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Model output discussion - 20th Feb onwards

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2 minutes ago, Nouska said:


Signs in the 8-14 day chart of the high moving north and low heights moving into Iberia from the NE. If the pattern is in regression mode, maybe not so easily identified on the NH section the NOAA chart shows.

The analogue chart, centred day 11 - some cold March CET figures in the years featured.

500hgt_comp_00gfs814.gif

 

Just wondering what those analogue charts are of please?

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2 minutes ago, feb1991blizzard said:

Just wondering what those analogue charts are of please?

500mb height anomalies which are related to pattern reanalysis going back in the archives. Details below link.

http://www.cpc.ncep.noaa.gov/products/predictions/erf_tools_info.php?outlook=610&var=500&tool=an

Product Interpretation: The upper air map shows the 500 hPa heights (black lines, meters) and anomalies (red for positive, blue for negative, meters) which result from averaging together the observed maps having the 10 highest pattern correlations with the official forecast. These 10 analogs are selected by performing a pattern correlation of the official forecast with observed maps in a 35-day time window centered on the centered date of the forecast, over the Pacific-North America region (60W westward to 175E, 20N to 70N), for observed maps from 1950 to 2010, and ranking the maps by their correlation scores. The 10-analog average map is then correlated with the original forecast over the PNA region, and the value of the correlation is listed in the upper left corner of the map. The 500 hPa anomalies represent the deviation of the forecast from the 1981-2010 average of 30 observed 500 hPa height maps for the same calendar period covered by the forecast. For 6-10-(8-14-)day forecasts, the averaging period of the forecast covers the centered date listed at the bottom of the image and the 2(3) days before and after the centered date, for a total for 5(7) days.

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2 minutes ago, Nouska said:

500mb height anomalies which are related to pattern reanalysis going back in the archives. Details below link.

http://www.cpc.ncep.noaa.gov/products/predictions/erf_tools_info.php?outlook=610&var=500&tool=an

Product Interpretation: The upper air map shows the 500 hPa heights (black lines, meters) and anomalies (red for positive, blue for negative, meters) which result from averaging together the observed maps having the 10 highest pattern correlations with the official forecast. These 10 analogs are selected by performing a pattern correlation of the official forecast with observed maps in a 35-day time window centered on the centered date of the forecast, over the Pacific-North America region (60W westward to 175E, 20N to 70N), for observed maps from 1950 to 2010, and ranking the maps by their correlation scores. The 10-analog average map is then correlated with the original forecast over the PNA region, and the value of the correlation is listed in the upper left corner of the map. The 500 hPa anomalies represent the deviation of the forecast from the 1981-2010 average of 30 observed 500 hPa height maps for the same calendar period covered by the forecast. For 6-10-(8-14-)day forecasts, the averaging period of the forecast covers the centered date listed at the bottom of the image and the 2(3) days before and after the centered date, for a total for 5(7) days.

Thanks.

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The mounting excitement generated by one run at 06z doesn't seem to have bee transmitted to the GEFS 06z anomalies. An oversight that I'm sure will be corrected shortwith as I'm positive the 06z det. cannot be wrong.

gefs_z500a_5d_nh_41.thumb.png.0e7c634262gefs_z500a_5d_nh_61.thumb.png.eb7e19344agefs_t2ma_5d_eur_45.thumb.png.f10c9b9605

And back to zonaliy as is previously indicated by the EPS at 00z

Out of interest the ECM upgrade starts at 12z tomorrow.

gefs_z500a_nh_61.thumb.png.bd3efe05b348e

 

Edited by knocker

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Indeed, as expected the GFS operational was a massive outlier, and the coldest run of the bunch - the bulk of members still going for the milder upper air holding out here, before gradually trending colder (rather than a huge initial blast of cold). One to keep an eye on, but for the moment it appears this has a low-ish probability.

Edited by mb018538

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10 minutes ago, chionomaniac said:

Now - you are not hand picking charts here are you knocker?  For instance - the T2 5-10 day mean anomaly chart would be overridden by the strong WAA seen at the beginning and middle of that period rather than the CAA right at the end. And the H500 anomalies tend to fit in with the overall expected pattern. The 06Z is the extreme version of this pattern and possible for the UK but probably somewhere in Europe will see the CAA hit hard.

