Model Output General Discussion

[Iceni]

It's NOT an opinion it's a fact...it will 'breakdown' but why go on about all the time.

Yeah it will breakdown — probably early March is my preference.

I think so many of us have been looking forward for years for something like this — a proper cold/snowy/frosty spell over the Christmas period — we'd rather relish the anticipation. It's a bit like getting ready for a party and having somebody remind you of all the clearing up to be done the next day.

Edited December 15, 2009 by Iceni

[cyclonic happiness]

Ok, no more comments about a possible breakdown seen as its offending people. I constantly see posts I dont perticularaly like, people ramping up this cold spell to epic proportions with little or no evidence and based on oppinion. Do you see me attacking those views? absolutly not. People wont agree, but If Ikept ramping up this cold spell Id be a hero. Shame your not allowed to have different oppinions to everyone else. soory about this off topic post, this will be the last 1.

Haha, this is a real can of worms isn't it?

Oh well, I not too bothered tbh, i just am looking forward to the next few days, we are only into the second week of winter so who cares about "breakdowns" they will happen anyway.

I do think that folk shouldn't leap on others though when a perfectly reasonable observation is made?

Jed is just looking and reiterating what is shown in the charts, I forgive him

[Optimus Prime]

Oh for heavens sake whats getting boring is all this bickering! if Jed wants to talk about a breakdown let him, and i will be talking about a breakdown in a post coming up shortly

Don't worry in a subliminal way I'm always looking for a breakdown but I won't post my thought unless I have reliable data to back it up and won't make it a one short paragrapher. Will be looking forward to your breakdown analysis shortly then.

[Nick.F]

we can avoid all the bickering, if we all employ the Ignore function to ignore the posters who post what we don't want to hear.

That way you only hear what you want to hear, or the info from those that you believe have something worthwhile to say.

I for one ignore large numbers of posters.

***back to my ice cream***

[Harsh Climate]

Thanks cyclonic and nick.

And just for the record Im not a mild ramper, I love snow and cold! god knows why when im a postie and Im out in it lol. All im trying to do is interprate the charts as I see them in a neutral way, that way I find it easier to get a better understanding than letting my heart rule my brain. The moment the signs of a breakdown diminish, itl be the moment I state that. anyways lets move on and enjoy the fantastic snow prospects

[jethro]

Can we all get back on topic now please folks.

[Snowly does it]

Gentle Reminder

Anyone is free to discuss model output of any kind in the thread. One person's boredom is another's thrill.

I am about to trim the thread of some recent comments and discussion which is not related to model output. If you wonder where your post has gone - that is where. If I can find a home for it I will, if not it will disappear.

It's going well, let's keep it that way and enjoy the day.

EDIT - there, that will do for now.

Next chapter!

[Frosty.]

Just read through 2 pages of bickering

The GFS has put back the potential return to less cold or mild until probably christmas day which gives plenty of scope for further delays along the lines of what the current ecm is showing. I'm very happy with the ecm which has been performing strongly again since the blip it suffered last thursday. Still all to play for and a very wintry spell is literally knocking on the door and about to kick it down, a double whammy of wintry weather to gorge ourselves on during the next week so we will have to leave room for all the turkey and mince pies afterwards.

Edited December 15, 2009 by Frosty039

[nick sussex]

Evening all

The rollercoaster model day will soon be drawing to a close with the upcoming gfs 18hrs run. Overall we’ve seen some very good output with the odd rogue scroogelike one thrown in to keep our feet on the ground.

Alot of debate in the thread regarding the Greenland block, this isn’t actually weakening its edging westwards and this is part of the reason that the extended outlook becomes very complicated. NOAA in the USA are pretty certain that the high will retrogress towards Canada :

A STRONG AND RETROGRADING POSITIVE ANOMALY AT HIGH LATITUDES OF

THE NORTH ATLANTIC AND CANADA FAVORS CLOSED CYCLONES UNDER ITS

BASE IN THE LOWER 40S LATITUDE. A NEGATIVE ANOMALY RETROGRADING

THROUGH ALASKA FAVORS RIDGING IN WESTERN CANADA...AND COULD ALLOW

FOR A SOUTHERN STREAM MOVING THROUGH THE SOUTHWEST LATE IN THE

PERIOD. THE MODELS AGREE ON THESE IDEAS.

Now if we look at the mean height comparisons between the ecm and gfs good agreement on the upstream pattern.

http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html

We can see here those positive anomalies have edged westwards with a broad swathe of negative anomalies to the south. Some of the uncertainty in the outlook is to how much if any this southern arm of the jet amplifies, we want it to remain flat and running as far east into the med as possible and staying to the south of the uk.

Much of the output does hint at some sort of attempted breakdown from the sw and this is where chaos is likely to ensue in trying to call this correctly, in these situations with fronts moving in from the sw it can be a slow affair, sometimes fronts grind to a halt, occasionally pressure starts to rise again to the north edging the fronts south again.

We have to remember here there is no sign of the PV returning to the north and pressure will remain high to the northwest, we should also take into account the dangers of a western based neg NAO setting up.

In terms of tonights ecm ensembles the operational run is well supported but is one of the coldest solutions for days 9 and 10.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

However there is still a good clustering of coldish members. The gefs ensembles show a split later but with quite a few members staying cold upto Xmas.

Although later we see the models lift the upper air towards -5 on the 850's we should take into account there will be cold conditions remaining at the surface here any slack flow will help this , any east or se flow ahead of an incoming depression should still be able to bring some snow esp for inland areas as this will be pulling a flow off a very cold France or low countries but it does become again complicated as we have two lows one centred probably over France and the other to the north of the uk, in terms of the interaction between these again another variable to throw into the mix.

