Model Output Discussions 12z 01/09/2016

[I remember Atlantic 252]

26 minutes ago, Grimers said:

Especially for SW parts of the UK!

hard to say, looking at charts before not enough cold air to the south, colder air will be moving South, but only looks snowy for Scotland/300m further south

[knocker]

34 minutes ago, Grimers said:

Especially for SW parts of the UK!

Not this time around Grimers but the jet is getting itself sorted

[Frosty.]

I think Grimers is right, the highest hills of sw england could get some wet snow as the colder air digs south.

[bluearmy]

Good to see us dissecting a day six chart from late October in respect of what it might deliver in January!

excellent continuity upstream from ECM op re the system leaving the eastern seaboard day 7

[Grimers]

The GFS model and the ECMWF model show a low over NW Ireland bringing moderate SW winds and average temperatures to all parts of the UK tomorrow and a low over the Faroe Islands bringing moderate NW winds and cool temperatures to all parts of the UK on Tuesday.

       

Edited October 16, 2016 by Grimers

[January Snowstorm]

As the masses leave their Summer hibernation........

Height rises look increasingly likely as we head towards month end. Extraordinary to look at even if it is a month too early.

Rinse and repeat and November could work

[summer blizzard]

1 hour ago, Steve Murr said:

Yeah ^^ im not convinced yet - The mecca ECM has let us down over the last 3  years so Im waiting for the signal to reach 120

however UKMO GEM onboard as well

if so -AO ensembles will tank tomorrow

S

I think people forget that day 10 verification right down to about 7 is still less than 0.5. We're still not advanced enough that we can guarantee the weather that far out. 

52 minutes ago, Grimers said:

Interesting, as the wind direction would be SE not S and there would be snow as SW parts of the UK would be close enough to the low if the uppers were cold enough.

I agree that the winds are SE there (though the SW would still risk an onshore flow pushing up the dew point but it's worth noting that the uppers are not the be all and end all in terms of snow. In the midlands for example a SE wind is very important for snowfall quite often because it indicates that cold surface air is undercutting the occluded front even when a look at the ordinary chart may show a southerly wind. 

That situation come December would be a classic M4 event i feel with snow anywhere between there and Birmingham.

Edited October 16, 2016 by summer blizzard

[Grimers]

Just now, summer blizzard said:

I agree that the winds are SE there (though the SW would still risk an onshore flow pushing up the dew point but it's worth noting that the uppers are not the be all and end all in terms of snow. In the midlands for example a SE wind is very important for snowfall quite often because it indicates that cold surface air is undercutting the cold front even when a look at the ordinary chart may show a southerly wind. 

That situation come December would be a classic M4 event i feel with snow anywhere between there and Birmingham.

Thanks for your detailed explanation.

[knocker]

And the ecm keeps the deep upper low to the south west and promotes a plume.

[Ali1977]

Day 10 shows some warm air coming into the south, however it's a North / South battle with some very cold air close to the North - which in the set up would evebtually win out. 

[booferking]

Just now, knocker said:

And the ecm keeps the deep upper low to the south west and promotes a plume.

Plume to deep cold inside a day or 2 will make that cold feel even colder when it digs in

[Man With Beard]

There's certainly something going on this October. You'd normally look at a chart like this and think the pattern is going to get flattened pretty soon, if not by the first trough then by the one after

Yet by T96 we have

And the next Atlantic trough completely goes under

And it's happening over and over again at the moment. The tendency to build northern heights.

Consistency with this morning at D10 - a staggeringly high pressure near Iceland and a jet looking stuck to the south. If the trough to the NE got in on the act there'd be some fun a few days later (but I bet there'll be another Scandi High there by that time!) 

For some mad reason (probably inspired by Steve Murr's "Winter Thoughts" post which was extremely interesting), I checked out the past 150 years of Octobers just now. Yes, many with northern blocking (and a real run of Octobers in the early 2000s, all of which ended up not particularly cold) but I don't think there's a single one with such a resilient Scandinavian High. What it all means ... who knows!!

