Model Output Discussion

[carinthian]

Good morning and it is certainly that looking at ECM and UKMO latest charts. I do not look beyond 144 hour, but up to then both in agreement for a week long cold spell at least. One day the wind flow from deepest Siberia, the next straight down from the North Pole itself. We must enjoy these situations and as for snowfall prediction, almost impossible, so just go with the flow!

C

[David-kig]

I think the GFS is over cooking the breakdown, it all happens very very quickly, before you know it the whole of EU is warm again, i can't see this coming off, not of course saying we won't become warmer, i think we will, but in the process will see a good dumping of snow. Lets hope though that the METO has got there 16 day forecast right, and that the cold does stick around over christmax, would be nice to see for a change.

yes there is hints but as you say proberly over progressive in terms of a breakdown. if im correct ukmo doesnt even look like having a breakdown so i wouldnt worry aout a break down at te moment. as its in f1 2 it will change like everything is. the genral pattern is still changing alot which is quite surprising

[Iceberg]

Yet another stunning ECM chart it's at 168Z which is a bit FI ish, bit the consistance has been their to sit up and take notice.

*Remember we are not saying you have to wait this long for snow(This is as well as wed/thur/fri

This is sub 520 air, Heavy snow, slow moving fronts the absolute works, thanks to the LP coming out of Scandy and the fantastically placed GH.

[cooling climate]

Excellent charts this morning with the Euro's leading the way and the GFS now trying to catch up.

ECM is rock solid again this morning and the t192 chart that should be out shortly should be an

absolute cracker.

With the Euro models outputs this morning the country file programme today should silence the

doubting Thomasa's.

Lovely easterly feed from the Euro's this morning with a bitting east wind and snow showers

the middle of the week onwards looking very cold and wintry.

Deep FI but if ECM is right then rather than a break down the cold digs in even harder.

Edited December 13, 2009 by cooling climate

[Iceberg]

very good chart thanks for that

No probs, there is FI but even the realistic timeframe is has 30-40mph winds, Streamers, and lots of snow and cold at 120, and snow before that at 96 as a slack low moves over.

[carinthian]

has the latest ecm come out the 00z if so can you explain is it just as good as the 12z

hi David,

Just as good if not better. Could see even deeper cold air in the vicinity of this run and if I was to predict post 144 hours, a link up of the Siberian and Greenland highs is on the cards. Then that would be the true ace card for a prolonged winter cold spell !

C

[Eugene]

Stunning ECM 00Z and GEM 00Z runs showing no mild breakdown at all throughout its run :o

[Iceberg]

If i was being honest I wouldn't rate the ECM(much as I have been raving about it) coming off like that, the LP that brings the fantastic weather, forms from a short wave modelled between Greenland and Canada at 72Z, it travels around the Arctic circle over Greenland and into Scandy, it might come off and I know that ECM is keen on it, but I want to see it on the charts in 2 days time.

[cooling climate]

No other word for it, an Absolute stunning run from the ECM this morning I think I will have to get some more

loft insulation for the pipes if this run verifies.

Bitter cold, snow, no sigh of a break down running up to Christmas.

You can't get better than this.

[Snowstorm1]

Can some one please sum up the models this morning by the look of the comments ukmo is now backing ECM and gfs is terrible but starting to follow ecm :o

[David-kig]

No other word for it, an Absolute stunning run from the ECM this morning I think I will have to get some more

loft insulation for the pipes if this run verifies.

Bitter cold, snow, no sigh of a break down running up to Christmas.

You can't get better than this.

would u say that the ukmo fully supports it? i just got a feeling that gfs has it realisticly still think that has a better chance of coming off

[Iceberg]

ECM ensembles for reading show that the 12Z yesterday although not a total outlier, was probably one of the 10-20% coldest runs, However even the EPS mean maximum temp for Reading doesn't get above 3C from Wed (when the real cold arrives) onwards.

Some days the temp won't get above 0.

I think what all the charts are showing is that the real cold and wintry weather doesn't start until Wed onwards, which has been the case for several days now.

Thursday is the real start (even the METO autogenerated maps are showing this and this is based on the poor 12Z output from yesterday).

Anyway it will be interesting to see todays 00Z ECM EPS ouput for Reading in a couple of hours time.

[Terminal Moraine]

As good as the ECM looks in the outer reaches it is a rare event to get a low moving south from the Svalbard area, and deepening as it does so; in fact without trawling through years of charts I can't remember one in winter doing what is projected by the latest ECM run, at least not to that degree.

