guessing at why the mean 2m temps slowly falls by a couple of degrees from D10-15 for London. That type of expert analysis I leave for IF, Knocker, BA and others, who have more info. However I assume the clustering shows that there is a fall off in a zonal flow within the latter part of those extended 5 days, that is if the GEFS are anything to go by. I was in fact referring to several posts that suggested the next 10 days had trended colder than average, when neither the GFS or ECM ops suggest's that.

 

GFS 06z London 2m temps: Meteociel_-_Diagrammes_GEFS_pour_Londres 4.png

 

 

Hi

I am not talking about the ensemble clusters within the ECM suite, I don't have access to them,  I am talking about the clustering of colder solutions later in the run.

The point being that if we are to analyse ensembles in this format and commenting on them it makes sense to comment on the most striking feature as well as the more mundane aspect.

 

You analysis of not rending colder than average over the next 10 days is okay and I accept the context in which it was written is reasonable but it is somewhat seeing the output from narrow perspective in that ignores trends IMO. 

It will be essentially zonal over that period and temps will come in around or perhaps little above average but there is the possibility some Northern parts will see some snow as early as next week (toward end) and that risk looks likely to increase into the weekend and then again into the following week.

This is the current trend as low pressure tracks further South with time and the Azores high is slowly displaced.

 

Granted ECM Op is slightly more resistant to colder shots in the zonal flow digging further South but it still produces this for next weekend.

 

 

What I am trying to say is that limiting ourselves to a mean average picture for the next 10 days doesn't accurately portray the trend for colder weather to become more prominent from later next week.

All of this is subject to change but that is currently what the ensembles and output suggest IMO.

 

That is not tot say I believe a full pattern change to a more blocked regime is imminent. I arbitrarily rated that at only 20% for around mid month this morning. But there is a clear signal for a colder zonal regime to take over and after a stormy period for the zonal flow to relax somewhat allowing a window of opportunity for blocking to form.

 

This turned into a much longer post than I imagined and I don't have a problem with your overall analysis, all I wanted to say is that we should not ignore trends within the output and look at the outlook as a static picture, ie average for next 10 days.

 

Anyway, forgetting about trends for a moment there is the possibility of all kinds of weather shenanigans later next week with snow possibilities for the North being the least of them.

[Chris K]

Patience...it's coming.

 

 

I'm not falling for that again

[Tamara]

I wouldn't rule out winter 2015/16, but I am talking about this winter, this month. Patience grasshopper..it's coming. 

In the light of 'conversations' of yours on going today elsewhere, its a pity you aren't being serious Barry, and have more to do with previous MOD thread discussions

 

This winter, so far, has featured one short, punctuated pattern change just after Christmas. It was transitory, but nevertheless it was a pattern change. It featured retrogression of the entrenched Pacific pattern, which in turn pulled the downstream mid latitude ridging (Azores High) north-westwards and led to the short wintry phase with snow for at least some parts of the UK , even though many missed out in that respect.

 

This pattern was spotted from a couple of weeks or so back around mid December and verified accordingly. It did not meet expectations suggested at the time in the sense that stratospheric developments did not progress bullishly in the way anticipated then and prevented a more sustainably high latitude blocking pattern - but, thus far this winter, it represents the one (albeit modest) boulder that has landed in the fast flowing westerly current and held it up for a few days at least...

 

Looking ahead, as previously posted ( and working on an reasoned anticipatory basis of a rinse and repeat sequence) my suspicions at present point to a re-run of the same amplified evolution,  perhaps around mid January, as we saw in late December

 

The better looking distant charts we are starting to see, look to be carbon copy of the Atlantic amplification charts we saw from mid December as a result of exactly the same cyclical -AAM pattern that established itself during December.

 

The final result that verified however, was a much tamer version than the distant FI charts - and even some of the day 7/8 charts which featured over amplification of the pattern. We get used to seeing these however these days more generally.

 

I wont 'go there' though in terms of risking any renewed model supremacy verification battle 

 

Already numbers of FI chart perturbations are once again suggesting tanking -AO cross polar ridging at post mid month distance, and alluringly point to more than a transitory amplified ridge developing from them. With a significant turn of developments, this might indeed be conceivable - but unless we see a stratospheric rabbit produced out of a hat, and get a better tropical convective progression signal across the Pacific than seen in December, it is best to view these (should they verify) as evolving in a similar way to December and not get too carried away.

 

Even if it is totally understandable to want to look out for something infinitely better than tram-line zonality.

 

Changing wave lengths will be increasingly on our side as we head further and further through January and closer to February - and the likelihood of the vortex succumbing finally increases more and more with time. With this in mind also, on the working assumption that the prevailing -AAM pattern will continue *see below*  there should be rather better chance of attempted connection of Atlantic ridging to heights from the NE than seen at the end of December.

 

*(We should bear in mind that -AAM patterns can lock in existing seasonal patterns and tend to be obdurate and change only with seasonal wave lengths)*

 

So ( assuming the Atlantic signal evolves and grows accordingly) it is conceivable that we might see something better come the post mid month period than a Euro High next time around to follow any Atlantic ridge - but make no bones, that Azores High and +NAO is a stubborn beast under this regime and we need tougher medicine to arrive than we have seen thus far

Edited January 3, 2015 by Tamara תָּמָר

[Mucka]

Good to see this afternoons output making less of the possible storm at day 6 either developing it less and/or having it track further North.

 

[Captain Shortwave]

Day 6 charts

UKMO

 

GFS

 

Parallel

 

So the UKMO still wants this low to hit Scotland and Northern England/Ireland. The GFS misses the UK completely and the parallel is in between bringing strong winds to the Hebrides and Shetland/Orkney Isles. Mild too with temperatures hitting 14C in the north east and double figures widely. Before then, the coming 5 or so days are fairly quiet though still changeable.

Dubious about the intensity of that PM shot at day 8 (widespread 850s of -6C look a little over the top).

Edited January 3, 2015 by Captain shortwave

[knocker]

The GFS (P) still running the low north of the UK (just)  and one hopes it stays that way

http://weather.graphics/gsm/ygfs_t1534_global.php#

Edited January 3, 2015 by knocker

[TonyH]

I wouldn't rule out winter 2015/16, but I am talking about this winter, this month. Patience grasshopper..it's coming. 

You have been saying that for months Barry

[Eugene]

Day 6 charts

UKMO

 

GFS

 

Parallel

 

So the UKMO still wants this low to hit Scotland and Northern England/Ireland. The GFS misses the UK completely and the parallel is in between bringing strong winds to the Hebrides and Shetland/Orkney Isles. Mild too with temperatures hitting 14C in the north east and double figures widely. Before then, the coming 5 or so days are fairly quiet though still changeable.

 

 

Mild sector looks very transient on friday before much cooler air on Saturday on GFS 12Z OP, don't overexaggerate the coming weeks mildness, you also forgot to mention the warm sector bringing a spell of heavy rain friday.

[Banbury]

Mild sector looks very transient on friday before much cooler air on Saturday on GFS 12Z OP, don't overexaggerate the coming weeks mildness, you also forgot to mention the warm sector bringing a spell of heavy rain friday.

very much so, 12z makes it colder quicker

[snowangel32]

Why is it when mild is showing in Fi people presume its a done deal and winter is over. But when it shows colder conditions its presumed it wont happen when both have an equal chance. I know we have all been led up the garden path many times but one time our luck has to change. Love your enthusiasm frosty never change mate.

[Gustywind]

Mild sector looks very transient on friday before much cooler air on Saturday on GFS 12Z OP, don't overexaggerate the coming weeks mildness, you also forgot to mention the warm sector bringing a spell of heavy rain friday.

And with the strength of the wind it won't feel mild even if it does hit double figures.

[Woollymummy]

Didn't something like this happen last year (big cold snap in Eastern USA, heating up of West Coast USA including Alaska), and then we got loads of storms?

Edited January 3, 2015 by Woollymummy

[TonyH]

Why is it when mild is showing in Fi people presume its a done deal and winter is over. But when it shows colder conditions its presumed it wont happen when both have an equal chance. I know we have all been led up the garden path many times but one time our luck has to change. Love your enthusiasm frosty never change mate.

Because it has a much less than equal chance of being cold as we predominantly get mild SW winds during Winter in the UK.

