Model Output Discussion - 7th-13th November

[chionomaniac]

Look at the NH view at 168-192 Chiono, vortex split??

It's an interesting chart at T+216 but not going to lead to anything in the short term due to the spoiler. The Atlantic trough is not going to undercut from there. However, we will be in a better position for when the next the attempt occurs. Still some way to go yet though to get out of the mild flow.

[Cheshire Freeze]

It's an interesting chart at T+216 but not going to lead to anything in the short term due to the spoiler. The Atlantic trough is not going to undercut from there. However, we will be in a better position for when the next the attempt occurs. Still some way to go yet though to get out of the mild flow.

Yeah, as I said, I think the 00z was progressive with the pattern change and I completely agree with you in that I think if we can get to a position as advertised by the ECM at 192-216 hours then cold will not be far behind. Great output from the ECM this evening. This is going to be a slowburner of a pattern change but I have a feeling we'll feel the chill when it occurs.

Edited November 7, 2011 by CreweCold

[cyclonic happiness]

@ Crewecold.

I took the liberty of adding in direction arrow to show some of the folk who are new to this malarkey of model watching, what we should be excited about.

Note the wind directions are straight from the pole!

(and don't bother accusing me of ramping....I'm not bovvered! )

[summer blizzard]

While the ECWMF clearly has a better long wave pattern in FI, i think that the GFS shows that we are likely to get a cooler pattern either way. This chart in the high resolution time frame would be great for frost..

Ensembles still stick to at least one member going -5C from the 17th.

[Cheshire Freeze]

The thing to note about the long wave pattern of the ECM is that it is very reminiscent of last November/December in as much that the vortex isn't centred as one great big round mass- it's globular with little chunks of it being thrown down towards more mid latitudes which suggests an amplified jet stream and a willingness for ejections of cold to quite modest latitudes. Like I said the 12z is a great output for cold fans even if the conditions in Britain aren't frozen at that stage.

[Gavin Hannah]

Bring on the cold! Some nice and interesting images in the Ensembles.

P5 is my fav, albeit, its still two weeks away.

[johnholmes]

So much potential on this chart, a nice big block over the Arctic ridging towards the UK with a trough setting up to the NE.

I think the ridge is actually from the SE, always has been. The colours tell the story in simple terms if you like. Yellow/orange is 'real' 500mb heights, blue not.

[Isolated Frost]

And the ECM has taken the bftp juice and has given us another beauty personally. So much potential. Retrogression there on a mass scale and lows gliding from the sw, a death to the euro block, and high pressure building in the arctic. Pv is the right place at the right time and long stretch northerlies reaching e europe. Promising signs. I'd love that 32 day ECM chart- it's consistent currently, and could deliver some very cold air nearby.

GFS not on board and that's the problem, no retrogression, but a southerly tracking jet and a struggling northward subtropical ridge. All getting mixed up and easterlies/south easterlies likely from there, with some frosty nights likely as hp moves in. Just need that GFS to start retrogressing the situation in the next few runs- 18z will be fun to watch.

Game on.

[snowfall09]

And the ECM has taken the bftp juice and has given us another beauty personally. So much potential. Retrogression there on a mass scale and lows gliding from the sw, a death to the euro block, and high pressure building in the arctic. Pv is the right place at the right time and long stretch northerlies reaching e europe. Promising signs. I'd love that 32 day ECM chart- it's consistent currently, and could deliver some very cold air nearby.

GFS not on board and that's the problem, no retrogression, but a southerly tracking jet and a struggling northward subtropical ridge. All getting mixed up and easterlies/south easterlies likely from there, with some frosty nights likely as hp moves in. Just need that GFS to start retrogressing the situation in the next few runs- 18z will be fun to watch.

Game on.

Given the potential we have here looking at the charts does it look like this winter may be worse than the last winter?

[Isolated Frost]

Given the potential we have here looking at the charts does it look like this winter may be worse than the last winter?

These charts have no effect on the severity of the upcoming winter, just the possibility of a pattern change come mid-November.

[nick sussex]

_{I'd sum up tonights output as follows:}

ECM _{looks good at first sight, but no undercut with the limpet trough not disrupting although it splits the} PV _{, cold air into eastern Europe and Russia but the orientation of the ridge to the ne is unfavourable and it would need a big leap of faith to get to real cold from there.}

GFS _{looks underwhelming at the beginning but at least delivers some surface cold and takes some energy into Iberia but doesn't split the} PV_.

