Model Output Discussion - cold spell to end Autumn

[Dennis]

Look HIGH pressure rising above russia near half dec 2017

Edited December 2, 2017 by Dennis

[stewfox]

Next Fridays commute could be interesting if these max temps play out

[Met4Cast]

Well the GFS definitely isn't buying into the toppler idea that the ECM is suggesting, UKMO 144 would likely go on to topple the high too, there's not enough Northwards amplification. 

So, we have two key points of interest. Thursday/Friday with the low pressure moving Eastwards, will it drag cold air South in time for widespread snow? At the moment, the GFS is the only one really suggesting it will (though ECM/UKMO would likely bring some back edge snowfall, just not as widely) 

Then we have next weekend to watch, will the high sink Southwards as per ECM/likely UKMO or remain over Greenland/Blocked as per GFS? 

I suspect the ECM is under-doing the heights a little but I also suspect the GFS is overdoing them. Whatever happens, it's great model watching at the moment. 

Edited December 2, 2017 by Danny*

[nick sussex]

A really great trend from the GFS 06hrs run.

If I was being a bit picky the low centred a bit more se and edging slowly in that direction would be better but overall within T168hrs this is very promising for coldies.

We just need the ECM to stop playing Scrooge but given both the GFS and UKMO today its possible we'll see some move from it tonight.

[Ali1977]

4 minutes ago, stewfox said:

Next Fridays commute could be interesting if these max temps play out

Any snow will lie and drift if those winds are as strong as projected too - could be a really potent wind chill/blizzard 

[Day 10]

Fantastic start to the weekend and continued with the 6z GFS and at 132, it's creeping closer!

Very happy with this:

[The Northern Ramper]

It's been quite an exciting upturn in events this last 24 hrs and the ukmo has been rock solid in its output.

 

Next weekend could be epic.

[Chesil View]

A truly exceptional run from a cold and snow point of view on the gfs 06z.

Edited December 2, 2017 by Broadmayne blizzard

[Frosty.]

12 minutes ago, Broadmayne blizzard said:

A truly exceptional run from a cold and snow point of view on the gfs 06z.

Yes it's stunning..praying it's right...always wanted to hunker down in a big blizzard thing and the 6z would fulfill my wish and then some!

more thrilling output to come i'm sure! 

Edited December 2, 2017 by Frosty.

[BLAST FROM THE PAST]

Even at t252 with another LP disrupting and looking like sliding as it approaches.  Note also how the warm sector is closing rapidly as it approaches the UK......mind you that scenario is likely to chop and change at that range

I mentioned yesterday in the Dec CET thread......RJS revised his Dec CET downwards.......to 1.9c!  

Sitting here at home, front door open as floor man doing cutting etc......it’s brass monkeys enough as it is.....if models are right....

Going upstairs to prep skirting for glossing to try and keep warm.

BFTP

Edited December 2, 2017 by BLAST FROM THE PAST

[Tracy Flick]

Springtime in Poland, wintertime in Germany?  It's like The Producers, but in reverse.

[Iceaxecrampon]

HP building but temps not an the cold side.

Floodgates opening.....

Good Lord........ 

And it doesnt seem to be going anywhere fast.

 

[West is Best]

Very quickly as heading out. Three cracking cold runs. ECM the least impressive but still good.

I think we all guessed the GFS would make the low a little fuller and less intense as the day approached. It does have a habit of over-deepening the darned things. But the upside of that is in some ways a more impressive imbedded cold regime with substantial snow risk for a wider area. It's still going to feel bitingly cold.

Game on.

[West is Best]

1 hour ago, Steve Murr said:

 

The ECM mean clustering has many more colder solutions that the op & control at day 10/11 for debilt..

That's great to see. This is looking very positive at the moment. Fingers crossed. We've been let down sooooooo many times but this is still a very impressive early winter loading. Now we want the North Wind to pull the trigger.

[nick sussex]

Okay my last post till later!

Regarding the UKMO, although that might not get the high further north like the GFS 06hrs run any energy being ejected off the upstream troughing is likely to run around and se on its eastern flank.

The UKMO can not follow the ECM and deliver its output because the upstream PNA ridge at T144hrs is much more amplified this means as that amplified wave moves east at T168hrs it will keep the PV further to the nw. You can clearly see it has a negative tilt to the troughing over the ne of Canada at T168hrs and much less progressive than the ECM and look further upstream it remains more amplified.

 

The ECM flattens the pattern out which ejects too much energy east.

 

The good thing here is both the GFS and UKMO can evolve to keep the cold even with different views of that high.

This is a very good sign, we just need the ECM to start backtracking.

 

Edited December 2, 2017 by nick sussex

[Mokidugway]

If as there seems likley to be an event , remember  to keep an eye on elderly  or infirm neighbours and relatives and don't forget to feed the birds they'll thank you for it 

[gottolovethisweather]

Well, the breakdown to something nearer average regarding Air Temperatures makes inroads to all of us this weekend. That crept up on me, and the model outputs a bit sooner that might have been predicted at the start of the week, hence why I for one, do not look beyond D5/D6 when talking specifics at the surface. Some have had snow during the past week, nothing particularly long-lasting but a pleasant surprise for late Autumn, for sure. Admittedly, my interest as a coldie wanes over the next few gloomy, occasionally wet days but piques again by December 6th through to the 8th December. This Fax chart hardly screams excitement, does it, in fact, it looks pretty horrific for a coldie located IMBY. 

