Model Output Discussion 1200 hrs 15/11/14

[legritter]

Todays output is like waking up on Xmas morning expecting to get your new Playstation and realizing you've hit a time warp and now have to make do with the Binatone tennis game!

 

This probably won't mean a thing to younger members!

 

Overall the ECM once again has led yet another fantasy tour and its now dropped last nights more positive output for coldies and replaced it with yesterday mornings horror show, the upstream pattern flattens out and the PV moves into Greenland.

 

I don't think the French have a term for crud but lets just call it crudé  !!!

 

The ECM ensembles have lost that strong easterly cluster with jut a smaller amount hanging onto the precipice!

 

So yesterday mornings ECM was Alien 1, this mornings Alien 2, I really don't want to see a third instalment this evening.

 

As for the other NWP pretty much in the same boat bar the GEM , the problem really is just too much energy spilling eastwards and the flat pattern over the USA and Canada means theres nothing to help pull some of those low heights away.

 

This is Ripley last survivor of the Nostramo signing off......... still waiting to be rescued from this mild void!

The above post reflects my feelings on current output .A few tasty charts though at the end of P GFS today .but we all must remember that this time last year a very big long lasting weather event wasn,t that far around the meteorological corner ,Just a case of waiting Gang ,this Mild damp gloomy overlasting spell is  giving my Brussels the MOLD .I,v nearly cracked it with posting charts ,thanks to those posters for Help ,so far  everything i,v tried as gone into cyber space .Lets hope tonights chart runs give us some needed cold .

[knocker]

Latest tweet from Matt Hugo

 

 

It's a very long way away & is the 06z GFS but this kind of pattern and evolution is what I think will develop in Dec

 

https://twitter.com/MattHugo81

[nick sussex]

There are still some uncertainties over the USA in terms of shortwaves and you'll note how the ECM phases two shortwaves over the ne USA at T120hrs:

 

 

It's the only operational run of the major models to do this, we're left today with hoping that the ECM operational run is wrong and so I bring you  this from the NCEP  state discussion for New York:

 

LONG TERM /TUESDAY THROUGH FRIDAY/...
THERE ARE STILL SIGNIFICANT DIFFERENCES IN THE MODELS HANDLING OF
A FULL LATITUDE TROUGH STRETCHING FROM THE GREAT LAKES TO TEXAS
TUESDAY MORNING...AND MORE IMPORTANTLY HOW A NORTHERN STREAM
SHORTWAVE DIVING DOWN FROM N CENTRAL CANADA INTERACTS WITH THIS
TROUGH IN THE MIDDLE OF THE WEEK.

THE 00Z ECMWF IS THE STRONGEST WITH THIS NORTHERN STREAM
SHORTWAVE...AND HENCE ULTIMATELY DEEPER AND CLOSER TO THE COAST
WITH THE ASSOCIATED SURFACE LOW. THE CMC IS THE SLOWEST WITH THIS
FEATURE AND DOES NOT HAVE MUCH IF ANY PHASING WITH THE FULL
LATITUDE TROUGH...SO ITS LOW IS WEAKER AND FAR ENOUGH OUT TO SEA
THAT THERE WOULD BE LITTLE OR NO IMPACT. THE GFS HAS ABOUT THE
SAME STRENGTH OF THE NORTHERN STREAM SHORTWAVE AS THE CMC...BUT
IS FASTER AND HENCE HAS ENOUGH PHASING WITH THE FULL LATITUDE
TROUGH TO HAVE ITS LOW BE A BIT STRONGER AND CLOSER TO THE COAST
THAN THE CMC. THE 00Z GEFS AND ECMWF ENSEMBLE MEANS ARE IN FAIRLY
GOOD AGREEMENT WITH THE OPERATIONAL GFS. SO BASED ON THIS...FOR
NOW IT APPEARS THE ECMWF IS AN OUTLIER AND HAVE LEANED MORE
TOWARDS A NON-ECMWF SOLUTION AT THIS TIME.
 

 

 

 

 

 

 

[Duane S.]

Lots of posts about wishing the block away, reset etc. Putting aside the fact that that is a very high risk strategy, a full on retreat of the block and Atlantic onslaught looks very unlikely to me. No doubt we are looking at a battle royale between east and west,especially with the strong jet that will be emerging off the Eastern seaboard in the next couple of days but even if we see a progressive pattern take shape over the next couple of weeks or so, that block is very likely to be omnipreset for the most part of this winter so we had better get used to it and its influence on us (direct or otherwise).

