Model Output Discussion 29th December - Into mid-Winter.

[Dennis]

MJO looks better now - i think things will be more clear to the winter soon

[Summer Sun]

2 minutes ago, snowy weather said:

What's the reason it is so mild in the UK and Europe is in the freezer?

I mean like what is the current synoptic setup to cause these conditions and weather split?

 

One reason is the stubborn high as we can see below

Once it finally shifts far enough west the floodgates to colder air open with highs ranging from around 3c in the north to 7c in the south

[snowy weather]

3 minutes ago, Summer Sun said:

One reason is the stubborn high as we can see below

Once it finally shifts far enough west the floodgates to colder air open with highs ranging from around 3c in the north to 7c in the south

Thank you so much, I understand. It's rotten luck isn't? They got a meter is snow south Italy . The whole of Europe is cold and snowy

[Mucka]

GFS ensembles solidly behind the Op as we might expect. That somehow makes me more confident it is wrong.

Edited January 8, 2017 by Mucka

[IDO]

The ARPEGE says no:

The GEFS at D6 have zero supporting the UKMO take. In fact a good cluster even quicker with the Atlantic breakdown. The trend is in the other direction:

D6 mean

[Summer Sun]

GFS mean and Control going for more of a westerly at t144 

UKMO going for a northerly

Let's see what ECM comes up with around 18:30

[Weathizard]

Crucial ECM tonight coming up, UKMO + ECM vs GFS is something that is normally a done deal, the GFS eventually backtracks last but in this case and because of Sod's law you can't help but worry!!

Couldnt care less about the GFS ensembles I barely look at them after their massive fails recently.

[SMU]

19 minutes ago, IDO said:

The ARPEGE says no:

The GEFS at D6 have zero supporting the UKMO take. In fact a good cluster even quicker with the Atlantic breakdown. The trend is in the other direction:

D6 mean

Sorry mate your wrong again - maybe you are rushing to prove the GFS is going to be correct-

If you compare mean with mean GFS is working towards the Euros as demonstrated @ 168 with more amplifcation on the 12z V 06z means -

12z (first ) shows more energy seperation & better amplification & a cut off low now which will migrate south with time as the pattern amplifies more...

 

Also if you zoom in on the UKMO GFS APERGE 114 v 120 its close to the UKMO over NE states in terms of flow

in order aperge UkmO GFS

 

 

Edited January 8, 2017 by Steve Murr

[Man With Beard]

5 minutes ago, Summer Sun said:

GFS mean and Control going for more of a westerly at t144 

UKMO going for a northerly

Let's see what ECM comes up with around 18:30

GFS usually good at Iceland. I'm not counting any chickens.

[nick sussex]

Please don't shoot the messenger!

...POTENT SHORTWAVE REACHING THE WEST COAST TUESDAY...

PREFERENCE: BLEND OF 12Z GFS/06Z GEFS MEAN

THE DETAILS OVER THE PACIFIC MAY BE DIFFICULT TO MODEL WITH
PRECISION...AS A FAST MOVING AND POTENT SHORTWAVE TROUGH IS
FORECAST TO SLIDE UNDER THE RIDGE POSITION AND THEN UNDER THE
BROAD SCALE GYRE OFF THE NORTHWEST COAST OF THE UNITED STATES. THE
WAVE OF INTEREST WOULD THEN SLINGSHOT INTO CALIFORNIA/OREGON
TUESDAY AND RACE QUICKLY TOWARD THE ROCKIES...WHILE THE GYRE
PERHAPS STABLES OUT AND BEGINS TO DIP SOUTHWARD AS A POSITIVELY
TILTED TROUGH. MODEL AGREEMENT IS NOT BAD...CONSIDERING...BUT
THERE ARE IMPORTANT AMPLITUDE AND TIMING DIFFERENCES. WHAT STANDS
OUT IS THE UKMET POORLY HANDLING THE NORTHERN STREAM OVER WESTERN
NORTH AMERICA...AND THE ECMWF ACTING VERY QUICKLY TO SHEAR OUT /
WEAKEN THE POTENT SHORTWAVE AS IT UNDERCUTS THE GYRE. FAVORING A
SOLUTION WITH A BIT BETTER SHORTWAVE DEFINITION...WE PREFER THE
GFS...SUPPORTED ESPECIALLY BY THE 06Z GEFS MEAN. THE 00Z CANADIAN
WAS ALSO CLOSE TO THIS PREFERENCE.
 