I think everyone can see now why its an impossible forecast past this weekend for detail, for the timebeing FI def starts past this point.

Given all the output the north has the better chance of a White Xmas with the risk reducing as you head south, but i really wouldn't want to call this.

Edited December 15, 2009 by nick sussex

[chrisbell-nottheweatherman]

Thanks Nick. I'd be interested to hear your thoughts on whether you feel a zonal setup would be likely to last well into the New Year or whether you think that any incursion from the SW would be short-lived? I know you explained how uncertain and chaotic the breakdown is looking, but, in terms of longer-term factors, do you agree with GP in the advanced model discussion?

[nick sussex]

Thanks Nick. <_< I'd be interested to hear your thoughts on whether you feel a zonal setup would be likely to last well into the New Year or whether you think that any incursion from the SW would be short-lived? I know you explained how uncertain and chaotic the breakdown is looking, but, in terms of longer-term factors, do you agree with GP in the advanced model discussion?

Well GP is certainly great at the teleconnections and i think theres a good chance that January could become interesting, however as we've seen from the past you never know when an unexpected variable might pop up. I think what is most striking about the winter so far is no sign of a strong polar vortex setting up shop near Greenland and there remains the possibility of more northern blocking.

To be honest I think the next weeks model watching will be nerve shredding enough without worrying too much about January!

[chrisbell-nottheweatherman]

Well GP is certainly great at the teleconnections and i think theres a good chance that January could become interesting, however as we've seen from the past you never know when an unexpected variable might pop up. I think what is most striking about the winter so far is no sign of a strong polar vortex setting up shop near Greenland and there remains the possibility of more northern blocking.

To be honest I think the next weeks model watching will be nerve shredding enough without worrying too much about January! <_<

I agree about the next few days - unlike some I'm not obsessing about a breakdown, just curious. I'm waiting to see what guys like yourself make of the pub run!

[Upgrade]

I agree about the next few days - unlike some I'm not obsessing about a breakdown, just curious. I'm waiting to see what guys like yourself make of the pub run!

Thursday's easterly looks to be even stronger, so far from the first 48 hours of the charts..... amazing!

Edited December 15, 2009 by jimmyay

[mcweather]

Thanks for your input Nick. Concise and interesting as ever. I have a feeling there could well be a few surprises in this unusual situation.

[iowpompeylee]

hi all when are the next charts out????? please let me know!!!

[michelle]

hi all when are the next charts out????? please let me know!!!

As far as I know it's coming out now.

[SNOW-MAN2006]

more percipitation down the east coast so far on this run.... now out to 69 hours... marginal at NE ENGLAND coast though with temps climbing to 3 or 4 degrees... right down the east coast though plentiful showers with temperatures widley at 1 or 2 at the coast...

[Altohumorous]

Some promising upgrades of potential snow/cold today, I might have to put the weeping, wailing, and gnashing of teeth on hold again! Probably all change back again tomorrow, perhaps what matters is the timing of the last set of models before the main events themselves. If tomorrow is downgrade, then thursday might be perfect timing for upgrade :lol:

Easterly/NEasterly and instability now looking very good for east and parts of central and southern England. If it comes off for you lot I wont begrudge, I'll just be happy to know it can happen still in these islands. What happens on the coast will be of particular interest.

Liking the look of the showery troughs progged in the flow on the northern side of the low too, and the tighter isobars, will certainly feel bitter in that. Will be very interested to know the actual temperatures that result from this, SST's must be relatively high.

The way it's gone this week, the 4 days before the northerly incursion now seem like a lifetime so not much point commenting on that scenario yet. As for FI - not even on my radar!

Still, will be interesting to know if that stalling Arctic cold front will pep up and turn to snow in Scotland and the north of Ireland, once the cold tries to dig in behind

[Yeti]

http://www.wetterzentrale.de/pics/Rtavn901.png

Just look at the amount of shortwaves in the flow! It's a shame it's turning out to look a bit messy.

[iowpompeylee]

As far as I know it's coming out now.

thank you!! what are the times the charts come out???10pm what about the morning etc??? im quite new so getting to know the runs?? is that trough still making its way southward tomo?????

[winterfreak]

thank you!! what are the times the charts come out???10pm what about the morning etc??? im quite new so getting to know the runs?? is that trough still making its way southward tomo?????

Here's the chart timetables....

[SNOW-MAN2006]

Saturdays Front has been downgrades i fele in terms of percipiation, especially for the middle slice of the country.... still plenty of time for change though however...

[Thundery wintry showers]

Progged temps on the 18Z look a lot more realistic than on the insane 12Z. Perhaps there was some kind of error in the temp progs that NOAA has sorted for the 18Z runs? Otherwise the run is similar- perhaps a slightly less intense easterly than was shown on the 12Z.

[TEITS]

Saturdays Front has been downgrades i fele in terms of percipiation, especially for the middle slice of the country.... still plenty of time for change though however...

Personally if we're looking for detail over this weekend then to be honest at the moment its a waste of time. Very diffcult to predict what disturbances will develop within this polar flow.

As for the breakdown thats being discussed. Again personally I feel its a waste of time but I do respect members if they want to look this far. I just can't be bothered at the moment due to the potential over the next few days plus the models will really struggle beyond +120.

[Geordiesnow]

Progged temps on the 18Z look a lot more realistic than on the insane 12Z. Perhaps there was some kind of error in the temp progs that NOAA has sorted for the 18Z runs? Otherwise the run is similar- perhaps a slightly less intense easterly than was shown on the 12Z.

northerly comes in slightly quicker on this run than the previous runs which aint to bad.

It seems to me that height rises might try and build to the North and we see these are starting to come into play now a little with the 2nd low much further South than previous runs giving the potential to alot of snow for some. Also those easterlies following the low are getting closer. :lol: