Model Output Discussion 01/09/17

[Singularity]

  

At 6 days range we find that ECM has by far the most mid-Atlantic ridging, and yet as much as UKMO differs to ECM there, it also differs to GFS with respect to the blocking over W. Asia, which is more akin to the ECM run as there is a cut-off low (out of shot in the UKMO chart due to the weird cut-off) with the ridge building around it, rather than a low still attached to the jet stream off the N. Atlantic.

As with yesterday, this is heavily dependent on how flat the jet pattern is across the N. Atlantic and into Europe. GFS remains stubbornly flat, ECM stubbornly not so, and UKMO is still lodging at halfway house. This is not helping with predictions for next weekend's weather but of course it tends to become more common during the winter season when the range of possible mobility to the pattern grows much wider.

[Singularity]

 

Funny how the 06z often seems to be more inclined to sharpen ridge-trough sequences (i.e. planetary waves).

[SMU]

Tentative signs from the ECM today & now the updated 06z that the vortex rather like last year starts off in a disjointed mode-

The ECM even goes so far as to promote a split around 240-

It all looks very pretty seeing High pressure scattered over the pole with one setting up shop over Scandi & the energy going SE..

long may it continue

Edited November 5, 2017 by Steve Murr

[Polar Maritime]

The 6z GFS shows stronger Heights building over Greenland into Wk2, And the Jet way South.

 

[booferking]

Huge Siberian high extending in to the Arctic along with Atlantic blocked off win win situation along the lines with gavs long range forecast outlook and alluded by some members last night from the EC.

[tinybill]

this the earlyest i can see of snowin the  uk in FI  all i can say things are lookng interesting  for this winter!!!

Edited November 5, 2017 by Polar Maritime
It's Fantasy Island not formula 1 ☺

[coldwinter]

Surprised there hasn't been more chatter about the ECM ens this morning. Very impressive ensemble mean with a strong blocking signal out to the end of the run from Scandinavia through the Taymyr region to the Aleutians, signal for troughing into Europe too. 

Only two clusters on the ECM ens right at the end, big signal for blocking over scandi on the biggest. Even the second has a signal for blocking to the north. Certainly, if this were to verify it would put the polar vortex under some stress, along with a possible strong Siberian high forming. I notice the 06z GFS has also cottoned on to the Siberian high theme. Would expect some decent wave activity if this comes off? Interesting times.

Ryan.

 

 

 

[SMU]

Some impressive ensembles - not in terms of deep cold but notable for lack of an organised vortex...

For example

[snowray]

Anyone notice the AO potentially falling like a stone as we go towards mid month?

[knocker]

Just had a passing glance at the 06 (don't normally bother) and it's nodded very much in the direction of this morning's ecm with more amplification later this week before becoming generally unsettled as the upper flow veers a tad NW.. The gefs anomaly has a lobe of the Canadian vortex tracking east to northern Scandinavia that reinforces the trough to our east whilst doing no favors to the Russian ridge.  So still looking at temps a tad below average.

[northwestsnow]

Much better 6z GFS- hopefully ecm is onto something with this high latitude blocking signal and we will reap the dividends just in time for December, all eyes on the meto update.Hopefully the below average theme will be maintained for later in the month.

[bluearmy]

28 minutes ago, snowray said:

Anyone notice the AO potentially falling like a stone as we go towards mid month?

apart from a post every day saying it's going negative on all the extended ens  ............... nah 

[northwestsnow]

6 minutes ago, bluearmy said:

apart from a post every day saying it's going negative on all the extended ens  ............... nah 

Haha yes you certainly have been watching like a hawk Blue.

My feeling is the AO looks good for going neg mid term, the fly (as ever) is the NAO, would like to see the Atlantic blocked then we potentially are in business.

METO updates being watched closely from my perspective- a scandy block later in november would be very much appreciated.

and right on cue the meto update still talking of HP in control later in the month with temps below average. 

