Model Output Discussion 01/09/17

[Dennis]

2 minutes ago, swfc said:

Could be a boom of a run post 228 hours!! Hopefully

indeed

[bluearmy]

Six clusters by day 8 on the eps - methinks patience is a virtue on this ........

[feb1991blizzard]

Yet only 2 by the end of the run, 1 very decent one, 1 absolutely dyer one.

Edited November 23, 2017 by feb1991blizzard

[Man With Beard]

EC clusters hot off the press! 

T192: Various options but in the main, ridging towards Iceland and troughing towards Europe - always a good pattern for UK cold but up for grabs whether it's a dry cold or a wet cold. The flatter cluster only has 10% support.

T240: much more variation - generally some sort of flattening but unclear if it will lead to the destruction of northern heights and more westerly pattern thereafter, or a Scandi high or simply another trough getting through the pattern and a rebuild of Atlantic heights + colder reset behind once more. I would still back the UK being in the colder air at this point: (And I would add - I think the reason for 6 clusters is more because of the situation at D10 situation rather at D8)

By T312, back to two clusters again; one that sees a continuation of Atlantic heights and trough to the east, and the other cluster which builds a strong high just to the east. Neither cluster likely to be mild - on cluster 2, the milder air is likely to bypass the UK to the NW.

It must be pointed out though, growing experience of comparing clusters with the full ensemble set is telling us that we should not expect all members within a cluster to look exactly like the cluster - there's likely to be quite a bit of variance within each individual cluster too. Particularly when the model only comes up one or two clusters, I feel a bit wary of taking the clusters too much at face value. But I think there's enough evidence here to suggest something cooler than the norm is the preferred option in week 2.

 

Edited November 23, 2017 by Man With Beard

[swfc]

7 minutes ago, Dennis said:

indeed

Close but no cigar.still better nhp and alignment on the 6z

[Sky Full]

Despite disappointing developments, this is where the main models say we will be by the 29th November (+144):

ECM        

GFS        

UKMO    

GEM       

Not bad when you consider it is not yet winter proper.....

and I wouldn't swap this outlook for the conditions we had on the same day last year:

            :   

So not too bad then, considering what we have endured in recent years  .

              

 

[nick sussex]

After seeing the GFS 00hrs run I expected better from the ECM which adds a complication with a less clean evolution in its early timeframe.

Todays ECM isn't as good as last night because the early messier set up doesn't get the high as north.

It still looks cold with winds falling light later there could be some very frosty conditions, the UKMO looks much better at T168hrs with energy heading se.

In terms of the upstream pattern lots of uncertainty with how amplified that might be and this has a knock on effect on how energy spills into the Atlantic.

More amplified will help hold the  PV further to the nw and with that a chance to get energy disrupting under the high.

I'd not read too much into the later timeframe given comments from NOAA today:

THE UPSTREAM PATTERN REMAINS AMPLIFIED
ALOFT AS AN ENERGETIC ERN PACIFIC TROUGH THREATENS THE WEST COAST.
THE MODELS NO LONGER OFFER A WELL CLUSTERED ENVELOPE OF SOLUTIONS
WITH THE FORECAST STRENGTH/TIMING OF THIS FEATURE DAYS 3-7. MODEL
RUN TO RUN CONTINUITY BECAME ABYSMAL TODAY WITH THE GFS MORE
PROGRESSIVE THAN EARLIER RUNS AND THE ECMWF LESS PROGRESSIVE AND
MORE DIGGY/AMPLIFIED. GIVEN ABOVE NORMAL UNCERTAINTY...PREFER AN
ENSEMBLE MEAN APPROACH USING THE 12 UTC ECMWF ENSEMBLE MEAN AND TO
A MUCH LESSER EXTENT THE 18 UTC GEFS MEAN. CONSIDERING WATER VAPOR
FLOW/UPSTREAM FLOW AMPLITUDE AND CONTINUITY HOWEVER...OPTED TO
LEAN STRONGLY ON ECMWF ENSEMBLES THAT OFFER LESS PROGRESSION/MORE
AMPLITUDE THAN GEFS/NAEFS...ALBEIT NOT AS MUCH AS THE 12 UTC
ECMWF. THE NEWER 00 UTC ECMWF HAS EASED FROM 12 UTC ECMWF
AMPLITUDE. THIS FEATURE IS THE KEY TO THE SUBSEQUENT DOWNSTREAM
FLOW EVOLUTION NEXT WEEK IN A PATTERN THAT GUIDANCE SEEMS TO BE
EXTREMELY SENSITIVE TO THE DETAILS OF MID-UPPER LEVEL SUPPORT TO
LEAD TO SURFACE CYCLOGENESIS
 

 

 

 

 

 

[Singularity]

With the Canadian vortex lobe looking to try and invade Scandinavia it seems that some form of 'lean' of the ridge toward the Svalbard area is going to hard to avoid, in which case there's the potential for a period of NE to E flow if the blocking can put up a fight in that area. I'm watching out for any signs of LPs splitting away from the Canadian lobe as opposed to the whole thing shoving its away across. Gradually accruing low heights in the Scandi/NW Asia region without wiping out the blocking.

