Model Output Discussion - 31/10/2014 and Beyond

[legritter]

Can someone tell me please, is the PV in general always "the enemy"? Like, would it be better if just never was there all winter (for cold and snow). Or do we need it to form but in the right places, or form and burst? how exactly does it work. Because im not sure if I want to be looking for no signs of PV or a ruined one, or do we need those dark purples but just not over greenland etc?

First off there are many members of Net weather who can and will i,m sure answer your question .as you quote it depends where the P vortex forms and hangs out just like a drinker down his local favourite pub .But probably not where it hung out last winter or even closer to us to our north north west .the further away from us probably the better to allow high pressure in our location south of the pole ,in general terms high to our north low to our south ,but there are so many possible synoptic situations that can set up including a strong PV and other alignments you could probably fill a book .model watching very interesting at the moment and charts show some action weather on its way to our shores .i,m realy looking forward  to the winter discussions ,my prams full up with toys ,prozack being picked up tomorrow ,two boxes of straws on order ,Lamp post or floodlights at the ready .just read some old Met magazines on winters past ,bring it on ,STellas all round cheers .

[stodge]

Just a quick look at the 06Z GFS output (and it's really good to have the Parallel as another point of reference). Looking into FI and I thought I'd look at the Hemisphere overview at T+240:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014110406/gfsnh-0-240.png?6?6

 

The main Op run shows the blocked pattern transitioning to something more mobile and perhaps a sign of a second PV lobe setting up over NE Canada

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014110406/gfsnh-0-336.png?6

 

Four days later and it's not got very far with the main lobe over Siberia and strong heights over the Pole.

 

http://modeles.meteociel.fr/modeles/gfsp/run/gfsnh-0-240.png?6

 

The Parallel at T+240 showing good WAA into Greenland with the main PV lobe perhaps further west though that's not easy to tell.

 

http://modeles.meteociel.fr/modeles/gfsp/runs/2014110406/gfsnh-0-336.png?6

 

At T+336 and is that PV starting to get its act together and could it end up closer to Europe than Siberia ? It's a blocked scenario as the PV in Russia has created large blocking HP to the east over Siberia and to the west over Scandinavia.

 

As others have said, I would not look to the east for my cold this side of Christmas - the North Sea remains warm and will do so into the New Year. Looking North is a different matter if you want precipitation but the other option for cold (as distinct from snow) is our old friend the inversion. I wonder if the atmospheric environment this winter is going to be more conducive to anticyclonic conditions - the Parallel hints at the possibility with a weak or fragmented PV and good polar heights.

 

What worries me about the Parallel is the strat temperature modelling which suggests a warming to the Siberian side and the colder temperatures migrating west. Oddly enough, the OP does the same - the strength and anomalous cold of the stratosphere and the PV dominated last winter of course.

[nick sussex]

Can someone tell me please, is the PV in general always "the enemy"? Like, would it be better if just never was there all winter (for cold and snow). Or do we need it to form but in the right places, or form and burst? how exactly does it work. Because im not sure if I want to be looking for no signs of PV or a ruined one, or do we need those dark purples but just not over greenland etc?

The PV is not a problem by itself but often we end up with it stuck to the north which means cold is impossible with that scenario. Generally you'd want to be looking at it split up as this gives the best opportunities for cold into the UK.

 

The PV can aid cold spells into the UK, we have seen this in the past where a chunk drops south into Russia and that cold is fed west into western Europe. Last winters dismal attempt at cold was primarily caused by the main PV setting up in eastern Canada which just sends a lot of cold air piling into the Atlantic, this fuelled the jet and because we had no decent blocking to the north or nw this just sent low after low into the UK.

 

Theres somewhat of a perception that cold in the eastern USA is bad news for the UK however this isn't always the case, the problem isn't so much cold there but if theres any blocking to the north to deflect those associated lows further south.

 

So far this autumn we have seen a reluctance to form one large PV over Greenland and whilst that background pattern remains you'll at least have some decent foundations for cold.

Edited November 4, 2014 by nick sussex

[johnholmes]

 

 

As others have said, I would not look to the east for my cold this side of Christmas - the North Sea remains warm and will do so into the New Year. Looking North is a different matter if you want precipitation but the other option for cold (as distinct from snow) is our old friend the inversion. I wonder if the atmospheric environment this winter is going to be more conducive to anticyclonic conditions - the Parallel hints at the possibility with a weak or fragmented PV and good polar heights.

 

 

 

what about Nov-Dec 2010 that was not from the north but off the N Sea to give this very low lying area its heaviest known snowfall, 35 cm overnight 30/11-01/12

[summer blizzard]

Models have taken another long term step forward in my opinion..

 

Firstly we have the Euro which undercuts all the way to Italy. By doing so it's still dragging in warm air but it's opening the door for the Greenland ridge to push down cold air without being stopped by that high..

