Model Output Discussions 12z 30/11/16

[Mapantz]

The 18Z OP run (around second to third quarter of it) keeps most of those LP's from crossing the UK directly West to East, and moves them more Southwest to Northeast. While that might not seem important, I don't think it is indicative of a stormy pattern developing. There's not a huge amount of precip showing for most of the UK up to 240hrs either. It is only the OP run after all, its not showing exactly what most are wanting, but I don't think it is a horror show either.

Edited December 4, 2016 by Mapantz

[Frosty.]

10 minutes ago, BLAST FROM THE PAST said:

Karl

Oh yes reasons to be cheerful.....GFS imo showing signs of the potential troughing that could be pretty cold ahead

 

BFTP

 

That's encouraging news fred

The Gfs 18z certainly comes to life through low res with some very stormy weather crashing in from the Atlantic..hold on to your hats and batten down the hatches is the message from the 18z in Fi!

[bluearmy]

16 minutes ago, Gael_Force said:

This the MSLP probabilities for the GEFS 12z run. Have set for sub 1000mb and don't see much in the way of low pressure in the late stages of the run.

Setting the bar very high there GF!  The eps at day 15 have a 20/40% chance of a circulation establishing gulf of genoa with mslp below 1011 mb.  We need to start somewhere ! 

[Gael_Force]

5 minutes ago, bluearmy said:

Setting the bar very high there GF!  The eps at day 15 have a 20/40% chance of a circulation establishing gulf of genoa with mslp below 1011 mb.  We need to start somewhere ! 

There was no option between 1030 and 1000mb, .... sorry.

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=0&mode=2&proba=1

Maybe 18z, for all its faults, is showing a path down to the Med.

Edited December 4, 2016 by Gael_Force

[Frosty.]

39 minutes ago, feb1991blizzard said:

 the actual FI ensembles now are very good (relative to the norm), just not sure whether they will grow or not.

Agreed, I'm surprised the mood is so low with these encouraging signals, hope for even better as time goes on!

[Singularity]

14 minutes ago, knocker said:

 If you compare the chart with one that does have the 500mb analysis you can see that the surface HP will almost certainly be centred W/SW of the UK which will be under a NW flow

Did you see my post on differences in timing washing out signals, since backed up by ba?

I suppose the way to look at it is a reduced chance of HP being centred W/SW of the UK, which given climatology is worth noting. It would take a truly extreme signal to move the ensembles away from climatology strongly enough to produce a clear displacement of the ridge at more than 10 days range.

I'll copy this into the new thread when it opens.

[Scandinavian High.]

Looking like a cooling trend as  we hit mid month ..

[Cheshire Freeze]

14 minutes ago, abbie123 said:

Looking like a cooling trend as  we hit mid month ..

The number of colder runs increase, sure- but it's feast or famine looking at that. A continuation of above average conditions or a plunge to much cooler weather (which wouldn't be hard given the upcoming synoptics). 

[karlos1983]

Encouraging indeed 

Not much mild in the final third of the run. 

Ps good to see you in higher spirits today frosty RE: cold 

Edited December 4, 2016 by karlos1983

[Man With Beard]

Yet another hopelessly split ensemble set - 12 out of 22 get high pressure either up to the UK or to the north of it in the D10-D15 stage - still not a big enough cluster to sing about - yet not so small to dismiss. Slightly more taste for a Scandi High on this one, too. I think we'll be waiting a couple of days yet for any clearer direction, and a lot longer for specifics - but I still think the UK high is a good early bet, so perhaps cold but not snowy by mid-December (and as far as can be seen beyond)

[Frosty.]

35 minutes ago, Frosty. said:

Agreed, I'm surprised the mood is so low with these encouraging signals, hope for even better as time goes on!

I'm encouraged by some of today's output, it's not as bad as some are making out..think back to the mess we were in this time last year, now that was pain!