For all we know, the ridge could still align better and give us the almost-cross-polar ridging via linkup with the Arctic High, but this really is the ultimate outcome representing the best of luck having gone our way. 

Even if the cold spell doesn't make it beyond Thu/Fri next week, it seems the blocking will be sufficient to seriously perturb the stratosphere. The usual slowing down of the progression toward an upper-stratospheric ridge making its way poleward is in evidence in the GFS runs of the past few days, but this by no means represents a reduced chance of occurrence; I have seen plenty of these slowed down before and they've tended to come through in the end - but you see, that's tended to be during Jan-Feb, when the delays place the response within an increasingly undesirable time period as we head away from the prime winter weeks. On this occasion, time looks to be on our side, which makes for a nice change .

[karlos1983]

14 minutes ago, nick sussex said:

 

More amplified will help hold the  PV further to the nw and with that a chance to get energy disrupting under the high.

I'd not read too much into the later timeframe given comments from NOAA today:

 

 

Yes I've been following the discussions quite closely the past couple of days, I wish we had this from the Likes of the Met, Mind you I guess you could say we do it for them  in here 

A lot of uncertainty in their musings. Interesting times.

 

Edited November 23, 2017 by karlos1983

[Dennis]

bring it down pls  (zonal winds)

[Methuselah]

59 minutes ago, Sky Full said:

Despite disappointing developments, this is where the main models say we will be by the 29th November (+144):

ECM        

GFS        

UKMO    

GEM       

Not bad when you consider it is not yet winter proper.....

and I wouldn't swap this outlook for the conditions we had on the same day last year:

            :   

So not too bad then, considering what we have endured in recent years  .

              

 

Aye. If one can say that anything is certain, it's that the upcoming two weeks don't look at all bad...indeed, if we do get a blast of true Arctic air, snow could feature even for those of us living darn sarf...

Let the models be our guide to the overall synoptics, but leave the finer details up to the day-to-day weather?

[weirpig]

Gfs Opp and control  both on the warm side of the mean.  alot of cold runs in there aswell.

[ArHu3]

48 minutes ago, Singularity said:

With the Canadian vortex lobe looking to try and invade Scandinavia it seems that some form of 'lean' of the ridge toward the Svalbard area is going to hard to avoid, in which case there's the potential for a period of NE to E flow if the blocking can put up a fight in that area. I'm watching out for any signs of LPs splitting away from the Canadian lobe as opposed to the whole thing shoving its away across. Gradually accruing low heights in the Scandi/NW Asia region without wiping out the blocking.

For all we know, the ridge could still align better and give us the almost-cross-polar ridging via linkup with the Arctic High, but this really is the ultimate outcome representing the best of luck having gone our way. 

Even if the cold spell doesn't make it beyond Thu/Fri next week, it seems the blocking will be sufficient to seriously perturb the stratosphere. The usual slowing down of the progression toward an upper-stratospheric ridge making its way poleward is in evidence in the GFS runs of the past few days, but this by no means represents a reduced chance of occurrence; I have seen plenty of these slowed down before and they've tended to come through in the end - but you see, that's tended to be during Jan-Feb, when the delays place the response within an increasingly undesirable time period as we head away from the prime winter weeks. On this occasion, time looks to be on our side, which makes for a nice change .

Yesterday iirc Judah Cohen tweeted that in spite of all this activity GFS saw no pole ward wave activity Flux except for in the oper (but none in the members). Has this changed (more member support) ? 

 

 

Edited November 23, 2017 by ArHu3

[nick sussex]

Just looking at the latest ENSO update from NOAA .

In terms of the current La Nina , after a big drop in ssts during October recent weeks have seen a stabilization which is good news.

We want a weak La Nina with the coldest ssts centred over the central Pacific. This has in the past correlated with below average winters in Europe.

This also means the MJO can play a bigger role rather than the signal being muted. Of course there are other teleconnections to factor in but we don't want to be facing an uphill battle against an unfavourable ENSO signal.

PS for new members heres the ENSO regions:

 

 

Edited November 23, 2017 by nick sussex

[bluearmy]

3 minutes ago, nick sussex said:

Just looking at the latest ENSO update from NOAA .

In terms of the current La Nina , after a big drop in ssts during October recent weeks have seen a stabilization which is good news.

We want a weak La Nina with the coldest ssts centred over the central Pacific. This has in the past correlated with below average winters in Europe.

This also means the MJO can play a bigger role rather than the signal being muted. Of course there are other teleconnections to factor in but we don't want to be facing an uphill battle against an unfavourable ENSO signal.

 

Last ecm MJO forecast I saw was very reflective of 2010 with big wave in October and smaller one to follow.

[mountain shadow]

52 minutes ago, Dennis said:

bring it down pls  (zonal winds)

Potential reversal at the start of Winter proper, great potential for well below average start to the season

[northwestsnow]

2 minutes ago, mountain shadow said:

Potential reversal at the start of Winter proper, great potential for well below average start to the season

Yes MS  even if we dont get a reversal theres nothing there to suggest a rampant vortex just yet...hopefully we can make hay while the goings good.

While i love snow im also hoping we get a cold high later next week..:)

[coldwinter]

25 minutes ago, nick sussex said:

Just looking at the latest ENSO update from NOAA .

In terms of the current La Nina , after a big drop in ssts during October recent weeks have seen a stabilization which is good news.

We want a weak La Nina with the coldest ssts centred over the central Pacific. This has in the past correlated with below average winters in Europe.

This also means the MJO can play a bigger role rather than the signal being muted. Of course there are other teleconnections to factor in but we don't want to be facing an uphill battle against an unfavourable ENSO signal.

PS for new members heres the ENSO regions:

 

 

Interesting, the research of Wenjun Zhang however found a correlation between an eastern pacific based La nina with a negative NAO. And central based with a +VE NAO.

https://link.springer.com/content/pdf/10.1007%2Fs00382-014-2155-z.pdf 

[gottolovethisweather]

2 hours ago, Sky Full said:

Despite disappointing developments, this is where the main models say we will be by the 29th November (+144):

ECM        

GFS        

UKMO    

GEM       

Not bad when you consider it is not yet winter proper.....

and I wouldn't swap this outlook for the conditions we had on the same day last year:

            :   

So not too bad then, considering what we have endured in recent years  .

              

 

Agreed and whilst I'm not one for delving into discussions over deep FI charts, the short-term Synoptics are favouring more of the UK to see November wintriness than during most recent years. The usual suspects will likely see the largest amounts of snowfall with even some temporary accumulations. A right ole wintry mix for the rest of us up to the timeframes denoted by those later charts. We should see a colder than normal November this time around and that in itself is something coldies should be happy to witness, historically-speaking. The ECM version above, denoting a cold continent is much needed if lowland parts of England are to witness their first snows of the season and some further seasonal frosts might also aid the cooling pattern. @Bring Back1962-63's post from last night is an excellent read if any folk had missed it. If you're pushed for time in reading the frantic updates in here, please do check that out. 

Edited November 23, 2017 by gottolovethisweather

[nick sussex]

3 minutes ago, coldwinter said:

Interesting, the research of Wenjun Zhang however found a correlation between an eastern pacific based La nina with a negative NAO. And central based with a +VE NAO.

https://link.springer.com/content/pdf/10.1007%2Fs00382-014-2155-z.pdf 

Thanks for the link I'll have a read.

[Gael_Force]

13 minutes ago, coldwinter said:

Interesting, the research of Wenjun Zhang however found a correlation between an eastern pacific based La nina with a negative NAO. And central based with a +VE NAO.

https://link.springer.com/content/pdf/10.1007%2Fs00382-014-2155-z.pdf 

Yes, that was my understanding too .... -NAO more likely with central based El Nino; reverses to the coast for La Nina but it's maybe based on the likes of the above research. It's all researched on historical weather patterns but oceans are warmer and the arctic is a bit different in terms of low ice; will those theories hold good for now and in the future?

Edited November 23, 2017 by Gael_Force

[Singularity]

1 hour ago, ArHu3 said:

Yesterday iirc Judah Cohen tweeted that in spite of all this activity GFS saw no pole ward wave activity Flux except for in the oper (but none in the members). Has this changed (more member support) ? 

 

 

Hello - I've not seen strat for ens yet today but I think he was saying 'im just showing the op here' rather than that the ens show no support - most likely ens are more mixed timing-wise which dilutes the signal too much to clearly show what he wanted to.

GEFS reportedly more progressive than EPS with strat warning as of yesterday evening - would be surprised if much has changed

[ACCOUNT DELETED]

 

Post deleted and will be moved to another thread.

 

 

 

Edited November 23, 2017 by DJ RY

[nick sussex]

From what I've read of that La Nina research it doesn't distinguish between strong and weak La Nina but simply uses the rolling 3 month average of -0.5 or below.

Its not clear whether it was the strength of the signal which tipped the balance rather than just the location of the biggest anomaly.

The key component in terms of anomaly is that the greatest departure isn't situated in vector 4 but 3.4 towards 3. 150 to 120, the research saw the positive NAO because the greatest departure was towards 4.

But I find it strange that the research didn't seem to divide up La Nina into strong and weak phases because that's critical in terms of the effects.

The strong La Nina will often over ride other teleconnections so I'm not convinced by that research. Its like a piece of the puzzle was left out.

 

[Summer Sun]

Although GFS is colder for next week it doesn't look we'll see much in the way of snow away from the usual hot spots

Early December is looking quite dry away from northern Scotland which would suggest high pressure should never be too far away for early winter

 

Edited November 23, 2017 by Summer Sun