Model Output Discussion - 30th November onwards

[in the vale]

Great post Steve. I have been watching the ECM charts closely since about the 25th, and also the local ECM-based surface predictions on yr.no which have showed just how much the small NH variations can alter the local weather forecast. I agree, the ECM has pretty much kept to it's theme on the NH scale, which should be considered a good performance. However, for those folk who seem to believe that UK weather forecasting is a straight-forward science, huge frustrations creep in here when models show what they want to see one day and not the next. At anything more than (on average) 84-108 hours out, the theme is all you can rely on. Once I learned that, the stress disappears and the learning begins.

[chionomaniac]

Would agree entirely on the thoughts that the GFS under amplifies by 2/3rds whilst the ECM over amplifies by a 1/3rd, Steve. No model is perfect, but interestingly it is this issue that so often can create all the heated discussion in this thread. And quite often the UKMO is that model in the middle - it's just that it only goes to T+144!

[Mair Snaw]

Wow just spent some time reading Steve Murr's fantastic post... many thanks Steve for the time and the effort you put into constructing such a post...for somebody like myself who is pretty new to model watching i find your post's along with Nick Sussex and Teits are the ones i always look out for along with Frosty...how dull would this place be without Frosty ramping it up?? this really is what this thread is about and its the reason i come back every November till April....

[Mucka]

Thanks for the comments ( around 2 hours for the post)

Anyway- changes afoot on the GFS- Major- the jet looks like going over the Scandi low as opposed to under it this time around....

 

It will alter the post 192 projections - but possibly still to flat for a big easterly....

 

S

 

 

Fantastic post, absolutely spot on with the analysis not that my word means anything.

You might get an argument from one or two about being the first to spot the potential of a Scandi ridge though 

 

 

 

If it is ever going to get there this run it is taking the long way around. Improvements early in the run though over 12z which the ensembles should shed more light on as to whether it is run to run variability or maybe a trend to be continued tomorrow.

[bobbydog]

Would agree entirely on the thoughts that the GFS under amplifies by 2/3rds whilst the ECM over amplifies by a 1/3rd, Steve. No model is perfect, but interestingly it is this issue that so often can create all the heated discussion in this thread. And quite often the UKMO is that model in the middle - it's just that it only goes to T+144!

 

i hope that is correct Ed, the GFS is amplifying the potential scandi high in this run-

 

 

add another 2/3rds.....

Edited December 2, 2013 by bobbydog

[nick sussex]

The GFS thankfully doesn't mess around and delivers this low similar to the ECM, this is important, we don't want a flat low moving through, we need that high over the eastern USA to be sharp and dig south, this will help sharpen the troughing to the west of the UK and send more energy ne rather than east:

 

 

 

 

 

[bluearmy]

just an observation on the ecm extended. the ecm op day 10 shows a route to advecting the cold our way as the ridge spreads nw towards se greenland. this will force the rump of the split flow se and drive the depressions through s europe. the 10/15 day ecm charts do show that there is a propensity for this ridging into se greenland broad area. if a surge in the jet occurs at the same time as this movement of the ridge then this could well be the mechanism for forcing the undercut of our blocking with the southern arm taking control..

[karlos1983]

Quite a difference on the 18z compared to the 12z GFS

 

12z

18z

[Cloud 10]

The GFS thankfully doesn't mess around and delivers this low similar to the ECM, this is important, we don't want a flat low moving through, we need that high over the eastern USA to be sharp and dig south, this will help sharpen the troughing to the west of the UK and send more energy ne rather than east:

 

gfsnh-0-168.png

 

It doesn't get much sharper than that!

 

[Gavin Hannah]

At t186 on the GFS so far and the Atlantic is looking far more amplified than the 12Z.

 

[nick sussex]

It doesn't get much sharper than that!

 

gfs-5-186.png

Yes a nice way to end the evening outputs, regardless of what the lower resolution GFS comes up with we're on our way! Hopefully the SS Easterly doesn't capsize before we reach the end of our journey!