It would be foolhardy to write off any cold snowy episode though until at least April

Edited January 3, 2015 by TonyH

[mountain shadow]

Mid month cold snap showing again on the GFS old..

http://max.nwstatic.co.uk/gfsimages/gfs.20150103/12/312/h850t850eu.png

If we're lucky we might squeeze a 3 day colder spell before the zonal pattern returns.

[chrisbell-nottheweatherman]

Didn't something like this happen last year (big cold snap in Eastern USA, heating up of West Coast USA including Alaska), and then we got loads of storms?

Indeed - this pattern is, AFAIK, fairly similar.  Apologies to Mods for one-liner - as things are quieter here now, I thought a response to the question would be OK.

Edited January 3, 2015 by chrisbell-nottheforecaster

[Banbury]

Mid month cold snap showing again on the GFS old..

http://max.nwstatic.co.uk/gfsimages/gfs.20150103/12/312/h850t850eu.png

If we're lucky we might squeeze a 3 day colder spell before the zonal pattern returns.

Why do you say this? that is an odd comment

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015010312/gfsnh-0-384.png?12

 

The 384 chart is the last one we see and it doesn't show Zonal returning?????

[Polar Maritime]

Again GFSP shows some pretty cool/cold Pm shots from the N/W around the 10th, With a Meridional Jet driving the flow.. Pulling snow showers over the majority of the UK with -4/-5 850's. Further into the run the Arctic High seems a little stronger, With Heights also pushing up into Greenland blocking the Atlantic and drawing a Northerly of types again, Similar to this mornings run, A good trend to see.

 

Edited January 3, 2015 by Polar Maritime

[bluearmy]

Didn't something like this happen last year (big cold snap in Eastern USA, heating up of West Coast USA including Alaska), and then we got loads of storms?

Different reasons upstream - this time last year was the vortex dropping way south into ne states. Now it's a big high pushing the cold south. The jet stream wavelength is also much shorter providing the mild/cold variation we currently gave.

[Snowman.]

Mid month cold snap showing again on the GFS old..

http://max.nwstatic.co.uk/gfsimages/gfs.20150103/12/312/h850t850eu.png

If we're lucky we might squeeze a 3 day colder spell before the zonal pattern returns.

 

You're already talking about the end of a potential cold snap that rests 13 days away!

 

I think the first on the list is to get it here first!

[mountain shadow]

Why do you say this? that is an odd comment

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015010312/gfsnh-0-384.png?12

 

The 384 chart is the last one we see and it doesn't show Zonal returning?????

Jet is running over the top of the high pressure, the next low pressure exiting the US will flatten the ridge and sink the high back to the Azores. The PV will likely be strengthening again by this time as the PV moves back to the pole and reinforces the Westerly regime..

http://max.nwstatic.co.uk/gfsimages/gfs.20150103/12/384/npst30.png

Unless, there are some major strat or trop changed soon then this potential colder spell mid month might be our last shot, still loads of time for changes though.

[Snowman.]

An almost true Greenland high.

 

[mountain shadow]

You're already talking about the end of a potential cold snap that rests 13 days away!

 

I think the first on the list is to get it here first!

Absolutely, everything in FI is completely hypothetical.

An almost true Greenland high.

 

Chart of the season, will we get there though!! Pray to the snow Gods.

[bluearmy]

Two parallels which have ended with a greeny high which looks likely to be cut off. Good trends. Much prefer the para to show this in its low res than the normal gfs.

onwards and upwards onto the ens.

[Mark Bayley]

GFS continues to a hint at the PV relenting somewhat as we progress past mid-month. A light at the end of the tunnel? A possibility of the MJO reaching phase 7 supports a mid-Atlantic ridge as indicated by the OP and P. The GFSp ends very nicely.. 

[Banbury]

Jet is running over the top of the high pressure, the next low pressure exiting the US will flatten the ridge and sink the high back to the Azores. The PV will likely be strengthening again by this time as the PV moves back to the pole and reinforces the Westerly regime..

http://max.nwstatic.co.uk/gfsimages/gfs.20150103/12/384/npst30.png

Unless, there are some major strat or trop changed soon then this potential colder spell mid month might be our last shot, still loads of time for changes though.

All hypothetical as that isn't being shown to be happening