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Model Output Discussion - 05/01/2016 18z onwards


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Posted
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
  • Weather Preferences: Sunshine and 15-25c
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
2 minutes ago, Chris101 said:

Hi all, I don't write much on here, but still read everyones thoughts and obviously learn a lot from the very knowledgable.

Am i right in thinking that you can have the worlds most expensive computer to model but at the end of the day accuracy comes from the data that you put into it. Now i was always under the belief that the areas we want to get the cold from are very data sparse areas compared to the amount of data that is available from the more zonal areas, am i right in thinking if you put a ton of data in from zonal areas and considerably less from our North that this is why models can be way too progressive for a return to normality.

Cheers Chris

I doubt it.. they will input data in from the world over as the climate and weather patterns are global..so not just data in our area of the world.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
2 hours ago, nick sussex said:

Never assume that things will go right with this type of set up! lol Margin for error always needs to be factored in especially when you're dealing with shortwaves and undercutting. For that reason the ECM gets a Green light from me, the UKMO Orange.

The undercut isn't just down to the high to the north but the interaction upstream of low pressure which digs the cold into the eastern USA this helps to draw energy away from the main low to the west of the UK.

Anyway I'm not here to deflate the mood, I'm happy that the ECM has picked up the UKMO baton which the UKMO has fumbled with this morning. Not quite the GB relay team disasters, as everyone knows whose been here for years I tend to get picky and look for what can go wrong, once I'm happy that theres sufficient margin for error I will ramp away!

I echo your thoughts Nick; UKMO has adjusted to a faster, further north track for the ex-subtropical low which means we're relying more heavily on the upstream low pressure interactions. I suppose the counter argument has to be that it would be unusual for ECM and UKMO to have such interactions incorrectly modelled at +96 to +120 range when they're in agreement - much more so than for GFS to be wrong, based on recent NCEP guidance.

I notice GFS has decided to add the complication of a possible interaction between the cold air over the UK and milder Atlantic air on Saturday, with a frontal snow event possible for some... but this depends on the sliding low not behaving as well as we'd like for prospects next week, as ECM for example keeps the boundary well west of the UK. 'You win some, you lose some' seems to be the message from that model this morning... :crazy:

 

Longer term, I'm not too concerned whether it turns milder again or not by next weekend, say, so long as we see some hard frosts at times during this coming spell. The reason is that I see this as a chance to pre-condition the ground to some extent ahead of Feb's potential. Those soil temps need to come down!

 

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
Just now, carinthian said:

Rtavn1922.thumb.gif.ab07fb14c9c48b109a4eRtavn1922.thumb.gif.ab07fb14c9c48b109a4eRtavn1922.thumb.gif.ab07fb14c9c48b109a4e Looks like GFS now in a rush to bring in super mild Tm overnight next Wednesday into Thursday.Any transient snow would melt away before the sleep is rubbed away from your eyes. We will see.

The lack of comments on the 06z GFS speaks for itself really, best taken with a pinch of salt past t+144. Many of the 00z GEFS members were still blocked  over the UK at t+168.

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Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.

Shocking 06z - tiny flicks in the balance  of the jet early doors have huge effects downstream - Butterfly effect I think it is called.

 

 

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Posted
  • Location: Home :Peterborough Work : St Ives
  • Location: Home :Peterborough Work : St Ives
4 minutes ago, Chris101 said:

Hi all, I don't write much on here, but still read everyones thoughts and obviously learn a lot from the very knowledgable.

Am i right in thinking that you can have the worlds most expensive computer to model but at the end of the day accuracy comes from the data that you put into it. Now i was always under the belief that the areas we want to get the cold from are very data sparse areas compared to the amount of data that is available from the more zonal areas, am i right in thinking if you put a ton of data in from zonal areas and considerably less from our North that this is why models can be way too progressive for a return to normality.

Cheers Chris

Hi Chris

 

Yes its true to a degree. This link from Reading University explains how weather models are affected by Chaos Theory   http://www.met.rdg.ac.uk/~ross/Documents/SchoolTalkA.html

For this reason, put very simply, Met Offices run ensemble forecasts varying the initial conditions to get a range of outcomes.