 

Days 11-16 850 anomaly pattern

gefs_t850a_5d_nh_65.thumb.png.fbd672636f

Naughty boy!

 

 

It hurts me that you think I  would stoop to such calumnies chio. Oh I'm not doubting CAA into Europe but as yet I need to see some support for this from the EPS in the medium time frame vis the UK which is what we are talking about here. After that well..........................

Edited by knocker

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26 minutes ago, mb018538 said:

gefsens850London0.png

So both control and deterministic gone that way now....

Interesting.

MIA

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1 hour ago, mushymanrob said:

sorry old chap, i dont agree with that satatement, these charts have been most consistent now for several days, of course there has been tweeks but youd expect that in an ever changing atmosphere, but no more that id expect.

they are a very long way from supporting these fi cold charts, which have a habit of modifying greatly - they have done so every time such cold charts are shown in fi this whole past 5 months.

i have no idea what day 16 might bring, or the second half of this month , ill stick with the noaa's, when they show something - ill believe it

The first NOAA chart I showed - a tiny bit of amplification. The second one - a lot of amplification. I suppose we could agree to disagree on what a "tweak" means ;)

I just think it's important to have open discussion about the NOAA, because although it's useful it's not gospel. I think it needs questioning when it stands alone - and indeed, when any anomaly chart opposes the ops/clusters starkly. For instance, about 4-5 days ago John Holmes categorically stated that the NOAA and other anomaly charts showed "no potential at all" for the Azores High to move over the UK - well, here's today's ensemble means for just D7:

gens-21-1-168.png

EDM1-168.GIF?07-12

 

 

Edited by Man With Beard

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58 minutes ago, Man With Beard said:

The first NOAA chart I showed - a tiny bit of amplification. The second one - a lot of amplification. I suppose we could agree to disagree on what a "tweak" means ;)

I just think it's important to have open discussion about the NOAA, because although it's useful it's not gospel. I think it needs questioning when it stands alone - and indeed, when any anomaly chart opposes the ops/clusters starkly. For instance, about 4-5 days ago John Holmes categorically stated that the NOAA and other anomaly charts showed "no potential at all" for the Azores High to move over the UK - well, here's today's ensemble means for just D7:

gens-21-1-168.png

EDM1-168.GIF?07-12

 

 

i find the anomaly charts are pretty stable, for a period of 'x' days then they have a re-alignment .... abit like correcting yourself whilst driving through fog at night. the charts you posted shows just that. what i dont think ive ever seen with them, is a total switch - replacing high with low/positive with negative.

ive found that when the anomalies stand alone, they are still proven accurate more times then not. that has happened several times over the winter period - remember those stunning easterlies? noaa's said no... they were correct and just yesterday the gfs and ecm op runs backed off from their over progressive eastward track . the noaa's said 'no' and they again were proven accurate.
 

as i see it, its about % 's... which suite is most accurate for the timespan in question, NO one model is infalible, the noaa's are not always right. but they do appear to be more accurate , no, they ARE more accurate then the ops for the timeframe they pertain to.

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1 hour ago, Man With Beard said:

The first NOAA chart I showed - a tiny bit of amplification. The second one - a lot of amplification. I suppose we could agree to disagree on what a "tweak" means ;)

I just think it's important to have open discussion about the NOAA, because although it's useful it's not gospel. I think it needs questioning when it stands alone - and indeed, when any anomaly chart opposes the ops/clusters starkly. For instance, about 4-5 days ago John Holmes categorically stated that the NOAA and other anomaly charts showed "no potential at all" for the Azores High to move over the UK - well, here's today's ensemble means for just D7:

 

Well here is the 8-14 from five days ago. Judge for yourself.

814hghts.20160302.fcst.thumb.gif.9723fee

I see absolutely no need for yet another discussion about the NOAA as it has been discussed ad nauseum and there is nothing to be gained by yet another repeat. John has explained his rational for using the charts on numerous occasions supported by statistics from his extensive archive. Also accompanied by an explanation on how to use them. Now given his many years experience as a senior forecaster I find this pretty compelling.

At the end of the day it's just down to individuals whether they use them as a very useful guide or not but given the abject flummery that is often accepted in this thread without question, often in fact with great elation, I find the continual 'questioning' of NOAA distinctly odd. Or do I?

Edited by knocker

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2 hours ago, Nouska said:


Signs in the 8-14 day chart of the high moving north and low heights moving into Iberia from the NE. If the pattern is in retrogression mode, maybe not so easily identified on the NH section the NOAA chart shows.

The analogue chart, centred day 11 - some cold March CET figures in the years featured.

500hgt_comp_00gfs814.gif

 

id agree there are signs of pressure building northward, and indeed a high cell centered over/just to our north, wouldnt suprise me. that though is just 1 option that can be gleaned from these charts, on the other hand of course it might just end up as a weak ridge northward off the main cell centered further south.

one thing they dont currently allow for though is that large anticyclone over scandinavia the current ecm predicts. and i suspect that why posts championing the noaa's are unpopular - because they dont currently allow for that easterly so many seem to desire.  of course the ops might be proven right, the noaa's inaccurate on this occasion - time will tell.

never really got my head around those analogue charts, they (like other data sources) require extra time getting to understand fully. i like the 500mb charts because they are easier to understand, and are proving to be pretty accurate  that suits my level of understanding. :)

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3 minutes ago, knocker said:

Well here is the 8-14 from five days ago. Judge for yourself.

814hghts.20160302.fcst.thumb.gif.9723fee

I see absolutely no need for yet another discussion about the NOAA as it has been discussed ad nauseum and there is nothing to be gained by yet another repeat. John has explained his rational for using the charts on numerous occasions supported by statistics from his extensive archive. Also accompanied by an explanation on how to use them. Now given his many years experience as a senior forecaster I find this pretty compelling.

At the end of the day it's just down to individuals whether they use them as a very useful guide or not but given the abject flummery that is often accepted in this thread without question, often in fact with great elation, I find the continual 'questioning' of NOAA distinctly odd.

well said sir!
bib - i think that only happens when they dont support a current op run showing a desired synoptic chart...

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3 minutes ago, mushymanrob said:

i
never really got my head around those analogue charts, they (like other data sources) require extra time getting to understand fully. i like the 500mb charts because they are easier to understand, and are proving to be pretty accurate  that suits my level of understanding. :)

Just treat them as you would an the anomaly chart Mushy.

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22 minutes ago, knocker said:

Well here is the 8-14 from five days ago. Judge for yourself.

814hghts.20160302.fcst.thumb.gif.9723fee

I see absolutely no need for yet another discussion about the NOAA as it has been discussed ad nauseum and there is nothing to be gained by yet another repeat. John has explained his rational for using the charts on numerous occasions supported by statistics from his extensive archive. Also accompanied by an explanation on how to use them. Now given his many years experience as a senior forecaster I find this pretty compelling.

At the end of the day it's just down to individuals whether they use them as a very useful guide or not but given the abject flummery that is often accepted in this thread without question, often in fact with great elation, I find the continual 'questioning' of NOAA distinctly odd. Or do I?

Knocker - Mushy - I am not questioning the NOAA. I think it is really useful, and I always check it. After all, I use it plenty of times myself as part of an overall assessment of the models. But what I cannot accept, and I think many others on here would agree, is an attitude of "the NOAA doesn't show it, so I won't believe it".

Actually, Knocker, I may well be on the very same page as you because when I saw that chart, I thought "there's a hint of the Azores High approaching the UK", and I thought "this may develop into a UK High". But what I sense from some posts on the NOAA is "this will not further develop into anything else. The NOAA says this, so this is how it will be!"

Surely the wise forecast 5 days ago would have been to say "Signs of pressure rising from the Azores towards the UK, not enough to make a forecast of a UK high upon though".

EDIT - just read your post further up the thread Mushy - yes ok, we're kind of saying the same thing then. A good guide, but not infallible. I'll let it go for now ;)

 

Edited by Man With Beard

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8 minutes ago, Man With Beard said:

Knocker - Mushy - I am not questioning the NOAA. I think it is really useful, and I always check it. After all, I use it plenty of times myself as part of an overall assessment of the models. But what I cannot accept, and I think many others on here would agree, is an attitude of "the NOAA doesn't show it, so I won't believe it".

Actually, Knocker, I may well be on the very same page as you because when I saw that chart, I thought "there's a hint of the Azores High approaching the UK", and I thought "this may develop into a UK High". But what I sense from some posts on the NOAA is "this will not further develop into anything else. The NOAA says this, so this is how it will be!"

