Model Output Discussion - January 11th.

[ChartViewer]

Sorry mate your being contradictory. You used the T168 chart and said that's not what we want to see at that range but then accused SM of looking at FI.

The Azores ridging north started at T96 and looking at the whole run it isnt great. All 3 models are now showing the same pattern but could change i dont doubt that. However

1. Firstly lets have perspective here.....When people are posting a panel map showing a -18 some newbies might see it and take it as gospel ...Now if I was posting a Bartlett at T240 id be shouted down...so lets have some consistancy

2. I still think you may see some change but tonight is first night in a while all 3 models are trying to edge the Azores ridge northwards...consistancy?

3. I looked at T0 to T168 ECM and could not see any reason that cold could and I mean sustained cold could see our shores with daytime temps at 0-2 and snow and real cold. Backing up the earlier big 2 models.

Im happy to say sorry i got it wrong but right now the models do not show sustained cold tonight

Regards

Edited January 11, 2012 by ChartViewer

[Paul]

Just to clarify for any who are unsure - if your post consists of something along the lines of:

"This run is awful, maybe the 18z will be better"

or

"This run is an upgrade, it's going to snow and be -10c here for weeks"

or

"I hate the cold weather so this run is great as it's going to be mild all the way"

Then please post it into the model mood thread - that thread is specifically for this type of post - in fact any post which is more about how you feel about the models than the actual model runs themselves:

http://forum.netweat...el-mood-thread/

Then this thread can be used for actual model discussion...

Thanks

[shedhead]

Well all 3 big guns go for a slider between 96-120hrs, so that now looks pretty much nailed as a short to medium term evolution, what happens beyond this remains as clear as mud and therefore in the land of pointless speculation imo.

[nick sussex]

I think the best thing all round is to concentrate on synoptics upto maximum 144hrs.

Seeing as the models are determined to wring every last bit of drama out of the current situation. I have zero faith in anything shown past that point in terms of operational runs.

You really can't get a more complicated set up, as they say timing is everything here, the PV acts like a magnet to those shortwaves which as you can see form to the south and run ne, at the same time pressure is rising to the ne, what gets there first shortwave or ridge?

On the face of it theres agreement at 144hrs between the models, for now. Given recent days I doubt that will last for long.

In terms of the ECM, it gets there in the end but the PV still looks too far east, its supposed to be going west but obviously has decided to change its mind.

The NOAA discussions will be illuminating or not as the case maybe, what happened to the main negative anomaly being further west towards western Canada!

[Frosty.]

The 12z runs are generally following the latest meto 6-15 day update with a milder and more unsettled spell returning next week as the jet strengthens yet again but at least we get a frosty weekend coming up and frosts so far this winter, and including november, have been as rare as hens teeth.

[ITSY]

ECM goes for a colder evolution - -5C uppers covering the country by +240. As said earlier, this will take a while to figure out - best leave it till the weekend for anything close to concrete. just can't help myself!

[ChartViewer]

Yes from T96 to T168...Not T168 onwards which cold lovers are trying to do....So no contradiction unfortunately as the models show.

Regards

In fact if you run the animation you will see what happens but I doubt you will............Azores ridge northwards from T96 to T144-168...Pretty much where i stopped commenting on yes?....Not looking out T192 and beyond.

Oh and I did justify the post with the last sentance so please stop caveating what I said with certain words.

Edited January 11, 2012 by ChartViewer

[cooling climate]

I would certainly bank this chart with the prospect of several cold or very cold days to follow and

if the synoptics played into our hands then perhaps a visit from the real beast.

FI yes but the building blocks start long before that. It also coincides with the earlier update from

NOAA with regard to the PV being dislodged westward.

[wolvesfan]

Evening all,

Posters need to learn quickly not to hang on every run,GFS 12z op one of the mildest runs viewed amongst the ensemble members,the ensemble mean still dips below the long term average after the 19th as it has for a few days now.ECM also ties in with the GFS trending cold from the 19th,that is the big picture not individual runs that show diffrent outcomes.

A trending -ve AO is pushing cold out of the polar region south into the northern lattitudes,the mods are still getting to grips with this but the pattern weve seen this winter is set to change dramatically from around the 19th.

[winter watcher]

I think the best thing all round is to concentrate on synoptics upto maximum 144hrs. - Nick Sussex

Nick i agree to concentrate on the reliable up until that crucial 128+ - 168. However just a thought is that we keep seeing cold if not very cold runs in to the realms of FI however hardly no mild runs.

Correct me if i am wrong but this chopping and changing could go right to the wire and i mean T48 as not only due to the complex situation but also other factors as per the GP theory and effects that go with this?

[Thundery wintry showers]

In the shorter term we are set for a pattern change to colder and brighter weather (although the last few days have had some sunny breaks in many eastern and southern areas- it's mainly in northern and western areas where the "brighter" part will be felt very strongly). A frontal system will progress southwards tonight and tomorrow, bringing a brief bout of rain and strong winds across northern and western Scotland, then fizzling into an area of cloud and sporadic light drizzle as it heads south across England and Wales.

The airmass behind the front will not be especially cold (the main thrust of Arctic air is set to head east into Scandinavia) but skies associated with that airmass are mostly clear, so we can expect mostly dry sunny weather from it during Friday and the weekend, possibly lasting into Monday, with the high ideally positioned (centred in the North Sea) to prevent much moisture coming in off the Atlantic or the North Sea. Temperatures will get up close to the seasonal average by day (5 to 7C typically across the UK, though rather below where any fog patches persist, while frost should be quite widespread by night with fog patches.

It may well turn out to be a short colder anticyclonic "snap" before milder air pushes in from the west, rather than the prelude to a battle between the Atlantic air and continental air, but it would be wrong to say that there is nothing "seasonal" in store for us for the foreseeable future.

And yes, a very snowy-looking T+240 chart on the ECMWF, but at that range even the ECMWF is generally unreliable. It's a plausible enough evolution though from where we end up at T+168, thus highlighting the fact that an initial Atlantic "win" doesn't mean we can't have opportunities for something snowier into the last third of January.

[BLAST FROM THE PAST]

ECM produces some consistency today in subsequent runs. Its the trigger LP we look for as we look for the arctic Russian HP to back west. If there is some higher pressure to our W or SW then a link up occurs bringing v cold easterlies. Again though GFS ditches it until well into FI so we continue to wait for continued consistency. I really think the retrogression exists and its E / NE we look, continue to look.

BFTP

[Andy_]

A nice surprise to come back to from cooking the tea, the ECM keeps up its cold pattern change. Some not so subtle differences between the 0Z and the 12Z, in which we have two areas of WAA over NW Russia and Far NE Russia, rather than an area of warmer air over the Arctic which was provided by the 'Aleutian Ridge'.

Two different setups northern hemispherically, but crucially two that still allow cold to filter into North Western Europe.

Supporting charts:

0Z

12Z

[bluearmy]

_{the solution of the 00z and 12z} ecm _{in FI is not too different for nw europe. there are differences way to our north where the total split in the vortex is prevented by energy over running svaalbard at T144 but beyond that, the idea of the depression in the north atlantic driving the trough se to meet the chunk of p/v marooned in se europe is the same. its just that on the 12z with a stronger jet, the pattern is shifted a tad further east.}

_{this se driving trough is a gefs trend that we've seen a lot over the past few days. obviously the heights to our ne prevent the jet heading east and eventually something has to give which is the trough energy going se. looks ok to me though i suspect its not a pattern with massive} ens _{support considering the meto 14 dayer fromt his morning. maybe the 12z} ecmens _{will play catch up a bit ?}

[bobbydog]

just a quick question, i'm sure i'm not the only one wondering, - the op run is quite often an outlier (be it mild or cold) so how is it chosen as the op run? is it due to the fact the ensembles are computer generated but the op run has human input with added factors/teleconnections that the computers cannot see?

thanks in advance,

rob

[Polar Continental]

One can’t help but be reminded of this.

Jan 20th 1947

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00119470120.gif

Tonights ECM output

http://www.wetterzentrale.de/pics/Recm481.gif

Jan 22 1947

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00119470122.gif

We all know what followed

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00119470126.gif

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00219470126.gif

Tonight's evolution is somewhat similar, though more long winded. Interesting viewing at any rate.

[Paul]

just a quick question, i'm sure i'm not the only one wondering, - the op run is quite often an outlier (be it mild or cold) so how is it chosen as the op run? is it due to the fact the ensembles are computer generated but the op run has human input with added factors/teleconnections that the computers cannot see?

thanks in advance,

rob

The operational run is the GFS, still computer generated with no human intervention, but at a different resolution and with slightly different physics (until the ensemble upgrade later this month).