 

06z the best run for a long time, if you want to look at the big picture.

Edited November 22, 2014 by s4lancia

[Tamara]

Posted by Tamara תָּמָר on 10 November 2014 - 13:28 in Forecasting Model Discussion 

< The pattern looks to cycle, wash, spin, and repeat. I do think that it is best to be prepared for some less than enjoyable model watching with suggestions of a fairly mild NW/SE split , temporarily, after the current period of model watching interest finishes

.

< The next time around the SAI/ wave breaking -AO feedbacks will be stronger with greater repercussions hemispherically. It is common for a long period of AO phase dominancy (this season negative!) to be preceded by an opposite spike as zonal wind profiles with the polar field are re-shuffled. The AO/NAO lose their seasonal disconnect as we plough onwards into and through winter. Cold pooling to our NE will deepen and more extensive westwards and southwards. Over the coming month or so, resurgent tranches of wave activity are likely to draw deeper blood from the polar vortex that we increasingly pick up the scent

As the models start to fade the modest height anomaly to the north of the British Isles and the AO trends less negative, this heads towards the last week or so period of November where at face value the large scale pattern may look much less appealing than now (as referred to yesterday) but in fact it represents a time when interest of proper future cold prospects has greater justification than it does at present....

--------------------------------------------------------------------------------------------------------------------

 

...And so we see good agreement in the short term for the AO to turn positive during this latter stage of the month in line with those early expectations. Notwithstanding the east vs west stalemate, and pendulum swings along the crossroads (us!) of that boundary - the models are well advertising this switch of phasing (just for now) across the polar field

 

Tropospheric/stratospheric activities continue robustly (as recent posts stress repeatedly!..) but, also as expected, for the timebeing have continued to deny us the fun and games in terms of cold and snow very emphatically in favour of the Americans. This, as well as some way distance to our east over Asia where the other main mass of cold air in the NH lies, beneath another distinct lobe of vortex that resides there. Too far away (at the moment) to threaten entertain us

 

Wave activity flux has sure done a good job on the vortex in terms of stretching it and splitting it, but in the process leaves that characteristic dumbell type imprint with distinct lobes over Greenland/Canada at one end, and over Central Asia at the other end.

 

　

We should think in simple terms of the vorticity energy transport involved in this stretching process as being the catalyst for lowering heights over the pole (turning the AO positive), and, for a time, strengthening the net effect of the westerlies and appearing to give the upper hand in the 'battle' for a while to the atlantic.

 

The stand-off in our sector in the NH is the direct result of the presently unfavourable throw of the dice in terms of 'that' vortex split. We have opposing forces of vorticity in the 'wrong place' pitching against the ally of deepening cold pooling, courtesy of a Siberian High feeding off the significantly noteworthy autumn seasonal snow advance over Eurasia - which in turn is giving the blocking high to our east its own distinct stamina. Stamina that *should* eventually prevail in our fortunes as time passes.

 

Aside from the vorticity energy to our NW, and a NAO profile which has been generally just neutral at best atm, the High to our east is presently orientated not quite right to assist proper cold air advection too much further west from its eastern land of promise. This unfavouarble orientation is in truth actually also hampering feedbacks, in relative terms, from fully maximising the highly encouraging trop/strat wave feedback activity bombardment on the vortex we continue to see - which kind of shows in a backhanded way what a very good job it is doing already!

 

Other than the specific troposphere to lower/mid stratosphere warming activity we saw in Nov/Dec 2010 f.e (and which is absent this year) it is traditionally too early in the season to expect powerful enough wave activity (such as an SSW for instance) to detonate unfavourable vorticity lobes into minute pieces and fully reverse upper zonal winds and polarity from west to east to east to west. Splitting of the vortex certainly indicates the great success that persistent wave activity has on the vortex and keeps it very disorganised, but splits aside as we have seen already, as long as it attains only this dumbell profile than the status quo persists....

 

However.. having said it is too early in the season, this year we have an infinitely stronger Eurasian feedback response compared to last year. But then things have to be better than last year anyway. However, not only that, it is also working so well already when pitched in comparison against November analogues preceding cold UK winters.

