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Model Output Discussion - Stormy Period Inbound...

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As an aside Michael Ventrice is giving a talk today to the AMS, Subject.

 

How do we know when the Madden Julian Oscillation is actually impacting mid-lat circulation?

 

I for one hope a transcript becomes available.

Edited by knocker

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The storms for the end of the week look like verifying as damaging and extreme:

 

attachicon.gifA_48hrbw.gif

 

Apart from the storms Friday and Saturday, we have another one around a week tomorrow. The GEFS are relatively confident of this though timing, track and intensity issues:

 

attachicon.gifMeteociel_-_Panel_GEFS 16.png

 

Temps for the next week look no worse than average for the south: attachicon.gifgraphe6_1000_306_141___Londres ( 8).gif

 

The D8-10 mean anomalies show the differences between GFS and ECM. The heights in the US are more amplified on the ECM than the GFS and conversely this makes the ECM more zonal. The GFS having less energy allows greater potential for phasing the height builds in the Atlantic between the PV flow:

 

attachicon.giftest8 (2).gif

 

NOAA show low confidence re 8-14 day anomalies so it is difficult to know which way it will go; maybe towards the middle. GEM wasn't showing any height rises over the last 5 days re the signal the GEFS picked up, however yesterday their members moved in that direction and again they continue the theme. Looking through their ENS and they are as spread as to a solution as the GEFS.

 

The only main signal from the GEFS showing any sort of continuity from D10 is that the flow moves towards PM>TM so I would expect a more seasonal feel to the weather.

 

 

Hi IDO,

How is ECM more zonal than GFS?

They are both zonal, the only real difference is that ECM more efficiently (more organised) transfers the PV East and so generally keeps a cooler flow with deeper trough and makes less of the warm sectors.

This can also be seen using the anomaly charts you posted as well as the comparison charts I posted earlier explaining this.

GFS 06z runs move toward the Euros slightly but that is the fundamental difference between GFS and the Euros out to day 10 IMO.

Edited by Mucka

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Well been a few days since I last posted and today I have mixed feelings with regards to the output.

 

Firstly the signs towards a colder 2nd half of Jan continue. However my mixed feelings are that from around mid Jan it appears a colder NW,ly could develop which could bring snow showers for NW England/Scotland/Wales. My negative feelings towards this is it looks as though it will be via HP to the W of the UK rather than significant blocking towards the NW of the UK. On a positive thereafter the GFS and some GEFS members want to track a LP SE with pressure rising behind this to the N/NE of the UK bringing a possible E,ly.

 

So in summary it looks likely to turn colder mid month but this doesn't appear to be a prolonged freeze. At the moment we shall have to remain patient but I am encouraged with the trend especially as we head towards the last week of Jan.

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Massive Atlantic block in the never reaches of FI on the GFS 06z control. Is this the turning point of our winter we have had so far?

 

 

post-19256-0-51971900-1420631904_thumb.p

 

 

 

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Hi IDO,

How is ECM more zonal than GFS?

They are both zonal, the only real difference is that ECM more efficiently (more organised) transfers the PV East and so generally keeps a cooler flow with deeper trough and makes less of the warm sectors.

This can also be seen using the anomaly charts you posted as well as the comparison charts I posted earlier explaining this.

GFS 06z runs move toward the Euros slightly but that is the fundamental difference between GFS and the Euros out to day 10 IMO.

 

I have highlighted the area where the anomaly varies:  post-14819-0-96583200-1420631879_thumb.g

 

The isotherms are closer together on the ECM as it exits the US. That would probably be why the ECM transfers the PV more efficiently west to east, because of that more intense zonal flow, where as the GFS mean allows for more (potential) Atlantic ridging because it is less intense.

 

IMO.

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Snow risk not bad for Northern areas

http://modeles.meteociel.fr/modeles/gens/runs/2015010706/graphe3_1000_264_27___.gif

 

GEFS still singing the same hymn and NOT being pushed back,now showing 18th for heights to our w/sw  and low heights to our e/ne

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240  it was showing this at 300z the other day

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=0&ech=240

General cooling theme looking good.

Edited by winterof79

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I have highlighted the area where the anomaly varies:  attachicon.giftest8 (2).gif

 

The isotherms are closer together on the ECM as it exits the US. That would probably be why the ECM transfers the PV more efficiently west to east, because of that more intense zonal flow, where as the GFS mean allows for more (potential) Atlantic ridging because it is less intense.