Edited November 5, 2017 by northwestsnow

[Methuselah]

I simply don't get this obsession with the NAO (as an entity in its own right)...Surely, whenever the synoptic forecasts are suggesting HP somewhere near Iceland, Greenland the NAO will trend negative? 

Unless of course, I'm missing something?

[bluearmy]

no effective MJO  to be influencing the nwp going forward which means that's one variable that can't scupper the current outlook if it fails to verify. 

06z gefs AO/NAO summary plus day 16 height anomoly (consistent)

    

[bobbydog]

14 minutes ago, Ed Stone said:

I simply don't get this obsession with the NAO (as an entity in its own right)...Surely, whenever the synoptic forecasts are suggesting HP somewhere near Iceland, Greenland the NAO will trend negative? 

Unless of course, I'm missing something?

i think you've just answered your own question there pete...

[NeilN]

1 hour ago, Steve Murr said:

Some impressive ensembles - not in terms of deep cold but notable for lack of an organised vortex...

For example

I might get a white birthday this year then?!! 

[bobbydog]

Just now, nn2013 said:

I might get a white birthday this year then?!! 

probably not. but if the trend of blocking and a disrupted vortex continues, jesus might get a white birthday....

[NeilN]

1 minute ago, bobbydog said:

probably not. but if the trend of blocking and a disrupted vortex continues, jesus might get a white birthday....

That would be nice to see on that day! 

[Polar Maritime]

Just sensible model discusson please in here.. ☺

[phil nw.]

Quite rightly signs of a disorganised vortex always raises interest but this early in the season i am always wary of it lasting.We will inevitably see zonal winds increase as the pv continues to cool and the key issue will be how quickly they filter down to the lower levels of the Stratosphere so always worth monitoring those on that thread.

The Atlantic still holds sway for us over the next week to 10 days as the Greenland trough continues to extend se so rather cold at times as the winds come from the north west with some occasional rain and hill snow and night frosts.

ECM Mean days 5/10

Gefs graph

shows that at least we can expect more seasonal temperatures with little sign of a mild spell.

[Man With Beard]

14 hours ago, bobbydog said:

from memory, no. novemb pleaseer 2010 is the only one that comes to mind and that was a precursor to a decent winter (well first half anyway) 

but thats not really my point. i've just been trying to point out that a strong siberian high *can* increase the chances of a colder winter in europe. i'm not suggesting the models are right at the ranges we are seeing it, or  that a big S.H. guarantees anything but considering recent winters, i see it as a positive step for the season as a whole. rather than create interest, it just seems to have created cynicism. (not from yourself). i was simply throwing it in for discussion. i wish i hadn't bothered...

Bobbydog you're absolutely right to bring up the SAI issue, it does have backing in research and if the link has somehow been erased by global warming then that remains hypothetical at best. You raise good points!! (but I still think a November chase has merit)

Talking of a November cold snap, a potentially wintry EC control cluster (supported by 60% of members) in FI today, with strong northern heights and the Atlantic going underneath:

 

Edit: ah, @coldwinter I see you beat me to it

Edited November 5, 2017 by Man With Beard

[jules216]

3 hours ago, bluearmy said:

no effective MJO  to be influencing the nwp going forward which means that's one variable that can't scupper the current outlook if it fails to verify. 

06z gefs AO/NAO summary plus day 16 height anomoly (consistent)

    

bluearmy,that is a fantastic height anomaly for November, now I am getting a tad excited as that is  uncanny similar to the re-analysis of height anomaly for Novembers which were precursors to most negative -AO winters, which GP alluded to back in 2012 strat. thread.pacific is little different but N.Atlantic,Europe and Asia is spot on

[SMU]

UKMO 144 shows showers turning increasingly to snow for Scotland especially the hills ( which will get a pasting )

Even higher elevations of NI could see some wintryness !

Also UKMO shows a huge early season blizzard for the NE states of the US...

Edited November 5, 2017 by Steve Murr

[bluearmy]

Another very interesting gfs fi hemispherically