Although the GFS may be breaking things down a bit too hastily the overall picture certainly looks more plausible and for all the criticism it did model the current area of high pressure pretty accurately from about 240 hours out.

The question is, does it model the return of the Atlantic as accurately? It's certainly been fairly consistent over recent runs in showing a breakdown shortly before christmas ( with a widespread, if temporary, snow event )and mild weather to follow.

A bit closer to the here and now and all three of the main models agree on a chilly and damp start to the week, turning cold by Thursday but with little snow apart perhaps from the higher ground in eastern areas close to the coast.

Edited December 13, 2009 by Terminal Moraine

[PersianPaladin]

Lots of variability in terms of pinning the location of that shortwave as the high ebbs NNW. Expect more variability in the output for the period going into Thursday 00z.

[Iceberg]

A bit closer to the here and now and all three of the main models agree on a chilly and damp start to the week, turning cold by Thursday but with little snow apart perhaps from the higher ground in eastern areas close to the coast.

Sorry TM, have to disagree with the last bit, Meto and ECM are showing alot of instability for Thursday, with LP moving across the south, GFS is the only model giving little snow come the end of the week.

Cheers

[johnholmes]

As good as the ECM looks in the outer reaches it is a rare event to get a low moving south from the Svalbard area, and deepening as it does so; in fact without trawling through years of charts I can't remember one in winter doing what is projected by the latest ECM run, at least not to that degree.

Although the GFS may be breaking things down a bit too hastily the overall picture certainly looks more plausible and for all the criticism it did model the current area of high pressure pretty accurately from about 240 hours out.

The question is, does it model the return of the Atlantic as accurately? It's certainly been fairly consistent over recent runs in showing a breakdown shortly before christmas ( with a widespread, if temporary, snow event )and mild weather to follow.

A bit closer to the here and now and all three of the main models agree on a chilly and damp start to the week, turning cold by Thursday but with little snow apart perhaps from the higher ground in eastern areas close to the coast.

that looks a pretty good summary of how things appear on the two models to me as well TM-both main models keep cold/v cold into about T+216 but then GFS makes the Atlantic low the main theme with EC doing its thing with the northern low-that part from T+216 looks odd, more odd than the GFS version to me.

As you say not much precip over this week certainly no large amounts anywhere on the 00z run.

Edited December 13, 2009 by johnholmes

[PersianPaladin]

As good as the ECM looks in the outer reaches it is a rare event to get a low moving south from the Svalbard area, and deepening as it does so; in fact without trawling through years of charts I can't remember one in winter doing what is projected by the latest ECM run, at least not to that degree.

Although the GFS may be breaking things down a bit too hastily the overall picture certainly looks more plausible and for all the criticism it did model the current area of high pressure pretty accurately from about 240 hours out.

The question is, does it model the return of the Atlantic as accurately? It's certainly been fairly consistent over recent runs in showing a breakdown shortly before christmas ( with a widespread, if temporary, snow event )and mild weather to follow.

Good point and I concur. I think generally the sub-polar jet tends to feed a bit too much return flow as the upper trough enters north of Scandi (in past experiences) and it skirts east of the UK into central Europe. The signal for continued block over Greenland to develop is obvious, but whether that bares any benefit for the UK appears to be among the least likely scenarios.

Like Iceberg, I think your last sentence is a bit too dismissive. There is potential for lowland convective snow showers in much of eastern England on Thursday/Friday.

Edited December 13, 2009 by PersianPaladin

[Frosty.]

The ECM 00z is about as wintry as it could possibly get in the uk with an upgraded E'ly by T+96 and then a full blown N'ly blast by T+144 which just intensifies into an Arctic blast of epic proportions, if that verified we would be looking at severe blizzards across scotland and the n.isles would probably be looking at a dec 1995 style event which brought 30 foot snowdrifts. Somehow, I can't see the reality being as extreme as those charts show and some middle ground will probably be settled on as the timeframe edges closer, excellent ukmo 00z as well which is a huge upgrade on yesterday's 12z which had toys being chucked out of prams.

[David-kig]

Sorry TM, have to disagree with the last bit, Meto and ECM are showing alot of instability for Thursday, with LP moving across the south, GFS is the only model giving little snow come the end of the week.

Cheers

well to sum things up on a point of view it could go anywhere esp gfs changing quite abit every run i hope it follow ecm but just feel its got its on way on this

whens the gfs parlell out?

