Model Output Discussion - 31/10/2014 and Beyond

[SMU]

06z GFS - waste of space....

We never see an ECM 06z do we.

Wait for the 12s & the NOAA AO updated ensembles -

[SMU]

Just around the allignment of the PV wedge over russia at 144-

 

NAVGEM

144

http://modeles.meteociel.fr/modeles/navgem/runs/2014110706/navgemnh-0-144.png?07-11

 

Notice the flow around that vortex is SSW

 

UKMO

http://www.meteociel.fr/ukmo/runs/2014110700/UN144-21.GIF?07-06

SSE - which would be poor

 

When we get our great cold spells the models ALWAYS show SSE poor to start with the correct allingment through time, so this is one of observational trending I want to view in the next 24 hours.....

 

Its not all about looking at the atlantic......

[Vorticity0123]

Currently, we are experiencing a rather blocked pattern, with low pressure areas moving from the Atlantic over the UK and getting cut-off toward the Mediterranean.  This seems to be occurring due to a large high pressure area over eastern Europe, which is preventing the Atlantic lows from moving into Western Europe. Instead, the cut-off lows are causing large rainfall totals in the Mediterranean, with also some flooding taking place there (for example: see link below)

 

http://www.euronews.com/2014/11/06/italy-swamped-by-flash-floods-/

 

The pattern can be seen in the GFS chart below:

 

GFS surface level pressure and 500 hPa heights (colours) 06Z run, analysis (T0)

 

One can see troughing (blue to yellow colours) dipping from the UK into the Mediterranean, which causes a continuous flow of low pressure areas moving along that line (blue line on picture). Furthermore, high pressure can be seen over eastern Europe, with warm air being advected toward Scandinavia (green colours edging northward, follow red line)

 

There does seem to be a much advertised, though slight, pattern change on the way, with signs of high pressure becoming more prevalent to the north of the UK. To show the pattern change in general, take a look at the NOAA 6-10 day chart:

 

NOAA 6-10 day 500 hPa heights (green lines) and anomalies (broken lines) forecast.

 

The main difference is that the warm air advection (WAA) has reached a more westerly position, now reaching as far as Greenland (which can be seen by the green lines edging poleward toward Iceland from Scandinavia, red line). The elongated trough over the UK and the Mediterranean is still visible, though (see blue line).

 

As a result of the further advance of the warm air advection, high pressure is more likely to establish itself between Scandinavia and Iceland (with the ususal precautions). Note that confidence in this forecast (mainly the upstream part) seems to be fairly high, with the CPC (climate prediction center) giving a score of 5 out of 5 regarding confidence level of the 6-10 day forecast¹. However it is important to bear in mind that this high level of confidence in the American sector does not immediately translate to a high level of confidence over Europe.

 

Sources:

¹http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

http://www.euronews.com/2014/11/06/italy-swamped-by-flash-floods-/
http://www.wetterzentrale.de/topkarten/fsavneur.html

Edited November 7, 2014 by Vorticity0123

[Polar Maritime]

The 6z stills shows the Models struggling with the cut-off Low over the UK, With maybe the Atlantic winning out drawing back in a N/W flow.. Another variation of many others to come im sure, Before we are anywhere near a consensus. 

 

Edited November 7, 2014 by Polar Maritime

[chionomaniac]

The parallel GFS has suggested increased wave activity in the greenland area - if only we could see the lower strat charts from T+180

[mushymanrob]

I feel that unless we get tropospheric led wave 2 activity breaking significantly into the strat from Greenland area with the corresponding tropospheric WAA, then we will not get the major early season cold outbreak that is potentially being touted. The anomalies are great to look at, but as of yet they are not going to lead to major cold coming from the east for a number of reasons. The background state is wonderful for later in the winter when cold will be deeper, but not now. I am probably one of the few who doesn't want to see a disturbance in the upper strat that is too strong this early in the season because I think that the ebb and flow of the subsequent recovery will delay the next wave hitting. 

 

Other factors such as the MJO phasing and Cohen background anomaly match, tend to reinforce these thoughts. All is good, but unless we get that wave 2 activity to our NW then the cold will remain just out of reach. Any splits modeled so far have not been in the right area for us.

 

hi

 

can i ask you to explain what the bib means please?... i dont know what a 'wave 2' is, nor what the WAA is...

[chionomaniac]

hi

 

can i ask you to explain what the bib means please?... i dont know what a 'wave 2' is, nor what the WAA is...

Hover your mouse over WAA and lo behold...... it says warm air advection. A process where warm air from latitudes further south is moved into the polar latitudes ahead of a trough. It will then reinforce any blocking in that region.

