Model Output Discussion - 18z - 25th Nov onward

[Cloud 10]

All eyes on the ECM tomorrow morning.

Will it be more of this.. or this..

[Staffordshire]

i rarely post in here but i have never seen such a mix in thoughts and emotions over a few hours haha! im fairly confident now though!

[Panayiotis]

Looking at Accuweather, it has below temps for my area for the 1st half of December!

Edited November 26, 2012 by panayiotis

[Great Plum]

Looking at Accuweather, it has below temps for my area for the 1st half of December!

Isn't that because it takes those temps off the latest GFS run?

Some excellent ensembles for what it's worth from the 18z tonight...

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Better the further north you are but even in London, the mean stays at around -4/-5 for quite some time and is below average throughout...

[Panayiotis]

Isn't that because it takes those temps off the latest GFS run?

Some excellent ensembles for what it's worth from the 18z tonight...

http://www.netweathe...;type=ens;sess=

Better the further north you are but even in London, the mean stays at around -4/-5 for quite some time and is below average throughout...

Probably yes but it has been showing this for quite some time now.

Edit:Chart now in original post.

[Weathizard]

Ensemble mean for my location not great when you compare it to northern areas, I look on with envy sometimes in spells like this! Still not going to get too hung up on all that, far too much still to come to the fore too take ensemble means ect as gospel.

I shall look forward to the 00z's, SURELY the ECM must back down, if it doesnt in the next two runs then I will be very worried as if it doesn't the GFS/UKMO probably will.

[Thundery wintry showers]

The key differences around T+120 to T+192 are associated with the re-invigoration of a northern arm of the jet and building pressure to the south which, on the ECMWF operational run, ends up seeing low pressure systems track over northern Scotland by T+168 and cutting off the northerly flow.

http://cdn.nwstatic..../ecm500.168.png

The GFS 18Z also gets there eventually, but the lows coming in off the Atlantic keep filling out and sinking underneath the extensive Arctic blocking through the high resolution part of the run. For instance at T+168 we see the jet aligned NW-SE at our end of the Atlantic and keeping depression tracks to the south of the blocking, keeping us in a northerly flow:

http://cdn.nwstatic....168/h500slp.png

The ECMWF ensemble mean shows a fair amount of support for a breakdown of the northerly regime but at T+168-192 the operational is a clear mild outlier, as the ensemble mean 850hPa temperatures never get above the 0C mark. Even on the ECMWF the breakdown occurs at T+168, and in these sort of "northern blocking" setups I've known the models go for a breakdown as soon as T+120 only to ditch it completely (I remember a few UKMO runs bringing in mild SW'lys during the December 2009 cold spell for instance)

Edited November 26, 2012 by Thundery wintry showers

[SnowObsessor90]

This is certainly going a tense few hours coming up, hopefully I won't be waking up to people saying "credit to ECM", anything else would be quite frankly a bonus.

[Cheshire Freeze]

RE: 18z run......awesome synoptically, even in FI with repeated snow events possible. Especially good when compared to ECM. I fear a switch from UKMO and GFS in the morning though......how often have we seen that eventuality?!

[Cheshire Freeze]

This is certainly going a tense few hours coming up, hopefully I won't be waking up to people saying "credit to ECM", anything else would be quite frankly a bonus.

ECM is the daddy of the models, rarely wrong at that timeframe! This is what I meant when I said people should keep a level head the other day!

[Snowy Easterlies]

or how about some sort of middle ground how often do we see that eh

[Snowy Easterlies]

ECM is the daddy of the models, rarely wrong at that timeframe! This is what I meant when I said people should keep a level head the other day!

agree the blind faith can be equally annoying as the pessimistic posts, a level head is the right way to view things

[lorenzo]

ECM Winning - cannot disagree there - so not wrong at that time frame (usually) NOAA put a big line underneath it - if it is wrong then a continued wobble until 1900 tomorrow - key story is will the UKMO hold.

Right now though FI is 96 hours and right on it is that Canadian Low exiting NE CONUS > Greenland.

Time yet...

[london-snow]

@CrewCold - Unless i have been viewing a diffrent n-w forum thread over the past week than in my mind people have been level headed. Posters will always share diffrent views on the same output owing to their locations.

I think we all knew that the change to cold was never straight forward let's face facts it never is. However i must admit i am not too down in the dumps with the ecm tonight as some are. Faxes and the other big two are going against add to that a very good forecast shown on the countrylife this evening and also a good update from the noaa stating that they don't agree with the ecm at this point in time.

Positive for me going into the morning.

