Model Output Discussion - Into Winter

[rwtwm]

Thanks @Catacol & @bluearmy for the responses. 

So (checking I understand) the BOM interpretation is preferred, both because it lines up better with the background signals and because the model has a better perceived skill in that part of the world.

If the plot posted by @Met4Cast is to be believed, I guess the question of lag times and amplitude duration are moot. But I think the question is still worth considering. If the MJO rattles through 4 phases on short order, does that mean the effects don't have a chance to propagate, or does it just look like enhanced mobility to us?

I can't say I'm blown away by the velocity potential chart, because I'm not sure quite what it means. From what I've read in the last 20 or so mins, it looks like it might be to do with the jet slowing down and spreading out over the Pacific? 

I think the MJO plots I'm used to are showing convection. But maybe I've been seeing them both and not realising there are distinct measures?

[Rob 79812010]

Taking account of some of the longer term models and seemingly some confidence that the latter part of December could be colder, I think it all looks pretty good. Should be slightly below average temps at mid point, probably 0.5 to 0.7 degrees, a colder back end of the month should result in a cold December overall. 2 years running! Not so bad really

[Vikos]

39 minutes ago, Catacol said:

Another op run for Sat 16 Dec showing a wave break. 

This would be quite a fast response to the passage of the MJO though not perhaps for a resurgent GLAAM profile. 

GFS has a habit of picking up on trends at the outer edge of model usefulness, dropping them, bringing them back....and then other models grab the idea at 240h. I'm not convinced the timing is right - I think it will take longer....but Sat 16 might be a decent outer marker to bench mark trends and timings against. 

EC Control, too, as it renders 15 days ahead (op only 10 days)

[Dennis]

AO 4-12 forecast 

from 12th more interesting signs come in, lets see iceland chart HPa to it also 

[Downburst]

I tell you what. Looking a the spread of those MJO plots really tells you how hard more than 10 days forecasting is, if not borderline impossible to be honest thinking about it. If you can't get that very complex forecast correct, the the knock on effects given this etc and try to predict weather in North West Europe for 20 odd days ahead? I think it's a lesson to everyone to be conscious of that, not only do we not know what phase we will be in, we don't know the amplitude, all we have is the mean really and a good look at the spread making that mean. I'd be even more careful of this Phase 7 to 8 for end of month, it doesn't have to happen.

[Dennis]

5 minutes ago, Downburst said:

I tell you what. Looking a the spread of those MJO plots really tells you how hard more than 10 days forecasting is, if not borderline impossible to be honest thinking about it. If you can't get that very complex forecast correct, the the knock on effects given this etc and try to predict weather in North West Europe for 20 odd days ahead? I think it's a lesson to everyone to be conscious of that, not only do we not know what phase we will be in, we don't know the amplitude, all we have is the mean really and a good look at the spread making that mean. I'd be even more careful of this Phase 7 to 8 for end of month, it doesn't have to happen.

true on how you see it, weather is weather and we try to see what can happen 

all is monitoring and we like it 

[Derecho]

12 minutes ago, Downburst said:

I tell you what. Looking a the spread of those MJO plots really tells you how hard more than 10 days forecasting is, if not borderline impossible to be honest thinking about it. If you can't get that very complex forecast correct, the the knock on effects given this etc and try to predict weather in North West Europe for 20 odd days ahead? I think it's a lesson to everyone to be conscious of that, not only do we not know what phase we will be in, we don't know the amplitude, all we have is the mean really and a good look at the spread making that mean. I'd be even more careful of this Phase 7 to 8 for end of month, it doesn't have to happen.

Yup which is why I'm very cautious when there is any hype surrounding an SSW or MJO. Great tools in the energy weather forecasting market where speculation rules, sentiment is of most importance and telling a convincing story sells but whether that story manifests itself is an entirely different question altogether.

Once in a while though it comes together which is the jackpot worth chasing from a coldie perspective.

