General Model Output Discussion

[Matty M]

Some subtle changes, but the general theme is maintained:

http://www.wzkarten.de/pics/Rtavn1201.html

http://www.wzkarten.de/pics/Rtavn1202.html

These details will be firmed up over the next few days, there's a lot to happen beforehand!

Would you honestly call them subtle or am i over reacting on the 18z?

Such huge changes around T72, Ridge around 150/200miles further southeast?

[MP-R]

Thanks Paul B and bluearmy. Don't usually post in the MO discussion but interesting to know the conditions associated with possible outcomes.

[Optimus Prime]

Low Pressure further south and east on this run. Very plausible scenario and would send most of the snow into NW mainland Europe. Basically what the Countryfile and Joe laminate floori was trying to get at.

[Neilsouth]

ahh... the pub run

No doubt this is probably an outlier, but it isn't the end of the world.. SE still stands to get a pasting

Maybe

But what gets me is , why such a model change in what 6h+ hours? hasn't even been a day yet and it's all going down hill for end of the week!... Though it is true the 18z is a pub run

[PB22]

Would you honestly call them subtle or am i over reacting on the 18z?

Such huge changes around T72, Ridge around 150/200miles further southeast?

In the grand scheme of things I'd say they are subtle Matty. As Darren said, it may be a synoptic outlier, the ensembles will tell us more. In any case its only one run.

[Neilsouth]

http://www.wetterzentrale.de/pics/Rtavn1262.png

http://www.wetterzentrale.de/pics/Rtavn1264.png

http://www.wetterzentrale.de/pics/Rtavn12617.png

In comes the north east blast , getting pushed further and further away though

[weather eater]

No where near as good as the 12z thats for sure on the 18z!!

Low pressure over Europe develops a little stronger and the high pressure doesn't develop as fast, net result is a weak nortrherly flow for Friday instead of the easterly flow...

No doubt though a syonptic outlier....

It might be an outlier; but then again we run into the fact that the UK is small, the margins for error are tight, small detail changes make big differences for us. That's why I said in an earlier post, if my wife asks me on Monday what the weather will be doing at the weekend, I tell her that I'll let her know later in the week. As it is things have just been delayed a bit.

[Serendipity]

GFS pulls the event back to being a SE event on Friday with this run - big changes in my eyes? it moves everything eastwards by a significant amount?

edit - mean south eastwards

[PB22]

One thing I would suggest is that the models may be slowing the evolution somewhat, but it could actually end up with a more potent easterly:

http://www.wzkarten.de/pics/Rtavn1441.html

[Optimus Prime]

Surface temperatures for Friday and Saturday are actually a little colder on this run indicating perhaps a more low level cold flow. Maxima between -1c and -4c over much of England.

[Derp Patrol]

It's one run, I wouldn't take too much from it, just wait for the ensembles. This happened last week with the positioning of the low pressure, it turned out to be inbetween what the GFS predicted and the other models, although the other models were closer.

[Neilsouth]

http://91.121.94.83/modeles/gfs/run/gfs-2-150.png?18

lol , low pressure intense snow comes towards the south east on SUNDAY now

[Optimus Prime]

A bit of a strange run, maybe an outlier. It's still a good 4 or 5 days away so there will be more changes. Could be a trend towards moving the easterly further back, intensifying it or actually a move towards the easterly not really making itself present over England at all.

It is named the Pub Run for a reason so best just keep this run in the back of our minds.

[kold weather]

HUGE differences in terms of upper patterns, the GFS at 144hrs is actually a carbon copy of the 12z ECM it has to be said at upper levels...even to the actually kinks in the upper low, thats quite amazing.

Big LP blowing up towards Greenland...

Get ready for the longer term downgrade compared to the GFS 12z run..hope so badly this is an outlier in terms of the pattern past 120hrs...

[J10]

Even though it may delay the Easterly by 24 hours, the cold is here now, so it is not as crucial as it would be if were waiting for the cold to arrive, as it usually is.

However notable the difference in opinion reflecting the location of the posters.

This just goes to show things are not nailed on for this weekends weather.