[Blue max 90]

Trending colder by mid month surely! ECM 12z ens down to circa 5/6c max temps, 18z GEFS members looking promising with high pushing up towards scandi, and MO predicting cool down and blocking mid month. All around the Christmas period. I know it's FI but trends got to start somewhere?! 

[Catacol]

Funny place the model thread. Sometimes I wonder when Capt Hook might turn up... or perhaps Peter himself. We do know we live in a real world and not NeverNeverLand?!

In the real world a Sunday summary. Having now had 7 out of 8 nights of hard frost since 27th Nov I have to say a good start to the season. That's more frost than the whole of last winter, and no floods either. Blue skies, beautiful landscape. This is a key ingredient of the winter wonderland I like to see.

Snow? Not yet. But all the drivers are either still in place or certainly not absent at least. Looking 7 days ahead, and still 4 days from the mid month point I've rather nailed my colours to:

Wind speeds in the lower strat and trop at 60N looking good. Nothing here to indicate a zonal express, though this graph is an average of course, so that needs acknowledging. 

Wave 2 attack peaks in 7 days time according to current forecast

and average temps at 30hpa still forecast to be a good bit above average, again accepting this is a global average

 

Wave 2 squeeze evident here, with vortex firing into Eastern Europe

 

MJO forecast today is an improvement on the last few days, with the depth of the plunge into a GWO 2 orbit becoming less steep and indications now of movement into 3. Signs also in the extended modelling of AAM starting to pick up. A trend? Hopefully. As Tamara has pointed out, we need AAM to bounce back upwards if we are to get pacific support for amplification due to the much discussed disconnect between a Nina ocean (all be it very close to neutral) and an atmosphere that has maintained more of an amplified Nino signature for a while now. 

Mike Ventrice's tweet earlier today, copied onto this thread, is a significant indication of another expert foreseeing a maintained active MJO.

Conclusion? No change to the forecast yet. The warm up this week is a bit of a disappointment as we had all hoped to keep heights far enough north to maintain the chill, but no zonal express inbound and height rises likely to return as we approach week 2. The slow progress of the MJO is making me think that the second bite of the cherry in around 10 days time will hit a mid lat block as a ceiling, and therefore a cool down for sure but no snowmageddon. However once we get into the last third of the month wintry cold certainly possible. Downward propagation of strat disruption should have started to effect the trop by then, and with a fair roll of the dice we hope to see the GWO entering a favourable orbit at this point. Not going to predict beyond Xmas week yet. I have some suspicions... but I'm not skilled enough yet to project in public more than a month in advance so will keep my suspicions to myself for now.

Level headed approach needed. If the above should start to look out of place, and a move towards a different outlook becomes apparent to me, I will be the first to post it and change the forecast.

Edited December 5, 2016 by Catacol

[Geordiesnow]

1 hour ago, CreweCold said:

The number of colder runs increase, sure- but it's feast or famine looking at that. A continuation of above average conditions or a plunge to much cooler weather (which wouldn't be hard given the upcoming synoptics). 

As others have said, its always at the infamous D10 plus range and also people on here were getting excited when some GFS FI runs were showing Northerlies and Greenland highs and we know how that turned out!

Ensembles don't mean an awful lot too me, the only very slight encouragment I can see if the potential to drop some weak heights from the Arctic. The models still about show this but not one output suggests this will affect our weather in anyway however despite looking unimpressive, those heights can affect our weather if it all favours correctly. I'll personally only start to get excited about significant cold prospects if the UKMO and ECM(before 144 hours) are hinting at such possibilities and at the moment they are not.

On another note, I think sunshine amounts across Southern areas will be very low this week indeed, looks like further North and especially Scotland, Thursday should be the brighter and marginally cooler day before the very mild air returns on Friday with its cloud and rain.

[Seasonality]

We may be in a position where the ensembles are leading the way. Op run on 18z again at the mildest end in the second half of the run. This isn't only for the UK but for Central Europe too. I've included the Warsaw ensembles as you can clearly see the split of the chillier cluster heading lower around 12 December. UK will trend the same I suspect so the prediction of a colder turn of the weather mid-month may be a good prediction. I certainly would be pleased if it was as it would be a victory for the experts in the face of unfair criticism from some quarters.