Edited October 16, 2016 by Man With Beard

[Frosty.]

The Ecm 12z eventually shows warmer air flooding up from the south but T+240 is showing cold air close to the far NE of the uk and very cold air across northern scandinavia...fascinating charts. The week ahead shows a ridge of high pressure building in from the southwest which brings some fine weather but with cold nights and slight frosts with mist and fog patches and still a risk of a few showers, especially in the e / se.

[summer blizzard]

The GFS at day 11 shows us how we're just 6 weeks too early..

Uppers for inland areas like me less than 5C too high. 

[Man With Beard]

7 minutes ago, knocker said:

And the ecm keeps the deep upper low to the south west and promotes a plume.

We've seen a few attempts at this haven't we, and of course it is possible. Such "plumes" (can we really call it that in deep autumn???) are even more unlikely to get from D10 to D1 than in the summer, because the thread of warmth is narrower and it is far easier to mix colder air in to the pattern. I'm a bit surprised you are emphasising this scenario since back in July you were often talking down such possibilities when they appeared at D10! Out of interest, how do you think the trough to the NE would interact with the pattern after D10?

[SMU]

Remarkable inter-run consistency from the ECM - with mouthwatering charts developing post 192 -
However the transition is 144-168 

This is the first real model test into 2016 - the GFS not 100% keen but coming on board - The ECM goes the whole hog -

If it does verify then on the 26th oct we will be heading into Nov with a sub -3 AO & - sub -2 NAO..
Also should it land the October -AO will be smashed - Poss sub -2 ( only sub -2 in 66 years )

So much to contemplate.....

[knocker]

23 minutes ago, Man With Beard said:

We've seen a few attempts at this haven't we, and of course it is possible. Such "plumes" (can we really call it that in deep autumn???) are even more unlikely to get from D10 to D1 than in the summer, because the thread of warmth is narrower and it is far easier to mix colder air in to the pattern. I'm a bit surprised you are emphasising this scenario since back in July you were often talking down such possibilities when they appeared at D10! Out of interest, how do you think the trough to the NE would interact with the pattern after D10?

To be fair MWB I wasn't emphasizing the possibility but seeing as most posts this evening were musing about things extremely unlikely to happen I thought mention of another was in keeping with the general tenor.

 Regarding your question I suspect the HP will retrogress further to Greenland and the two upper lows to phase, and depending what happens to the mid Atlantic ridge which I suspect will collapse we will see HP Greenland and a broad are of low pressure with regard to the Atlantic. May be a pepped up jet. But I have no particularly meteorological reason for saying that.

Edited October 16, 2016 by knocker

[ANYWEATHER]

Good Evening All. A 2010 Winter??? Anyway,A spooky outlook as at T+240 both ecm and gfs kindly agree,,,,

[phil nw.]

There's certainly a different late October Atlantic pattern showing as usually by now Greenland/Icelandic heights are falling away and the Atlantic jet is waking up.I suppose it is in a fashion but what drive there is appears to be heading south east as the blocking high redevelops over Scandinavia next week.

Jet stream ens stamps at T168hrs. 

 

The charts below are the pressure/850 means for next Sunday and are in good agreement

We can see that cold air coming south on the other side of the block across Russia/Scandinavia and starting to head into E.Europe.

For us though we are closer to the Atlantic trough and the orientation of the pattern with our wind flow more from the south/south east means our temperatures will stay around average for the time being.

Fascinating to watch how all this evolves towards November as the Arctic continues to cool down.Currently those +ve anomalies remain modeled to our north right to the end of the GFS ens run so plenty of interest on this still.

[Frosty.]

Following a rather chilly week ahead, especially when we see an increase in night frosts and mist / fog patches from midweek. The Ecm 12z ensemble mean shows a gradual change to milder weather from the south during next weekend and into the following week, much as the earlier operational.