[LomondSnowstorm]

ECM Winning - cannot disagree there - so not wrong at that time frame (usually) NOAA put a big line underneath it - if it is wrong then a continued wobble until 1900 tomorrow - key story is will the UKMO hold.

Right now though FI is 96 hours and right on it is that Canadian Low exiting NE CONUS > Greenland.

Time yet...

It's gripping, I'll tell you that much, at least one of the great model watching spells this forum's seen. However, for me, there are three key factors here, two of whom are leaning towards me supporting the UKMO and the other of which is still in progress at the moment.

1) The NOAA guidance has been pretty bullish over the cyclogenesis of that low. Given that it essentially has local knowledge it'd be hard to go against that, but equally it's hard to go against the ECM at that timeframe too.

2) The Fax chart. Although clearly the Met Office are more likely to go with their own model, the fact that MOGREPS is being so bullish about it and that they went directly with the UKMO with no alterations suggests they are relatively confident over this one. But again, we've seen them being wrong before.

3) And this is something I didn't notice until now which is unfortunate because I feel this is one of the key points here: there is actually a high resolution US model that goes out to +84 called the NAM, which, I believe, is THE critical model at the moment and is in the process of finishing off its 00Z run. It only covers the US but it goes sufficiently far east to cover the area, and if this sides with UKMO it'd be very hard to see the ECM being right here.

[Cheshire Freeze]

@CrewCold - Unless i have been viewing a diffrent n-w forum thread over the past week than in my mind people have been level headed. Posters will always share diffrent views on the same output owing to their locations.

Without wanting to sound argumentative,some members have not been level headed in the slightest; taking it as a given that we WOULD see a severe winter spell rather than understanding the rules of probability.

[asjmcguire]

How quickly people forget the rollercoaster between the GFS and the ECM in November 2009 AND December 2010.

First the GFS was on board and the ECM wasn't.... then the ECM backtracked and followed the GFS just in time for the GFS to change to the sort of output that the ECM had previously been showing back and forth and back and forth - until eventually the models all started falling in line - with the odd "oh god here it goes again" run from time to time.... what is even more annoying - is that at least 2 other people have pointed this out in this very thread and yet - everyone has completely ignored it. NO weather model is infallible and it doesn't matter how wonderful and glorious you believe your favoured model to be, all models have flaws and biases, all models have data quality issues and all models can perform below expectations. By all means air your opinion on the output of the models - but you don't have to ram your point of view down other peoples throats!

[SnowObsessor90]

ECM is the daddy of the models, rarely wrong at that timeframe! This is what I meant when I said people should keep a level head the other day!

We'll see, if it does indeed turn out to be game over in the next few hours then you can rightly give yourself a pat on the back for constantly taking the glass half empty/balanced approach but for now I'd rather remain hopeful. It's better than the other option of crying myself to sleep anyway.

[LomondSnowstorm]

Ok, my final post of the night. The North American Mesoscale Model 00Z for Thursday at 12pm:

The 12Z ECM for Thursday at 12pm:

The 12Z UKMO for the same timeframe (note isobars are every 4mb instead of 2mb as per above charts):

Clearly the crucial low off the eastern seaboard is much deeper than the ECM and closer to the UKMO (depth of 996mb I believe). This means that the ECM 12Z would have to be significantly better at modelling the eastern seaboard at +96 hours than a US based mesoscale model at +84 hours for it to be correct. I'd be surprised if the ECM didn't back down today on this basis.

Edited November 26, 2012 by LomondSnowstorm

[Wilxy]

Half an hour to go then its time to see whether the gfs 00z can continue its trend along with the UKMO, and hopefully the ECM will come on board, even if it doesn't it will be intresting either way to see what the models come up with.

[dallas]

If I remember correctly we had the same model concerns in 2010, then all of a sudden complete model agreement at T96 and everybody wodering what all the fuss was about

[The Eagle]

@ 72 hrs it does not look like the 00z GFS is going to back the UKMO unfortunately. Hope i'm wrong.

[Cheshire Freeze]

Maybe towards the ECM here.... low exiting eastern seaboard looks like it's going to push energy east rather than north. Coup for the ECM?

[Zenarcher]

It does look like the GFS 00z is starting to agree with the ECM now.

[Cheshire Freeze]

It does look like the GFS 00z is starting to agree with the ECM now.

Like I said earlier, the writing was on the wall. The ECM is rarely wrong at that timeframe.

Let this be a lesson to people getting ahead of themselves before we have proceedings within the 96-120 hours timeframe.

Edited November 26, 2012 by CreweCold