_{So both the big two longer range models have some good and bad for cold lovers.}

_{Perhaps best for the timebeing to just look at the ensembles and what the overall teleconnections are suggesting and put both those operational runs aside.}

Edited November 7, 2011 by nick sussex

[Isolated Frost]

_{I'd sum up tonights output as follows:}

ECM _{looks good at first sight, but no undercut with the limpet trough not disrupting although it splits the} PV _{, cold air into eastern Europe and Russia but the orientation of the ridge to the ne is unfavourable and it would need a big leap of faith to get to get real cold from there.}

GFS _{looks underwhelming at the beginning but at least delivers some surface cold and takes some energy into Iberia but doesn't split the} PV_.

_{So both the big two longer range models have some good and bad for cold lovers.}

_{Perhaps best for the timebeing to just look at the ensembles and what the overall teleconnections are suggesting and put both those operational runs aside.}

Yes good little summary there. GFS doesn't look like retrogressing- more like keeping a similar pattern with frosts likely later on, and the wettest weather for the south, mean winds from a mildish south-easterly/easterly quadrant. The GFS gives enough for some mild, dry and cool, frosty weather.

The ECM says this pattern will go, that Euro high sinks, retrogresses, troughs/lows move to the south of us again as that subtropical ridge follows on it's usual pattern. The pv is disrupted and the high gives cold weather for scandi and e europe, however imo, a trough moving e into the channel, and a slight dis-orientation of the pv moving the cold air into germany could easily divert some cooler east and north east winds.

Personally something in the middle. Mild and dry, then average (perhaps a tad frosty at times), and then the possibility for some wintry showers and milder air before months end. However another blast from the north could penetrate and that's what is important about tonights runs. Interesting albeit frustrating as always, and the ensembles should provide a clearer picture. 18z GFS rolls out from 930pm of course so the watch continues then.

[Frosty.]

Some positives on tonight's Ecm model as there was this morning for at least an outside chance of a severe wintry spell evolving in the next 3 weeks but if not, at least we are going to lose the 15-16c temps and replace them with 7-10c next week with some overnight frosts where skies clear and will allow fog to form. Even though the odds don't favour anything wintry as such, with such a mega cold block developing across northeast europe then there is always a chance so it's something to keep an eye on.

[BLAST FROM THE PAST]

So CC what do you think the ECM will bring this evening. My guess is a halfway house between the full retrogression to Greenland and none at all. A flirt then retreat!

c

Yes a flirt but no full push.....yet. Timing for coldpush is last week of November,but what is interesting is how the models are showing the potential synoptic change down the line. RJS has the timing for cold in UK as towards end of Nov way before any model or teleconnection suggestion. Confidence is growing fast for this timing especially as we see models flirting with the retrogression. Shed head i think mentioned cold sinking south to eastern Europe is the form horse.....if over last few weeks then yes...but if talking last few autumn/winters...then no.

More flirting to come but next week there will be strong FI signals for full on push.

BFTP

[snowfall09]

Yes a flirt but no full push.....yet. Timing for coldpush is last week of November,but what is interesting is how the models are showing the potential synoptic change down the line. RJS has the timing for cold in UK as towards end of Nov way before any model or teleconnection suggestion. Confidence is growing fast for this timing especially as we see models flirting with the retrogression. Shed head i think mentioned cold sinking south to eastern Europe is the form horse.....if over last few weeks then yes...but if talking last few autumn/winters...then no.

More flirting to come but next week there will be strong FI signals for full on push.

BFTP

essentially this could only be the start, is that what your saying ?

[ANYWEATHER]

Looking at both gfs and ecm I dont see a shred of evidence of anything cold in the next ten days! Im sorry for you cold lovers and perhaps at the end of the month we will see something different, but low pressure to the west and southwest of the uk and high pressure to the east and northeast of the uk , will keep the cold locked up in the Poles, with the Polar Vortex also helping to lock in that cold at the top of the World. What this does as shown by the chart below is to keep the jet stream way to the North of the Uk, so in summery a lot of weather what we have had before in recent weeks, rain, wind especially for the West and sometimes dull often calm conditions for the East especially, limited frost.... but the talking point will be MILD....!! :smilz38:

[Frosty.]

Spot on Fred, I am a lot more optimistic about cold prospects than in recent weeks when there was really nothing in FI for coldies to look forward to but that is changing now, the models are finally showing an end to this very mild autumn with at least a chilly feeling week next week, it could be a stepping stone to a much colder spell before the end of the month. I hope the NOAA continue to pour scorn on how the gfs is handling the upstream pattern and to be honest, the ecm is usually better at predicting the type of pattern it is currently hinting at.