[SMU]

that looks a pretty good summary of how things appear on the two models to me as well TM-both main models keep cold/v cold into about T+216 but then GFS makes the Atlantic low the main theme with EC doing its thing with the northern low-that part from T+216 looks odd, more odd than the GFS version to me.

As you say not much precip over this week certainly no large amounts anywhere on the 00z run.

Hi John/ TM-

as above-- good summary- however like Iceberg i do disagree around the amount of PPN especially on the UKMET model- at 144 the model has all the key ingredients for heavy snow in the E/SE & south-

* Deep Cold pool ( I would hazard a guess without looking the 1000- 850 thickness is in the 1270's)

* Advection over a warm sea-

* very low 500 heights-

perfect spawning conditions-

The ECM does model no cold breaking down by making sure that the pressure remains stable over Greenland generating trough disruption & allowing shortwave activity along the English Channel-

Very Dec 81- just at a better angle....

Whatever the MET go with today- all be it ECM or UKMO- the Country file forecast will be interesting ( or the farmers forecast as some of us still call it!!!!)

Steve

[Iceberg]

that looks a pretty good summary of how things appear on the two models to me as well TM-both main models keep cold/v cold into about T+216 but then GFS makes the Atlantic low the main theme with EC doing its thing with the northern low-that part from T+216 looks odd, more odd than the GFS version to me.

As you say not much precip over this week certainly no large amounts anywhere on the 00z run.

John,

I am genuinely interested do you think that the LP that the ECM and Meto have crossing the south of the country on Thursday wouldn't give very much precip ?.

To me it would be an ideal precip generator.

Cheers

[bluearmy]

as i posted yesterday, the ecm remains rock solid with its general evolution right into fi. i think the low res of the GFS past T180 is stark on the last few runs as it struggles to cope with the blocking between greenland and canada and the likely behaviour of the jet off the eastern seaboard. just as we saw astonishingly cold fi's earlier in the week, now we see mild alternatives. of course it will turn milder at some point - just seems that the low res GFS isnt the tool to trust on this one for timing.

as PP posted, the scandi trough is unlikely to quite make it as far as ecm shows but even a small correction ese would be ok. the UKMO making rather more of the iberian low by T144 which ramps up the flow. ecm and gem do not agree to this extent with gem very shy regarding CAA until the trough swings down from the northeast.

[johnholmes]

John,

I am genuinely interested do you think that the LP that the ECM and Meto have crossing the south of the country on Thursday wouldn't give very much precip ?.

To me it would be an ideal precip generator.

Cheers

to be honest Ice its not too clear just how much precip there is going to be-based on GFS very little-based on Met then maybe rather more-I'm reluctant to post saying much as some will mis read it and think lots of snow!

I'm waiting to really make my mind up for how the 12z deals with later in the week, all 3 models that is

not ducking the issue-just not totally sure of how the end of the week is going to pan out.

[Frosty.]

The southward ridging from the greenland high is much better on the ecm 00z which would keep the N'ly going longer, the gfs 00z shows less ridging and the atlantic lows are further north with a swifter breakdown. IMO the gfs is again keen to blow the cold block away without much of a fight although a snow to rain event would occur on the gfs before mild air wins but it's probably going to be very close to christmas day before a mild regime establishes or it may remain cold and blocked as the euros suggest. The gfs N'ly would bring a lot of snow showers to northern & eastern coastal areas but inland areas would probably be cold and sunny unless troughs swing south in the polar flow.

[johnholmes]

Hi John/ TM-

as above-- good summary- however like Iceberg i do disagree around the amount of PPN especially on the UKMET model- at 144 the model has all the key ingredients for heavy snow in the E/SE & south-

* Deep Cold pool ( I would hazard a guess without looking the 1000- 850 thickness is in the 1270's)

* Advection over a warm sea-

* very low 500 heights-

perfect spawning conditions-

The ECM does model no cold breaking down by making sure that the pressure remains stable over Greenland generating trough disruption & allowing shortwave activity along the English Channel-

Very Dec 81- just at a better angle....

Whatever the MET go with today- all be it ECM or UKMO- the Country file forecast will be interesting ( or the farmers forecast as some of us still call it!!!!)

Steve

hi Steve

see my reply to Ice

I'm unsure just how much both convection off the relatively warm N Sea and the overall trough/low will show on later runs-hence my making the comment I did.

I'd agree there is the potential IF the two elements I've mentioned do occur.