[snowblues]

I thought there would be more comments this evening with the ecm out look.At T 168 and onwards, there i saw a nice long lobe of high pressure in Russia forcing its way across,pushing the pressure away to the north of the UK.Has it been ther on previous runs. mike

[bobbydog]

The operational run is the GFS, still computer generated with no human intervention, but at a different resolution and with slightly different physics (until the ensemble upgrade later this month).

thanks paul

[Tim Bland]

I thought there would be more comments this evening with the ecm out look.At T 168 and onwards, there i saw a nice long lobe of high pressure in Russia forcing its way across,pushing the pressure away to the north of the UK.Has it been ther on previous runs. mike

Problem is its always jam tommorow! we need to see the cold backing west being brought forward not always in FI. It seems all the background signals are there but the cold Synoptics only show in the low res part of the output. The jet is just too powerfull IMO

[bluearmy]

Problem is its always jam tommorow! we need to see the cold backing west being brought forward not always in FI. It seems all the background signals are there but the cold Synoptics only show in the low res part of the output. The jet is just too powerfull IMO

but the ecm 12z is very similar to the 00z. the bringing forward of the cold has only been from progressive op runs undercutting too early before the arctic high has pushed far enough into our part of the NH. the models will continue to 'play around' with the correct solution. the strength and orientation of the jet will dictate timing.

[nick sussex]

I think the best thing all round is to concentrate on synoptics upto maximum 144hrs. - Nick Sussex

Nick i agree to concentrate on the reliable up until that crucial 128+ - 168. However just a thought is that we keep seeing cold if not very cold runs in to the realms of FI however hardly no mild runs.

Correct me if i am wrong but this chopping and changing could go right to the wire and i mean T48 as not only due to the complex situation but also other factors as per the GP theory and effects that go with this?

Personally ensembles well into FI are a waste of time when you're dealing with a very complicated set up, even if the whole cluster shows -10 850's I'd still be very dubious.

Set ups like northerly topplers are generally easier to model and zonal flows again are okay for the models. The ensembles in this instance are less prone to be wrong upto 240hrs.

In terms of FI I don't think things are quite so bad as T-48hrs.

I know everyones bored to death of the PV but its really down to that, if it doesn't move away from the heart of Greenland then its very difficult to get cold into the UK.

You can sustain cold to a point with the PV in western Greenland but say a cold spell more than five days you will need a signal to develop blocking in that region, easterlies by their very nature cannot sustain, you only get extended cold with easterly/northerly alternating because of background signals for higher latitude blocking.

Of course given the winter so far I'm sure most would be happy to just see any cold that came with snow even if it was for a few days.

[Backtrack]

My model output analysis

GFS 12z

Short term:

In the short term, it looks like a weak Northerly airflow will develop tomorrow thanks to the Azores High ridging Northwards. High pressure will gradually ridge its way Eastwards over the British Isles introducing sunny days with temperatures sitting at or slightly below average. Turning increasingly frosty overnight with temperatures falling as low as -7C in rural areas. Temperatures may struggle to make freezing in central Scotland. The jetstream looks like tracking up past Iceland for a short amount of time at least, allowing the Azores High to ridge in far enough Northward to allow this change in weather for a time at least.

Medium term:

High pressure remaining in control in the medium term, meaning bright days with respectable amounts of sunshine, frosty by night, eventually turning more unsettled and colder from the North West with snow showers in the far north. Elsewhere looking quite wet. The polar vortex looks like strengthening over Greenland, which is not a good omen for cold weather fans. We see the jetstream sat right over our roofs, which is going to prevent the Azores High from ridging further north, and pushes the pressure back South of the UK, preventing any kind of blocking out West, meaning to respite from the Atlantic just yet.

Long term:

A poor run in the longer term for cold weather fans with any colder air from the west or north west being quickly pushed away. Tentative signs that we may see a more Southerly tracking jet allowing pressure to rise for a time. With an ever weakening polar vortex to the North West. Tentative signs also that we may see a pressure rise over Europe, including Scandinavia, a good sign for cold in the longer term. Overall, not going into any more detail regarding longer term analysis as the models are up and down like a yo-yo, the law of averages tells us that the 18z has a good chance of been a colder run. Don't look into the longer term in any detail, instead use the GFS ensembles to judge trends and patterns.