 

We therefore should remain optimistic on credible grounds that a final detonator can arrive to explode this loaded gun scenario (as I described it explicitly the other evening). Because of the accelerated feedback pattern, such a detonator has some chance of preceding the timing of classic mid winter occurence that characterise SSW's

 

I don't apologise at all for the repeated and drawn out mantra of this post -  less face value knee jerk response to morning/evening individual model suites is a good thing In short, repeated explanations of what is driving the winter pattern and how that might change its path significantly differently to last winter are a well intended antidote to the diurnal highs and lows of responding to face value model output - especially as the models own uncertainties are reflected in complete lack of intra day continuity - and we best get used to this happening for some time yet to come....

 

Of course there are, as always, things that can go wrong and worsen MOD moods . By that I mean factors that could mitigate the -AO feedbacks from their full potential to deliver our mid latitude cold. A much more coherent MJO signal emerging from the Central and Eastern Pacific would serve to heighten a more widespread El Nino response which in turn would assist further the -AO feedbacks in maximising that potential towards an SSW. Why is this? Well, the trademark signature of strong Aleutian Low and bolstering of the Siberian High is very well teleconnected by a full El Nino reponse (we are talking weak ENSO but coherent SST/Atmsophere response here). Also arctic sea ice profiles are not 100% condusive for maximum amplification of the pattern in our segment of the NH and, currently, have been rather assisting heights on the 'wrong' side of the pole.

 

However, in the round, the overall Eurasian feedback is the strongest feedback and the one still expected to override any such mitigating feedbacks. So far, the models are advertising the Cohen winter template to a tee. I will leave the designated tecchie experts to keep discussing and providing updated developments on this on the stratosphere thread

 

Could it be that the longer term modelling is starting to sniff out those needed changes as above and showing how the stalemate eventually resolves itself with weightings towards our east rather than the atlantic?  ie. the Aleutian low and better aligned Siberian High signature that leads to a pot of gold? The long term ensembles are tentatively suggested this in the 2 week and beyond period. No surprise to see the Canadian lobe weaken and Siberian sector become dominant on these suggestions

 

 

 

Timing open to debate, but still greater things might be apparent in both tropospheric modelling and ammunition fuelled stratospheric modelling by this time. Rinse and re-cycle stage 3 (I'm losing count though)   

 

This evolution, should it occur as suggested, is patently obviously not the end of the process to UK cold, but simply another progressive and very important stage towards final detonation.

 

Well worth tolerating stalemate and the offering of wintry gifts away from the UK in the meantime

[Jason M]

I understand the reasons for people wanting the block to stay, but in reality relying on a Russian high to ridge back far enough to impact us with cold uppers is likely to lead to disappointment IMHO, especially with energy moving over the top of the block. This is a 'mildfest' set up for NW Europe(at 850 level anyway) simply because we will keep winds from the south. In January a SE flow might be sufficient, but it won't be in early winter.

I think we need the block to recede. I suspect then that we will get a southerly tracking jet and some proper northern pressure rises. I can't see the Atlantic rolling for weeks with the background signals, but we may need it to get through unless we want to waste weeks under a non descript south easterly.

As others such as John Holmes have suggested, we are a long way from seeing any major wintry outbreak.

Edit: by saying we are a 'long way from cold' that doesn't mean I don't think it wont happen. I just don't think it will happen in the next 3 weeks!

Edited November 22, 2014 by Jason M

[tinybill]

good afternoon early December   could be fun  first sigh of the white stuff!!!

[bluearmy]

Longer term AO already trending back neutral to negative as we enter December

[jmatt81]

Longer term AO already trending back neutral to negative as we enter December

 

The 1st December seems to be the tipping point as forecast is very split.

[Barry12]

UKMO 12z day 6 is much better than the 00z, with the block much further west

 

[Winter Cold]

UKMO this afternoon wants to send a big low straight down south on the 12z, with the eastern block building again over it up towards Iceland. This looks interesting to me?

 

 

EDIT: Great minds Barry haha

Edited November 22, 2014 by Winter Cold

[Captain Shortwave]

Huge difference at day 6

Block holding firm to our east, though nothing outstanding temperature wise on the horizon

GFS

GFS pushing the Atlantic through, by day 7 its a typical mixed westerly pattern establishing over the UK.

GFS parallel

Between the two but even the parallel gets us into a westerly flow a day or so later.

 

Whilst he GFS seems progressive, the removal of low heights from the Siberian side may allow the high to relax and retreat eastwards somewhat. Either way no sign of cold again even at beyond 7-10 days out. Despite the extended ensembles suggesting the Canadian lobe relaxing, the nearer term suggests the opposite with low heights becoming specifically concentrated over the Greenland/Canadian region. 