Its this shortwave energy that's the main point of contention as it heads across the USA and how and if it phases with low heights over the ne USA.

What the UKMO and ECM do is rush this across more quickly then this phases with low heights into one system which holds back energy from spilling into the Atlantic. NCEP will do a further update later on to include the ECM 12hrs run. In terms of the GEFS not wanting to know about the easterly, its probably the fact that most might have the same handle on that shortwave energy. Of course its not just down to this as to whether we get the easterly however we really need the ECM and UKMO to stick to their guns with their view upstream because we need that cleaner evolution. If the ECM does stick to its guns then hopefully NCEP might stop the GFS love in!

[ArHu3]

12 minutes ago, snowy weather said:

Thank you so much, I understand. It's rotten luck isn't? They got a meter is snow south Italy . The whole of Europe is cold and snowy

no it's not over here in Holland (and I mean Holland not the Netherlands) sucks too 

[IDO]

Hi Steve. That will show amplification after D7 as the GFS are now trending with the next Azores wave to build heights SW to NEE.

That is no use to the UK as we enter a milder ridge which fails to build anything cold further down the line; eg:

D8 control for example: 

2 minutes ago, bobbydog said:

Why are you trying so desperately hard to pee on everyones fireworks?

Its because the UKMO and ECM are notorious with height bias in the Greenland region at that range. I keep saying it and every time they fail but here is the link: http://www.wpc.ncep.noaa.gov/mdlbias/

Look at the UKMO 10 day bias and it is clear why the UKMO is wrong with the ridge at D5-6 IMHO. Watch the ECM backtrack.

[Don]

I believe the GFS went against the Euro models in the run up to the January 2013 cold spell, when it was stubborn and wanted to rapidly break down the spell pretty much up until the last minute before backtracking?  However, that's not to say the same thing will happen this time mind.

Edited January 8, 2017 by Don

[Geordiesnow]

6 minutes ago, bobbydog said:

Why are you trying so desperately hard to pee on everyones fireworks?

With all due respect, he is just posting what the charts are showing and it shows we can't afford to get too carried away with what the UKMO is showing. All that said, you expect the GFS to be worse case and UKMO best case as we go forward. Either way, there is nothing wrong with IDO post there.

[BARRY]

2 minutes ago, IDO said:

Hi Steve. That will show amplification after D7 as the GFS are now trending with the next Azores wave to build heights SW to NEE.

That is no use to the UK as we enter a milder ridge which fails to build anything cold further down the line; eg:

D8 control for example: 

Its because the UKMO and ECM are notorious with height bias in the Greenland region at that range. I keep saying it and every time they fail but here is the link: http://www.wpc.ncep.noaa.gov/mdlbias/

Look at the UKMO 10 day bias and it is clear why the UKMO is wrong with the ridge at D5-6 IMHO. Watch the ECM backtrack.

UKMO was right over NY when every model said cold

 

[Johnp]

As I said a couple of weeks back, in these scenarios, where there is model disagreement, always go for the one showing the mildest option.

This came true a couple of weeks back when UKMO wasn't on board and sadly I expect the same this time too!

[Summer Sun]

None of the GFS perturbations show the UKMO northerly at t144 doesn't mean UKMO is wrong of course it wouldn't be the 1st time GFS has got something spectacularly wrong in the short range                                                                                                                                                                                                                                                                                                                                                                    

A pretty big ECM coming up tonight you would feel           

Edited January 8, 2017 by Summer Sun

[Long haul to mild]

5 minutes ago, nick sussex said:

Please don't shoot the messenger!

...POTENT SHORTWAVE REACHING THE WEST COAST TUESDAY...

