Model Output Discussion - 5th December - 11th December

[kold weather]

Well here is a new thread for the new week. Some parts have finally had snow over the past 24hrs, but now the models seem to be at a cross-roads with how the pattern will evolve. Some models suggest we will get an attempt at a slider low which could introduce another variation of zonality. Other models attempt to bring in a high pressure cell from the Atlantic and settle things down.

Which solution is right? Or is it the case that both are wrong?

Discuss here folks!

[Costa Del Fal]

Quite a change across many of the Models it seems this morning. Any high pressure for this weekend and early next week has been ditched or kept well to the South with Low pressure systems continuing to blow in, sometimes setting up to our NE briefly. Essentially perhaps a continuation of the pattern were in right now, maybe a little milder.

[DeepSnow]

Yes it looks that way, im only just starting to understand how to read the models so correct me if im wrong, but by looking at the GFS on Netweather thismorning the -5C Uppers never really make it to the South of the country now? So looks like the South might be staying milder according to that run, though the North still gets some chance for cold and snow! As ever, its just one run so won't take it at face value!

Edited December 5, 2011 by DeepSnow

[Costa Del Fal]

I did forget to mention that the 00z GFS Pressure ensembles are a HUGE outlier and the rest keep things more settled, but most of the other models keep an unsettled influence, maybe high pressure extending into the South at times but nothing to the extent the GFS seems to want.

Edited December 5, 2011 by Blizzards

[ANYWEATHER]

Yes it looks that way, im only just starting to understand how to read the models so correct me if im wrong, but by looking at the GFS on Netweather thismorning the -5C Uppers never really make it to the South of the country now? So looks like the South might be staying milder according to that run, though the North still gets some chance for cold and snow! As ever, its just one run so won't take it at face value!

The Gfs model at the moment seems to be struggling, to say the least, some really bad and wrong output from this model in the last few days, Ecm is the one to follow at the moment......

[mountain shadow]

Models backing up the teleconnections and upper stratosphere forecasts this morning with HP pushed south and a zonal outlook likely. Good news for the drought arease and ski resorts though.

[DeepSnow]

The Gfs model at the moment seems to be struggling, to say the least, some really bad and wrong output from this model in the last few days, Ecm is the one to follow at the moment......

Ok cheers, just looked at ECMWF looking better than GFS for cold in the Medium term, could do with just some frosty mornings let alone snow atm!

[kold weather]

GFS following the ECM and ditches any cold in the south and keeps it mild down there, a little more complex further north still but pretty much a zonal outlook with little in the way to get excited about.

Still overall looks around average on the models this morning so its not a total disaster. Hopefully we get one or the other and not something inbetween like we had most of Autumn...

[Brum Watcher]

GFS from a mild outlook to a total flip to a zonal and at times colder outlook, ECM seems to be more reliable and decent mid range.

Also FI eye popper (trend) at the end.

Edited December 5, 2011 by Brum Watcher

[Cecil Hogmanay Melchett]

well after a major but not unexpected let down last night i was hoping to be cheered by the models.

I should have known better,theyr'e pretty awful for anyone wanting snow.

Might sound drastic but im not expecting any snow this side of chrimbo with the models setup as they are.

[AWD]

well after a major but not unexpected let down last night i was hoping to be cheered by the models.

I should have known better,theyr'e pretty awful for anyone wanting snow.

Might sound drastic but im not expecting any snow this side of chrimbo with the models setup as they are.

I don't think anyones been expecting any snow in southern England for a while now this side of the new year! But that's to be expected with background signals and model progress! It's only one month, there's another two to go yet, with potentially more support from the background signals etc!

Models to me, don't show anything particularly cold or particularly mild for the next couple of weeks! Fridays cold blast has been restricted to Scotland now, with the south staying average in terms of temps, maybe slightly above on some days! For most of the run the country is being bathed in uppers of 0c! Maybe slightly higher at times in the south, and slighty lower at times in the north! With depressions coming in off the Atlantic, it will all feel rather average out there! Cool in the wind and rain, pleasent enough in any sunshine, although frosts do look limited on this run!

