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Just a quick follow on from this, but the EC32 has had its upgrade and changes are evident for December. However, the signals for December are particularly weak on this last run. There doesn't seem to be a signal for a +NAO nor does there seem to be a signal for significantly -ve height anoms to the NW, in fact there is a weak signal for higher than average pressure over Greenland by mid-December. That being said, the signals are particularly weak so it's anyone's guess what December will produce, but 'raging zonality' doesn't seem on the cards. What is also interesting is the continued complete lack of any significant MJO phase. For at least 2 weeks running now the EC32 EPS MJO prediction maintains near 'neutral' conditions throughout the forecast period. It just doesn't seem to want to get going and this variable is likely to remain rather useless for medium/long range predictions for now. As usual, it's just a case of watching and waiting to see if anything materialises... Cheers, Matt.

Thanks for the update matt , I think that has to be a good signal to be honest as a lot of folk are really talking up a zonal month, but with no clear signal really gives us some hope ! If I remember rightly the cold outbreak last January was bought about from an immediate trop response from the MMW that occurs a few days earlier , my point in all this is although there was a SSW , we was left with a lobe of the vortex over Greenland , which acted to feed the Atlantic weather systems which contributed the NAO staying slightly positive , but what we have was a week area of high pressure across Iceland that helped deflect the low pressures south . Obviously the set up was different to what we have now , but going into December with no strong NAO forecast we leave the door open to something similar possibly ? If we can get the jet to dive south with an increase in wave 2 activity , along with a trough into Europe then I believe we may well be on too something ?! I also see there is a warming forecast in the gfspost-9095-0-79433200-1385108037_thumb.jpIt seems stronger than what it has been , maybe something to watch? Is that an indication of wave 2 activity picking up which in turn causing warming ?
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I mentioned the stagnant MJO on the MOD thread yesterday - it certainly does add to the uncertainy the longer the signal remains at low amplitude and progress is very static especially if this persists for any considerable amount of time with wavelengths getting longer and longer into the winter. But that is a long way ahead and focus is on the coming couple of weeks or so atm.

 

From what I can glean, the -EPO positive height anomaly position over the US west coast and Alaska is set to continue to be a feature of the pattern into December and perhaps beyond. With the AO staying positive in line with a strong +QBO style vortex, we depend upon any wave activity forecasts not just verifying, but being stronger than what we have seen already to make any impact. We also need them to continue to keep the vortex pinned towards Siberia otherwise we will get into an even flatter and also milder pattern quite easily. At least in my opinionPosted Image

 

I suspect that the weak signal on the EC32 is in respect of the currently modelled high pressure zone over the atlantic persisting but unless we see significant troposphere/lower stratosphere activity then there is little chance of this high pressure amplifying much towards Greenland beyond a toppler type of regime. Against the background of a strong vortex, that is likely to intensify further into December in line with traditional peaking (especially with a westerly QBO) then any positive statosphere forecasts in FI very much need to verify and preferably upgrade to prevent much of the first half of December and quite possibly beyond being rather uneventful as I see it.

 

On the basis of all this, it is hard to see anything other than a +NAO through the first half of December at least, whatever the EC32 model might suggestPosted Image

 

The upper warming forecasted over Asia might get interesting for the much longer term if the vortex profile can stay the right side of the pole..caveats as above. Another reason for longer term forecasts needing to verify.

Edited by Tamara תָּמָר
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I mentioned the stagnant MJO on the MOD thread yesterday - it certainly does add to the uncertainy the longer the signal remains at low amplitude and progress is very static especially if this persists for any considerable amount of time with wavelengths getting longer and longer into the winter. But that is a long way ahead and focus is on the coming couple of weeks or so atm.

 

From what I can glean, the -EPO positive height anomaly position over the US west coast and Alaska is set to continue to be a feature of the pattern into December and perhaps beyond. With the AO staying positive in line with a strong +QBO style vortex, we depend upon any wave activity forecasts not just verifying, but being stronger than what we have seen already to make any impact. We also need them to continue to keep the vortex pinned towards Siberia otherwise we will get into an even flatter and also milder pattern quite easily. At least in my opinionPosted Image

 

I suspect that the weak signal on the EC32 is in respect of the currently modelled high pressure zone over the atlantic persisting but unless we see significant troposphere/lower stratosphere activity then there is little chance of this high pressure amplifying much towards Greenland beyond a toppler type of regime. Against the background of a strong vortex, that is likely to intensify further into December in line with traditional peaking (especially with a westerly QBO) then any positive statosphere forecasts in FI very much need to verify and preferably upgrade to prevent much of the first half of December and quite possibly beyond being rather uneventful as I see it.