 

IMO.

 

I have to say, based on one output as your post seems to be, you are reading rather a lot into what the two charts actually show-just my view on this IDO. I would urge cation about which, over several days shows more zonal that is if either does, and remember that consistency from each model with itself and the other main 2 is required and that is something that is not totally being shown over the past week-again in my view.

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I have to say, based on one output as your post seems to be, you are reading rather a lot into what the two charts actually show-just my view on this IDO. I would urge cation about which, over several days shows more zonal that is if either does, and remember that consistency from each model with itself and the other main 2 is required and that is something that is not totally being shown over the past week-again in my view.

 

 

Yes agree and my caveat on my initial post was that NOAA on their 8-14 had low confidence in that period and I suggested that maybe the two models would move together. We can see from ECM D7 height bias that they are over egging the US ridge hence my assumption they would move towards the GFS:

 

post-14819-0-49347200-1420634067_thumb.p

 

Though looking at the GEFS around D12 there is much scatter so all models will be struggling with the upcoming pattern variation.

Edited by i'm dreaming of...

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The GEFS at 06z has the mid Atlantic ridge with Hudson trough aligned north/south down the eastern seaboard. The Scandinavian trough more NE/SW giving a muted meridional flow. At T360 it loses the Hudson trough and the Scandinavian is aligned N/S over the North Sea but still with the mid Atlantic ridge but weaker so more zonal but then it is T360. Inconclusive so the old mantra, await the 12z.

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Following an increasingly wintry 6z op run, it's very nice to see a large number of wintry 6z perturbations. Lots of eye candy so far today and lots of potential for snowy and frosty weather during the next few weeks..things are looking better for coldies :-)

post-4783-0-60333900-1420635910_thumb.pn

post-4783-0-56836700-1420635916_thumb.pn

post-4783-0-20474600-1420635923_thumb.pn

post-4783-0-84124600-1420635929_thumb.pn

post-4783-0-51103200-1420635936_thumb.pn

post-4783-0-82587600-1420635942_thumb.pn

post-4783-0-07400700-1420635951_thumb.pn

post-4783-0-39988300-1420635959_thumb.pn

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You don't get many of these to the pound!

 

 

London ENS...

 

graphe3_1000_306_141___Londres.gif

 

Looking COLD to me!

 

Northern England 2M temps...

 

graphe6_1000___-1.9811320754716988_54.04

 

Interesting to note that the Op wasn't really a cold outlier... 

And is that a -10 i see?

 

Cheers!

 

I am highlighting this post from earlier on as it backs up my thoughts as to what may develop beyond the 11th January. What you can clearly see from viewing the ensembles spreads is for an Average to cool Temperature trend to start making its presence felt with milder days becoming fewer and farther between. All of this suggests to me that a rPM or PM sourced airmass will become the dominant flow as we head deeper into FI, of course that is not to say that TM incursions won't exist at all but days such as Friday with predicted Highs in the low teens Fahrenheit will be very much the exception to the norm, potentially writing them off for January as a whole, given the blocked Atlantic signal and lessening impact of the Azores High down from around the 13th January onwards as modelled by the ECM and UKMO

 

The NH Jet which is soon to be at record speed strength (240mph forecast) is shown to weaken by around the aforementioned latter timescale too. As indicated on the chart attached above, the snow risk probabilities for London by way of example are at low risk levels at best, although that's quite something given the lack of snow since March 2013 in this region and I anticipate they will remain that way until the NH Jet does weaken. In fairness, this aspect proves there is not too long to wait, should you be of a cold Winter disposition and is another signal to grasp while we can. By which time, during early next week I anticipate the outputs will inevitably increase wintry potential further South with D4 through to D7 charts, i.e mid-January and beyond providing more hope for widespread wintriness than at any time during the season so far, although I would expect transient snowfall/wintry showers to be the main theme of the weather when it does arrive. 

 

For now, I would anticipate that we should forget about wanting the rarity of entrenched deep cold but we should embrace the PM flows and its associated streamers which might well lead to something better along the line. A Channel Low development remains an intriguing outsider for the middle part of January according to a few recent runs of the GFS P for Southern England, but we'll wait until the ECM and UKMO pick up on such things within the reliable.

 

Looking forward to a chilly weekend and hopefully some brightness then eyes on next week. 

