Model Output Discussions 06z 04/11/16

[Blessed Weather]

4 minutes ago, No Balls Like Snow Balls said:

 

That tweet was accompanied by a great looking mean 500mb anomaly chart from the ECM Ensembles! Hopefully it's a lucky 13% cluster of members!

[phil nw.]

Just looking at today's London graph and it shows another colder spell towards the end of next week.This following the somewhat milder period coming up

which is mirrored in the ECM mean chart-day 8

suggesting a cold front with polar air moving south east around 17/18th -so something colder from the north west does look the likely option with some Atlantic ridging.

[Mucka]

Nice looking UKMO 144 as far as Polar heights go and chilly NW flow

 

Wouldn't take much tweaking to develop a cold pattern.

[That ECM]

Nice way to start the weekend. Strong block NE and hints of blocking to the NW as well...

[Ravelin]

6 minutes ago, That ECM said:

Nice way to start the weekend. Strong block NE and hints of blocking to the NW as well...

I was just going to post that, it'll be interesting to see where the GFS take it from there, especially that low over Greenland. Overall it's better than the GFS 6z at the same time frame I'd say.

Edited November 11, 2016 by Ravelin

[Ravelin]

13 minutes ago, Ravelin said:

it'll be interesting to see where the GFS take it from there, especially that low over Greenland.

Basically it ends up to the north of the UK, going nowhere fast against the block to the East. Be nicer if it managed to dive south.

Edited November 11, 2016 by Ravelin

[gottolovethisweather]

23 minutes ago, Mucka said:

Nice looking UKMO 144 as far as Polar heights go and chilly NW flow

 

Wouldn't take much tweaking to develop a cold pattern.

 

Yes, the 17th November once again showing up as the key timeframe for start of another nationwide chilly interlude, perhaps? The 528DAM line is as far south as the North Midlands by then as well.

[Singularity]

 

GEM asks the question; "What if the Atlantic trough digs south while still west of the UK?" - and the outcome looks like a good explanation for the signal in recent ensemble suites for anomalously high heights across the Eurasian sector. The question then is whether they can build far north enough to at least bring us calm, chilly weather with frost and fog potential (achieved by GEM for the SE). 

To go further than that, we need a nice sharp trough Thu-Fri next week that disrupts and deposits a substantial cut-off low over Central Europe or thereabouts. GEM has a go at this but the cut-off low is too shallow.

 

The GFS 12z has also had a bit of a go, but the Atlantic jet barely allows a ridge to develop, so the next trough is able to barge in before any decent ridge building can occur across Eurasia. We still get something though, and the run happens to produce another trough disruption on day 11 - so we may at least have a good chance of escaping the worst of the wind and the rain except perhaps in the northwest. Until, that is, a trough passes through on its way to Europe as heights rise to the W and N toward the turn of the month... assuming of course that the longer-term signals prove to be somewhere close to the mark.

I'm not entirely sure what to make of the UKMO 12z at +144, but it looks to me to have a more developed trough over eastern Canada than GFS at that timeframe, which is more in line with the ECM 00z where such a configuration proved sufficient for a decent (but brief) mid-Atlantic ridge while the trough ahead of it disrupted and dropped a decent cut-off low through Central Europe. Had it not been for a hyper-progressive day 9-10 output, I reckon that ECM run would have turned out similar to the GEM 12z, but with a better cut-off low and so more of a chilly continental feed across the (far) south of the UK.

Oh hang on - GEM managed to get to that anyway:

 

Sure, the uppers are lame, but it can be surprisingly cold at the surface in such a situation.

You may have noticed my lack of mention of a proper easterly potentially setting up - I believe the model guidance would have to be underestimating the rate of change to a more positive AO state in order for such an outcome to take place. We know the models can be guilty of this, but that doesn't guarantee that they will be on a particular occasion so all we can do is watch, wait and speculate! That being what I've just enjoyed doing right here 

 

[Frosty.]