Things will change still yet anyway, but if you read the Meto further outlook, that looks like something similar to the way we seem to be going!

[Glacier Point]

The ensemble means hold some persistence to the ridge solution this morning so we might need to strike a half way house between good cross model agreement with the operationals for a much more zonal outlook and the mean ridge solution - probably high pressure closer to the south than shown although FWIW, with angular momentum probably about to fall again (take a look at the SOI dailys), the persistence of a deep upper low around Iceland appears the way to go. What does appear to have happend again, the models in the 5-8 day timeframe have been woeful in forecasting the NAO during the last few weeks, and the UKMO models does not appear to be immune to this.

Edited December 5, 2011 by Glacier Point

[wolvesfan]

Mornin all,

Yesterdays mid atlantic pressure build from the GFS now gone,too much power in the vortex at the moment.

ECM,showing pretty standard early winter zonal weather for most.

No signs of the SW flow one or two were predicting either which is a big plus for us cold fans.

[shedhead]

well after a major but not unexpected let down last night i was hoping to be cheered by the models. I should have known better,theyr'e pretty awful for anyone wanting snow. Might sound drastic but im not expecting any snow this side of chrimbo with the models setup as they are.

Whilst the chance of widespread snow remains very low, if yesterdays runs from GFS had verified the chances were zero under that big mid latitude high. OK there might have been a hope of colder weather if that high had drifted into to right position further down the line, but the chances of that were also very small. Like it or not this zonal/unsettled pattern looks as if it's going to be tough to break, but of course that is good news for the 2% of the populus that live on ground above 300m across the north - it's just the other 98% that will be left frustrated...

Edited December 5, 2011 by shedhead

[snowmadchrisuk]

Whilst the chance of widespread snow remains very low, if yesterdays runs from GFS had verified the chances were zero under that big mid latitude high. OK there might have been a hope of colder weather if that high had drifted into to right position further down the line, but the chances of that were also very small. Like it or not this zonal/unsettled pattern looks as if it's going to be tough to break, but of course that is good news for the 2% of the populus that live on ground above 300m across the north - it's just the other 98% that will be left frustrated...

Whilst the chance of widespread snow remains very low, if yesterdays runs from GFS had verified the chances were zero under that big mid latitude high. OK there might have been a hope of colder weather if that high had drifted into to right position further down the line, but the chances of that were also very small. Like it or not this zonal/unsettled pattern looks as if it's going to be tough to break, but of course that is good news for the 2% of the populus that live on ground above 300m across the north - it's just the other 98% that will be left frustrated...

Although you only need a setup like today's to get some Snow further South , Through the Early hours Snow has been falling at randam places though out the country including the Midlands and as far South as South Wales. For any prolonged lying Snow on low ground even in Scotland there is no way round it except a Greenland or Scandi High . Today is a really good example of Cold Zoneality . The GFS this morning would leave us open to shots of Cold such as today from the NW. Have to big up the euro's though as they really didn't want to know about the euro high extending over the whole country at the end of the week.

[johnholmes]

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

shows how the models have performed over the last few days at 5 and 6 days for 500mb heights over the northern hemisphere. As usual ECMWF and UK Met are ahead of GFS which had a really bad patch in the last 3rd of November.

Looking over the past few days and a zonal flow on the 500mb anomaly charts has always been indicated. Faint signals at times of a more settled spell edging up from the SW for southern areas in the 10-15 day time frame.

[BLAST FROM THE PAST]

Although you only need a setup like today's to get some Snow further South , Through the Early hours Snow has been falling at randam places though out the country including the Midlands and as far South as South Wales. For any prolonged lying Snow on low ground even in Scotland there is no way round it except a Greenland or Scandi High . Today is a really good example of Cold Zoneality . The GFS this morning would leave us open to shots of Cold such as today from the NW. Have to big up the euro's though as they really didn't want to know about the euro high extending over the whole country at the end of the week.

Indeed we are in cold zoneality and the overall outlook is thankfully not a flat pattern with endless and continuous SW'ly winds and Tm airmasses and doesn't look like being the pattern either. I mentioned yesterday that the height rises to east at present IMO are incorrect and IF any colder shot that comes our way will be from a NW'ly to N wind direction. Interesting tentative signs of an Atlantic block developing for midmonth? Long long time away though and the way the models are lets be more wary of FI.

We are currently in cold category at the moment, lovely day ahead down here...sunny and max of 5c. Very seasonal shall we say? :smiliz19:

BFTP

Edited December 5, 2011 by BLAST FROM THE PAST

[weathe20]

Certainly no more high pressure anymore.

[492]

http://www.uni-koeln.de/math-nat-fak/geomet/meteo/winfos/arcisoTTPPWW.gif

With a bit of imagination there is a northerly component in the flow at 60 deg north between the meridian and 90 deg W. Also notice how the flow crosses the pole and heads towards the UK. Greenland has a -40 deg isotherm the same as Siberia. No doubt this was modelled a few days ago but to see it in reality is quite striking.

[MisfitDog3]

On the various ensembles there is a light blue line on a much colder trajectory than the others. Which model is that please?

[Tim Bland]

Possible back edge snow friday morning as a cold front moves south?

http://www.netweather.tv/index.cgi?action=nwdc;sess=

[snowmadchrisuk]

Indeed we are in cold zoneality and the overall outlook is thankfully not a flat pattern with endless and continuous SW'ly winds and Tm airmasses and doesn't look like being the pattern either. I mentioned yesterday that the height rises to east at present IMO are incorrect and IF any colder shot that comes our way will be from a NW'ly to N wind direction. Interesting tentative signs of an Atlantic block developing for midmonth? Long long time away though and the way the models are lets be more wary of FI.

We are currently in cold category at the moment, lovely day ahead down here...sunny and max of 5c. Very seasonal shall we say? :smiliz19:

BFTP

Indeed we are in cold zoneality and the overall outlook is thankfully not a flat pattern with endless and continuous SW'ly winds and Tm airmasses and doesn't look like being the pattern either. I mentioned yesterday that the height rises to east at present IMO are incorrect and IF any colder shot that comes our way will be from a NW'ly to N wind direction. Interesting tentative signs of an Atlantic block developing for midmonth? Long long time away though and the way the models are lets be more wary of FI.

We are currently in cold category at the moment, lovely day ahead down here...sunny and max of 5c. Very seasonal shall we say? :smiliz19:

BFTP

Liking the 6z GFS Snow chance for Southern England as the Colder Air undercuts ..

[shedhead]

06 GFS does little to help clear up the confusion, bringing HP back in from the SW, albeit not as strong or as far north as during yesterday. Gotta say though the evolution being touted in the medium term (132-168hrs) looks much more plausable.... unfortunately!

[BLAST FROM THE PAST]

Liking the 6z GFS Snow chance for Southern England as the Colder Air undercuts ..

Knowing the models wouldn't be surprised to see the GFS in deep FI swing totally opposite direction...that's FI!!

BFTP

[Nick F]

Differences apparent again after t+96 between 00z ECM/00z GFS and 06z GFS, once Friday's deep low close to the north moves away.

06z GFS brings a more pronounced upper wave downstream across the Atlantic off NE Canada following Friday's lows which enhances the ridge to our west and thus the potency of the northwesterly on Friday, with maybe some back edge snow along the rain band sweeping southeast. Unfortunately the jet re-ajusts to a much more northerly track as the wave works through next weekend, with higher pressure across the south and milder southwesterlies returning early next week.

But given ECM's more southerly tracking jet, it may not be worth fretting over this one operational run until susbsequent runs pick up on developments upstream.