PREFERENCE: BLEND OF 12Z GFS/06Z GEFS MEAN

THE DETAILS OVER THE PACIFIC MAY BE DIFFICULT TO MODEL WITH
PRECISION...AS A FAST MOVING AND POTENT SHORTWAVE TROUGH IS
FORECAST TO SLIDE UNDER THE RIDGE POSITION AND THEN UNDER THE
BROAD SCALE GYRE OFF THE NORTHWEST COAST OF THE UNITED STATES. THE
WAVE OF INTEREST WOULD THEN SLINGSHOT INTO CALIFORNIA/OREGON
TUESDAY AND RACE QUICKLY TOWARD THE ROCKIES...WHILE THE GYRE
PERHAPS STABLES OUT AND BEGINS TO DIP SOUTHWARD AS A POSITIVELY
TILTED TROUGH. MODEL AGREEMENT IS NOT BAD...CONSIDERING...BUT
THERE ARE IMPORTANT AMPLITUDE AND TIMING DIFFERENCES. WHAT STANDS
OUT IS THE UKMET POORLY HANDLING THE NORTHERN STREAM OVER WESTERN
NORTH AMERICA...AND THE ECMWF ACTING VERY QUICKLY TO SHEAR OUT /
WEAKEN THE POTENT SHORTWAVE AS IT UNDERCUTS THE GYRE. FAVORING A
SOLUTION WITH A BIT BETTER SHORTWAVE DEFINITION...WE PREFER THE
GFS...SUPPORTED ESPECIALLY BY THE 06Z GEFS MEAN. THE 00Z CANADIAN
WAS ALSO CLOSE TO THIS PREFERENCE.
 

Its this shortwave energy that's the main point of contention as it heads across the USA and how and if it phases with low heights over the ne USA.

What the UKMO and ECM do is rush this across more quickly then this phases with low heights into one system which holds back energy from spilling into the Atlantic. NCEP will do a further update later on to include the ECM 12hrs run. In terms of the GEFS not wanting to know about the easterly, its probably the fact that most might have the same handle on that shortwave energy. Of course its not just down to this as to whether we get the easterly however we really need the ECM and UKMO to stick to their guns with their view upstream because we need that cleaner evolution. If the ECM does stick to its guns then hopefully NCEP might stop the GFS love in!

Or put another way, this forum may not be a pretty place to be come 6.30 tonight!

It's quite an education on here; I never knew before how much a seemingly innocuous area of low pressure on the West coast of the USA could affect our weather down the line!

[blizzard81]

4 minutes ago, IDO said:

Hi Steve. That will show amplification after D7 as the GFS are now trending with the next Azores wave to build heights SW to NEE.

That is no use to the UK as we enter a milder ridge which fails to build anything cold further down the line; eg:

D8 control for example: 

Its because the UKMO and ECM are notorious with height bias in the Greenland region at that range. I keep saying it and every time they fail but here is the link: http://www.wpc.ncep.noaa.gov/mdlbias/

Look at the UKMO 10 day bias and it is clear why the UKMO is wrong with the ridge at D5-6 IMHO. Watch the ECM backtrack.

I wouldn't be surprised if you are correct on this. I have noticed this over many years. Also the backtrack seems to happen on a Sunday evening, just to make our thoughts of going back to work even more depressing! 

[radiohead]

7 minutes ago, nick sussex said:

Please don't shoot the messenger!

...POTENT SHORTWAVE REACHING THE WEST COAST TUESDAY...

PREFERENCE: BLEND OF 12Z GFS/06Z GEFS MEAN

THE DETAILS OVER THE PACIFIC MAY BE DIFFICULT TO MODEL WITH
PRECISION...AS A FAST MOVING AND POTENT SHORTWAVE TROUGH IS
FORECAST TO SLIDE UNDER THE RIDGE POSITION AND THEN UNDER THE
BROAD SCALE GYRE OFF THE NORTHWEST COAST OF THE UNITED STATES. THE
WAVE OF INTEREST WOULD THEN SLINGSHOT INTO CALIFORNIA/OREGON
TUESDAY AND RACE QUICKLY TOWARD THE ROCKIES...WHILE THE GYRE
PERHAPS STABLES OUT AND BEGINS TO DIP SOUTHWARD AS A POSITIVELY
TILTED TROUGH. MODEL AGREEMENT IS NOT BAD...CONSIDERING...BUT
THERE ARE IMPORTANT AMPLITUDE AND TIMING DIFFERENCES. WHAT STANDS
OUT IS THE UKMET POORLY HANDLING THE NORTHERN STREAM OVER WESTERN
NORTH AMERICA...AND THE ECMWF ACTING VERY QUICKLY TO SHEAR OUT /
WEAKEN THE POTENT SHORTWAVE AS IT UNDERCUTS THE GYRE. FAVORING A
SOLUTION WITH A BIT BETTER SHORTWAVE DEFINITION...WE PREFER THE
GFS...SUPPORTED ESPECIALLY BY THE 06Z GEFS MEAN. THE 00Z CANADIAN
WAS ALSO CLOSE TO THIS PREFERENCE.
 