[Mucka]

UKMO GFS 120 comparisons,

Quite similar with UKMO making a better job of pushing some positive heights/WAA North which results in an interesting 144

The question would then become can we get the next low to disrupt SE which would help with any upstream amplification or even with enough undercut, can we pull in some colder air from the N/NE?

It's unfortunate it is a period that coincides with the jet firing up across the Atlantic as the less energy hitting any fledgling high the more likely any favourable trough disruption.

We certainly need it modeled by ECM as well and hopefully strengthen before taking it too seriously though.

 

Edited December 5, 2016 by Mucka

[knocker]

The high pressure slips away south over the next couple of days allowing Atlantic fronts, tracking NE, to effect north west Scotland by tomorrow evening. Today will be mainly cloudy south of northern England and quite cold apart from the south west.

The large complex upper trough in the Atlantic dominates proceedings for the next few days generating a succession of small surface lows that track NE. As the trough has also induced some renewed Azores ridging this will generally mainly effect the west and north west of the UK

By Saturday 00z there is a new brief amplification burst resulting in an upper low south of Iceland  with associated trough running south to the west of Ireland which is about to deconstruct under renewed pressure from the Azores HP. This it duly does resulting in a cut off low over Scotland and another west of Iberia. On the surface this translates to a depression tracking west to east bringing rain and strong winds to Scotland.

From this position it's all downhill with the Atlantic dominated by a new large upper trough which frankly looks an utter mess on the surface but portends some very unsettled weather over the UK for a number of days.

A brief summation.

This week not too bad with the systems mainly impacting the west and north west with HP remaining influential elsewhere so still fairly dry but from the weekend it's downhill with the arrival of Atlantic fronts and rain and strong winds. The temps during all of this higher than average.

One thing still to note whist all this is going is that the Canada - eastern Europe conduit remains open with some very cold air out east.

But fear not the GEFS is still sniffing the coffee

Edited December 5, 2016 by knocker

[That ECM]

36 minutes ago, knocker said:

 

But fear not the GEFS is still sniffing the coffee

Let's hope the ECM is smelling the coffee too!!! Not perfect by any means but much improved.

[bluearmy]

So those day 10 charts full of potential are now at day 6 ( look NH not N Atlantic). The ops then do what ops do which is to over complicate things. Impossible to know if the polar split will drive cold our way earlier than currently looks likely. The ens will probably not manage to decipher the polar profile effectively in the 6/8 day period and the ops will make a dogs dinner post day 6/7 as they generally do. 

Looking at the current trend which is to drive the WAA up the meridian far enough to prevent the Siberian segment heading west around day 6 and you have a starting position over the pole that many would give their proverbial right arm for. 

the next runs could easily back the pattern back to a Siberia/Canada axis but we are dependant upon events over the other side of the hemisphere as well as n America and the n Atlantic so plenty can change in either direction. The return of seasonal temps seems ever likely as pressure rises again. 

[booferking]

Going by this Anomaly Chart we are looking good from mid Dec through to mid Jan.

This could be a long cold spell if we could lock it in fingers & toes crossed

Edited December 5, 2016 by booferking

[knocker]

Now that's what I call potential

[malc]

4 minutes ago, knocker said:

Now that's what I call potential

What conditions would you expect that to bring Knocker?

[Gustywind]

Presumably S/SE winds off the continent, so cool, cloudy, light winds, terrible air quality.

[TSNWK]

5 minutes ago, malc said:

What conditions would you expect that to bring Knocker?

In my view that looks like good pontential for heights over europe and mild and cloudy air wafting up. No deep cold there.

Edited December 5, 2016 by TSNWK

[Gustywind]

4 minutes ago, malc said:

What conditions would you expect that to bring Knocker?

 

Just now, Gustywind said:

Presumably S/SE winds off the continent, so cool, cloudy, light winds, terrible air quality.