 

 

GFS in the high res brings heights over Greenland to 1050mb (stronger than previously forecast) but still looks potentially very wet with the stalled trough.

 

[Summer Sun]

Something colder maybe developing during the last 7 to 10 days if the ens is onto something

 

Edited November 4, 2014 by Summer Sun

[Purga]

Average looking ENS 850 temp plots which are a bit (rather than a lot) above average so more 'seasonal' with a trend downwards to 'average' towards the end.

 

Nice to see some more cold runs appearing at the end as well.

 

PS: Apologies SS you beat me to it!

Edited November 4, 2014 by Purga

[mushymanrob]

It can give the correct wave length across the northern hemisphere to put the UK on to the cold side of a ridge downwind from N America, but it does not always work, the wavelength is critical.

The current output from the anomaly charts shows the pattern I refer to, nearly but not quite for a deep cold incursion if it was mid winter

the EC-GFS version below with NOAA 6-10 and 8-14 along very similar lines. Thus showing the other idea of slow moving wave patterns. This one looks to last 5-10 days possibly longer.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

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

 

 

I suspect rob, that if some of those who have predicted a cold n American winter are right, that we could well be worrying about west based -NAO's quite a bit. howevwr, seeing as its early November and not February, I'm just going to enjoy the ride as Im sure there will plenty more opportunities ahead.

 

 

I believe positioning is critical. Ive seen ridges and blocks where a couple of hundred miles east and west of the ridge you've got +10's and the -10's. 

 

 

cheers guys.

[Yarmy]

The majority of the UK sees below normal 2m temperatures over the next 8 days

 

8 day anomaly

 

 

Normal 2m temps

 

 

Expected 2m temps

 

 

 

 

Quite a difference for the British Isles from the 00Z mean Knocker posted this morning:

 

 

Edit:  Didn't read the legend, doh. Thanks, all.

Edited November 4, 2014 by Yarmy

[Gael_Force]

Two different timescales, Yarmy - cool anomaly is for now to the 12th and Knocker's chart is for the 5 day mean for 12th to the 17th.

 

PS. The new tabular graphics for ECM De Bilt - is the width of the coloured bar the percentage of likelihood of a temperature - I'm a bit lost, sorry.

 

Edited November 4, 2014 by Gael_Force

[IDO]

Quite a difference for the British Isles from the 00Z mean Knocker posted this morning:

 

 

Hi. The above anomaly is for later in the month (12-17th) and the Summer Sun anomaly(4-12th) is more of a reflection on the next 48-60 hours where we have some cold nights and below average days. I think from  Thursday temps trending near average, or above. Many of the pro forecasters suggest November around 2-3c above average for the E/S/SE. 

 

The GFS op from the 06z is not a cool run: 

[SMU]

Updated NOAA ens now trended down to -4 & the zonal wind across 75n especially from alaska to moscow will drop through the floor to negative -

If someone could post the link:

Interesting the latest gfs anomaly shows below ave surface temps the UK

Interesting as I was saying that a few days ago ....

Still looking very interesting in the 9-12 day timeframe....

S

[Swave Snow]

Updated NOAA ens now trended down to -4 & the zonal wind across 75n especially from alaska to moscow will drop through the floor to negative -

If someone could post the link:

Interesting the latest gfs anomaly shows below ave surface temps the UK

Interesting as I was saying that a few days ago ....

Still looking very interesting in the 9-12 day timeframe....

S

 

I believe you Steve

[Tim Bland]

12Z GFS is rather underwelming.... Hence the lack of posts I suspect.   Some WAA going up to greenland but there is never enough blocking to stop the westerly flow. Slowly slowly catchy monkey though folks.  I would rather save the true Greenland block for December when it will count!

[Barry12]

GFS P and GFS are very different at just day 6

 

 

I'd discount the GFS 12z, UKMO 12z looks more like the GFS P

 

Edited November 4, 2014 by Barry95

[SE Blizzards]

Todays GEM 12Z

 

Day 10 chart..

 

 

Greenland - 1065MB

Edited November 4, 2014 by SE Blizzards

[Barry12]

Todays GEM 12Z

 

 

Greenland - 1065MB

 

If the ECM 12z is anything like that tonight, expect a melt down!

 

[garbagebags]

12Z GFS is rather underwelming.... Hence the lack of posts I suspect.   Some WAA going up to greenland but there is never enough blocking to stop the westerly flow. Slowly slowly catchy monkey though folks.  I would rather save the true Greenland block for December when it will count!

 

It sure counted in Nov in 2010!

[garbagebags]

If the ECM 12z is anything like that tonight, expect a melt down!

 

 

 

Am I missing something??

[SE Blizzards]

Am I missing something??