 

However, it is what develops afterwards, D4 and beyond which starts this coldies' heart racing. Check out the 528DAM line and follow that in subsequent updates; also the sinking HP and where it wants to go is also key.  For an idea as to how things might get one's coldies' heart racing is indicated below and also by other forum users posts up thread by this timeframe.

 

 

By D5 (still just about in the accurately forecastable realm), Synoptically things are moving very quickly, indeed.

 

 

By D6, it is borderline FI but wow! Take said chart and its specifics with a truckload of salt, but it SCREAMS potential. Please don't stress over the details post D6 as they will change and certainly will do so in the run-up. However, I would say there has to be at least a 60:40 percent chance right now in favour of a significant wintry weather event occurring by the 8th December as this has repeatedly been modelled to happen over the past 36 hours or so. Enjoy the model rollercoaster ride over the coming days.

 

Cheers

gottolovethisweather

Edited December 2, 2017 by gottolovethisweather

[Met4Cast]

Solid set of EC ensembles this morning.

Obviously the usual scatter in the extended but a very large cluster for a continuation of cold, the ECM OP clearly in the warmer few by the end of it's run and interestingly the GFS hardly the coldest of the bunch, either.

Edited December 2, 2017 by Danny*

[blizzard81]

1 hour ago, bluearmy said:

I see a lot of excitement on here without too much evidence. Anyway, I hope to see some upgrading of the output once it reaches T120/96 to justify it. 

The extnded eps drifting away a bit from the depth of the sceuro anomoly by the end of week two - looks like cool zonality although it seems the Canadian lobe spouting out every few days is responsible and it may well be quite different in a few days as the modelling gets a better handle on how upstream will develop. The meto currently seem to be ok on this with their outlook. 

I suppose your feet on the ground post is very much with ecm in mind. I just hope it is off the mark as the ecm ops have been all over the place this week. It will probably be right though this time knowing our luck. Not taking much notice of the 06z gfs as it often throws out the most stella  runs. It has surpassed the 18z for this over the last couple of years. The 12z runs will be very crucial imo. 

[Derecho]

Morning

Well an interesting day while I’ve been away. We have gone from mid Atlantic ridge and transient northerlies to potential height rises over Greenland, third time lucky?

It looks certain that a low will cross the UK on Thursday leaving cold air in its wake from the north. Thankfully it’s not as deep as the earlier GFS runs predicted… (phew!). The three main models agree on this cold air being over us on Friday and Saturday at least. So some agreement in the models at last!

ECM                                                           GFS                                                       UKMO


Well…. Subtle differences are evident over Greenland, first the ECM which has an attempt at ridging around T144. The high sinks as a result and we get a toppler northerly instead. This is then followed by a chilly-ish north westerly but doesn’t offer much in snow potential. Not bad but not particularly exciting for a coldie either.

ECM T192                                                ECM T240


UKMO represents a halfway house between ECM and the 06z GFS, heights to our NW are stronger but are centered to the W of Iceland rather then fully joining with Greenland. The high is more likely to sink but this would be a slower process and could try again later. That’s my interpretation of it, the high could push through Greenland as it’s a close call.

The 06z GFS however shows that the Greenland high is much stronger and therefore the energy over NE Canada is held back. The northerly is more sustained and we get a southerly tracking jet. This run is more likely to produce snow showers and perhaps longer spells of snow if a channel low gets involved.

GFS T192                                                  GFS T240

Overall the placement of that low over N Canada will have some degree of influence on what happens over Greenland.

Some good output this morning though and the potential for a spell of snowier and deeper cold emerges again. No sign of any zonal weather at least for the foreseeable future!

Here are the ratings

GFS 8-8.5/10 – We get a prolonged period of cold with snowy potential, the Greenland high may not collapse as easily as this run shows

UKMO 7-7.5/10 – Greenland high not as strong (more focused to W of Iceland) but sustained northerlies at least are a distinct possibility

ECM 5.5/10 – A toppler northerly and rather cold but not enough for potential snow events after it passes

[Daniel*]

This has been posted but impressive ECM ensembles ECM 00z goes off on a tangent  from the 10th, therefore one can insinuate majority of the pack are more akin to more amplified GFS/UKMO with protracted cold instead of fleeting. Average for London the mean sees highs no higher than 5C from the 8th all the way to the very end 16th, you don’t see that often I’ll tell you that. 

Edited December 2, 2017 by Daniel*

[Summer Sun]

Firm agreement now for a sharp drop in temps later next week and this takes us through to the 2nd half of Dec maybe a rise closer to average as we get into the 2nd half of the month but that is a long way off yet

[Derecho]

GFS 06z not without support from the ensembles and the control run looks pretty similar.

My personal fave is P5, brrrrrrrr

 

[Frosty.]

Looking at the GEFS 6z mean, hopes are high for another cold plunge from the arctic later next week with wintry showers, frosts and ice returning, at least for a time. The big question is how long it will last and how potent it will be but a cold blast does look likely following the milder benign blip!

[Mokidugway]

5 minutes ago, Frosty. said:

Looking at the GEFS 6z mean, hopes are high for another cold plunge from the arctic later next week with wintry showers, frosts and ice returning, at least for a time. The big question is how long it will last and how potent it will be but a cold blast does look likely following the milder benign blip!