General Model Output Discussion

[cooling climate]

Excellent chart at t240 with what looks like a omega block has formed.

Big freeze part3 according to the ECM. we shall see.

[cold snap]

Im very pleased with GFS tonight.the easterly has pushed away JUST outside the country waiting to return ,It could at any time come back its really trying hard,look below

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

[Nick F]

The ecm is now showing good consistency in the pattern upto 168hrs. And this trend is now being picked up by the rest of the models. The huge block extends a ridge westwards by 168hrs and the Atlantic trough looks favourably aligned here, in most recent winters it has been the cold snaps interspersed with long milder interludes or just mild! could this be the winter of the blink and you'll miss them milder snaps! Still waiting for the rest of the ecm to come out but so far very encouraging. At 192hrs the cold is well and truly back, if the Atlantic trough disrupts at this point and sends a shortwave under the block then time to get the woolie hat and ear muffs out once again!

Yes, good news for cold lovers. Key is the Atlantic trough retrogressing to the NW Atlantic and amplifying big time by t+168 with splitting vortex forming across the NW Atlantic as upper trough disrupts and splits with the deep cold pool over N Greenland - this allows the ridge to retrogress out of NE Europe with easterlies developing. So perhaps just a brief respite to less cold before freezing weather returns from the east next week.

Also, look at that deep cold pool to north of Greenland moving SE towards N Scandi/NW Russia, could back SW eventually ... with deep cold later in the month?

Though of course, GFS may not support and ECM may back away from this idea. But the way the upper patterns have been behaving since the cold came in December, i wouldn't be surprised if ECM's easterly verifies.

Before then, perhaps snow for many on Wednesday, heaviest in the west and southwest but most seeing some flakes as the Atlantic front progresses north and northeast during Wednesday and first half of Thursday, see my latest blog:

http://forum.netweather.tv/topic/59644-new-year-cold-spell/page__st__17#entry1738646

[chionomaniac]

Just seen your post Nick. I was going to say the ECM t192 chart should certainly cause a stir.

T216 is fantastic, game on.

Blimey, that's totally at odds with the ECM's lower strat forecasts so I wasn't expecting that. Mind you the strat forecasts are yesterdays so I never get to see fresh info. I thought the easterly would make a reappearance - but so soon? Crucially the strengthening polar vortex is kept away from Greenland and long may it continue. The initial easterly air source would probably be cold not very cold but the longer that an easterly held the colder it would get especially with a NEasterly developing if we extrapolated to T+264.

[Snowyowl9]

This doesn`t surprise at all ECM has been showing for a number of days now,this winter is going to be a cold one.

http://www.wzkarten.de/pics/Recm2161.gif

[mcweather]

Just when people thought it might be safe to use the M word. ECM tells the Atlantic where to get off.

[Thundery wintry showers]

The easterly is out in FI, especially in view of the uncertainty for this coming week, but it's notable that the ECMWF is sticking to its guns and the GFS has moved towards that evolution- also the UKMO T+144 isn't inconsistent with it.

Milder air looks like winning out by next weekend, but for most, probably no more than average for mid January, and odds are shortening against it being temporary. I still think the "no-man's land" scenario is more likely than the easterly reload at this stage though.

Still limited ensemble support for the easterly on GEFS but some colder members are starting to appear:

http://charts.netweather.tv/ensimages/ens.20100111/12/t850Norfolk.png

[bluearmy]

Blimey, that's totally at odds with the ECM's lower strat forecasts so I wasn't expecting that. Mind you the strat forecasts are yesterdays so I never get to see fresh info. I thought the easterly would make a reappearance - but so soon? Crucially the strengthening polar vortex is kept away from Greenland and long may it continue. The initial easterly air source would probably be cold not very cold but the longer that an easterly held the colder it would get especially with a NEasterly developing if we extrapolated to T+264.

even the 'progressive' GEFS mean has our frigid air no further away than the dutch/german border, so a renewed easterly flow will bring that air back within a day. what interests me C, is that there remains a propensity for the blocking to surge into greenland as soon as we see a smidgeon of WAA into the area. surely, there must be something this winter that is encouraging this to happen. it is a repeating theme this season when in winters past, we could have days of WAA in that direction with the resultant two day toppler to be thankful for. we know that great winters of the past have seen repeated blocking over greenland. is there something going on in the trop around greenland which is encouraging this blocking to establish itself. its like a limpit this winter.

[TEITS]

At 216hrs it's almost there, if the energy cuts under the block here comes big freeze part 3! Of course there is along way to go and its a complicated set up. The crucial part of the run comes at 144hrs to 168hrs, so still too far out to be sure but at least the trend is there. The ecm ensembles should hold alot of interest this evening!

Indeed Nick and what impresses me is the consistency from the ECM.