 

On the basis of all this, it is hard to see anything other than a +NAO through the first half of December at least, whatever the EC32 model might suggestPosted Image

 

The upper warming forecasted over Asia might get interesting for the much longer term if the vortex profile can stay the right side of the pole..caveats as above. Another reason for longer term forecasts needing to verify.

blimey that dosnt sound good.lets hope the wave activity gets its act together in the coming weekd. And if we can get the warming over asia to strengthen then things may well go as we hope. All is not lost . The wave activity is putting the vortex under pressure hence the move to siberia which although may not allow greenland height rises , it does allow amplification along with temporary northerly outbreaks. Is there any thing in the pipe line regarding mountain torques ?
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blimey that dosnt sound good.lets hope the wave activity gets its act together in the coming weekd. And if we can get the warming over asia to strengthen then things may well go as we hope. All is not lost . The wave activity is putting the vortex under pressure hence the move to siberia which although may not allow greenland height rises , it does allow amplification along with temporary northerly outbreaks. Is there any thing in the pipe line regarding mountain torques ?

Its not easy for me to restrain myself in this wayPosted Image ...I would much prefer to be ramping things believe mePosted Image As others have posted, its not that there isn't anything forecasted in terms of activity that could prove of greater interest and potential - it is more a case of very much depending on these forecasts being accurate, otherwise the NH pattern could quickly become less appealing from a cold wishing povPosted Image

 

The warming over Asia, should it persist and grow, might provide interest further into the winter in terms of greater impact on the vortex from our point of view this side of the atlantic. We might be looking to the north east as the winter progresses. In the meantime I think some folk in parts of the US are going to be the beneficiaries.

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I mentioned the stagnant MJO on the MOD thread yesterday - it certainly does add to the uncertainy the longer the signal remains at low amplitude and progress is very static especially if this persists for any considerable amount of time with wavelengths getting longer and longer into the winter. But that is a long way ahead and focus is on the coming couple of weeks or so atm.

 

From what I can glean, the -EPO positive height anomaly position over the US west coast and Alaska is set to continue to be a feature of the pattern into December and perhaps beyond. With the AO staying positive in line with a strong +QBO style vortex, we depend upon any wave activity forecasts not just verifying, but being stronger than what we have seen already to make any impact. We also need them to continue to keep the vortex pinned towards Siberia otherwise we will get into an even flatter and also milder pattern quite easily. At least in my opinionPosted Image

 

I suspect that the weak signal on the EC32 is in respect of the currently modelled high pressure zone over the atlantic persisting but unless we see significant troposphere/lower stratosphere activity then there is little chance of this high pressure amplifying much towards Greenland beyond a toppler type of regime. Against the background of a strong vortex, that is likely to intensify further into December in line with traditional peaking (especially with a westerly QBO) then any positive statosphere forecasts in FI very much need to verify and preferably upgrade to prevent much of the first half of December and quite possibly beyond being rather uneventful as I see it.

 

On the basis of all this, it is hard to see anything other than a +NAO through the first half of December at least, whatever the EC32 model might suggestPosted Image

 

The upper warming forecasted over Asia might get interesting for the much longer term if the vortex profile can stay the right side of the pole..caveats as above. Another reason for longer term forecasts needing to verify.

 

Hi Tamara, great post.

 

I am still undecided how much weighting to put into Strat developments though thanks to those who post so eloquently in this thread, especially Chino for his initial work and continued insight,, I am convinced there is clear correlation between warming events and blocking patterns.

I was wondering though, what were the signals (strat developments in evidence) for the current MLB we are seeing as GFS picked up on this at the start of November?

Edited by Mucka
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Hi Tamara, great post.