Its this shortwave energy that's the main point of contention as it heads across the USA and how and if it phases with low heights over the ne USA.

What the UKMO and ECM do is rush this across more quickly then this phases with low heights into one system which holds back energy from spilling into the Atlantic. NCEP will do a further update later on to include the ECM 12hrs run. In terms of the GEFS not wanting to know about the easterly, its probably the fact that most might have the same handle on that shortwave energy. Of course its not just down to this as to whether we get the easterly however we really need the ECM and UKMO to stick to their guns with their view upstream because we need that cleaner evolution. If the ECM does stick to its guns then hopefully NCEP might stop the GFS love in!

Not what we wanted to hear! I do fear there is something depressingly realistic about the spoiler GFS runs. It reminds me of the failed cold spells in 2012 (?) when GFS was first to sniff at the downgrades and ECM and finally UKMO were last to back down. ECM has a known bias for amplification as we saw back then. I really hope we won't see a repeat of that again in 2017...but I do fear it. UKMO has a "too good to be true" look to it.

[Met4Cast]

Well.. yesterday I said I wouldn't get excited while the ECM op is out on it's own. The UKMO is now in agreement with the latest ECM op. 

ECM has been remarkably consistent the last few runs but consistency hasn't meant anything so far this winter given that the only thing it's been consistent in is being wrong. 

I'd much rather be in the position we're in now with UKMO & ECM vs GFS though. Todays charts so far has given slightly more confidence in the longer range colder outcome. 

If the ECM sticks with it's guns tonight, expect the GFS to come kicking and screaming. If it backs down, it's over. At time frames of T96, there's not a lot of time for this to nail itself in. 

We'll know by tonight who's right. Given the winter so far, probably the GFS. 

[tight isobar]

Lets 'remember' there are two valid points here....

The ecm's notoriety of excelling of over amplification. .and the gfs nearly constant desire for flattening/mobility. ..leaving the ukmo to one side for now. ..

massive 12zzecm this evening. ..and should cast some decent light on prognosis. 

And yes two completely different scenarios via short waving. ...

[Geordiesnow]

I think the crucial point on the ECM run will come at 96 hours where you can compare it to the UKMO and see how much ridging we have and just how far Southwards the NWly flow gets. The UKMO has lower pressure and thicknesses than the GFS so if it looks like the UKMO at that stage, I will be encouraged. What happens after that will always be subject to change but it we see some sort of ridging like the UKMO then at the very least we should have a bit more of an extended cold period than the GFS.

At least the initial NW'ly blast looks more or less nailed barring the details, its now whether we see a quick return to more milder conditions or not.

[nick sussex]

1 minute ago, Long haul to mild said:

Or put another way, this forum may not be a pretty place to be come 6.30 tonight!

It's quite an education on here; I never knew before how much a seemingly innocuous area of low pressure on the West coast of the USA could affect our weather down the line!

Lol! Well we are governed by what happens upstream. That Pacific shortwave energy is important because its the handling of that by the models in the early stages which snowballs downstream into either a messy Atlantic picture or the cleaner one of the UKMO with that more amplified ridge.

Essentially the earlier ECM flattens that shortwave energy out this runs east then theres some amplification working south from Arctic Canada which then phases that with the low which the GFS wants to push se.

The overall NH picture upstream isn't the point of contention. The models are solid behind the PV elongating and dropping south, if you have a ridge to the east of that then the easterly is very much game on because as the PV drops south it will force the ridge ne'wards. If you don't get the ridge ahead and have shortwave energy hanging around then you get phasing and no proper easterly.

[bluearmy]

There is a middle ground whereby the outcome is more amplified than GFS but less than ecm/ukmo?  I also thought that there were more GEFS members keen to amplify the ridge further north than I saw on the 06z suite around day 7/8.

the NCEP discussion isn't great to read and many are assuming that ECM will backtrack. The eps this morning were already saying that the op solution was overdone but ukmo 12z raised expectations again. 

I'm afraid we can trust the ops post day 6/7 but the differences are well ahead of that. it's rare that either model proves to be correct with a disagreement like this. Likelihood is that One will quicken and one will slow down. Question remains is whether that completely removes the possibility of getting the ridge far neigh north to advect deep cold as far as the uk.