ECM 12z

Short term:

In the short term, as expected, the ECM 12z is pretty much the same as the GFS. Small changes though. The ECM allows the UK to hang on to slightly colder uppers for a little longer, meaning temperatures could well sink lower overnight than what the GFS suggests. A look at the hemispherical chart shows us that there is no change at all in the Polar Vortex, remaining the same as the GFS's suggestions in the short term at least. As you would expect, frosty nights and sunny days on offer, temperatures perhaps slightly lower come nightfall.

Medium term:

The medium term again is similar to the GFS with subtle changes such as slightly lower pressure over Spain, and a slightly weaker PV over Greenland and the North West. The ECM does offer a major change over Eastern Europe however. We see the cold pool much shallower than what the GFS offers, the ECM also offers a much colder pool of air over Europe that the GFS, with slacker pressure sandwiched in between, resulting in higher upper air profiles over the United Kingdom, so slightly milder in the medium term from the ECM. Another major change is out in the North West Atlantic. The GFS offers a much deeper Polar Vortex, with the air circulating over Greenland, keeping the Arctic air bottled up. However the ECM seems keen to model a much shallower PV offering MUCH colder air out in the NW Atlantic. Perhaps giving any NW'erly feeds more of a 'kick'.

Long term:

The ECM offers a colder solution than the GFS in the longer term. I will not go into much detail about the longer term, as the ECM is also up and down like a yo-yo. But tentative signs of a pressure wise out west, which could promoting temporary blocking over Greenland with a Northerly scenario over the United Kingdom, as opposed to the NW'erly being shown on the GFS. We see higher pressure beginning to ridge in over Scandinavia with the ECM suggesting a MUCH more aggressive, colder pool of air than the GFS over Eastern Europe.

UKMO 00z:

Short term:

I really don't need to write about the short term again. It's very similar to what the other two models are showing. This being average, or slightly below at times in the day with lots of sunshine on offer, with cold, clear and frosty of a night, dropping below -7C at times in parts. The UKMO offers a few changes in terms of pressure. We see the Azores High further west, resulting in a slightly colder flow at T+72hrs on the Met Office with the winds having more of a Northerly tint to them in the East. A deeper low over Scandinavia on the UKMO as opposed to the other two models, stopping the Azores High ridging as far Eastwards as per the ECM and GFS.

Medium term:

Changes in the medium term from the UKMO, offering a much weaker looking high over the UK. UKMO goes against the other big two, by not allowing the Azores High to link up to the subtropical ridge to the South, instead we see a cut off low preventing the link up, and also retaining a deeper low over Europe, stopping higher pressure from spreading Eastwards. The UKMO offering a slightly weaker PV than the other big two models, but not substantially so.

Medium +1 term:

In the long term, the UKMO has a slack flow over the UK with minimal high pressure influence, the HP being much weaker, and more compact, resulting in a slightly stronger Southerly flow. A look at the hemispherical chart shows a stronger PV, with the arctic air spilling as far southwards as the GFS, leaving the ECM on its own in terms of Arctic air in the Atlantic. Remaining around average, perhaps becoming more unsettled as we progress.

Edited January 11, 2012 by Backtrack

[shotski]

One can’t help but be reminded of this.

Jan 20th 1947

http://www.wetterzen...00119470120.gif

Tonights ECM output

http://www.wetterzen...ics/Recm481.gif

Jan 22 1947

http://www.wetterzen...00119470122.gif

Hi PC, I posted the same two charts on last nights thread as I felt a similar pattern to 1947 "could" be on the cards.

But it got as much interest as Palace Vs Cardiff

[Bristawl Si]

For what it's worth in this debate, latest thoughts from Ian F -

Eventually more unsettled mid next week as blocking high shifts - but crucially, uncertain timing and 'evolution' - in another tweet he's mentioned possible transient wintry stuff for our area.

Make of that what you will - my interpretation is one of an uncertain situ evolving through next week (certainly not clear cut even to the Pros...at this time) - all to play for i reckon.

Will the models 'settle down' in next couple of days? Will we have a small scale west/east 'battle' somewhere over the UK next week? Will the atlantic win out? Or will the HP forming to our East win the day?

Interesting times ahead for model watchers, me thinks.

Edited January 11, 2012 by Bristle boy