Edited by gottolovethisweather

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Following an increasingly wintry 6z op run, it's very nice to see a large number of wintry 6z perturbations. Lots of eye candy so far today and lots of potential for snowy and frosty weather during the next few weeks..things are looking better for coldies :-)

Yeah I suppose those charts do look good if you live in Yorkshire!!!!!!

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Above average temps from the 06z GFS

Chart weatherbell

 

post-12275-0-72339700-1420636400_thumb.p

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Following an increasingly wintry 6z op run, it's very nice to see a large number of wintry 6z perturbations. Lots of eye candy so far today and lots of potential for snowy and frosty weather during the next few weeks..things are looking better for coldies :-)

Following on from those i thought i would take a look into my "Yorkshire outlook crystal ball" Model.Look what i found...

http://modeles.meteociel.fr/modeles/gens/runs/2015010706/graphe3_1000___8.113207547169807_61.740890688259114_.gif

 

:drinks:  shame its Norway

Edited by winterof79

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Not sure of its relevance but the sun is currently having a strong geomagnetic storm , be interesting to see what impact it has on model output in next few days and on our weather as there seems to be some sort of correlation with sun activity and northern hemisphere winters

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Overall maybe, but day to day the ECM  says....

http://www.meteociel.fr/modeles/ecmwf.php?ech=0&mode=0&map=3&type=0&archive=0

Probably cool/cold for many.Very questionable.

 

The ECM op for the next 10 days average at worse for London with many much milder days:  post-14819-0-00709000-1420637536_thumb.g

 

Not many cold nights either so that looks a clear CET positive anomaly period, which currently stands at +1.9C to the 6th. So far from November, +2.0c (Nov) and +0.8c (Dec). Sums it up!

Edited by i'm dreaming of...

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I look at the bigger picture, those perturbations bring wintry weather to all parts of the UK. I never use any imby bias to my posts..ever!!!!

Having run through the GEFS both on the 0z and 06z runs there are some reasonable charts as you have posted (and no reason why you shouldn't have either :-)).

That said, these are snapshots at certain points within a predominantly zonal set up. Running through the individual members most are rattling things through west to east at a good lick. Also, there is no getting away from the fact that the biggest signal right out to the end of FI is now zonal across the GEFS. This trend was evident yesterday (albeit the pub run ensembles moved back the other way). I think the 06Z set are even more zonal than this mornings early morning run.

Time will tell of course but I don't really see any change at the moment. The zonal signal is not as overwhelming as it was leading into this week, so it could change after 10 days, but its still odds against. Based on gut feeling and experience I suspect that we are looking now to the very back end of the month at earliest.

Not convinced by some of the snow projections we are seeing from GFS either. Although, purely my opinion and therefore accepting others will disagree I tend to ignore any projections of widespread lowland snow on a PM northwesterly as in practice it very rarely verifies (Steve Murrs hen's teeth come to mind).

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The ECM op for the next 10 days average at worse for London with many much milder days:  attachicon.gifensemble-tt6-london ( 8).gif

 

Not many cold nights either so that looks a clear CET positive anomaly period.

Hence my post was for many,and backed up by the 850s which would not relate to above average for many Midlands northward.

Surely people must understand that in summer London is several degrees warmer but in winter the opposite.As shown here for e.g.  http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-4-168.png?6

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I have highlighted the area where the anomaly varies:  attachicon.giftest8 (2).gif

 

The isotherms are closer together on the ECM as it exits the US. That would probably be why the ECM transfers the PV more efficiently west to east, because of that more intense zonal flow, where as the GFS mean allows for more (potential) Atlantic ridging because it is less intense.

 

IMO.

 

 

Hi IDO,

Right I'm with you but I don't see any potential for a ridge within the 10 day time-frame within GFS, only more prominent warm sectors which is why ECM is the better run IMO. GFS just delays the transfer and so has low pressure forming further West causing more of SW/NE gradient to the flow and bringing the Azores high more into play.

I guess it is semantics whether one run is more zonal than another but they are both very zonal, sometimes the GFS is windier, sometimes ECM.

Edited by Mucka

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Hence my post was for many,and backed up by the 850s which would not relate to above average for many Midlands northward.

Surely people must understand that in summer London is several degrees warmer but in winter the opposite.As shown here for e.g.  http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-4-168.png?6

 

Of course colder for anyone in the north and Scotland but as the CET shows anyone south of there (the majority) have experienced a mild NDJ so far and no changes in the next 10 days IMO. Most people live in cities so showing a city forecast is fair.

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