Your comment in regards to the data sets is I believe a well accepted fact ( or is it an urban myth) it certainly seems to be the case when the models try to model say an Arctic High then the variability of the models can be extreme

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
12 minutes ago, Glacier Point said:

[Cut to save too much repetition]

The main point to draw from this signal is that angular momentum will begin to rise again during week 3 (early Feb). This gives a stable GWO phase 7-6-5-6 type look to the pattern for the next 2-4 week period, with phase 6 being a strong attractor within the base state. Composite is very consistent and now familiar as we turn towards the back end of Jan into Feb...Scandinavian trough, anomalous ridge centred just south of Greenland. Those looking for early spring warmth in the first part of Feb may be disappointed.

56962b8d786c1_ferbphase6gwo.thumb.jpg.6e56962b850f36a_stableangularmomentumfeb.t

Thanks for your very well informed thoughts GP, looks to me like there's plenty there to support a theme of a west-based negative NAO transitioning to a more east-based affair late Jan into Feb. From that I imagine we'll be seeing a fair number of finely balanced cold/mild situations over the coming fortnight which will require strength of mind to remain cool headed throughout.

I'm waiting for GEFS to smell the coffee and stop sending the GWO toward phase 8... the usual bias at play but from your post I gather it may also be a case of the central Pacific signal not being represented well enough?

Tamara messaged me a week or so ago about the potential for such a favourable GWO orbit setting up in (early) Feb, and I have other valuable contacts indicating the same general theme as well. The potential is so very high in this respect but where exactly will a SSW fit into this I wonder?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
58 minutes ago, Nick F said:

There you go John: http://www.cpc.ncep.noaa.gov/products/predictions/814day/analog.php

06z looks quite progressive again, with lifting jet energy NE of the U.K.

many thanks Nick

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
4 minutes ago, Glacier Point said:

GFS has too much bias towards the MJO in phases 8 and 1 which invariably transposes too much negative pressure on angular momentum.

Re Strat - not sure we'll get a proper warming, more another perturbed vortex albeit a pretty significant one.

Well, that has got me thinking. Certainly the longer range model signals haven't fitted neatly into a wave-1 or wave-2 type event... but signs of the vortex getting shunted right down to Europe and elongated as well. Perhaps it could simply act to support the trop pattern developing below?

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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

Fascinating model watching recently with the outcomes evolving daily.

GFS 06z going in the 'usual' direction although when I clicked on the FI charts I thought I had made an error and brought up the UKMO / ECM 120hr charts!

Rtavn3241.gif

could there be a move back to the Scandi trough / mid Atlantic High being picked up as GP suggests? Better still if the cold block can hold through.

The Reading EPS show a lot of uncertainty going forward with cold clustering a significant feature.

t02gsy.jpg

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Posted
  • Location: Milton Keynes
  • Location: Milton Keynes

V good support for the 06 op from the GEFS ensemble it has to be said.

Mean at 144

gens-21-1-144.thumb.png.486b65c4b8a2bf15

ECM at the same time (-6) - bascially the ridge tilts to the NW rather than the NE and the euro trough is much deeper

EDM1-144.thumb.gif.740a1f42e698e59f57783

This arises because the depth of the trough in W Atlantic at t90 and the angle of it  are very different and therefore amount of energy going SE - still plenty to be resolved

GEFS t90

gens-21-1-90.thumb.png.7a63108ae356d9238

ECM T96

EDM1-96.thumb.GIF.8cd53439549e8c886140c4

 

Edited by swilliam
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

the link Nick provided, see above, shows as one would expect from similar sources, a very similar pattern to the 8-14 from NOAA last evening. What is interesting that it shows +ve heights across the large trough Canada/eastern US.

 

looking back at the post from GP on longer term connections and the 500mb anomaly charts he suggests are quite similar again to the link that Nick gave above.

Edited by johnholmes
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
  1. There are more prolonged colder blocked solutions from the GEFS 06z perturbations which hold the Atlantic at bay and the mean still looks cold out to next midweek. I have seen more than enough evidence so far today from the ukmo and ecm 00z in particular to extend and deepen the cold next week with lots of wintry options on the table and no swift return of mild Atlantic muck!:cold-emoji::)

3_144_850tmp.png?cb=781.png

10_144_850tmp.png?cb=781.png

15_144_850tmp.png?cb=781.png

21_144_850tmp.png?cb=781.png

Edited by Frosty.
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Posted
  • Location: Banbury
  • Location: Banbury
16 minutes ago, Frosty. said:
  1. There are more prolonged colder blocked solutions from the GEFS 06z perturbations which hold the Atlantic at bay and the mean still looks cold out to next midweek. I have seen more than enough evidence so far today from the ukmo and ecm 00z in particular to extend and deepen the cold next week with lots of wintry options on the table and no swift return of mild Atlantic muck!:cold-emoji::)