The reason I was confident this morning is due to what i've been preaching these past few days. This is if you want to know whats likely to happen then check the archives rather than the models. We are seeing a similiar trend in the ECM that happened during the classic cold winters. This pattern is the atlantic making an attempt to move in before the blocking reintensifies. Many think the famous cold winters consisted of endless sub zero temps when inactual fact their were the odd occasions when a brief thaw arrived.

Speaking of a thaw but have the Met O made a typing error in their 6-15day forecast. Due to the synoptics I would suggest the SE is more likely to remain cold than the NE. Looking at the models and the phase between the Atlantic vs Scandi HP is likely to result in a flow off the continent. If this happens then obviously the SE is more likely to remain cold than the NE. We have seen this today with the temps as Newcastle/Aberdeen reached 4/5C whereas parts of E Anglia remained at 0/1C.

Going back to the ECM and obviously it would be silly of me to say another cold spell is definitely going to happen. However at this stage next week is more likely to be influenced from the E rather than the atlantic!

[phil nw.]

12zECM would soon renew a cold setup.

Every chance looking at the end of the run that the main part of the vortex would drop down to our NE as the upper block extends towards Greenland.

http://www.wetterzen...cs/Recm2401.gif

This evolution was being hinted at on 00z and indeed the ext. ens.showed colder members further on.

http://www.weerplaza.nl/15daagseverwachting/default_pluim.asp?r=midden

Tonights ecm ens. should be interesting.

Edited January 11, 2010 by phil n.warks.

[BLAST FROM THE PAST]

This 12ECM and the 12z GFS is the sort of evolution I have in mind as that is what my posts have tried to explain. The jet remains on its new preferred southerly track but interruptions occur within the solar and lunar disturbances. This less cold interlude is just a buckle with a drive south again from weekend. Watch the models really go for this as the wek progresses.

Now looking further ahead, the retrograde to Greenland is plausible and indeed the retrograde will almost be 'too effective' allowing LPs to breakthrough as it moves too far NW. Now this is where it gets very interesting, A renewed bitter cold pool will develpo to NE and we could se a very similar episode develop in early Feb a swe have just seen. IF this happens...and its a big IF for me at this stage although signals are strengthening towards that...then it is likely to be as cold BUT may, may be even longer lasting as I think Feb is likely to be a more locked in month than any other. That is just me voicing my thoughts currently re Feb.

Watch the model consensus swing towards cold for next weekend for another week [this week won't be mild either.

BFTP

[cooling climate]

even the 'progressive' GEFS mean has our frigid air no further away than the dutch/german border, so a renewed easterly flow will bring that air back within a day. what interests me C, is that there remains a propensity for the blocking to surge into greenland as soon as we see a smidgeon of WAA into the area. surely, there must be something this winter that is encouraging this to happen. it is a repeating theme this season when in winters past, we could have days of WAA in that direction with the resultant two day toppler to be thankful for. we know that great winters of the past have seen repeated blocking over greenland. is there something going on in the trop around greenland which is encouraging this blocking to establish itself. its like a limpit this winter.

I think its possibly due to higher pressure over northern Canada so far this winter (probably due to enhanced brewer dobson circulation during last year and more ozone in this area) which slides over Greenland any chance it gets.

Any block further east that starts to retrograde has a better chance of pushing heights up over Greenland. Thats the way I see it anyway oh plus we have a strong north Atlantic tripole which favours a - NAO this winter and a El Nino southerly tracking yet.

Edited January 11, 2010 by cooling climate

[kold weather]

What is quite interesting to see on the models is how we need the Atlantic at total full tilt to breakdown this set-up. Whenever that happens as soon as the jet weakens again or a slight shift in the PV will cause the whole lot to shift back westwards again. The upcoming spell reminds me of the very slow evolution we began in late Jan 91 towards that big easterly.

A breakdown of sorts looks certain but I'm still seeing signs of cut-off lows trying to develop and whnever you get that as long as the PV is either far enough north/west then your always likely to get a decent shot at high pressure building from Europe.

One well worth watching IMO, though I suspect the ECM is taking any possible evolution to its limit.

[chionomaniac]

even the 'progressive' GEFS mean has our frigid air no further away than the dutch/german border, so a renewed easterly flow will bring that air back within a day. what interests me C, is that there remains a propensity for the blocking to surge into greenland as soon as we see a smidgeon of WAA into the area. surely, there must be something this winter that is encouraging this to happen. it is a repeating theme this season when in winters past, we could have days of WAA in that direction with the resultant two day toppler to be thankful for. we know that great winters of the past have seen repeated blocking over greenland. is there something going on in the trop around greenland which is encouraging this blocking to establish itself. its like a limpit this winter.

The only thing going on around Greenland is the polar vortex's inability to stay there! Normally the PV will oscillate around a small pendulum swing - this year it's like there is a frog attached -it's hopping around everywhere! As is often the case with any season once the pattern is set it takes a lot to budge - we know that from previous winters to our detriment.