[Ali1977]

No real eastily forming on this run, plenty of time for things to change, maybe quicker than expected!!!

[Mark Neal.]

No real eastily forming on this run, plenty of time for things to change, maybe quicker than expected!!!

Maybe not, however there has been a shift over recent model runs as a whole of a potential down the line for a blocking high to the NE allowing a potential for Scandi High, wether we can get an easterly flow and bring cold upper win westwards later is still rather up for scope and something to watch out for. A continental flow for SE especially after a mild blip next week looks a form horse but model inconsistency says 'need more runs'.. Great posts by Mr Murr and Nick Sussex as usual always fun to read on here ( & Blue Army!)Keep up the good work folks! A fun winter of model output discussion to come

[bobbydog]

 

 

 

 

well if that's under-amplified...... greenland high-five......???

[BLAST FROM THE PAST]

For me I think its going to be a case of no pain no gain for time being.  Yes I believe the block to east will occur, just where, will be important.  Just as a a call it may be a close but no cigar call down the line....for now.  Fascinating model watching, but with the way the ECM edged back I won't put too much weight on a 'successfully cold' eastern block for the UK yet.  The overall idea as we progress seems sound with troughs digging south in Atlantic with main LP to our NW, a ridge to our east....but a flow from southern quadrant down the line is my early call.  

 

BFTP

[Matty M]

People need to remember how important a Greenland high is. In my experience a greenland high is key to sustaining a significant cold outbreak.

And although there are positive signs this evening with increased amplification of the rossby waves and disruption of PV, there has been one constant and that is the positioning of a very low heights in and around Greenland. If this gets in cemented for the coming months, it will be very difficult to get a prolonged cold spell to affect B&I.

[SnowObsessor90]

This run shows pretty us much in no mans land whilst the PV gathers it energys for an eventual full on  Zonal onslaught, I could totally see this happening which would pretty much wipe out the rest of this month and Jan

[cooling climate]

Lets hope the UKMO has something more inspiring tomorrow morning as

that is the only model that that seems to take the middle ground with the

ECM way, way to amplified as Steve Murr's post quite obviously shows and

the GFS lurching from one direction to the other.

The lower stratosphere geopotential charts certainly offer some hope for

a northeasterly type airflow.

[Convective]

Hopefully a bit more chopping and changing over the final few days as we approach the first winter event, albeit 36 hours doesn't seem too long parts of Scotland could see some significant falls (for so early in 'winter'), especially over higher ground. T850s widely -5°C to -10°C around northern areas and into the Midlands and even further at the moment. Like I said, hopefully a bit more chopping and changing over the final few days, namely more westerly than the low looks to set at the moment.

[nick sussex]

OMG do people realize we have 14 ECM runs, 28 GFS runs and 14 UKMO ones before we can be sure of an easterly! that would take us to T72hrs if things go well!

 

The deciding judge with easterlies is the UKMO that must be on board with the evolution if we get that far.

[bradymk]

This run shows pretty us much in no mans land whilst the PV gathers it energys for an eventual full on  Zonal onslaught, I could totally see this happening which would pretty much wipe out the rest of this month and Jan

I just died a little inside. Could you explain how you can see this happening? This run has moved towards the Scandi scenario but just does not quite make it in FI thats all, dont see any of this "zonal onslaught to wipe out december and jan that you are on about?

Edited December 2, 2013 by bradythemole

[jam]

And historically a brief warm spell and perhaps a couple of tries at an easterly before the real thing....

[bluearmy]

ECM is not way, way too amplified cc - one 'way' will do. I think that in two weeks time, those of us in the se will feel like we've been in a sustained cold spell Matty. gloomy and cold would be my expectation.

[swfc]

OMG do people realize we have 14 ECM runs, 28 GFS runs and 14 UKMO ones before we can be sure of an easterly! that would take us to T72hrs if things go well!

 

The deciding judge with easterlies is the UKMO that must be on board with the evolution if we get that far.

Take note of that final comment newcomers!!!

[bobbydog]

wibble.....

 

-edited for accuracy.....