Model output discussion - The Hunt For Cold

[weathergeek]

48 minutes ago, Lauren said:

I'd like to publicly address this actually.

As mods in threads such as this its very difficult to get a balance. I personally, have no issue with humour or quick one liner observations,  others feel it should be strictly model discussion. There are plans to have a more bantery thread for jokes and less scientific observation so that both needs are fulfilled so to speak.

And yes, I appreciate the hypocrisy of my post.

 

We still have a Model Discussion thread so couldn't that be kept for people who only want to see MOD and rename this thread as just "The Hunt For Cold"?!

I personally like the funny comments/pics etc, we get excited and want to express it with some lighthearted discussion etc ... it would also save the Mods a lot of time having to delete comments?! Just an idea

[Summer Sun]

3 minutes ago, Quicksilver1989 said:

So upstream things have helped inflate the Greenland block a bit and shunted the pattern further west. Rather then the high falling to our east it is now falling over us.

So we have a couple of days underneath a cold high.

However a signal is emerging for pressure to rise over Spain and if that does occur it will make it difficult for the cold air to our east to make its way to us. A nice NH view doesn't mean anything if the cold air is falling in the wrong places.

Ideally we would want to see some major trough disruption to the low out west, make its way across us and then leave cold air behind from the North. Big ask when pressure over Spain is rising.

2

And that is forcing the low in the Atlantic a bit further north than the 00z 

06z

00z

 

[sundog]

1 minute ago, northwestsnow said:

That low is a real pain in the wotsits!!!

Indeed. It's like an uninvited guest that just won't **** off

[Paul_1978]

1 minute ago, weathergeek said:

We still have a Model Discussion thread so couldn't that be kept for people who only want to see MOD and rename this thread as just "The Hunt For Cold"?!

I personally like the funny comments/pics etc, we get excited and want to express it with some lighthearted discussion etc ... it would also save the Mods a lot of time having to delete comments?! Just an idea

I’m sure we had a general “model chit-chat” type thread last year. However we’re in danger of having too many model threads as there’s at least two already. 

[bluearmy]

The Atlantic trough and downstream Iberian ridge are related 

if that trough is being overplayed then the blocking will divert it east or even se .....now we know how the models tend to underplay blocking and overstate troughs..............

[feb1991blizzard]

3 minutes ago, northwestsnow said:

That low is a real pain in the wotsits!!!

Yes - thats going to scupper us on this run again!

[Methuselah]

3 minutes ago, Summer Sun said:

And that is forcing the low in the Atlantic a bit further north than the 00z 

06z

00z

 

But it would take much, for some sort of secondary low to run into France?

 

[feb1991blizzard]

The low then scurries off east really quickly after becoming a permanent stationary feature, that means its not a terrible run but we could do with it happening quicker, also im not sure i but=y into the evolution.

[Geordiesnow]

Its one of those where cold air is not too far away but because of how the weather patterns work, its a set up where if the low don't allign itself correctly in the earlier part of the run, it will be hard to recover the pattern? Either way, even if it did show a screaming Northerly at 200 hours, we all know that does not mean that is what we will get but the idea of some sort of Northerly flow could be near by is something to be encouraged by?

As summer sun says, perhaps a brief 'warm up' if you can call it that, then perhaps colder again? Still so many more runs but in terms of the outlook for the UK weather, then its easterlies rather than westerlies at this moment in time. 

[BlueHedgehog074]

1 hour ago, Chris.R said:

 Surely with this being a continental  flow then  The most important things to look at for snow are DPs and boundary layer temps. That’s what my experience tort me last year anyway. 

You make a great point. I feel some (myself included) sorta get too drawn in by the 850 hPa temperatures on the models, that aspects such as the Wet Bulb temperatures, the 500 Dam thicknesses, precipitation heaviness, flow direction and looking out for favourable dew points to allow snow to fall (0*C or below), gets forgotten about at times. 

