Model Output Discussion 12z 04/12/2012

[southbank]

Only another 72 hrs before we know if its a blend of euros and gfs and exactly what type of feed sets in the uk a e or se feed , only thing is after 7 years on this site I have seen gfs throw runs up like this only to then spend the next 3 days backtracking , tomorrow and all the way up to Saturday model watching is gonna be one hell of a ride

[Snowman.]

Ummmmmmmm the 18z FI looks so unrealistic it puts a question mark over the higher resolution part.

Bin the run after 192hrs as the evolution looks extremely unrealisitc.

I noticed this aswell it looks as if it wanted to build heights north then the entire high is just slammed down on.

[Ice Day]

Note the strat polar vortex moving towards siberia as the run progresses which

could have big implications as we head towards christmas!

Good or bad?

[snowblues]

Polar vortex edges across the pole slowly but surley and sits over Sibera,as G.P has said in his posts.

[Daniel Miller]

Good or bad?

Good

[bobbydog]

i showed this chart to my land rover-

and a little bit of engine wee came out....

[TEITS]

Good or bad?

Potentially what we could see a few days before Xmas is the PV moving into Siberia and blocking towards our NW over Greenland. I say potentially because obviously this doesn't mean the UK will be cold but the GFS is consistently modelling the PV to move into Siberia and has done for a few days now.

Moving back to the much closer timeframe and I hope you're wearing your thermals tomorrow.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2012/12/04/basis18/ukuk/tmp2/12120515_0418.gif

[Severe Siberian icy blast]

Well after a dam miserable morning , I did get emotionally driven this morning , and I apologise for e negative comments I made , I'm normally quite level headed with it all but got out of bed the wrong side! But things looking all rosy again , just a bump in the mods hopefully , the signals are there for a freeze.

Also brilliant upgrades in the potential tomorrow morning now aswell which is fab, I love the but where fegiweather said ( 2cm or more in places!) that really does allow your mind to go AWOL and start thinking of all sorts of scenarios !!Hears hoping for a supprise or 2 over these next few wks . . .or days!!

[ITSY]

Right, i'm happily off to bed. IF, and it's a big IF, the ECM and/or UKMO have either the shortwave modeled like the GFS (preferably and) or the block enticed further West, I will start to get excited. Those two short and long term factors could be crucial to this upcoming possible Easterly. Night all.

EDIT: Forgot to mention the potential for Friday for the North of England. It will be rain throughout Thursday and Thursday night, but the potential remains for 4/5hours of snowfall on Friday morning for many parts in the region. Worth keeping an eye on.

Edited December 4, 2012 by ITSY

[Cloud 10]

Good or bad?

For you personally going by your user name and avatar,very good.

If the polar vortex was to shift over towards siberia,this would open the door for the blocking high

around Scandinavia to retrogress towards Greenland.

[SnowObsessor90]

As we've seen numerous in the past it can quite often be a lose, lose situation with the 18z. Either it's bad with overnight runs following the trend or it's good with the following output showing the inevitable downgrades so guess we'll just have to wait and see.....

[Ice Day]

Potentially what we could see a few days before Xmas is the PV moving into Siberia and blocking towards our NW over Greenland. I say potentially because obviously this doesn't mean the UK will be cold but the GFS is consistently modelling the PV to move into Siberia and has done for a few days now.

Moving back to the much closer timeframe and I hope you're wearing your thermals tomorrow.

http://expert-images...120515_0418.gif

Thanks TEITS. As a numpty, but trying to learn, what I have gleaned from thousands of hours spent on here for the last 7 winters, each time there's been a significant cold spell modelled, there are always wobbles from most, if not all, of the models on the way. This last couple of weeks of model watching have convinced me that something special could be round the corner, but it won't be plain sailing by any means but I think we'll get there in the end!

Edited December 4, 2012 by Ice Day

[TEITS]

GEFS control is probably even better than the GFS for the same timeframe.

[AWD]

Very cold night possible for many tomorrow night. Widespread frost.

[cold snap]

If we don't get some sort of easterly now it will be the Worse model data we have ever seen in my history

[SnowObsessor90]

If we don't get some sort of easterly now it will be the Worse model data we have ever seen in my history

Weren't we in a similar situation back in late Jan/early Feb or was that a bit different?

Edited December 4, 2012 by Anonymous21

[Continental Climate]

Weren't we in a similar situation back in late Jan/early Feb or was that a bit different?

I think we were anon a lot of the models back then were showing us fully participating in the european freeze but it never quite made it to these shores, maybe apart from the extreme south east

[Paul Sherman]

If we don't get some sort of easterly now it will be the Worse model data we have ever seen in my history

You should have been around a few years back just after Xmas If i remember rightly, GFS Nailed an Easterly to it's Mast within T72, And it completely vanished, that was one of the worst pendulem swings on here EVER!

[cold snap]

Just been speaking to Ian fergerson on twitter he says the gfs 18z fits in with ECM 32 dayer (@markydub)

[Southern Storm]

You should have been around a few years back just after Xmas If i remember rightly, GFS Nailed an Easterly to it's Mast within T72, And it completely vanished, that was one of the worst pendulem swings on here EVER!

I would love to read some posts from that time or even better pin the whole topic to all model threads as a cautionary tale.

[mezzacyclone]

You should have been around a few years back just after Xmas If i remember rightly, GFS Nailed an Easterly to it's Mast within T72, And it completely vanished, that was one of the worst pendulem swings on here EVER!

Those were the days, along with "mr crazysnowfansman"

[nick sussex]

If we don't get some sort of easterly now it will be the Worse model data we have ever seen in my history

You've obviously not suffered as much as the rest of us!

Easterlies and model output are not a marriage made in heaven, hence they're a total pain to forecast, always lead to more drama and by the end when you're suffering from nervous exhaustion you'd probably had settled for a northerly toppler!

However when they're good theres nothing quite like them, whether this one lives up to expectations only time will tell if it verifies.

Preferably we'd like to see deeper low pressure in the northern Med around Italy to increase the flow and set up some good convection off the North Sea. Also for you there in Ireland a stronger flow off the Irish Sea and a deeper level of cold would help.

In terms of the GFS 18hrs run it doesn't quite pass my strict quality control threshhold in the lower resolution, hopefully we can see even better synoptics.

The first and most important thing is that we get cross model agreement and the shortwave behaves in a festive manner!

[weather eater]

This is what i was saying earlier. The more westward the pattern the better.

The models have a history of moving a pattern far too east, However in time the pattern gets modeled further west each run as things firm up as we enter the later part of reliable.

Expect further upgrades on the 00z and the UKMO & ECM to start coming inline with the GFS.

I seem to remember it being the other way round unfortunately, west then further east.

Edited December 4, 2012 by weather eater

[cold snap]

You've obviously not suffered as much as the rest of us!

Easterlies and model output are not a marriage made in heaven, hence they're a total pain to forecast, always lead to more drama and by the end when you're suffering from nervous exhaustion you'd probably had settled for a northerly toppler!

However when they're good theres nothing quite like them, whether this one lives up to expectations only time will tell if it verifies.

Preferably we'd like to see deeper low pressure in the northern Med around Italy to increase the flow and set up some good convection off the North Sea. Also for you there in Ireland a stronger flow off the Irish Sea and a deeper level of cold would help.

In terms of the GFS 18hrs run it doesn't quite pass my strict quality control threshhold in the lower resolution, hopefully we can see even better synoptics.

The first and most important thing is that we get cross model agreement and the shortwave behaves in a festive manner!

Another excellent post nick ,thankyou

[johnholmes]

seems like i have been looking at those CPC charts for about a month now with people posting them in here i dont think they have ever come off

Utterly wrong, they predicted, if you look at the regular updates I show along with the 500mb anomaly checks that the 'cold' would start around 27-29 November, it did; they contiued to show the cold spell, along with the westerly hiccup that wound an awful lot of folk up on the model thread, which it did, they then showed that the upper flow would revert to north of west which it has. How much do you want mate?

They are at the moment not quite at 6 and 7's but close to it although the overall trend is still to show a cold and certainly not a mild spell of weather at the surface into the 3rd week of December.

As always the hiccup, if that is what it is, over the past 24 hours will be revealed as a hiccup or a trend after they revert back to showing a pretty similar pattern between the main 3 and also the NAEFS version in about 3 days time when they have settled into whatever they think it is going to do. My own personal punt would be back to cold. Whether that is NW based as the current cold is or more NE based I'm not sure.

My 500mb update will get done, I hope, during Thursday.

I hope this may help some newer folk to get a grasp of upper air patterns and that they are, in my view, more reliable at 6-16 days range, than the 4x or 2x daily synoptic outputs. I stress that is my view and others will disagree. However the 'success rate of these charts at these time scales is about 70% which I think is quite impressive.

Edited December 4, 2012 by johnholmes