[nick sussex]

This looks very similar to the ecm 12hrs run. Quite unbelievable cold piling south into the Med , also looks like i'll have to get the bobble hat and ear muffs out here!

There remains alot of uncertainty with that southern european low and until this is resolved then we should be a little cautious in viewing this. However the general, pattern remains very similar, its just the more local detail thats a little in question for the timebeing.

[morfius]

If the high off northwest Scotland combined with the high off Eastern Greenland, then we could be in with a chance of a decent(ish) northerly. This would be the best option as there is very little in the way of cold pooling elsewhere. (at 180)

[PB22]

HUGE differences in terms of upper patterns, the GFS at 144hrs is actually a carbon copy of the 12z ECM it has to be said at upper levels...even to the actually kinks in the upper low, thats quite amazing.

Big LP blowing up towards Greenland...

Get ready for the longer term downgrade compared to the GFS 12z run..hope so badly this is an outlier in terms of the pattern past 120hrs...

Wouldn't agree with a longer term downgrade at all Darren. I think you're worrying too much about FI in any case and looking for breakdowns that aren't there!

This run is remarkably similar to the ECM with pressure remaining strong to our north and northeast, and undercutting lows going into mainland Europe. Sensational synoptics, and no sign of an end to the cold:

http://www.wzkarten.de/pics/Rtavn2761.html

http://www.wzkarten.de/pics/Rtavn2762.html

Sensational stuff!

[TEITS]

Even though it may delay the Easterly by 24 hours, the cold is here now, so it is not as crucial as it would be if were waiting for the cold to arrive, as it usually is.

Excellent post and exactly right.

I know I sound like a broken record but these changes with regards to snow distribution will continue to change as the slightest difference in the synoptics makes a huge difference.

Im just concentrating on Tues and Wed and would advise those looking for the snowstorm next weekend to forget about it at the moment.

[John Cox]

All need to keep a level head including my fellow members in Ireland.

The general very good synoptics keep going with cold cold cold! Of course each run will change and there will be some scary ones.... But... wow what winter weather we have been having and our Irish met office keep the them going for the next 7 days.

These are memorable winter days. Enjoy whilst you can. We have been waiting years for this

[Paul]

Wouldn't agree with a longer term downgrade at all Darren. I think you're worrying too much about FI in any case and looking for breakdowns that aren't there!

Would agree there, hadn't seen the 18z before reading this thread and went to take a look expecting to see a very different run to anything we've seen of late, but it's actually still pretty unbelievable and very different to anything we've seen in recent winters!

[kold weather]

A much better 18z FI then I was expecting to be honest!

A cold flow at the surface, nothing too impressive synoptically but the upper high holds strong this run upto at least 300hrs...

As Nick has said the uppers upto 192hrs is VERY similar to the ECM indeed it has to be said.

[Lewis]

After checking out the run, later into FI it goes crazy and everything sinks.

But it's actually a good run..

It's the less "progressive" of the models, i was looking at the higher resolution charts, and the colder 850's stick around much much longer, right until Monday here with -8 to -9 850's still on E/NE flow.

We have to remember this is still some 5-6 days away, and in model terms anything can change whether it be upgrade or downgrade, certainly nailed on up until Friday i would say, after that... well it's guessing games to which scenario we get, it could be a slow break down with the colder air stubborn to push away giving memorable snowfall. Or it could just push aside very quickly and we end back up in a S/SW wind with milder conditions. Judging by the blocking and pattern, i would not be surprised if we end up with a slow re-load.

Lewis

[on the coast]

This looks very similar to the ecm 12hrs run. Quite unbelievable cold piling south into the Med , also looks like i'll have to get the bobble hat and ear muffs out here!

There remains alot of uncertainty with that southern european low and until this is resolved then we should be a little cautious in viewing this. However the general, pattern remains very similar, its just the more local detail thats a little in question for the timebeing.

The 18z looks quite a good run, although no snowstorm there is no sign of a quick breakdown?

[Rollo]

I would suggest we try to remember that the GFS has not been the best performer recently and wait until tomorrow before writing off what imo will be a memorable week.