Edited December 4, 2023 by Derecho

[Big Gally]

[Dennis]

good evening all 

all the best to you  even scandi will be much warmer 

 

the winterfun will return im sure

 

 

[Metwatch]

Strong WWB (Westerly Wind Burst) event forecast into the central pacific (red colours next to 180 at mid December, positive anomalies meaning westerlies) and the MJO forecast looking like that is certainly promising to me, coupled with the +ve AAM. The forecast from the BOM also posted earlier showing a high amplitude phase 7-8 before it heads into a very weak signal as tropical convection subsides when moving out of the Pacific.

Interesting to see when the model output in the 10-14 day time range starts showing robust signals of renewed high lat blocking, but I would think by next week in that time frame. Whether this brings the cold in to the UK is very uncertain but the probablilty of it being moved from higher to somewhere in the mid latitudes does increase more than usual.

In the shorter time frame closer to our locality, a succession of deep low pressure systems will be brought in by a southerly tracking jet this week, then afterwards, potentially high pressure moving in from the Atlantic to bring a respite next week.

Edited December 4, 2023 by Metwatch

[Mucka]

GFS still very progressive with the Westerly regime but given the models now seem to be in agreement a Scandinavian ridge won't come into play in the mid term, then it is all eyes on the Atlantic again to see if we can get a substantial ridge and avoid a W based -NAO.

My original thought posted here were that any new blocking would be in the Atlantic sector and not over Scandinavia with the fear being that the Westerlies could win out entirely and we would enter a more sustained zonal spell.

The hope was that we could get some favourable developments earlier with the lows disrupting SE against the cold block, and although GFS has proved to be over progressive, that hope now seems to be over.

So now, barring a  sudden change, our attention shifts back W and just beyond the mid term but certainly not deep FI so still plenty play for on whether we can resume blocking for mid month.

UKMO V GFS 144 (GFS extremely progressive but longwave not  greatly dissimilar with both showing the trough to N of UK and potential Atlantic ridge behind. 

 

Currently GFS, GEM, Icon all show the ridge attempt being overrun, so perhaps in deep FI a Scandi ridge could be the hope from any Atlantic amplification but for now I'll be hoping for upstream improvements and WAA into Greenland.

GEM

 

Edited December 4, 2023 by Mucka

[Chesil View]

2 hours ago, Catacol said:

Another op run for Sat 16 Dec showing a wave break. 

This would be quite a fast response to the passage of the MJO though not perhaps for a resurgent GLAAM profile. 

GFS has a habit of picking up on trends at the outer edge of model usefulness, dropping them, bringing them back....and then other models grab the idea at 240h. I'm not convinced the timing is right - I think it will take longer....but Sat 16 might be a decent outer marker to bench mark trends and timings against. 

Indeed so Catacol.  16th is the very earliest I,d be expecting to see anything worthwhile. An outer early marker as you suggest.

[MATTWOLVES 3]

Something worth pointing out regarding EL nino Winters that some do not mention often.. We are a long way downstream of events around the Pacific and there is know concrete evidence that they influence our conditions in a big way,due to other variables closer to home.

The 2009 very cold winter was I think a EL Nino Winter....so yeh promising you would say...on the other hand the 2007 Winter which was also El Nino was very mild!

There is some evidence to suggest that any benefits will come via the 2nd half of Winter...ie strong PV becoming weaker and more prone to breaking down January onwards.

So many things to keep an eye on in the coming weeks...especially the state of the SPV. 

I've included a chart which shows how things can play out.

Edited December 4, 2023 by MATTWOLVES 3

[Severe Siberian icy blast]

58 minutes ago, Mucka said:

GFS still very progressive with the Westerly regime but given the models now seem to be in agreement a Scandinavian ridge won't come into play in the mid term, then it is all eyes on the Atlantic again to see if we can get a substantial ridge and avoid a W based -NAO.

My original thought posted here were that any new blocking would be in the Atlantic sector and not over Scandinavia with the fear being that the Westerlies could win out entirely and we would enter a more sustained zonal spell.

The hope was that we could get some favourable developments earlier with the lows disrupting SE against the cold block, and although GFS has proved to be over progressive, that hope now seems to be over.