 

I must add, the polar profile has some positives regarding the state of the polar vortex, it just seems that we keep rolling snake eyes in the pattern stakes at the moment. 

Edited November 22, 2014 by Captain shortwave

[nick sussex]

The big difference upstream between  the UKMO and GFS and GFS P develops quite early on, the former sticks to the separate shortwave and not much phasing between T96hrs and T120hrs, the latter two phase those shortwaves and then flatten the pattern out.

 

The GEM also does the same as the UKMO, you'll from those NCEP discussions the uncertainty but both GFS's have backed this mornings ECM over the ne USA, we really do not want to see that phasing.

[SMU]

Afternoon All-

 

Minimal postings from me this week- updating winter forecast.

 

Good UKMO & GEM combined this afternoon.

http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0

not so much interest in the GFS

 

S

 

Actually the GEM is the best run of the year so far with a decent solid 2 wave pattern at 210...................

Edited November 22, 2014 by Steve Murr

[fromey]

hi guys, i dont post in here all that often but i have just read a quote from Joe B

 

"westward shift of GFS starting.. Should continue as model goes toward ECMWF."

 

i read some thing from Nick S that the NCEP where saying that it considered the ECM as a outlier.

 

can anyone explain,confused.com

 

thanks in advance

 

fromey

Edited November 22, 2014 by fromey

[snow mad]

http://www.meteociel.fr/modeles/geme_cartes.php?&ech=240&mode=0&carte=1 Yes Steve this chart is great

[Captain Shortwave]

hi guys, i dont post in here all that often but i have just read a quote from Joe B

 

"westward shift of GFS starting.. Should continue as model goes toward ECMWF."

 

i read some thing from Nick S that the NCEP where saying that it considered the ECM as a outlier.

 

can anyone explain,confused.com

 

thanks in advance

 

fromey

Well lets put it bluntly, any doubts about totally discrediting Joe B hae been vanquished.

This was this mornings ECM

So the correct statement would be;

"The eastward shift of the GFS is starting, it should continue as the model shifts towards the ECM."

That would be a more factual statement as this afternoons GFS is more progressive than its morning run.

[SMU]

Tonights UKMO is significant because its the first time so far this season that a projected pattern change has got into the UKMO firing range at 144-

 

The strong jet streak heading due south towards SW spain allows heights to build NW towards Svalbard...

 

As long as the ECM sees this similar trend ( & the 12z GFS ENS are trending this way) then things are starting to look very interesting in 8-9 days....

S

[knocker]

The GFS (P) has the Atlantic bowling along from T120 onwards with a depression nipping through the UK into Denmark on pretty strong jet. And the ops at T192

Charts weatherbell.com

Edited November 22, 2014 by knocker

[blizzard81]

http://www.meteociel.fr/modeles/geme_cartes.php?&ech=240&mode=0&carte=1 Yes Steve this chart is great

Great chart but such a shame the GEM never seems to verify!

[Barry12]

The UKMO and GEM are brilliant, I really wish we could see a day 7 chart on the UKMO, but you'd think it would trend a similar way to the GEM:

 

 

If the ECM is similiar to the GEM and UKMO there could be a melt down on here tonight!

[blizzard81]

Tonights UKMO is significant because its the first time so far this season that a projected pattern change has got into the UKMO firing range at 144-

 

The strong jet streak heading due south towards SW spain allows heights to build NW towards Svalbard...

 

As long as the ECM sees this similar trend ( & the 12z GFS ENS are trending this way) then things are starting to look very interesting in 8-9 days....

S

The ECM did seem to be seeing this trend but seemed to back away this morning. Lets hope it swings back again tonight.

[Gael_Force]

hi guys, i dont post in here all that often but i have just read a quote from Joe B

 

"westward shift of GFS starting.. Should continue as model goes toward ECMWF."

 

i read some thing from Nick S that the NCEP where saying that it considered the ECM as a outlier.

 

can anyone explain,confused.com

 

thanks in advance

 

fromey

 

It is always good to check the context of posts from American meteorologists - he's referring to snowfall in the US, whether that has any bearing for us is questionable.

[Gael_Force]

Great chart but such a shame the GEM never seems to verify!

 

The GEM has just had a big upgrade so past verification is no indicator for future performance.

Edited November 22, 2014 by Gael_Force

[Cloud 10]

The GEM has just had a big upgrade so past verification is no indicator for future performance.

 

It certainly has.

 

Moses himself couldn't part the vortex any wider.