Might have been John Holmes, (but don’t totally remember) that brought up the fact that at least 8 (or more), ingredients on the charts need looking out for to determine whether it’s cold enough for falling snow.

[Methuselah]

Not as deep and a good 200 miles south of where last night's 18Z took it; better advection of cold air?

 

[carinthian]

A bit of an update from over here. The picture below earlier shows the snow guns in operation all along the pistes. Hopefully, we await our first snowfall to develop over the next 24 hours as pressure falls ahead of a developing trough in the Eastern Alps. The big models all show a similar picture at 144t ( Iceland high cell and low pressure around SW Britain )Thereafter, big difference occur, basically UK/ECM against the American models.  What I am told by the experts over here , that their own model differs greatly as to the outcome at day 10. They stick with a strong Arctic ridge with a developing meridional flow and low pressure over Denmark. We will see > but they think the strength of the ridge and developing cold block to the NE will push back any mild intrusion from the Atlantic.

C

[Geordiesnow]

Just now, DiagonalRedLine said:

You make a great point. I feel some (myself included) sorta get too drawn in by the 850 hPa temperatures on the models, that aspects such as the Wet Bulb temperatures, the 500 Dam thicknesses, precipitation heaviness, flow direction and looking out for favourable dew points to allow snow to fall (0*C or below), gets forgotten about at times. 

Might have been John Holmes, (but don’t totally remember) that brought up the fact that at least 8 (or more), ingredients on the charts need looking out for to determine whether it’s cold enough for falling snow.

Its true in what you are saying but that won't apply here as temperatures on the continent at ground level will be too high although with uppers of -4 or so, temperatures for Wednesday under any rain will be around 5-6C which is colder than any rain at those uppers coming from the Atlantic. That is why its ashame this set up did not occur in the winter time as we may have more colder air wrapped around the low which would increase any chance of snowfall. 

Its one too keep an eye on but I would say any snow falling will be reserved to the very highest ground whilst lower levels will have cold rain. 

[bluearmy]

1 minute ago, carinthian said:

A bit of an update from over here. The picture below earlier shows the snow guns in operation all along the pistes. Hopefully, we await our first snowfall to develop over the next 24 hours as pressure falls ahead of a developing trough in the Eastern Alps. The big models all show a similar picture at 144t ( Iceland high cell and low pressure around SW Britain )Thereafter, big difference occur, basically UK/ECM against the American models.  What I am told by the experts over here , that their own model differs greatly as to the outcome at day 10. They stick with a strong Arctic ridge with a developing meridional flow and low pressure over Denmark. We will see > but they think the strength of the ridge and developing cold block to the NE will push back any mild intrusion from the Atlantic.

C

could well be .... the eps clusters are singular days 8 thru 11 high - tells you plenty, given that we know there isn’t a singular option ...... beyond that it’s hardly worth analysing as the preceding period is so uncertain 

[Derecho]

22 minutes ago, feb1991blizzard said:

Yes - thats going to scupper us on this run again!

Yup the low heading out of Newfoundland is the next major player. It forms around T105:

The it rapidly intensifies, could GFS be overplaying this? To be fair it is forming where very cold air starts moving over the warmer oceans:

 T132

The Greenland high still needs further strengthening to make the high stronger and pull some cold northerlies our way. However there is nothing to move the low North to the west of Greenland where we really want it. 

Alternatively the low pressure could hold station, that would help massively even if it was just another 48 hours or so but it starts advancing east.

 T168

If we get some deeper cold over western Europe we could then disrupt any low coming in from the west. Also a shallower low means less height rises to its SE. You can see at T168 the building blocks for a pressure rise over Spain start to form.

I expect something less progressive then what the GFS is showing but it is possible. It still gets things a bit colder again but if things alligned more favourably then we could get a pattern where that low disrupts, passes to our south and we remain in cold air.