3_144_850tmp.png?cb=781.png

10_144_850tmp.png?cb=781.png

15_144_850tmp.png?cb=781.png

21_144_850tmp.png?cb=781.png

Totally with that Frosty

 

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
1 minute ago, Banbury said:

Totally with that Frosty

 

Cheers, I'm not concerned about what the gfs / gefs is showing when we have such stellar euro output!:cold-emoji::D

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Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.

the up and downs of the model output. It is like all the overnight runs are binned, because the latest GFS at 06Z was poor for coldies.

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1 hour ago, mushymanrob said:

......... but the noaa 500mb charts predicted that for over a week now, so im not sure why the ukmo are getting the praise!  see the attached charts for jan 6th, and 12th, they have consistently suggested this pattern which is why some of us refused to believe the gfs mild solution. (ok the latest suggests a weakening of the ridge and the atlantic systems returning later next week? ).

 

That's strange seeing as that first blended 500mb chart from the 6th is 60% GFS -

Quote

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 15% OF TODAY'S 0Z GFS ENSEMBLE 
MEAN CENTERED ON DAY 11, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 
11, 10% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 10% OF TODAY'S 
OPERATIONAL 0Z GFS CENTERED ON DAY 11, 10% OF TODAY'S OPERATIONAL 6Z GFS 
CENTERED ON DAY 11, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 
11, AND 15% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11 

http://www.cpc.ncep.noaa.gov/products/archives/short_range/2016/01/06/PMDMRD.20160106.txt

 

Ironically the weakening ridge and returning westerlies from the 12th is less GFS at 40% (though still the largest component) -

Quote

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 15% OF TODAY'S 0Z GFS ENSEMBLE 
MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 
11, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 10% OF 
YESTERDAY'S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10, 20% OF TODAY'S 0Z 
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 5% OF YESTERDAY'S 12Z CANADIAN 
ENSEMBLE MEAN CENTERED ON DAY 10

http://www.cpc.ncep.noaa.gov/products/archives/short_range/2016/01/12/PMDMRD.20160112.txt

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Posted
  • Location: blackburn
  • Weather Preferences: heavy snow/ heatwaves
  • Location: blackburn
1 hour ago, Glacier Point said:

CPC analogues rolled forward days 10-12 confirm the idea that we are heading towards an Atlantic ridge / Scandinavian trough solution in the last week Jan into early part of Feb... which might be useful as the models seem to be losing all coherence as we approach the business end of the winter.

56962a8bc1594_cpcrolledforward.thumb.jpg

Relative angular momentum has peaked in the last few days and, as tendency in relative angular momentum (the rate of acceleration or deceleration) cannot be maintained forever, some negative tendency is expected in the next 10 days. Total and relative angular momentum will however remain high as a large surplus of westerly inertia remains in the atmospheric system, demonstrative of a fully coupled atmospheric - ocean circulation.

glaam_sig1-21_90day.thumb.jpg.8f8f6c5a85gwo_90d.thumb.jpg.5a48c7bc21f69b017f89f3

That places the GWO in a quasi stationary phase 6-7 orbit for the next 10 days. Composites are a bit messy but broadly align to Scandinavia trough a deep low in the Western Atlantic. This is complicated as we are approaching a monthly change, and February's composites hold some value.

56962a773023c_gwophase7jan.thumb.jpg.84f56962a822228e_phase7feb.thumb.jpg.537cd5

But generally Atlantic attack from the south-west and re-asserted Scandinavian trough as the theme.

The GFS and EC monthly and EPS MJO signals suggest the MJO to become coherent in the Indian Ocean and towards the Maritime Continent during weeks 2-3. It should be remembered that there will remain a low frequency signal for convective anomalies in the Central and Eastern Pacific as well, so the MJO projection onto the system will be altered and angular momentum will remain high. MJO composites alone of limited value and it should be stressed again that the MJO signal needs to be transposed onto the GWO.