So now, barring a  sudden change, our attention shifts back W and just beyond the mid term but certainly not deep FI so still plenty play for on whether we can resume blocking for mid month.

UKMO V GFS 144 (GFS extremely progressive but longwave not  greatly dissimilar with both showing the trough to N of UK and potential Atlantic ridge behind. 

 

Currently GFS, GEM, Icon all show the ridge attempt being overrun, so perhaps in deep FI a Scandi ridge could be the hope from any Atlantic amplification but for now I'll be hoping for upstream improvements and WAA into Greenland.

GEM

 

Not far away from good charts there. Once you have low pressure digging into Europe it opens the gap in the Atlantic up towards Iceland and Greenland for high pressure, and we all know what can happen then! 

[Rob 79812010]

Could anyone tell me what the op and control mean on an ensemble chart? Thankyou 

[minus10]

The op is the high resolution run of the model. It takes into account more smaller scale effects. The control has the same starting data as the op but it is lower resolution. The rest of the ens are also lower resolution however their starting data has been tweaked to reflect the variable state of the atmosphere. If the op and control runs are close then you can have more confidence that variations in output are not due to resolution...BUT...ecm has been upgraded so now all the ens have the same resolution as the op..including the control which has become a de facto op...this intended to increase the accuracy of the model...hope that makes sense... 

[MATTWOLVES 3]

5 minutes ago, Rob 79812010 said:

Could anyone tell me what the op and control mean on an ensemble chart? Thankyou 

What they mean? Ie the op the det run and the control run are similar..They are 2 runs from a possible 30 runs on gfs and as much as 50 on the ecm. With each run being started from a slightly different variation in initial conditions..the det tending to be higher resolution with the op 2nd..The mean is roughly an average of all ensembles in the run.

[Jason M]

Well, taking a snapshot of the GEFS at day 8, there is a possibility of a short northerly before the Atlantic air move quickly in. Other than that its really just a case of 'more runs needed'. Nothing overly warm, but nothing overly cold either.

[Rob 79812010]

51 minutes ago, MATTWOLVES 3 said:

What they mean? Ie the op the det run and the control run are similar..They are 2 runs from a possible 30 runs on gfs and as much as 50 on the ecm. With each run being started from a slightly different variation in initial conditions..the det tending to be higher resolution with the op 2nd..The mean is roughly an average of all ensembles in the run.

Thanks so much for that. As I'm fairly new to this, the mean sounds like a good one for me to keep my eye on . Find your posts really interesting by the way!

[Lukesluckybunch]

Azores high moving in at 144 ECM..lows moving southwest -northeast!general west southwest flow..no sign of any decent blocking!

[TSNWK]

18 minutes ago, Lukesluckybunch said:

Azores high moving in at 144 ECM..lows moving southwest -northeast!general west southwest flow..no sign of any decent blocking!

our only hope is ECM Day 9 - Cold has returned back over Scandi from day 7 - will day 10 show the slack heights to our north and north west build to the north east pumped up by our friend the greenland vortex  lobe - or will said lobe flatten the lot at day 10.

 

Start of new chase or another early night

 

[TSNWK]

3 minutes ago, TSNWK said:

our only hope is ECM Day 9 - Cold has returned back over Scandi from day 7 - will day 10 show the slack heights to our north and north west build to the north east pumped up by our friend the greenland vortex  lobe - or will said lobe flatten the lot at day 10.

 

Start of new chase or another early night

 

well kinda of tried.. was expecting worse - slim pickings when we think where we were last week, but could be lot worse and somethin we might want to see supported in the ensembles / control for starters...

 

[sebastiaan1973]

A tweet by World Climate Service. We heading to a Modoki El Nino.

[Lukesluckybunch]

11 minutes ago, TSNWK said:

our only hope is ECM Day 9 - Cold has returned back over Scandi from day 7 - will day 10 show the slack heights to our north and north west build to the north east pumped up by our friend the greenland vortex  lobe - or will said lobe flatten the lot at day 10.

 

Start of new chase or another early night

 

another boring run..any cold looks rather transient and short lived!

[Vikos]

The trend is your friend…

 

Mid-month the show will go into chapter two