 

I am still undecided how much weighting to put into Strat developments though thanks to those who post so eloquently in this thread, especially Chino for his initial work and continued insight,, I am convinced there is clear correlation between warming events and blocking patterns.

I was wondering though, what were the signals (strat developments in evidence) for the current MLB we are seeing as GFS picked up on this at the start of November?

The easiest way to answer this I guess is to look back a few pages of this thread around the first week or so of November and what appeared to be more significant than has proved to be the case wave breaking suggestions from the stratospheric models. As we know these were interpreted by the tropospheric models to initially suggest a greater degree of amplification from the current atlantic ridge than we now know is the case in reality. The ECM was suggesting a proper split in the vortex at one time and the ridge amplified towards Iceland and then Scandinavia. It has ended up translating to something less interesting than that.

 

This thread I am sure will obviously continue to watch future possible activity, but we should be mindful of the forecasts not meeting the realities and also the fact that it is going to take an increasing amount of armoury to make much impact on the vortex during at least the first half of the winter, as I see it anyway, although others might be more bullish than me about cold prospects Posted Image

 

The current downgrades obviously take nothing at all away from the very significant role that the stratosphere plays in our cold blocking fortunes - however, as always, there are various other factors to consider and it is still only November at the moment afterall !Posted Image

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The easiest way to answer this I guess is to look back a few pages of this thread around the first week or so of November and what appeared to be more significant than has proved to be the case wave breaking suggestions from the stratospheric models. As we know these were interpreted by the tropospheric models to initially suggest a greater degree of amplification from the current atlantic ridge than we now know is the case in reality. The ECM was suggesting a proper split in the vortex at one time and the ridge amplified towards Iceland and then Scandinavia. It has ended up translating to something less interesting than that.

 

This thread I am sure will obviously continue to watch future possible activity, but we should be mindful of the forecasts not meeting the realities and also the fact that it is going to take an increasing amount of armoury to make much impact on the vortex during at least the first half of the winter, as I see it anyway, although others might be more bullish than me about cold prospects Posted Image

 

The current downgrades obviously take nothing at all away from the very significant role that the stratosphere plays in our cold blocking fortunes - however, as always, there are various other factors to consider and it is still only November at the moment afterall !Posted Image

 

 

Hi Tamara, I meant to mention in my post that I wasn't scanning back through the thread because I am unsure what the lag time between various events and actual displacement/buckling of the jet might be.

What i was getting at is that GFS was picking up on MLB in its ensembles around November 3rd and if this was directly related or could at least be connected to strat developments?

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Without going around in circles here, I think the lack of anything of interest is evident as Ed (Chino) hasn't made an appearance for some time...Correct me if wrong!

 

The 12Z ECM from yesterday shows increase consolidation over the pole, not good;

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=30&forecast=all&lng=eng

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=10&forecast=all&lng=eng

 

The 10hPa in particular by day 8, 9 and 10 the vortex looks pretty 'fierce' to be honest and clearly after being located over Siberia does become relocated over the pole with time. Both zonal wind and temps as well continue to highlight a developing vortext with time;

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=u&lng=eng

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=t&lng=eng

 

Whilst the vortex remains over Siberia then this kind of pattern always seems possible;

 

http://www.meteociel.com/modeles/ecmwf/runs/2013112300/ECH1-168.GIF?23-12

 

This clearly highlights where the primary PV is and how pressure may build to the W and NW of the UK, given the possibility of higher pressure over and to the west of Greenland. However, if the ECMWF is correct in this instance and to an extent the GFS, then consolidation over the pole will probably reduce this more meridional flow (of late) and most probably signal a more typical zonal flow with particularly low heights over Greenland and surrounding regions as we progress into December.

 

I'm a fan of winter and cold weather, but as with a few of these years past I think this one will be another waiting game by the looks. December 2010 aside, there's not many December's in the UK that produce "the goods" and it takes time for possible 'cold patterns' to develop and I believe this year will be the same. As long as Christmas isn't a repeat of 2011 I don't care!

 

A case of 'putting a pin it' with regards to this thread for now.

 

Cheers, Matt.

 

NB: Here's another example from the 00Z GEM regarding the possibilties whilst the PV remains 'out east' over Siberia. If this verifies then it would be interesting, but not a fan of the GEM long term, short term excellent model though.

