GFS continues to hint at more amplified pattern than ECM

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gensnh-0-1-138.png

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gensnh-0-0-162.png

not bad. a cold weekend in prospect

been a while since we had an undercutting slider

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gensnh-0-1-180.png

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gensnh-0-0-180.png

Would be cold enough even down here for snow.

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gens-0-2-192.png

Hopefully cant get to work next Monday

LOL

The control is better for us cold fans

That little feature on Tuesday looks interesting on the NMM. Some cold air on its upper flank and heavy precip. ECM not showing the feature though.

GEFS6z for London appears to continue the consistent theme of recent days, although I've not bothered looking at the individual runs.

[quote=The Beast from the East;660608]

http://modeles.meteociel.fr/modeles/gens/runs/2015011106/gensnh-0-0-180.png

Would be cold enough even down here for snow.

I would agree looking like my best chance of the winter so far

Yes it does on ecm as a tiny short wave feature crossing  west to east also of intrest a little  later on ecm

@Polar Low:

Is there any reason why you quote things the opposite way round to the norm? It's making your posts very hard to follow :-)

To my untutored eye, this (12z) looks better than the 06z at the same point:

http://www.wetterzentrale.de/wz/pics/Rtavn1501.gif

J F F

This will please a few, very fast moving band

This might sound like a daft question, but which areas tend to get snow on a genuinely cold WSW'ly?

Trying to decide whether it's worth getting interested in Tuesday night's prospects. NW England does well on a WNW'ly, not sure about a WSW'ly, maybe we'll stay generally dry with some shelter from the welsh mountains?

It's a relatively rare setup so if anyone is in the know... ? 

J F F

Some more wintry ppn falling at the end of the week.

GFS and GFSP both struggling to get the cold air down next weekend and as a consequence we get a wintry mix rather than snow in southern and central regions. I think with these topplers you generally need them to hang around a tad longer than is currently being shown if you live farther south in the UK. Could be a non-event down here in terms of wintry precip next weekend.

Stop being a party pooper Brian - a little bit of hope is all that some of us have been left with.

Yes, I know you are calling it as you see it, but you don't have to be so brutal - please leave us with some illusions, however misguided they might be.

I need to be careful how I respond MM
I've stated all along that it's unlikely to be any more than a transient wet snow event for many if at all (Tues and Fri/Sat) and then back to the westerly. Would love to be proved wrong though.

Not everywhere in the NW will miss out, in a WSW flow places like Burnley northwards should do well - that's if the precipitation is actually in those areas. I think south of that area could get some sort of rain/snow shadow because of the Welsh mountains but in my experience we can still get some accumulation but not as good as a WNW flow. If it was a SE flow on Tuesday I would be more worried about missing out on the best of the snow. There isn't a worse wind direction than that.

For the record, you said this:

You then bowed out of the model output discussion as you were getting frustrated.

I've said all along that there's a decent chance of a colder-than-average week as it has been shown by the ensembles as being reasonably likely for over a week. Nobody was ever predicting snowy armegeddon down here. I did post when the ECM control run was showing snow and others posted some snowy charts too - but in all cases, it was made clear that it was very much unlikely to come off as was shown.

In the end it looks like we will get a week with overall below-average temperatures. Score one for GEFS and EPS, I'd say!

(And for reference, both GEFS and EPS continue to show a slightly below-average week to come:

http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=3&ext=1

http://www.weathercast.co.uk/services/ensemble-forecast.html?eps=london )

Control best again. Nearly the same as the 06z. UKMO looks very flat sadly

http://modeles.meteociel.fr/modeles/gens/runs/2015011112/gens-0-1-192.png

For those wondering why Euro Highs keep cropping up in GFS day 9 onward... the MJO conundrum continues to look like the main culprit:

The GFS operational now shows the decline of the MJO taking until phase 8 has been reached. Unlike back in December, this phase correlates to a strong positive height anomaly across Europe as can be seen above-right. You can even see a signal for low heights just west of the Azores which has also been turning up a lot in the GFS and GFSP runs.

Even at weak MJO amplitude the composite anomaly is so strong that a notable promotion of Euro Highs and Azores troughs is the likely response IF the GFS outlook for the MJO verifies.

By contrast, UKMO still has the MJO decaying in phase 6! That promotes a continuation of the Azores High tending to displace west and with troughs arriving from the NW. I did wonder if the 12z UKMO op run could still manage that from day 6, but cross-comparison reveals it to be very close to the ECM 00z op run, which was a good run for keeping that high displaced west, though not the best compared to the past few days, it has to be said.

ECM currently has the optimum MJO outlook, with a slow decay in phase 7 good for encouraging height rises to our NW and a general increase in high latitude blocking. This goes some way to explaining their recent persistence with a slowly sinking NW Europe trough for week 2, diverging strongly from GEFS. Having said that, the latest outlook does get close enough to phase 8 that some increase in the intensity of the subtropical jet could cause issues or at least interference such as appeared on the day 10 ECM 00z op run chart.

Finally, the raw GEFS output supports the GFS op strongly, but the bias corrected version is more like UKMO.

All this leaves me with no clear signal as to what is most likely to be the way forward. Obviously a halfway house between the two extremes (UKMO and GEFS) would be decent, but lately the MJO has been stronger and more progressive than most models have expected. GEFS have responded by shifting the decay to phase 8, but ECMF have remained solid on their phase 7 decay, and UKMO hasn't really shifted either.

If trends were to continue, ECM would start to show the decay being in phase 8 and the ensembles would become more like GEFS. Yet those GEFS would start to reflect a decay in phase 1, which promotes height rises to the NW, though potentially closer to the UK than Greenland. It will be an interesting and educational experience to see just how far the MJO actually ends up progressing before decay.

Mere speculation of course. With little movement from ECMF and UKMO despite corrections within the 24 hour range, it's possible that so such trend will occur in the first place. It depends how long the actual behaviour of the MJO continue to disagree with those two ensemble sets.

You may be wondering how I can be so sure that the MJO is a major player in all this. My answer has to be that I can't be absolutely sure, with my conclusions being based on the fact that the recent GEFS trend matches the trend in their MJO projections very closely, and the same goes for the ECM ensembles and their MJO projections. The correlation seems too strong to be mere coincidence.

I will have a read around to see if I can identify any other large-scale driving forces that could be responsible for these changes, or at least part of them. Most likely it would be a combination of that and the MJO if there is something.

Regardless, it seems that as far as conditions beyond about a week ahead are concerned, little faith can be placed in the entire ensemble suits of ECM and GEFS at this point in time.

While the models sort it out, there looks to be a lot of keep track of this coming week. Good timing I say! 

Looking like a great call from the MetO there and I'm glad I went along with it

Yes I stayed out of the thread for a few days because my contributions were being lost behind charts being posted (not by you BTW) from member 38 of the MFI run that had a snowflake over Carlisle at +672.
I do not deny the 'cool/cold' few days starting on Friday (mean CET to make a point not regional bias) was modelled and highlighted by several posters including yourself and well done. My argument is that some were expecting lowland snowfall and as it stands their is no conclusive signal and never has been.

next weeks gefs looking very interesting, us in glasgow should batten down the hatches