 

 

Edited November 18, 2018 by Quicksilver1989

[Summer Sun]

Whilst that low may not be in the best place for a few days a bit later it drifts east which opens the door to colder air again

[feb1991blizzard]

One thing that still gives me confidence is it seems the atmosphere is still pre-disposed to blocking, as soon as a ridge collapses, another one builds somewhere, its just doing enough damage to the strat each time to buy us another week - Strat-trop-strat-trop-strat-trop-tick-tock-tick-tock-tick-tock

[Methuselah]

From T+384, I'd expect the cold to win out, at least temporarily - who knows what's around the next bend? It's in the balance!

[JeffC]

5 minutes ago, feb1991blizzard said:

One thing that still gives me confidence is it seems the atmosphere is still pre-disposed to blocking, as soon as a ridge collapses, another one builds somewhere, its just doing enough damage to the strat each time to buy us another week - Strat-trop-strat-trop-strat-trop-tick-tock-tick-tock-tick-tock

Tick tock...Boom?!

[BlueHedgehog074]

6 minutes ago, Geordiesnow said:

Its true in what you are saying but that won't apply here as temperatures on the continent at ground level will be too high although with uppers of -4 or so, temperatures for Wednesday under any rain will be around 5-6C which is colder than any rain at those uppers coming from the Atlantic. That is why its ashame this set up did not occur in the winter time as we may have more colder air wrapped around the low which would increase any chance of snowfall. 

Its one too keep an eye on but I would say any snow falling will be reserved to the very highest ground whilst lower levels will have cold rain. 

Yeah, would be nice for things to be a little colder this week to increase chances of possible sleet or snow. But maybe the odd unexpected wintry event - even for some lower levels areas could still turn up, especially should any of the models be under-estimating the chilly conditions (as well as the cold pooling to our East in mainland Europe). If not, might have to accept some places likely seeing just chilly rain as you say, with anything wintry higher up. And even if that was the case, would personally rather have it dry lol. (Though I suppose those higher up would still have something to look forward to ).

[Scandinavian High.]

What is interesting is as this high pressure slips south east we have a rebuild in pressure to the north west with a north / n easterly flow .

[Chesil View]

Just a quick skirt through the models this morning. Points that stick out for me.

Firstly the permanent nature of high pressure around Iceland/east Greenland on both ECM and 06z GFS

And second that the ECM op appears to be edging towards the 'chance of even colder weather' as mentioned in the metro extended outlook yesterday.

Certainly a good place to be as we head towards the start of meteorological winter. 

[MR EXTREMES]

52 minutes ago, Summer Sun said:

And that is forcing the low in the Atlantic a bit further north than the 00z 

06z

00z

 

In my opinion that's a very suppressed heights to our south and southwest.

I remember in winter of 2010 when heights went from Azores to UK then Scandinavian then retrograde to Greenland.

The models are wide open to options.

One we have heights to our north then perhaps just maybe everything will go under the block.

But at the end of the ECM nearly all of Eastern and northern Europe including parts of the UK are in a cold flow.

Wouldn't be surprised to see easterly then bit milder then northerly then,

northeasterly then easterly the charts do have a little bit of 09/10 there.

[Duane S.]

Feb’s earlier comment about the atmosphere being at a pre-disposition to blocking is in a nutshell is why we have much cause to be optimistic going towards the first month of winter proper. 

There is no sign of a prolonged global flat jet. It’s a multiwave undulating feature that will wax and wane from the Pacific to us for the foreseeable. The models are going to have great difficulties interpreting downstream effects. The MJO in phase 5, not withstanding the big differences between the current NCEP and ECMWF forecasts, always seems to give poor data issues. I have always assumed it must be down to the topography of the locale, as opposed to a nice flat big ocean. I may completely wrong on that though.

It all makes for fun (and fraught) model watching, that’s for sure.

[Man With Beard]

Clusters D12... it's drifting away from a bullseye on the cold to needing upgrades

Basically, troughing needs to increase again over Europe, and decrease in the central Atlantic. We're chasing again now. 

Edited November 18, 2018 by Man With Beard