Model Output Discussion - 7th-13th November

[Robbie Garrett]

Ian Brown's ramped up cold. Very similar to when Craig Evans didn't predict record warmth last December, you know something cold's around the corner! Hahaha.

Arctic floodgates open as a massive hp belt from siberia to alaska evolves. PV looks immense by novaya semlya and we have lift off with the arctic front touching Hammerfest. Svalbard tickets booked and ready thanks!

North pole gets a nice ridge from Greenland, PFJ still south and that arctic air floods into Kiruna.

Game is still on really, and there is optimism personally for a cooler/cold last week of the month. PFJ just reacting well for us and PV setting up well.

So is the picture of the GFS/and my arrows pointing what direction the air masses will flow correct? Also seeing that high pressure is a western blocking and not a northern blocking, will it provide some possible monster snowfalls due to more moisture in the air as the HP flows clockwise, and meets the low pressure air (cooler) that is flowing counterclockwise?

Edited November 8, 2011 by Robbie Garrett

[johnholmes]

The runs in FI look very interesting, take a look at my take on things. Considering how LP and HP work, that looks very much possible - and even though this is so far away, the Jetstream follows the high and pushes the low southbound into Europe.

Its nice to see folk being enthusiastic and adding to their posts with charts using them to make predictions but Rob, a word of caution, take a look at the blue arrow on about 1020 or 1024 mb isobar. Track it back to where the air originated from?

Way south so that part is not going to be very cold at all.

[Robbie Garrett]

Its nice to see folk being enthusiastic and adding to their posts with charts using them to make predictions but Rob, a word of caution, take a look at the blue arrow on about 1020 or 1024 mb isobar. Track it back to where the air originated from?

Way south so that part is not going to be very cold at all.

I see what you mean, but the setup is their for it to drag cooler/colder air down than what is currently being shown. I know fully well not to go on forecasts, past the day, and not even then is it successful. But the western blocking will surely help as much as a northern blocking? as it will push any lows up towards the poles, with a gap right over the UK/Western Europe - surely that's more exciting than what we currently have, even if it brings on just clear skies and widespread frosts.

All I know is, it's going to be an interesting few weeks/months even of model watching!!!

Edited November 8, 2011 by Robbie Garrett

[mountain shadow]

1/2 the Oslo ensembles show a cold plunge on the 12z GFS, hopefully we can tap into it.

[bluearmy]

look back at the archived ecm runs for this date last year. you'll see the current output looks far more promising, what i cant see is the archived gfs runs. my recollection was that they were showing pretty amazing fi runs, as was naefs. thats what is pushing most reasonable folk on here to be less excited about the potential shown on ecm op fi.

btw, the 12z ecm op is well on the cold side of the ens for de bilt days 8 thru 10. the ens actually show a warming trend, tying in with one of stewart's earlier posts today.

Edited November 8, 2011 by bluearmy

[SMU]

Evening All-

Very encouraging ECM outlook tonight- the 15 day ensembles will most certainly contain some very cold members-

I suppose the disclaimer tonight is the GFS has no cold- so for now nothing certain, however the GFS has been very poor of late-

So IIRC I have been going about a pattern change in the 12-14 day range now for a few days- & the ECM today has made it the third run on the trott to model more or less the same evolution & tonights 240 chart is certainly the best yet, however the 192 & 216 day 8 & 9 are certainly demonstrating the wheels being 'in motion' at that time-

Just to clarify if people arent seeing a chart perhaps you should compare T0

http://www.meteociel.fr/modeles/ecmwf/run/ECH0-0.GIF?08-0#

thats a pool of +8 to +12c upper air

Compared with ECM Day 9 link

http://www.meteociel.fr/modeles/ecmwf/run/ECH0-216.GIF?08-0

A pool of -8 to -10 air flooding into the NW part of europe- edging towards the UK

thats a swing of around 20c @ 850 HPA---- that will certainly be a strong cold front-

Those concerned with the euro high have reason to worry, however at day 10 heights over Europe are rapidly falling-

If I show the jet flow across the NH

Uploaded with ImageShack.us

You will see the energy under Greenland is flowing west repelling any system off the NE coast & the flow is going round the pole & heading back SW through Scandi

The 264 chart would show the cold air further SW-

the key area to look is any shortwaves around the azores - they will need to push into europe to filter the cold west- otherwise we could end up with Southerlies-

The upper air heights at day 10 are VERY similar to Nov 2010- we will just have to get some low heights into Europe-

regards

S

[ISAAC]

excitement on here is inevitable, there is consistency in terms of cooling to an extent on the gfs and ecm, but its still beond t+240 never mind t+172.

if the models continue picking up on the pattern 48 hours from now, then we have something. there is no need point worrying about out what we can expect in terms of cold and snow at the moment. once we have a pattern in place that is 3/5 probability we can then take a step forward.

Its good to see alot of newbies on here, my advice to you lot is not to take every model and start analysing its ouput side by side, what is shown on the 12z may well be a gonner on the 18z or vice versa. Rather take them day by day. This is why i prefer the ECM as it updates just twice.

[snowfall09]

Evening All-

Very encouraging ECM outlook tonight- the 15 day ensembles will most certainly contain some very cold members-

I suppose the disclaimer tonight is the GFS has no cold- so for now nothing certain, however the GFS has been very poor of late-

So IIRC I have been going about a pattern change in the 12-14 day range now for a few days- & the ECM today has made it the third run on the trott to model more or less the same evolution & tonights 240 chart is certainly the best yet, however the 192 & 216 day 8 & 9 are certainly demonstrating the wheels being 'in motion' at that time-

Just to clarify if people arent seeing a chart perhaps you should compare T0

http://www.meteociel...ECH0-0.GIF?08-0#

thats a pool of +8 to +12c upper air

Compared with ECM Day 9 link

http://www.meteociel...H0-216.GIF?08-0

A pool of -8 to -10 air flooding into the NW part of europe- edging towards the UK

thats a swing of around 20c @ 850 HPA---- that will certainly be a strong cold front-

Those concerned with the euro high have reason to worry, however at day 10 heights over Europe are rapidly falling-

If I show the jet flow across the NH

Uploaded with ImageShack.us

You will see the energy under Greenland is flowing west repelling any system off the NE coast & the flow is going round the pole & heading back SW through Scandi

The 264 chart would show the cold air further SW-

the key area to look is any shortwaves around the azores - they will need to push into europe to filter the cold west- otherwise we could end up with Southerlies-

The upper air heights at day 10 are VERY similar to Nov 2010- we will just have to get some low heights into Europe-

regards

S

Wasn't the GFS models handling of last years pattern change rather poor aswel?

[ForeverPomeroysnow]

Wasn't the GFS models handling of last years pattern change rather poor aswel?

Yup snowfall09 I believe it was

[SMU]

If im honest I think they all were- I remember the GFS getting it wrong, but I also one ECM run in Feb

12z Feb 10th 2011- how the ECm got it so wrong at such a short range

http://www.meteociel.fr/modeles/ecmwf.php?jour=10&mois=2&annee=2011&heure=12&archive=1&mode=1&ech=72&map=1

S

[phil nw.]

ECM does flatter to deceive those looking for a way to cold.

Here is the mean chart at T240

The Dutch Ens. showing that the Op.was colder than the the avaerage at the end of the run,

and finally the mean hts. comparison for days 8-10

A lot of blocking around the Uk but the cruical thing is that it extends from Europe, south of the main jet,which would suggest that any ht.rises towards Greenland would not sustain under the pressure of the energy coming over the top.

I can`t see anything upstream yet that would change the wavelengths with those stubborn heights over the South East USA and our Euro.block locking us into the warm side of the Atlantic trough.

The extended ENs. are out for Holland and they also show a continuation of this mild pattern further on.

http://www.weerplaza..._pluim&r=midden

[nick sussex]

I think we can see from Steve M post in terms of that image why I keep droning on about energy being ejected off that trough into Europe, I expect I've bored everyone to tears by now!

But in case I haven't, in terms of this trough, for newbies we often see these spawning shortwaves, as you can see from that image and taking the ECM output lets say at face value it's where this goes thats crucial, what we're looking for is this to develop and run east, as this happens a shearing motion occurs on the main trough pulling this a little further west, often this will drain some energy away from it, as this 'trigger shortwave' heads east it lowers pressure in southern/central Europe squeezing any higher pressure well to the south and acting as a support for the ridge to the north.

If that happens you can wave goodbye to the mild and turn the heating up!

[chionomaniac]

Evening All-

Very encouraging ECM outlook tonight- the 15 day ensembles will most certainly contain some very cold members-

I suppose the disclaimer tonight is the GFS has no cold- so for now nothing certain, however the GFS has been very poor of late-

So IIRC I have been going about a pattern change in the 12-14 day range now for a few days- & the ECM today has made it the third run on the trott to model more or less the same evolution & tonights 240 chart is certainly the best yet, however the 192 & 216 day 8 & 9 are certainly demonstrating the wheels being 'in motion' at that time-

Just to clarify if people arent seeing a chart perhaps you should compare T0

http://www.meteociel...ECH0-0.GIF?08-0#

thats a pool of +8 to +12c upper air

Compared with ECM Day 9 link

http://www.meteociel...H0-216.GIF?08-0

A pool of -8 to -10 air flooding into the NW part of europe- edging towards the UK

thats a swing of around 20c @ 850 HPA---- that will certainly be a strong cold front-

Those concerned with the euro high have reason to worry, however at day 10 heights over Europe are rapidly falling-

If I show the jet flow across the NH

Uploaded with ImageShack.us

You will see the energy under Greenland is flowing west repelling any system off the NE coast & the flow is going round the pole & heading back SW through Scandi

The 264 chart would show the cold air further SW-

the key area to look is any shortwaves around the azores - they will need to push into europe to filter the cold west- otherwise we could end up with Southerlies-

The upper air heights at day 10 are VERY similar to Nov 2010- we will just have to get some low heights into Europe-

regards

S

Great post Steve but I do have one concern.