The Gfs 12z op run shows fleeting mild interludes, generally associated with spells of wet and windy weather but it's mainly on the chilly side and feeling more like winter at times, particularly for scotland with reloads of polar maritime air from the northwest, especially later next week with night frosts and occasionally wintry showers with snow on northern hills, especially across the NW.

Edited November 11, 2016 by Frosty.

[terrier]

Some very tasty looking output tonight especially the ukmo at 144. Gfs none too shabby either. And with the updates we are getting from Ian f and the signs from the models we don't get too see I think we could be looking at some very nice fi charts in the not too distant future. Exciting times ahead if you like the cold. 

[bluearmy]

Broadly speaking, the modelling in fi carves out a decent European upper trough. however the scecuro blocking (supported from Russian block) needs to become cut off (becoming a scrussian one) to provide a proper wintry solution. otherwise the best we likely see is a cold continental surface feed.

[northwestsnow]

2 minutes ago, bluearmy said:

Broadly speaking, the modelling in fi carves out a decent European upper trough. however the scecuro blocking (supported from Russian block) needs to become cut off (becoming a scrussian one) to provide a proper wintry solution. otherwise the best we likely see is a cold continental surface feed.

I get the feeling the longer range models are suggesting the jet travelling on a SE axis and eventually that huge block moves westwards blue.

I'm not detecting any slowdown of the Atlantic now to be honest - any potential north/north wester at the end of next week looks transitory as it stands..:)

 

[gottolovethisweather]

27 minutes ago, northwestsnow said:

I get the feeling the longer range models are suggesting the jet travelling on a SE axis and eventually that huge block moves westwards blue.

I'm not detecting any slowdown of the Atlantic now to be honest - any potential north/north wester at the end of next week looks transitory as it stands..:)

 

 

 

I think it'll be at least a three-day spell as things stand and being as by then it'd be the 20th November (darkest FI after that, basically unforecastable), I do not see any reason to be getting worried about the return of Southwesterlies for instance. Bring it on! I won't be up to much NWP output watching this weekend as they'll probably be all over the place as per usual.

 

Edited November 11, 2016 by gottolovethisweather

[Paul_1978]

14 minutes ago, northwestsnow said:

 

I'm not detecting any slowdown of the Atlantic now to be honest - any potential north/north wester at the end of next week looks transitory as it stands..:)

 

I can see where you're coming from after reviewing this afternoon's model output, but we've also got to remember the more positive news about the background signals and the "bigger picture". 

Im just glad it's only 11th November and winter hasn't even started yet! Plenty of time :-)

[Guest]

Hi all great model watching so far this autumn.. and i know we all look for trends at T240 and most cold spells are seen coming so was wondering has there been a cold snap or cold spell that just popped up out of know where....say T72 i know we had the infamous Ian Brown What The F**k moment in 2013 but other than that and if so would be interesting to see how it evolved and set up...

[BLAST FROM THE PAST]

There are for sure 'pointers' ahead but I think we are a way yet from seeing detail.  I have a feeling over next 5 days we will see some swings of outcomes.....with a theme in common.  Blocking, potential and some screamers.

 

BFTP

[Frosty.]

5 minutes ago, BLAST FROM THE PAST said:

There are for sure 'pointers' ahead but I think we are a way yet from seeing detail.  I have a feeling over next 5 days we will see some swings of outcomes.....with a theme in common.  Blocking, potential and some screamers.

 

BFTP

I'm just pleased for now that we will have a generally NW / SE jet axis with regular incursions of polar maritime airmass and all being well this will be followed by height rises to the w / nw with lowering heights transferring to the NE..I must say, things are looking much better for coldies longer term than last year when we were faced with a rampant polar vortex throwing low after low our way for months on end.

Edited November 11, 2016 by Frosty.

[booferking]

On 08/11/2016 at 22:21, Ali1977 said:

Just now, Frosty. said:

I'm just pleased for now that we will have a NW / SE jet axis with regular incursions of polar maritime airmass and all being well this will be followed by height rises to the w / nw with lowering heights transferring to the NE.

ECM is a banker @144

[karyo]

Pretty nice ECM at 144 hours, more amplified than the GFS and UKMO with a northwesterly.

