Model Output Discussion 23/11/2012 18Z onwards

[Bobby]

IF that is the case then why are 95% of other posters and the stratospheric lot, saying that this blocking will be hard to budge? This question is open to everyone by the way, just a little confused at the moment with regards to where we stand blocking wise? Obviously we have great sypnotics, a completely destroyed vortex but we don't have the real pool of cold uppers but if this first shot fails, which it probably will, where do we go from there?

+ Does the GFS in particular have a tendency to power up the Atlantic? I personally think it does.

Blocking, stratospheric warming doesn't mean cold and snow... depends where it's placed, how strong it is, what the jet stream is doing, what low pressure over Europe doing, how cold the cold pool is over Europe/Arctic, how active the Atlantic is etc.

A good few ingredients have to come together in this country to get proper cold and snow.

They are not as bad as you think, for example the pressure is quite high over Southern Greenland and all of the BI is covered in sub zero upper temps.

Those the anomaly upper temps not the upper temps...

Edited November 24, 2012 by Barb-

[Bristawl Si]

IF that is the case then why are 95% of other posters and the stratospheric lot, saying that this blocking will be hard to budge? This question is open to everyone by the way, just a little confused at the moment with regards to where we stand blocking wise? Obviously we have great sypnotics, a completely destroyed vortex but we don't have the real pool of cold uppers but if this first shot fails, which it probably will, where do we go from there?

+ Does the GFS in particular have a tendency to power up the Atlantic? I personally think it does.

Forget the numerous weather soothsayers on here

- just read GP's thoughts plus Chiono's, a dose of TWS, Steve Murr, Big John Holmes and a couple of others

[Bobby]

.

Edited November 24, 2012 by Barb-

[Downburst]

IF that is the case then why are 95% of other posters and the stratospheric lot, saying that this blocking will be hard to budge? This question is open to everyone by the way, just a little confused at the moment with regards to where we stand blocking wise? Obviously we have great sypnotics, a completely destroyed vortex but we don't have the real pool of cold uppers but if this first shot fails, which it probably will, where do we go from there?

+ Does the GFS in particular have a tendency to power up the Atlantic? I personally think it does.

If the blocking remains as shown it will be in the top 5 coldest first 10 day of December in 100 years. So cold and wet perhaps, but if it's 3 C in a northerly wind and raining and 2 in the afternoon you will know it's cold.

[AWD]

Latest NAE showing widespread rainfall over the weekend, upto 30mm widely, locally more no doubt.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2012/11/23/basis18/ukuk/prty/12112500_2318.gif

Maybe a bit of snow for the Scottish Ski industry too;

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2012/11/23/basis12/ukuk/prty/12112512_2312.gif

[weather eater]

Just to add to my post from earlier, that’s now four GFS runs today offering different evolutions for the crucial period 96hrs to 144hrs. No point worrying about ensembles and debating if we will see an early end to northern blocking, when we can’t get any agreement as to how we get there in the first place. To be honest the rainfall over the next few days is a far more pressing issue, one person already dead and damage running into millions already I would guess.

[Weathizard]

Thanks for the replies guys, including the less positive ones! Nice to see both sides, thats what its all about.

I suppose think ourselves lucky this year, this time last year it was a hideous sight, raging vortex and dreary rubbish weather, least we have a chance of something developing, concerned about all the rain though, could cause some awful flooding for already sunk places, luckily where I am is very hilly and flooding is at a premium, thoughts to anyone who is likely to be under water in a few days, have family who live in devon and they are saturated already.

Looking at the ensembles tonight they are very disappointing IF you are taking every run to heart, I've decided I'm going to do as advised and take each run as they come, I'm sure we'll see more ways this could evolve tomorrow, adios for now guys.

[Duane S.]

Strange how we all see things differently. Looks fine to me, just another GFS op run, another cold variation.

Looking at the ens, the most striking thing for me was the scatter early on in the south. At just +72 it starts and by just +96 there is a huge relative scatter with the op running very much on the milder side

And that is where FI is on this particular run.

Look at the bigger picture. Once this sets in sustained mild simply cannot return quickly. Like it or not, the cold is coming, whether it's 5 days away or 12, I fail to see how we aren't going to get a very decent first half of December at the very least.

Edited November 24, 2012 by s4lancia

[kumquat]

How can this be a downgrade?

Happy days for us model watchers...........not saying it can't go wrong, but things are on the up compared with recent times.

Of course it won't happen but nice trough passing through Ireland, West/Inner/All of Wales, NW England, Herefordshire, West Midlands on that frame, and ploughing through the SW england. Ist of December it is then.

[Robbie Garrett]

As per the email the MetOffice sent me a few days ago, it does seem that they are starting to firm up.