 

The wave 2 is the number of atmospheric longwaves present at any given time - time of which I wish I had more of to show you diagrammatically!

[MR EXTREMES]

The parallel GFS has suggested increased wave activity in the greenland area - if only we could see the lower strat charts from T+180

Noticed this the para is complete opposite to the control run.

it was only earlier today you spoke of the wave 2 but from what you were saying id of thought wave 2 would be better towards the end of nov for a more sustained winter wintry spell.

[mushymanrob]

Hover your mouse over WAA and lo behold...... it says warm air advection. A process where warm air from latitudes further south is moved into the polar latitudes ahead of a trough. It will then reinforce any blocking in that region.

 

The wave 2 is the number of atmospheric longwaves present at any given time - time of which I wish I had more of to show you diagrammatically!

 

oh yeah... lol.. thanks!

[snowstorm445]

Even if the 6z isn't as good for our part of the world as the previous run, the story is the same regarding the PV.

(http://modeles.meteociel.fr/modeles/gfs/runs/2014110706/gfsnh-0-192.png?6?6)

Completely in tatters, above average heights over the North Pole. Amazing stuff for this time of year.

[johnholmes]

Currently, we are experiencing a rather blocked pattern, with low pressure areas moving from the Atlantic over the UK and getting cut-off toward the Mediterranean.  This seems to be occurring due to a large high pressure area over eastern Europe, which is preventing the Atlantic lows from moving into Western Europe. Instead, the cut-off lows are causing large rainfall totals in the Mediterranean, with also some flooding taking place there (for example: see link below)

 

http://www.euronews.com/2014/11/06/italy-swamped-by-flash-floods-/

 

The pattern can be seen in the GFS chart below:

 

GFS001_EDIT.gif

GFS surface level pressure and 500 hPa heights (colours) 06Z run, analysis (T0)

 

One can see troughing (blue to yellow colours) dipping from the UK into the Mediterranean, which causes a continuous flow of low pressure areas moving along that line (blue line on picture). Furthermore, high pressure can be seen over eastern Europe, with warm air being advected toward Scandinavia (green colours edging northward, follow red line)

 

There does seem to be a much advertised, though slight, pattern change on the way, with signs of high pressure becoming more prevalent to the north of the UK. To show the pattern change in general, take a look at the NOAA 6-10 day chart:

 

NOAA 6-10_1_EDIT.gif

NOAA 6-10 day 500 hPa heights (green lines) and anomalies (broken lines) forecast.

 

The main difference is that the warm air advection (WAA) has reached a more westerly position, now reaching as far as Greenland (which can be seen by the green lines edging poleward toward Iceland from Scandinavia, red line). The elongated trough over the UK and the Mediterranean is still visible, though (see blue line).

 

As a result of the further advance of the warm air advection, high pressure is more likely to establish itself between Scandinavia and Iceland (with the ususal precautions). Note that confidence in this forecast seems to be fairly high, with the CPC (climate prediction center) giving a score of 5 out of 5 regarding confidence level of the 6-10 day forecast¹.

 

Sources:

¹http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

http://www.euronews.com/2014/11/06/italy-swamped-by-flash-floods-/

http://www.wetterzentrale.de/topkarten/fsavneur.html

very true V but others please be aware that their comments relate to upwind of and over the N American sub continent although obviously everything is linked. Just a word of caution from me. It looks good but as chio as pointed out not all the building blocks are aligned properly yet.

[Snowy L]

Regardless of whether the UK is cold or mild in the mid-term, the story has consistently been the same; a weak polar vortex. As long as this remains, then there will be opportunities for a favourable block to occur. That's all we can ask for at the moment.

[Man With Beard]

In times of uncertainty, I often find a correlation between the GFS ens mean and ECM ens mean a good indicator of certainty levels. When they agree closely, then the outcome is usually pretty close to what they say.

 

So I was pretty astonished to see such similarity in the D10 means today. Not just because they agree, but because they agree on such a darn unusual set-up at such long range:

 

 

 

Very, very close for D10 means. Also, you would usually expect the D10 to be much more muted, much more like a "seasonal average" chart - but these charts are both way off the seasonal average.

 

So I feel quite confident in saying:

- the AO will almost certainly go very negative

- The PV still won't have a grip on things

- Heights will be reasonably strong between Greenland and Scandinavia (I'm going by the colours (500mb), not the contours (1000mb))

- it will still generally be wet and possibly windy over the UK at D10, with temps around average or slightly below

- A possibility would then exist that cold air will be directed on towards the UK on the southern flank of a Greenland / Scandi block

- The depth of this cold will depend on whether the Arctic air can engage with the Greenland / Scandi block (not a given on these charts)

[summer blizzard]

After the excitement of last nights victory we rightly need to calm ourselves. 