[sebastiaan1973]

Excellent developments by ECM

I have the temperatures for De Bilt based on the 12h run

12: -2/-3

13: +3/-5

14: +3/+2

15: +2/-1

16: +2/-1

17: +4/0

18: +3/+1

19: -1/-2

20: -2/-4

21: -4/-6

[loadsa]

You can tell its been a great winter so far and facinating model watching with uncertainty at every run. By the distinct lack of winters over comments.

Where are they?

Are the instgators snowed in somewhere?

it is concerning

[BLAST FROM THE PAST]

we know that great winters of the past have seen repeated blocking over greenland. is there something going on in the trop around greenland which is encouraging this blocking to establish itself. its like a limpit this winter.

Try a solar driven pattern? For me its no 'coincidence' that since the perturbation cycle change in Feb 07 the jetstream has tracked a lot more south. This El Nino is not forcing this jet pattern south, it was going to be south anyway. -ve NAO correlates well with this perturbation cycle.

BFTP

Edited January 11, 2010 by BLAST FROM THE PAST

[sebastiaan1973]

@ weather, these are not GFS 12 temperatures but already the temperatures of ECM 12h run

[ANYWEATHER]

With a ginormous block to our East both gfs and ecm show one thing that can happen... :lol: :lol:

[nick sussex]

Latest comments from NOAA are positive for the pattern shown by the ECM and GFS.

SYSTEMS MOVING THROUGH THE MAIN BELT OF THE WESTERLIES WILL BE

PROGRESSIVE AS THE POLAR VORTEX MOVES FROM FAR NORTHERN CANADA

TOWARDS THE NORTH POLE..

IN KEEPING WITH THE SPIRIT

OF WHAT IS EVOLVING INTO A MORE TYPICAL FLOW PATTERN DURING EL

NINO CLIMATE REGIMES...WILL FAVOR THE GUIDANCE THAT MAINTAINS

SEPARATION BETWEEN THE NORTHERN AND SOUTHERN STREAMS WITH A

PREFERENCE TOWARDS STRONGER SOUTHERN STREAM SYSTEMS...

WHICH FAVORS

THE 00Z CANADIAN/00Z ECMWF/00Z ECMWF ENSEMBLE MEAN/00Z GEFS

MEAN/12Z GFS. THE PRESSURES USED A SIMPLE BLEND OF THE 00Z

CANADIAN AND 00Z ECMWF THROUGH THE PERIOD...WHICH MAINTAINED

REASONABLE CONTINUITY.

As one door shuts another one opens with the prospect that we could have the Holy Grail of a portion of the PV dropping into Scandi and this cold being advected westwards later. Anyway don't won't to oversell this as there are numerous hurdles to overcome before then.

[Frosty.]

The easterly is out in FI, especially in view of the uncertainty for this coming week, but it's notable that the ECMWF is sticking to its guns and the GFS has moved towards that evolution- also the UKMO T+144 isn't inconsistent with it.

Milder air looks like winning out by next weekend, but for most, probably no more than average for mid January, and odds are shortening against it being temporary. I still think the "no-man's land" scenario is more likely than the easterly reload at this stage though.

Still limited ensemble support for the easterly on GEFS but some colder members are starting to appear:

http://charts.netweather.tv/ensimages/ens.20100111/12/t850Norfolk.png

I agree, we could end up with neither mild or cold and be stuck in the middle looking longingly east although it is good to see the gfs and ecm both showing an E'ly again next week, way too far out to get excited about though and we still have this milder interval for next weekend with rain and strong winds which will melt a lot of the existing slushy snow cover.

[tinybill]

evening all being looking at all the models deep into fantasy land i don't think they know themselves ,just looking at the gfs its saying the mild weather going to win the battle even looking here

http://www.meteociel.com/modeles/gfs/precipitations/48h.htm there no sigh of the cold weather

there no sign of any snow coming our way, then you watch BBC weather this evening on there they saying the band going to fizzle out

but on the gfs maps they saying the battle Field further north!!!

[chionomaniac]

Look at the position of the PV at T+240 as modeled by the ECM:

Not really a split vortex - but a very displaced one and totally in line with what is occurring above it.

[BLAST FROM THE PAST]

Latest comments from NOAA are positive for the pattern shown by the ECM and GFS.

As one door shuts another one opens with the prospect that we could have the Holy Grail of a portion of the PV dropping into Scandi and this cold being advected westwards later. Anyway don't won't to oversell this as there are numerous hurdles to overcome before then.

Nick

I think the hurdles will have to be cleared through to end of Jan...BUT there are signs that

a] this pattern doesn't want to shift

b] When it does it will want to repositon, regroup and come back.

Its what used to happen in the 60s and 70s...what is apparent.. and for me is the ovewrriding factor/influence is the southerly tracking jet. With that in place retrograde and northern blocking is almost 'encouraged'....actually like am right now with todays output.

BFTP

Edited January 11, 2010 by BLAST FROM THE PAST

[The PIT]

Deep FI in ECM has the High back and well in control.