Model output discussion - 1st December onwards

[Captain Shortwave]

Anyways, being less of a grinch

First widespread frost in weeks in around a weeks time for the whole of the UK. 

 

Another messy run with no real polar air or mild air as we sit between the two with a slack pattern.

Edited December 5, 2015 by Captain Shortwave

[pdiddy]

agree with some of the comments here that this time next week is key if we are to see a pattern change.

Greenland shows some hints of warmer 850s, but a rather large spread drags the average down a little thereafter.  Hopefully by the end of this weekend, there is more clarity.

 

[Paul]

26 minutes ago, knocker said:

Looking at the outputs this morning I cannot find any substantial reasons that indicate major any change. To be honest the det. runs are such a mismash that anything after about five days is a guessing game or wishful thinking. The anomalies are broadly consistent with the upstream pattern although downstream they do play around a bit with weak ridging around the UK and the trough mid Atlantic around mid run.

In the ext period the ecm settles down. At T288 It has HP NE Canada (funny that) LP over the Pole. the vortex NW Greenland with a trough mid Atlantic with weak ridging to the south of the UK.  No significant change in all of this by T360 except the Atlantic trough becomes negatively tilted over the UK

The upshot of all this IMO are periods of unsettled weather with a few Pm shots bringing some very wintry conditions of wind, rain and snow in the north interspersed with some periods of more settled conditions particularly in the south as the HP pushes  in from the SW/S. This fluid changeable outlook will result in some big swings in temp but around average on the whole.

 

Agree regarding major pattern change, but both the GFS and ECM trending toward a more troughy type of setup, with the Euro high losing influence from later next week. 

As an example - all the recent 00z's (a John Holmes favourite - follow one run time at a time!) from both the GFS and ECM  for the 9th Dec are still quite flat zonal, with the Euro high well in place. 

 

Roll that forward to the 12th December, and although we only have 4 runs for that date from the ECM so far, it's showing  more troughing down into Europe in varying degrees, and in differing ways. 

So, as many have been saying - more polar maritime air likely to come into play, with the potential too (I'd have thought) for a transient northerly or two, nothing too long lived at this point though.

[Polar Maritime]

17 minutes ago, knocker said:

The upshot of all this IMO are periods of unsettled weather with a few Pm shots bringing some very wintry conditions of wind, rain and snow in the north interspersed with some periods of more settled conditions particularly in the south as the HP pushes  in from the SW/S. This fluid changeable outlook will result in some big swings in temp but around average on the whole.

Very much agree with that Knock, No major pattern change but something more seasonal. 

Edited December 5, 2015 by Polar Maritime

[johnholmes]

2 minutes ago, Polar Maritime said:

Very much agree with that Knock, 

ditto, along with agreeing with what Paul has posted. I will be more convicned though when all 3 of the anomaly charts show agreement of any marked change. The comment Paul makes about most the the northern hemosphere being not far from a westerly, this at 500mb, is very true. If you want a straw to clutch at then look at the ECMWF-GFS 500mb anomaly this morning. For once they look fairly similar and for the first time since they predicted the last colder spell, they both show a north of west flow into the UK. Not major but it is there, the second day for EC but the first for GFS. So far NOAA at either 6-10 or 8-15 shows nothing like this.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Beyond 15 days=20 December I do not pretend to know or be able to forecast so far ahead. One thing to watch for as you eagerly scan each output, and as Paul says at F1 then see how similar each run is to its last one (same time) is that the changes are consistent so 360h today shows the same at 336h the next day and so on.

Edited December 5, 2015 by johnholmes

[bluearmy]

Very much in Paul's corner - the general trend to remove the euro high anomoly to our South is what I see as being big news for nw Europe. Whether that verifies is another matter entirely! 

Edited December 5, 2015 by bluearmy

[Ali1977]

The high over the UK in FI could join up with the high Arctic and Siberian high looking at extreme FI...possible beast for Xmas......One major problem is that it is the GFS FI !!!!!

[phil nw.]

Certainly some trending to a colder regime from the end of the coming week.

A look at some data from the 00z gefs show a much weaker Atlantic jet in a weeks time with the mean track coming south.

 and the temperatures at the surface

Although the overall pattern remains it does modify with a developing split jet easing south,leaving the UK in a colder regime with temperatures closer to normal.Next weekend seems to be around the time when those Canadian +ve anomalies start to feed through removing the mild tm flow from the south west.

Nothing dramaticaly cold yet but a move to more seasonal conditions appear to be on the cards.

[Duane S.]

From where we currently are and teleconnections as they are, there is little sign or chance of a pattern change to sustained HLB for around 2 weeks time. But the signal to break down the Euro high remains and that could be hugely important going forward. Small steps.