[Isolated Frost]

Looking at both gfs and ecm I dont see a shred of evidence of anything cold in the next ten days! Im sorry for you cold lovers and perhaps at the end of the month we will see something different, but low pressure to the west and southwest of the uk and high pressure to the east and northeast of the uk , will keep the cold locked up in the Poles, with the Polar Vortex also helping to lock in that cold at the top of the World. What this does as shown by the chart below is to keep the jet stream way to the North of the Uk, so in summery a lot of weather what we have had before in recent weeks, rain, wind especially for the West and sometimes dull often calm conditions for the East especially, limited frost.... but the talking point will be MILD....!! :smilz38:

What? The jet is taking a southerly track on them charts.

[chionomaniac]

Yes a flirt but no full push.....yet. Timing for coldpush is last week of November,but what is interesting is how the models are showing the potential synoptic change down the line. RJS has the timing for cold in UK as towards end of Nov way before any model or teleconnection suggestion. Confidence is growing fast for this timing especially as we see models flirting with the retrogression. Shed head i think mentioned cold sinking south to eastern Europe is the form horse.....if over last few weeks then yes...but if talking last few autumn/winters...then no.

More flirting to come but next week there will be strong FI signals for full on push.

BFTP

I love your confidence, Fred, but the more I look at it the more I feel that this pattern change could fall flat very quickly. Where is the ECM to go if it has got the pattern right? Not to cold I bet. More likely to a pattern where the PFJ is north of the UK and a ridge is held over the UK to its south. That is the pattern that the GFS is already considering.

As I have said previously we will need another 'kick' to a further pattern change if cold is to follow and I can't see where that kick is going to come from. Especially when the Asian MT reduces without having a knock on effect with the stratosphere which is already far cooler than average. Patience may be needed here. I would be happily surprised to see snow before the end of November - but surprise it would be.

[BLAST FROM THE PAST]

I love your confidence, Fred, but the more I look at it the more I feel that this pattern change could fall flat very quickly. Where is the ECM to go if it has got the pattern right? Not to cold I bet. More likely to a pattern where the PFJ is north of the UK and a ridge is held over the UK to its south. That is the pattern that the GFS is already considering.

As I have said previously we will need another 'kick' to a further pattern change if cold is to follow and I can't see where that kick is going to come from. Especially when the Asian MT reduces without having a knock on effect with the stratosphere which is already far cooler than average. Patience may be needed here. I would be happily surprised to see snow before the end of November - but surprise it would be.

Hi C

Firstly, I am not talking intense cold or blizzards, but cold weather and a cold set up for last week of Nov. That's still two weeks away and beyond modelling, so any failure now is well anticipated and so for me to be revisited model wise in ten days, I hope that clarifies that I do not expect cold within next ten days.

BFTP

Edited November 7, 2011 by BLAST FROM THE PAST

[ANYWEATHER]

What? The jet is taking a southerly track on them charts.

I dont think they are , just look on the H500 hemisphere chart see where the predicted track of the jet is.....!

[lorenzo]

+144 looks pivotal on this run, yes the cold pools are in place, but that stubborn High looks to take the hit from that lobe of cold right on the chin and just cling onto its Scandanavian shelf without full erosion.

Ridges galore then follow, gradually out of East coast US and Azores, meanwhile the Scandi High merely shifts slightly NNW blocking potential Northerly incursions.

Looks like this pattern needs a further knock out blow....

Beginning of a trend perhaps and one chart earlier in this thread with 1055 nosebleed heights over Greenland...

Getting Interesting

[Isolated Frost]

I dont think they are , just look on the H500 hemisphere chart see where the predicted track of the jet is.....!

Sorry, might be subtropical jet but it does seem like a split off low in general to the south of the uk.

[chionomaniac]

Hi C

Firstly, I am not talking intense cold or blizzards, but cold weather and a cold set up for last week of Nov. That's still two weeks away and beyond modelling, so any failure now is well anticipated and so for me to be revisited model wise in ten days, I hope that clarifies that I do not expect cold within next ten days.

BFTP

I don't think anyone is expecting cold within the next ten days! It is the time after that that we are all interested in. The most likely way to cold is through retrogression of the Scandi High but if this doesn't occur (as is probably likely) then the pattern that is set after this could take a similar amount of time to reset and if the Scandi high fades then the upstream amplification will be all important. By this time last year we had already recognised and were getting excited by the potential in store for later on in the month. No such excitement yet this November.

[Glacier Point]

http://raleighwx.americanwx.com/models/ecmwfens/00zecmwfenshourly850mbTempAnomalyNH240.gif

ECM DAY 10 mean 850 temps forecasting values of 16 degrees C below normal for large parts of NW Canada and Alaska into the central Plains. Incredible stuff which IMO merits much more than our static trough to the west. Snow cover, which is already pretty healthy, looks set to explode in the next 10 days for the Northern Hemisphere.