 

Good news though is that both the Euro and parallel sing loosely from the same hymn sheet with heights near Belarus lower allowing us a route to cold once our low moves into central Europe..

 

 

[nick sussex]

The overall NH set up is good for cold potential but  a few issues remain.

 

Part of the problem is the initial trough disruption isn't sufficient, indeed if you look at the GEM which is the best in terms of cold it takes several attempts before you get to a great looking chart at T240hrs, the GFS P second best in terms of potential but you'll see it gets there because it manages to get the UK low separated from lower heights over Greenland:

 

 

Having said all this theres no output which you can't see potential in, I sense some frustration might grow in the thread if a good NH set up doesn't deliver, and some of this further added to by the ECM monthly and suggestions that the positive anomalies near the pole might begin to wane.

 

So what to believe, personally I'm not a great lover of a monthly ensemble which takes less resolution to begin with and the ECM monthly seems to do best when its dealing with a bog standard Autumn or Winter pattern.

 

The current synoptics are far from usual for this stage of the Autumn, indeed lets look at the past few weeks, does anyone remember the so called good agreement upstream for a flat pattern, apparently good agreement on the ensemble tools by CPC.

 

I think we've seen a background signal to amplify when the ensembles have been reluctant to, the split PV and those positive anomalies making that much easier.

 

For the timebeing because of the set up I'd keep an open mind about November prospects, whilst we haven't seen any real cold enter the more reliable timeframe we shouldn't discount this.

 

It's not like we're seeing a raging PV and are trying to believe output at T300hrs for some cold hope, in that set up you need a huge NH change to deliver cold, in the current set up its a few tweeks here and there, a lot depends on any trough disruption and exactly how well modelled those pressure rises are to the ne.

 

 

[Gael_Force]

One of the monthlies might be smelling the coffee - just a few days ago, the charts for last third of November had a very warm anomaly over the UK.

 

[SMU]

Updated NOAA AO trending.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

 

now changed to persistent negative.

 

I expect a downtick in values tomorrow to circa -3's poss touching the magical -4.

 

thanks

[Eskimo]

Well the 12z looks like turning into a thing of beauty

[Purga]

Well the 12z looks like turning into a thing of beauty

I'm sure there's a sort of beauty in wet and windy weather.

Edited November 7, 2014 by Purga

[nick sussex]

Better shape to the troughing near the UK and we lose the football shaped of the GFS 06hrs run, however its still attached to low heights over Greenland, preferably we want to see the trough elongated and ejecting energy ese into Europe.

[shaky]

Also the cold coming out of scandinavia is coming at more a south/southwest angle compared to the southeast angle it was showing earlier!!steve murr mentioned this earlier and told us to watch the angle of the cold coming in from the north east and it looks like its happening already on the 12z gfs!!heights are stronger as well!!

[Snowman.]

I'm sure there's a sort of beauty in wet and windy weather.

 

He's talking about the synoptics and the bigger picture.

 

Just because it isn't here doesn't mean it wont ever will be.

[Mucka]

UKMO still relatively disinterested in any significant trough disruption to our West but it is a slight improvement in pushing heights toward Greenland.

 

 

 

Edited November 7, 2014 by Mucka

[Purga]

He's talking about the synoptics and the bigger picture.

 

Just because it isn't here doesn't mean it wont ever will be.

It looks like a classic case of an early season -ve AO that looks tantalisingly good on paper but in reality produces nowt much but loads of unsettled cool / mildish weather for the UK. So near but yet so far. Sure it may lead to something better later on but equally it may not!

GFS 12z FI is a good example

The LPs trundling across the Atlantic will keep us on the mild side of the action - frustratingly and we've seen it so often before.

Edited November 7, 2014 by Purga

[nick sussex]

UKMO still relatively disinterested in any significant trough disruption to our West but it is a slight improvement in pushing heights toward Greenland.

 

 

 

Its not a bad chart really, if we get the following occurring:

 

Shortwave forms at the base of the trough, pressure rises to the ne start to put forcing on the trough, as the energy begins to shear away from the trough some of that heads away to the nw, at the same time the shortwave has run into France and the ridge to the ne has extended further sw.

 

This should then at T168hrs show a more elongated troughing running nw/se, preferably things would be easier if the troughing was so blown up to begin with. I still have my doubts about what the UKMO is doing with that trough.