The ensembles don't have any extreme cold members and you are basing an evolution on an ECM FI chart that presently doesn't has much support from the ensembles.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

I suspect that the Atlantic trough won't play ball and is going to stick around for a while longer yet.

[SMU]

Hi Chion-

The atlantic trough can sit there & we can still get very cold- It will need to steo back west a tad though to allow ridging North through Ireland ( like last year ) OR eject shortwaves east to support a cold push South-

Worst case scenario is shortwaves moving NE as they wont get under the block-

S

[phil nw.]

Great post Steve but I do have one concern.

The ensembles don't have any extreme cold members and you are basing an evolution on an ECM FI chart that presently doesn't has much support from the ensembles.

http://www.knmi.nl/e...agse/index.html

I suspect that the Atlantic trough won't play ball and is going to stick around for a while longer yet.

Yes i agree another good analysis by Steve explaining what could happen.

However it is speculative at this stage and i have to give my opinion based on the actual output,as explained in my last post.

[nick sussex]

Great post Steve but I do have one concern.

The ensembles don't have any extreme cold members and you are basing an evolution on an ECM FI chart that presently doesn't has much support from the ensembles.

http://www.knmi.nl/e...agse/index.html

I suspect that the Atlantic trough won't play ball and is going to stick around for a while longer yet.

I see your point Chiono but every change often starts with just the operational run going it alone and the ensembles taking a while to jump on board, the fact that the ECM has consistently split the PV and had a similar pattern since yesterday is cause for a glimmer of hope, of course that trough might just sit there and refuse to play ball and we end up with a southerly yet again and I suppose that would be the form horse, so of course the odds still favour the drab stalemate with a hint of faux cold perhaps.

But at least we've seen one operational run that has the decency to offer a modicum of interest, it maybe gone by tomorrow but its certainly the most interesting output for weeks.

[SMU]

Yes i agree another good analysis by Steve explaining what could happen.

However it is speculative at this stage and i have to give my opinion based on the actual output,as explained in my last post.

just remember the ensembles dont have the same resolution- I actually like the 240 Mean, it shows the top half of the block in all models-

What we need to see is over the next day or so- that block get modelled better & those ensembles will tumble

S

[damianslaw]

ECM performs much better than GFS when it comes to high pressure over europe and scandi - especially when the jet is weak, such as we have now. GFS doesn't handle such situations very well, but what it does often do better at is in forecasting 'shortwave activity'. Will be interesting to see whether ECM this evening is onto the right theme, if so, watch GFS fall into line with ECM in the coming days, and then it will be all eyes on GFS longer term in how it decides to position trough action to our west and developments to our NW.

Those looking for some cold weather should take comfort in the fact that the current synoptics are much more conducive to enabling something substantially colder down the line than if we were under a raging atlantic with jet on a firm westerly axis - absolutely no signs of this happening, and the outlook is very blocked. Also it is encouraging that we are seeing lower heights over the med, something those looking for cold would hope continues - suggesting we could be about to see a very split jet - shortwave development and atlantic trough disruption looks like being the most likely path to a colder shot than a significant build of heights over Greenland.

[chionomaniac]

just remember the ensembles dont have the same resolution- I actually like the 240 Mean, it shows the top half of the block in all models-

What we need to see is over the next day or so- that block get modelled better & those ensembles will tumble

S

I would love to see that happen as I desperately want to see a Greenland block occur without stratospheric support to show that it can happen! ( not that I believe that it can!). But it is a long way off and with limited support.

[SMU]

The Later 12's looked good tonight-

ECM, BOM, JMA

S

[nick sussex]

Early signs from the GFS 18hrs run are encouraging, upto 96hrs and its more amplified and less progressive than the earlier GFS. Could we be in line for some late drama!

[SMU]

huge change over greenland at 102 on GFS 18Z-

Much more amplified changing the orientation of the jet flow round the pole...

S

Murr & Sussex focussing on exactly the same area of the 18z!

Edited November 8, 2011 by Steve Murr

[wimblettben]

From what I can see the potential is out in FI so people should remain a tad cautious as it could well change in the next few days.

Better looking charts from the ECM nontheless. Seems to have changed the mood in here a bit.

[Backtrack]

huge change over greenland at 102 on GFS 18Z-

Much more amplified changing the orientation of the jet flow round the pole...

S

Murr & Sussex focussing on exactly the same area of the 18z!

Could you explain a little for us noobies? I don't understand what's changed from the 12z.

[lorenzo]

Worst case scenario is shortwaves moving NE as they wont get under the block-

S

Even worse they battle ground then draw energy and create a new Scandi High.. at least thats what was in lower resolution