So  whilst a PM airflow looks to be the most likely of the  colder outcomes for the mid month period, we could perhaps squeeze a decent mid lat high pressure out of this, bringing in more seasonal continental airflow for that period to the southern areas.

[Captain Shortwave]

GEFs coming out now, really isn't making much of the cooler spell at all

Into the further output, the 06z strengthens the rebuild of the Euro ridge though with a slightly different position

Centred over Eastern Europe if the anomaly is correct.

This becoming a trend in the GFS suite potentially with heights east of the UK and a trough just west of the UK with a cyclonic south to south west flow potentially.

The disappointing thing is the during the weekend in question here, the mean 850s don't even  drop below 0c across southern counties. I certainly hope this is just the 06z suite being a bit pessimistic about things.

[Frosty.]

The Gfs 6z shows a welcome change to much more seasonal conditions later next week with thurs/fri being the transition period to a  polar maritime airmass with showers becoming wintry, especially on hills and night frosts becoming widespread. Looking towards the end of the run shows  more significantly wintry potential.

[nick sussex]

Morning all

Well some very interesting overnight developments and the stakes are raised for cold lovers.

So looking at the current set up and expected evolution.

Currently we have a strong jet delivering the relentless monsoon to the UK and Euro high combo. This pattern is going to change as upstream over the USA we see a more amplified pattern, the models bring several lows developing in the southern stream of the jet. Now these can be both good and bad, thankfully the models have moved away from taking these too far east so less chance of a low phasing with troughing near the UK, we absolutely don't want phasing because as the upstream pattern amplifies you could end up on the wrong side of low pressure.

The trend to day is to build in weakish high pressure to the west, its at this point that those southern stream lows can help support cold rather than hinder it. You'll see that both the ECM and GFS cut a shallow low eastwards under that weak high around the T192hrs mark, this is now the "higher stakes" for cold lovers, much depends on the amplitude upstream past this point because troughing to the west will react to this either by sharpening up in that this would elongate and stretch disrupting more energy under the high near the UK.

In terms of the nuisance chunk of PV which is reluctant to leave Greenland, with low heights there the only way to much colder conditions is by way of a Scandi high set up.

You'll note that the GEFS is generally underwhelmed by notions of Scandi high pressure within the T240hrs mark, as a rule Scandi high evolutions are signalled by the operationals first with the ensembles slow to react, the often complexity of the evolution is poorly handled by the lower resolution of the ensembles.

I don't want to over egg the Scandi high set up but as both the ECM and GFS have similar evolutions this does raise the chances, the GFS 06hrs control does highlight how that upstream amplitude can help force more energy under any high pressure to the north/ne. It could be we might see a more eastern Greenland/west Scandi high type of set up if things fall into place.

Of course it might well go pearshaped this evening, we'll see this evening whether this trend can continue. Certainly though there are changes in the NH pattern and still quite a lot of uncertainty over the USA and Canada so its likely we've just embarked on a mystery tour of sorts.

 

[Shuga ice]

I agree with Frosty, there is a big change coming, the Euro high departing is going to be the biggest change as this has been the main driver overall.  Much more opportunities with its departure.

there will be plenty of eye candy in the next week.  I wouldn't be surprised if we had a white new year at the very least!

[knocker]

Hot off the press. So to speak. And a quick glance at the anomalies gives me no reason to alter my earlier post

Chart weatherbell http://www.tropicaltidbits.com/

 

Edited December 5, 2015 by knocker

[bobbydog]

some very sensible and realistic posts on here this morning. if we are to see a major pattern change to sustained blocking, its not showing within the range of the models... yet...

however, they do seem to be showing the jet gradually slipping south as december progresses (as per the Netweather forecast). at this point, from what we CAN see, i.e. some wintry incursions to a greater or lesser degree, with chances possibly increasing towards the second half of the month, it wouldnt be outrageous to suggest putting a small bet on a white christmas..... 

 

(edit-not sure why my font size changed there)

Edited December 5, 2015 by bobbydog

[johnholmes]

a request folks?

Has anyone got the link to the 30mb pole temperatures  currently, I used to have it but cannot find it now?

thanks

not this one by the way

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/

this one

Edited December 5, 2015 by johnholmes

[Snowman.]

2 minutes ago, johnholmes said:

a request folks?

Has anyone got the link to the 30mb pole temperatures  currently, I used to have it but cannot find it now?

thanks

 

Would it be this? http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2015120506&var=TMP&lev=30mb&hour=000

[johnholmes]

4 minutes ago, SN0WM4N said:

Would it be this? http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2015120506&var=TMP&lev=30mb&hour=000

thank you for your reply but no, it is the one I've got a photo shot of from anomaly charts several years ago but I cannot find it on the web. Very simplified type but it suited my approach?