[IDO]

Little change from the start of the week, where the models were showing a period of mobility within the background of the omnipresent quasi-blocks of a Russian & Azores Highs. They are bunching the lower heights to the NW and this meanders towards the UK, directed by the upper flow. So slow moving mobility from a general NW-W direction with frontal systems the main threat of precipitation within that vortex as it warms out on its slow crossing.

Therefore the next 10 days or so showing a milder flow preceding the cooler uppers that roll in as the vortex moves towards the UK. Then, after around D10 the GEFS have been playing around with height rises, as the PV relaxes as a driver in our quadrant; all to varying degrees: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=360

Not much instruction from FI on the GEFS, and with other variables that have been pinpointed by the more knowledgeable on here, little point in getting too hung up on current output at that range, but reasonably confidence this upcoming unsettled spell will be short lived.

Dr Cohen's update earlier this week also suggesting even the experts feel this setup is unprecedented, so anything is possible going forward: https://www.aer.com/science-research/climate-weather/arctic-oscillation

 

[Severe Siberian icy blast]

5 minutes ago, IDO said:

Little change from the start of the week, where the models were showing a period of mobility within the background of the omnipresent quasi-blocks of a Russian & Azores Highs. They are bunching the lower heights to the NW and this meanders towards the UK, directed by the upper flow. So slow moving mobility from a general NW-W direction with frontal systems the main threat of precipitation within that vortex as it warms out on its slow crossing.

Therefore the next 10 days or so showing a milder flow preceding the cooler uppers that roll in as the vortex moves towards the UK. Then, after around D10 the GEFS have been playing around with height rises, as the PV relaxes as a driver in our quadrant; all to varying degrees: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=360

Not much instruction from FI on the GEFS, and with other variables that have been pinpointed by the more knowledgeable on here, little point in getting too hung up on current output at that range, but reasonably confidence this upcoming unsettled spell will be short lived.

Dr Cohen's update earlier this week also suggesting even the experts feel this setup is unprecedented, so anything is possible going forward: https://www.aer.com/science-research/climate-weather/arctic-oscillation

 

Erm basing your forecasts on the gfs one then yes fair enough but you can see how the ecm even at t144 thinks quite differently. In fact going by the update earlier today this time next wk we could well be looking down the barrel of a long cold spell with cyclonic weather systems sitting on the UK... cold uppers/low pressure= zonal westerly? No 

[Chris K]

2 minutes ago, Severe Siberian icy blast said:

Erm basing your forecasts on the gfs one then yes fair enough but you can see how the ecm even at t144 thinks quite differently. In fact going by the update earlier today this time next wk we could well be looking down the barrel of a long cold spell with cyclonic weather systems sitting on the UK... cold uppers/low pressure= zonal westerly? No 

Reading IDO's post, I don't think he was suggesting a lengthy zonal westerly dominated period. Rather, a brief transitional pattern of unsettled weather before the outputs suggest a move towards a cool/cold NW flow towards the end of next week, which is 7-10 days away.

[Allseasons-Si]

Just a quick one from me...have guest's

"UNDERCUT ALERT" on the ecm @ 240.

Edited November 11, 2016 by Allseasons-si

[Frosty.]

17 minutes ago, Severe Siberian icy blast said:

Erm basing your forecasts on the gfs one then yes fair enough but you can see how the ecm even at t144 thinks quite differently. In fact going by the update earlier today this time next wk we could well be looking down the barrel of a long cold spell with cyclonic weather systems sitting on the UK... cold uppers/low pressure= zonal westerly? No 

The Ecm 12z isn't as cold as the 00z from next midweek looking at the 850 upper profile.

Edited November 11, 2016 by Frosty.

[Mucka]

Pretty good backing for the ECM from JMA, interesting.

 

Edit.

Just to elaborate.

Jet digging Southeast increased upstream amplification. Will be interesting to see if it can force some undercut of the Atlantic ridge in the extended run later.

Edited November 11, 2016 by Mucka