 

 

 

Forget the Temps, ...just look at the NH pattern that's developing.

 

I would imagine a Stonking -AO if the GEM 12Z verified.

Edited November 4, 2014 by SE Blizzards

[Tamara]

Some very intruiging developments shaping up in the Northern Hemisphere pattern right now that highly likely have significant implications for the late autumn slope into early winter.
Further to the occurence in Spring of this year, another Kelvin Wave has been surfacing in the Eastern Equatorial Pacific and Nino 3.4 is now approaching official weak El Nino status once more after its summer peak

 

 

 

This is sufficient to promote an characteristic El Nino 500mb response of a strong cyclically repeating Aleutian Low... in tandem with a tanking -AO index as well documented already on this thread. Good model/ensemble support is indicated for the retrogression of the upper low from Alaska to the Aleutians, much as already happened back in October. The presence of the Aleutian Low also teleconnects to a looping of the jetstream over the west US Coast (a +PNA).

 

 

The current/ongoing development of weak El Nino status in the upcoming weeks supports the sustaining of the Pacific jet downstream via an active sub tropical jet stream. Thus, with all said thus far about the upstream pattern, a good template is in place for the persistence of an atlantic upper trough continuing to disrupt towards the UK well into this month, carving out an early season -NAO signature.. whilst important window dressing also occurs on our side of the pole that we hope to see sustained and eventually back Siberian cold westwards in the months to come.

 

The SST/Atmosphere feedback and pressure pattern response, as described above, is uncannily similar to what was witnessed in the autumn of 2009 - and the similarities for sure don't stop there.

The Aleutian Low feedback response in place also assists in penning back what is already a recalcitrant polar vortex over Central Siberia. The SAI (snow advance index) has found its own road to converge on 2009 levels - and this even after some late month melt-off which had the index surpassing these levels with just a few days of the month remaining.

 

Extensive Eurasian snow cover further promotes upper polar vortex segment sticking over central Siberia and teleconnects to establishment feedback of High pressure anomalies above it over the polar field. In this way the SST/Atmospheric feedback dovetails with the Eurasian feedback process to perpetuate sustained Rossby wave breaking trigger mechanisms to ensure that the vortex remains unstable and increases the likelihood of HLB further establishing though the rest of this month and into winter. The stratosphere thread is already documenting provisional advertisement of these same wave breaking vortex disruptions that tropospherically led the descent into the fun and games of December 2009. That is not a forecast for 2014 of course   , but model indications of the same processes being a possibility once more this year are still obviously to be welcomed within the context of echoes of the encouraging background factors.

 

With the jetstream disrupting over and to the west/south west of us and still some residual lag warmth from a very warm autumn so far still to be mixed out, we best be prepared for plenty of unpalatable wet weather continuing in both the near term and probably intermittently in the few weeks to come. I wouldn't expect anything especially cold for a while yet. But who really cares at this early stage? In view of the progression of the bigger hemispheric pattern, then short term pain very conceivably holds long term gain on the basis that the shape and character of the upcoming winter season is looking much more like 2009/10 and 2012/13 than a year back

Edited November 4, 2014 by Tamara תָּמָר

[Duane S.]

I am sure this has already been posted about (no time at the mo to read through the last couple of days worth). This is indictive of what we can exepct this winter. The AO predictions over the past few weeks have been showing firstly a much higher spike than the +1 (peak) anomaly that we are currently experiencing and the predicted dip in value for next week was not showing a few days ago. This will very likely be a strong re-occuring theme over the coming months with some even sharper dips yet to come...

[Captain Shortwave]

The GEM sums it up really, you could literally nuke the north pole and the resulting Euro pattern would be exactly the same. Winds from a southerly vector with rain at times, especially in the south and west.

If the ECM is correct then we may see things dry out in more northern and eastern areas, though the penalty here may be a chilly and cloudy east to south easterly instead, so maybe that is the worse option.

[bluearmy]

Am I missing something??

 

 

its early november - if you want to appreciate this thread, you should be looking at the NH chart, not the atlantic and thinking beyond the first two thirds of the month.

[phil nw.]

The GEM sums it up really, you could literally nuke the north pole and the resulting Euro pattern would be exactly the same. Winds from a southerly vector with rain at times, especially in the south and west.

If the ECM is correct then we may see things dry out in more northern and eastern areas, though the penalty here may be a chilly and cloudy east to south easterly instead, so maybe that is the worse option.

Yes Captain no real change for us currently with things looking rather average under the continuing influence of a slow moving Atlantic trough.

Meanwhile over in NA and Canada that injection of cold showing up in the next few days as a deep upper trough digs well south taking very cold air with it over the mid west and eastwards.

 

 

 

Another early taste of Winter for them with snowstorms for parts of Canada spreading south into the New England states.

Edited November 4, 2014 by phil nw.