[phil nw.]

14 minutes ago, johnholmes said:

a request folks?

Has anyone got the link to the 30mb pole temperatures  currently, I used to have it but cannot find it now?

thanks

not this one by the way

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/

 

The Berlin graphs here John

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=all&alert=1&lng=eng

or Japan

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif

Edited December 5, 2015 by phil nw.

[IDO]

8 minutes ago, johnholmes said:

thank you for your reply but no, it is the one I've got a photo shot of from anomaly charts several years ago but I cannot find it on the web. Very simplified type but it suited my approach?

The one I like is: http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

Edited December 5, 2015 by IDO

[johnholmes]

15 minutes ago, phil nw. said:

The Berlin graphs here John

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=all&alert=1&lng=eng

or Japanhttp://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif

man ythanks phil that is what I wanted

[johnholmes]

11 minutes ago, IDO said:

The one I like is: http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

yep thanks you the one

not that it gives any hope to cold lovers in my view.

A year or two ago IF it climbed through the average and stayed some way above it then I reckoned on a 'cold' spell being highly probable anywhere from 15-25 days later!

I got at least 3 maybe 4 where it worked well but 2 or 3 where it did not.

ah well!

 

[bluearmy]

2 hours ago, knocker said:

Hot off the press. So to speak. And a quick glance at the anomalies gives me no reason to alter my earlier post

Chart weatherbell http://www.tropicaltidbits.com/

 

Keep tabs on that sceuro anomoly knocks. The extended eps built a Scandi upper ridge in two weeks and the extended ops are messing about with undercutting of the Atlantic jet.  not saying anything will happen but there are hints out there of possible pattern changes in a fortnights time.  Perhaps sooner although I suspect that could be the ops being over progressive. 

[Mucka]

I'm not surprised there is still a good deal of caution about any cold interludes, there are conflicting signals and the models have been struggling with the jet profile over Canada and energy coming off the Eastern seaboard. There is plenty going on upstream even in the 3 to 5 day period so much to be resolved however my thoughts remain the same as they have the last few days.

A strengthening signal for the jet to continue to want to dig south and increased amplification as we head toward mid month.

This will result in the weather staying mostly unsettled but with increasing prospects for wintry outbreaks, especially for the north, as the lows dig further South and we get ridging behind.

If correct we will slowly see less disturbed weather develop as we head toward last 3rd of the month and it still appears that the models will want to develop a trough into NorthWest Europe into the second half of the month so there will be scope for slightly longer and colder outbreaks from the NE later.

 

We have undeniably seen a trend toward cooler and less mobile weather being forecast from around a weeks time and that signal has slowly strengthened. Yes with so much upstream to be resolved it may be the models end up overrunning the signal and we lose out but why be pessimistic when the trend is our friend - for the time being at least.

I disagree with those who say there is no sign of blocking through December. Again it is true that the current output is predicting only transient ridges or weak high pressure overall but again the signal is strengthening that blocking could take hold later in December.

I don't personally think there is really much hope of s Scandi high until last 3rd of Dec but I think there are reasonable pointers toward precursors to such an event which themselves could deliver some cold shots and possible snow - a ridge in our vicinity being undercut and the possibility of a weak Icelandic high for example. This is not hope-casting, it is they way the output is currently trending. (not to say that won't change)

Again, just a few days ago several people were writing off the whole of December as Westerly dominated because there was so little cheer in the output, so we have already come a long way. 

In summary I don't expect to see any deep prolonged cold for the UK any time soon and more mild wet and windy weather to come but it is a sign of the times when an ECM chart showing cold and snow for the South receives only grunting approval. That chart would of put of the forum into melt down a couple of years ago. Maybe it is better that the forum is more grounded and realistic but there should always be room for fun as Steve put it (And this is not pointed at any posters including Tamara who's posts I enjoy) 

Talking up cold and snow for the UK can ear you Brownie points here but it can also earn you a lot of scorn when things go wrong, there is a lot of petty oneupmanship that goes on unfortunately but that's forum life.

I think we now have a good chance of seeing snow falling to low levels somewhere in England before December is out, lying snow will be harder to find, that has to be good news for coldies right?

Let's hope the output can firm up on any cold and deepen and lengthen it, if not c'est la vie, plenty of winter left - cheer up folks. 

 

[Ali1977]

No comments on the 12z pretty much sums it up, cooler spell next weekend then back to stormy spells.