[knocker]

2 hours ago, Man With Beard said:

We've seen a few attempts at this haven't we, and of course it is possible. Such "plumes" (can we really call it that in deep autumn???) are even more unlikely to get from D10 to D1 than in the summer, because the thread of warmth is narrower and it is far easier to mix colder air in to the pattern. I'm a bit surprised you are emphasising this scenario since back in July you were often talking down such possibilities when they appeared at D10! Out of interest, how do you think the trough to the NE would interact with the pattern after D10?

Well now having seen the the ext EPS you can scrub my first answer. It has no low to the NE and ends up more or less in the same ball park as the last run by T360. That is ridging North Sea area and positive anomalies Greenland with a weakening trough to the south west and another south of Greenland all indicates the proverbial upper flow veering SW from a more southerly quadrant. I'm not in any way suggesting this is definitive as there is far too much disagreement at the moment, particularly considering the range, and quite a few options on the table. Still I might tend to lean this way.

Edited October 16, 2016 by knocker

[Geordiesnow]

Whilst what the models show is interesting and whilst it will be fascinating too see how the potential battleground set up will develop, I do feel too much WAA heading into the polar regions can have a negative affect of disrupting the PV too much early in the season leading to a warm Arctic therefore potentially any cold we may get in the winter months could be more diluted, I always think the best winters for cold and snow tend to have a strong PV which builds and builds and then gets split by WAA in January/February.

As for what I'm seeing at this moment in time, unlike the last 2 weeks, we probably won't see a true easterly but it will be interesting too see just how much this reformed Scandinavian block will affect our weather, its one of those where we could either end up with a very warm Southerly/SE'ly but equally we could see a more chilly easterly drift.

[Mucka]

Starting to look like much of Northern/Central and Eastern Europe will be having ice days before October is out.

Starting to turn chilly in the UK as well, after some pleasant Autumn warmth, if current output is to be believed

Edited October 16, 2016 by Mucka

[Allseasons-Si]

Gp's torpedo arrived a year later,sorry mods

jokes aside

that Scandi block still holds firm way into la la land on the latest 18z gfs runs and that is a firm and solid outlook before it recedes into central Europe in the last few frames with some residual heights still around Greenland forcing yet another trough to dive SE,rinse and repeat from the gfs

@t144 hrs a neg tilted trough being forced SE against the block

and then being forced back NW toward Greenland by t192 hrs

then the energy gets split by 240 hrs by the block sending lp SE towards France and Spain and the result is another easterly before the atlantic takes over,OR will it!

the ECM however gives us a slightly better icing on the cake with a retrograde of heights transferring toward Greenland from t144 hrs of which the gfs didn't do,allowing the floodgates to transfer south much quicker,the gfs picked this up earlier only to drop it today,would it follow that ECM tomorrow?

from t144 hrs to t240 hrs

one last thing i forgot to post is the 8-14 day cpc chart of which i think i stuck on easterly drive

if that block holds to our N/NW, then we will get attacks of cold from the N/NE or east

by,i love this time of the year

 

 

 

 

Edited October 17, 2016 by Allseasons-si

[knocker]

Today the low to the west continues it's meander north thus the south and east pretty dery with frequent showers in the west and north west tending to die out later. And later the next trough arrives in N.Ireland and Scotland late on and a rain band tracks SE over night which will herald the arrival of much cooler Pm air as the winds veer to the NW.

The GFS this morning.

The aforementioned trough/upper low tracks SE to become a cut off upper low over Germany by midday Thursday. In it's wake the Azores HP ridges NE bringing some drier weather to most albeit cooler and still showers in the east courtesy the low.

But this ridging is transitional as a cold negatively tilted trough emerges from Greenland and moves east and subsumes it  This trough tends to deconstruct under the block to the NE and a large surface low pressure area materializes to the south west which edges NE over the UK bringing wet,showery and very windy conditions.from the SE by Sunday. This very unsettled weather continues to effect the UK for the beginning of next week as the upper low parks itself to the south west but it's all a bit messy and how far, and for how long, the trough will push the HP NE is by no means a done deal.

 

Edited October 17, 2016 by knocker