Surely the wise forecast 5 days ago would have been to say "Signs of pressure rising from the Azores towards the UK, not enough to make a forecast of a UK high upon though".

EDIT - just read your post further up the thread Mushy - yes ok, we're kind of saying the same thing then. A good guide, but not infallible. I'll let it go for now ;)

 

bib - yep i said that...

ok its rather a basic no nonsense post that i accept might be read a bit too black and white. but on the occasions they are wrong, they do correct themselves so to be fair its hard to think of a scenario when they wont show a mean chart thatll 'allow' for a surface synoptic?
 

ill try to moderate that tone then... :)

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4 minutes ago, Man With Beard said:

Surely the wise forecast 5 days ago would have been to say "Signs of pressure rising from the Azores towards the UK, not enough to make a forecast of a UK high upon though".

 

Well i'm not going to comment on what John said as, apart from anything else, I'm not familiar with the context. But regarding the 8-14 that is rather a large spread so developments late in the run may well take a couple of days to show up. I'm sure people realise that. And in fact I find the current situation is perhaps a case in point.

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ECM1-216.GIF?07-12 ECM

gfs-0-210.pngGFS

Not a million miles away from each other. Were the  GFS OP and Control such  huge outliers ? or a trend setters?

Looks to me like the GEFS are about to latch on to something

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=192

UK Outlook for Saturday 12 Mar 2016 to Monday 21 Mar 2016:

Saturday looks set to be mild, breezy and predominantly cloudy, with occasional drizzle in the west, and more persistent drizzly rain in the northwest. On Sunday, the damp and breezy weather is expected to become mainly confined to the far northwest, whilst generally brightening-up in the south and east. High pressure is then expected to dominate well into next week, to bring largely dry and settled weather, with temperatures probably above normal. Feeling rather warm and spring-like when the sun's out, but a risk of rural frost at night, and a possibility that colder conditions could extend from the east with time. Late next week, there is a tendency for more unsettled conditions to gradually develop, with temperatures returning to near normal.

 

Edited by winterof79

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High pressure already couple of hundred miles further N than the 6z at day 6

h500slp.png

SSW effects creeping into modelling now?

Though further S at day 8....not going the quick rote to cold on the 12z...could still get there though

h500slp.png

 

Edited by CreweCold

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Colder air for parts of Europe mild air hanging on for the UK

Cc9XXWbWoAU6Bsx.jpg12_219_mslp850.png?cb=657

Edited by Summer Sun

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Afternoon all ,I have been popping in most days for a good read .some interesting charts in the further outlook if its wintry weather you are looking for ,but before then some mild in the forecast ,lets hope that synoptics for a good lowland snow fall come together in the outlook it is getting late but theres every possibility but i,m sure it will take a good deal of luck .

well i got my fix early today ,nothing settling but definate magical flakes falling to greet the morning ,take care all cheers :yahoo:

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Looks like we have a split opinion here - 6z showing what could happen if it turns cold, while the 12z shows what could happen if it stays mild. That said, with a high sat slap bang over the UK for that long it could cause an inversion and turn cool/cold after a few days. Wait and see what the ECM shows us later!

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2 minutes ago, mb018538 said:

Looks like we have a split opinion here - 6z showing what could happen if it turns cold, while the 12z shows what could happen if it stays mild. That said, with a high sat slap bang over the UK for that long it could cause an inversion and turn cool/cold after a few days. Wait and see what the ECM shows us later!

An inversion is unlikely by this time of year, though the GFS operational doe suggest increasing amounts of sunshine with a lengthening diurnal range, especially in the north and west (Frosty nights but temperatures reaching the mid/high teens by day).

All conjecture at the moment thought. UK highs are rather rare beasts these days, but they tend to stick around for prolonged periods of time when we do finally see a mid latitude block build over us. This could very well be the case this time. To be honest to get a cold result from the east at this point in the year it really does feel like a case of beasterly or bust.

Worth noting the GEM and GFS parallel (06z) both go for a similar solution to the 12z GFS operational. I would probably favour that solution at the moment and would be a bit sceptical of anything trying to move that high away too quickly (Either by developing a cold pattern to pushing the Atlantic back through).

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