UK Outlook for Saturday 8 Dec 2012 to Saturday 22 Dec 2012:

As is usual, there are uncertainties in the forecast for this period. However, there are signs that northerly winds may be quite frequent across the UK. So, on balance, colder than average conditions are favoured, with a risk of frost and fog, and an increased risk of some snow.

When you consider for the best of late November into early parts of December, we might be looking at some snowfall.... to what we might get for the rest of December and in the fact Winter is quite incredible!! Now I am not ramping but synoptically 2010 was amazing, but looking at the all the singals from GP and other information available to us.... the signals for this winter overall are a lot better long-term!!!

On the other hand, there is no agreement from the models... 24 hours out looking at the latest ensembles. Maybe some agreement till Tuesday but even then it's not guaranteed...

Cannot wait to see these scenes again..

[summer blizzard]

Interesting model output showing the trough further north with a northerly which keeps me dry. The cold does however arrive on time on this run (30th).

[SnowObsessor90]

I'm hoping to see improvements throughout the output from this morning onwards. obviously it won't be the end of the world if there isn't or even if things start to take further turn for the worse but it'd help settle some nerves at the very least.

[SMU]

People still putting blind faith in the GFS 18z ensembles - oh dear oh dear.

Despite saying they are about as useful as a chocolate hammer we still think they add value.

06z & 18z ENS GFS isnt worth the internet space they takes up........

as for the rest of the runs- poor modelling today- look to tomorrow 12z to be the right solutions

S

[Hedgehog]

Spot on mate.

Lets use Dec 1978 as an example because despite the blocking it took a full 10 days before the cold air finally arrived.

http://www.wetterzen...00119781221.gif

My main focus is that blocking is continuing to be modelled right out to +384.

Well said - Stand back and look at the whole picture and the detail will follow

[Barry12]

People still putting blind faith in the GFS 18z ensembles - oh dear oh dear.

Despite saying they are about as useful as a chocolate hammer we still think they add value.

06z & 18z ENS GFS isnt worth the internet space they takes up........

as for the rest of the runs- poor modelling today- look to tomorrow 12z to be the right solutions

S

Why are they not as good, less data?

[The watcher]

People still putting blind faith in the GFS 18z ensembles - oh dear oh dear.

Despite saying they are about as useful as a chocolate hammer we still think they add value.

06z & 18z ENS GFS isnt worth the internet space they takes up........

as for the rest of the runs- poor modelling today- look to tomorrow 12z to be the right solutions

S

Wether they miss data or not, they could still be right. You don't need all the facts to solve a murder, sometimes extra evidence just leads to more suspects.

Surely balloon data from the previous release is still fed into the 18 and 06z? Would make sense to do so. If that is the case, I don't think any infliction to output is noteworthy enough to dismiss a run.

With the short term ensembles seeing spread as they did today (on all models) it is clear that we are still awaiting agreement on other near term factors before we can get a handle on the beyond.

I'm sticking to the anomalys until I see agreement on all the models in the short term. Still too big a risk to place any trough or heights within the space of 500 miles by day 5.

[etched Chaos]

Wether they miss data or not, they could still be right. You don't need all the facts to solve a murder, sometimes extra evidence just leads to more suspects.

Surely balloon data from the previous release is still fed into the 18 and 06z? Would make sense to do so. If that is the case, I don't think any infliction to output is noteworthy enough to dismiss a run.

With the short term ensembles seeing spread as they did today (on all models) it is clear that we are still awaiting agreement on other near term factors before we can get a handle on the beyond.

I'm sticking to the anomalys until I see agreement on all the models in the short term. Still too big a risk to place any trough or heights within the space of 500 miles by day 5.

Your analogy is wrong, more evidence just whittles down the suspect list. If all you had was a partial print, you'd have alot more suspects than if you had a thumbprint and DNA evidence. Which is much the same with the weather, data is essential, if something is missing data than you naturally have to be wary of it's results especially when everything is unpredictable. If it manages to luck into being right with less data, it does not make the idea that less data is more right, it just means that the model was right that time.

With the models being unable to pinpoint anything right now, surely you'd be more confident if a model had more data being fed into it? Rather than confident of something that has less. I just cannot see why anyone would put more stock into the 06z/18z at this very time unless the results it spews out aligns with your own weather bias.

[BlueHedgehog074]

The GFS 00Z continues to show troublesome rain for places for the next few days, most especially for Saturday with that tight isobared Low swinging up from the South-West bringing heavy rain North-Eastwards with it. Will be rather windy too with some possible tricky travelling conditions to and from work/events/activities. Monday and into Tuesday look particularly soggy for Southern areas still - especially the Midlands, and it could be rather cold too, as the Low to the South slowly passes Eastwards and pulls in a chilly North/North-Easterly wind. Possibly a small chance of the rain turning to sleet or snow over higher areas in the South as that colder airflow digs through. Next few days looks to be drier, but with wintry weather looking increasingly probable with the Easterly or North-Easterly winds on the GFS pulling in colder uppers from Scandi for next weekend onwards. With the way the models have been behaving, I expect the details regarding the even colder weather will still be liable to lots of changes. Even the exact positioning of the precipitation bands for next Monday and Tuesday is likely to be modified to some extent depending on the exact speed and location of that expected developing Low out to the West.