 

http://www.wetterzentrale.de/pics/Rgem2401.gif

Edited by MattHugo
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Yes, that pretty much sums up what I have been saying - I hope that the MOD thread factors it in to avoid any emotional rollercoasterPosted Image  Patience may be the watch word for the first period of winter - or a flight across the atlantic to find where the cold and snow is instead !!

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Signs of increased wave 1 and wave 2 activity at the 10 day range, but we need more....  more!!! Doesnt look to be enough to do anything other than cause a faint ripple.

 

Agree with posts this morning. Agree with nothing remarkable before Xmas bar a W to NW flow with enough arctic input to give the Cairngorms a very good start to the ski season.

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Not that I expected there to be at this stage of winter..

 

 

From the initial post in the thread, for November so far the 30hpa plot and predicted, looks like a solid result coming up for November, let's hope this continues and the Jan / Feb predictions follow the same route.

 

post-7292-0-30811000-1385205466_thumb.gipost-7292-0-09878200-1385205515_thumb.pn

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Some interest still in Wave 2 activity.

 

D4 forecast now to peak at moderate strength

post-5114-0-32484300-1385282753_thumb.gi

 

Then, interesting, a further bout appearing at the tail end of the run...

post-5114-0-59026100-1385282823_thumb.gi

 

I'm not convinced we are looking at significant enough activity to overly trouble the vortex (yet?) as the W-QBO is helping to constantly fuel the ever growing vortex but it all helps.

 

But, crucially, the PV looks to continue residing on the East of the Meridian, so to my mind that has to be a big plus. Bottom line is, things could look a heck of a lot worse than the currently do.

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Probably enough pressure on it to help maintain the amplified westerlies that ought to prevent too much mild air for December,

 

The question is - if there is going to be any great assault on the vortex when might it come? I bow to Chio's greater experience here... any thoughts?

 

Also - I need to learn to be more on top of what we are looking for globally to produce the MT event or change in AAM to precipitate a major warming. Here my understanding is still poor. Do any of the more experienced on here have anything they look for on the global synoptic charts as a potential precursor to a warming event? Or is that a bit like asking a magician to reveal his tricks!!!

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Here you go CH these are from the Mitchell paper and show the patterns prior to / and after displacement and splitting events.

 

As for GLAAM, still working hard to unravel it.. Bloody frustrating to learn, two steps forward one back half the time.

 

Frictional Torques lead into Mountain Torques, can be monitored here

 

post-7292-0-94237700-1385326244_thumb.pnpost-7292-0-22002800-1385326253_thumb.pnpost-7292-0-29408800-1385326251_thumb.pnpost-7292-0-18632400-1385326248_thumb.pn

 

There are many good papers in the technical papers thread to have a look at also, excerpt from Baldwin 2012

 

a. Vortex displacements
Preceding these events are often anomalously low pressure
systems over North America and high pressure
systems over western Europe and the Pacific. Associated
with this are warm temperature anomalies over
Northern America and an increase in blocking over
northern Eurasia.
 
b. Vortex splits
Preceding splitting events are anomalously low temperatures
over Eurasia, with a wave-2-like pattern
observed in MSLP.
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Thanks Lorenzo - good stuff. Not sure how useful 45 day average plots are going to be to a beginner like me - cant get my head around the variations of global pattern over 45 days that might produce a composite like those in the first image but it is a starting point for my brain. Looking at the profile prior to a split not sure we would want a split anyway from that!! HP to the north and low pressure to our south in a long sausage. Looks like Jan 87 heaven as it is! Profile post split is not a lot different.

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Hmmm, increase in wave 1 activity from 12z 24th EC:

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=ha1&lng=eng

 

Decrease then an increase in wave 2 activity;

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=ha2&lng=eng

 

Probably something and nothing, but still at this juncture worth highlighting. GFS gives us nothing medium or longer term and this pattern looks distinctly ominous;

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20131125/00/372/npst30.png

 

M.

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whilst zonal winds pick up in the medium term, they drop back again post day 8. just at the timescale that we see amplification showing in the trop modelling.(co incidence?) is it the wave activity causing the ebb and flow in these winds? scary as it looks, the vortex would be even stronger if the winds were allowed to strengthen unabated.

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