 

EMON_phase_51m_full.thumb.jpg.5e2b8f7be9twc_globe_mjo_vp200v2.thumb.jpg.e0a03fc5

The main point to draw from this signal is that angular momentum will begin to rise again during week 3 (early Feb). This gives a stable GWO phase 7-6-5-6 type look to the pattern for the next 2-4 week period, with phase 6 being a strong attractor within the base state. Composite is very consistent and now familiar as we turn towards the back end of Jan into Feb...Scandinavian trough, anomalous ridge centred just south of Greenland. Those looking for early spring warmth in the first part of Feb may be disappointed.

56962b8d786c1_ferbphase6gwo.thumb.jpg.6e56962b850f36a_stableangularmomentumfeb.t

As wind vectors, I would be thinking NW, N and NE, allowing for a bit of westerly flow days 7-10.

In dunces terms does this mean your torpedo is homing in on its target, or has it already hit and this is the aftermath....ta

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

ECM 00Z ensembles for London - and now there are NO mild runs before next Wednesday (20th). And no huge scatter until Friday (22nd).

Latest 15 days ensemble forecast temperature for London

However, virtually no precipitation after the 15th. Blizzards unlikely in the south-east at least. A minor snowy breakdown for mid-week is a possibility.

Latest 15 days ensemble forecast cumulated rainfall for London

So after a couple of milder ensemble runs yesterday morning and the day before, there is a decisive return here of the cold cluster that was showing last weekend. 

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Posted
  • Location: st albans
  • Location: st albans

Inertius - only 10% of that chart was op gfs.  The remaining 50% gfs was gefs

going back to Stewart's post, I was interested in the upper spread days 8/10 on the ECM earlier. Yesterday I misinterpreted this as being a renewed push of low temps from the NE. I believe it is far more likely to be the Scandi trough holding its position and continuing to influence nw Europe. (The cluster spread showing against the mean pushing the less cold uppers NE into Scandi) 

so so there is already a decent cluster of ECM members that keep the scand trough in place

 

 

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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL

 

Something to remember there perhaps, when looking at the ops.

 

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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.
1 hour ago, Nick F said:

 

I also find the NOAA CPC analog charts fairly good at picking up patterns too, these are based on official CPC forecasts for out to day 11 but using analogs of days in the past that matched the official forecast pattern within a 35 day time frame of the forecast period.

image.thumb.gif.69c3b3d4fac10b5af4cab119

more about how to interpret them here:

http://www.cpc.ncep.noaa.gov/products/predictions/erf_tools_info.php?outlook=814&var=500&tool=an

For years, I have been using these charts for the TWO CET competition monthly entries - my findings for anyone interested in using them.

They only show upstream analogues so of less value if pattern is highly anomalous to our east and any retrogression is anticipated.

They are 70% effective at picking out the likely overall temp departure in the CET region and on occasions identify some of the extremes - if you are brave enough to go with.

Used in conjunction with CET tables and the ESRL composite making page, a reasonable performance can be achieved.

I also use the GEFS analogue forecast charts that NOAA produce daily.  

http://www.esrl.noaa.gov/psd/forecasts/reforecast2/wx_maps/index.html#nh

ESRL page   -     http://www.esrl.noaa.gov/psd/data/composites/day/

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
28 minutes ago, Interitus said:

That's strange seeing as that first blended 500mb chart from the 6th is 60% GFS -

http://www.cpc.ncep.noaa.gov/products/archives/short_range/2016/01/06/PMDMRD.20160106.txt

 

Ironically the weakening ridge and returning westerlies from the 12th is less GFS at 40% (though still the largest component) -

http://www.cpc.ncep.noaa.gov/products/archives/short_range/2016/01/12/PMDMRD.20160112.txt

sorry to repeat the whole text but it i srelevant to what I'll post, even though very brief.

It is an average from whatever source, this can be GFS or whatever, but if you simply take it at face value, as I have generally done over the past 5-6 years, these 'changes' tend to even out. I have always said that great care is needed when using them and NOT to use them without looking at other outputs over the same or similar time scale. Do that and they will give good guidance for the overall weather pattern and the long wave upper air pattern over the 6-14 day time scale. They can and do give at least 5-6 days warning of significant changes in the long wave pattern, as they did with this incoming cold spell and its lasting longer than the synoptic models have suggested at times.

Each to their own of course but I find them very useful throughout the whole year. They are a bit 'iffy' at the seasonal change overs, for about 10 days I find, and like every model are unreliable if a Tropical storm/ex hrricane get into the north Atlantic.

An interesting post from Nouska-thank you for that

Edited by johnholmes
to add further information re Nouska
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