Having said that, there are some peculiar aspects about this run. Looking at some of the 00Z GFS charts close to (and at) the 144 hour period and you'll notice how squiggly the pressure patterns look (on Wetterzentrale/Netweather chart viewer) with all those wobbly white lines, most especially around the Scandi, Iceland and Greenland areas. In fact, the 144 hour chart itself is a perfect example of this - it's like looking as spaghetti. It's as if the GFS wants to try and develop billions of baby shortwaves on that chart. Just seems a little unclean for my liking to be sure it will come off like that.

The GFS does go for some sort of stoppage to the cold nearer to the end of its run, but it looks like a messy break-down process in my opinion with Lows seemingly randomly dotted about all over the place. But the GFS does seem to try bring the Polar Vortex back to life to the North-West.

Not a bad update for cold overall (even though it does not last throughout the update), but a bit of a strange run nonetheless too.

Edited November 24, 2012 by DiagonalRedLine

[snow drift]

Its getting closer!! Nice run to wake up to.

[Weathizard]

Snow drift - uppers are relatively poor and watered down though

Had a quick look at the models, GFS still looks very messy and strange as does the ECM to a certain extent but at least it retains the blocking, the ukmo is still completely solid at t120, how can that low be modelled so differently by UKMO at t120?

[Jupiters Winter]

1st ECM Wobble. A solution out of many I suppose if I am biased I would say it is wobble that will not be seen on the next ECM run,

[snow drift]

Snow drift - uppers are relatively poor and watered down though

Had a quick look at the models, GFS still looks very messy and strange as does the ECM to a certain extent but at least it retains the blocking, the ukmo is still completely solid at t120, how can that low be modelled so differently by UKMO at t120?

Because its five days away. Not worried about uppers at this time. Looking to get us in a cold pattern with good blocking in place. Then watch the uppers fall as time ticks on.

[Liam J]

Well I wish i'd never just looked at the 00z GFS & ECM runs.... Both show the Atlantic crashing back over our shores, I hope that idea gets dropped today but it is slightly worrying as both models show this one way or another.

GFS op was on the colder side of the ensembles from the 1st - 5th Dec.

Edited November 24, 2012 by Liam J

[IDO]

The 0z op continues the theme of blocking and does highlight what the ensembles have been saying for a while, that we are heading for a 5-7 day cold snap. Details are very hazy as to who will get the snow but as the 850s are borderline and transient there is unlikely to be a widespread snow event. Looking like a dusting at the moment for high ground and the north from about T168.

The trough disruption over the US is omnipresent through the run so we would expect a second shot. However on this op run the Scandi high meanders (from around T183) to its NE and gets lost in the ML. So although the NH remains amplified, there is (on this run) no favourable block to our north (NE or NW). This allows a high to fill in the Atlantic as it has no opposing force.

Still cool/cold, but slow moving so this may take some shifting: http://cdn.nwstatic....84/h500slp.png. Ties in with yesterdays CFS and JMA ( less cold spell towards middle of month).

Good ensembles: http://cdn.nwstatic....t850London.png. But no sustained low reading uppers, so no obvious sign of a longevity from a cold flow.

Shorter term the lows are now more likely to move SW to NE, so the Midlands, West, SW and NW will get the worse rain: http://www.weatherwe...uktotpcp90.gif. Totals show over 100mm of rain in the Midlands.

The Met has this morning shifted the pattern East, so slower change and less early potential:

http://cdn.nwstatic..../00/met.120.png

http://cdn.nwstatic..../12/met.120.png

ECMW showing a flatter pattern with the Atlantic not far away. There is a trend amongst all models towards this cold pattern being a rather short lived tame affair in respect of snow. Not that we should be surprised. More runs needed to add meat to the bones...

Edited November 24, 2012 by i'm dreaming of...

[Snowmad79]

Well I wish i'd never just looked at the 00z GFS & ECM runs.... Both show the Atlantic crashing back over our shores, I hope that idea gets dropped today but it is slightly worrying as both models show this one way or another.

And it's not the first set of runs to do so either. We'd have to say there is definitely a trend emerging for a breakdown however we still need to see what the UKMO has in store post 144hr as that is a good run and the Breakdown shown on the GFS is still deep FI.

No need for panic or worry right now though as it is only a "trend" and a blocked cold outlook is still odds on.

Edited November 24, 2012 by Snowmad79