General Model Output Discussion

[johncoolj]

hey do any of you think this winter could be the norm soon with the sun spot issue etc and im in dublin ireland do you tink we will get the cold weather back before the end of jan or will the warm air stay

[tinybill]

might be looking at wrong dare say some will say deep in to F1 is there another big blocking high building over Norway and that could bring winds direct from Iceland

Edited January 10, 2010 by tinybill

[Duane S.]

Watch this cold spell just evolve into another one. The average milder interlude won't make it and the Easterly will return. The block is being reinforced on the GFS at T+120. As I said yesterday any milder segment will get squeezed at both ends.

Yep, it will become 'less' cold for sure but I am becoming more and more convinced we are looking at an Easterly reload come the end of this week.

[igloo]

slow thaw by the looks of it the the runs today from the main models all seem to be in agreement this cold aint giving in very easy thats for sure

[J10]

There seem to be a lot more mild solutions compared to the last few days though.

True enough, but the mean is still below zero.

Again a different between the GFS and NAE at short range, which could make a big difference in the outcome for Tuesday. Again the GFS has this further north the NAE (up to Tues 12 Hz, keep it further south. The UKMO different again keeping it further south, and with a much smaller milder sector, right in the centre of the low. Much more snow in teh UKMO evolution compared to teh GFS version.

Did we actaully declare a winner in relation to the event before Christmas.

[phil nw.]

UKM more keen to bring in more Atlantic influence eventually.

But it must be said model accuracy is appalling at the moment.

The huge differences of that low approaching the SW around T48 have still a long way to go to be resolved. Amazing stuff.

Yeah yestreday`s fax had that approaching low further South Matty.

T60hrs. on is still uncertain so anything beyond will change.

100miles diference on the track of that Low changes things on the ground come Weds. on regarding surface temps etc.

[Nick F]

12z GFS brings Atlantic frontal precip as far east as the merdian before stalling on Wednesday, with snow falling roughly east of line from Liverpool to IoW before slowly fizzling out. Obviously this far off the progress of the front E and NE won't be resolved and the snow/rain line is a long way off to be forecasting, but shows the potential is there for the next snow event by mid-week. Snow always most likely in the north, where mixing out with milder Atlantic air is less likely.

[Freezing-Point]

might be looking at wrong dare say some will say deep in to F1 is there another big blocking high building over Norway and that could bring winds direct from Iceland

Do you mean Siberia?

[sandstorm2]

All you guys are a lot more experienced than me but for the life of me I can only see milder southerlies on the charts at the end of this week. There is a lot of uncertainty though and the track of this low coming in is very problematic.

SS2

[SMU]

12z GFS brings Atlantic frontal precip as far east as the merdian before stalling on Wednesday, with snow falling roughly east of line from Liverpool to IoW before slowly fizzling out. Obviously this far off the progress of the front E and NE won't be resolved and the snow/rain line is a long way off to be forecasting, but shows the potential is there for the next major snow event by mid-week.

GFS is very very similar to feb 6 1996- although the trough was more elongated to the south then

http://www.wetterzentrale.de/archive/ra/1996/Rrea00119960206.gif

could be very good for someone..... Im surprised you said only IOW- gfs has PPN all the way to London- but the core of the PPn in your zone-

Incidentally I have still have the forecasts for that period on video tape- in the days when they showed the radar!!!!!!

sandstorm- the above chart is like your comments- winds southerly- but the winds trace back to the cold dry continent-

S

Edited January 10, 2010 by Steve Murr

[tinybill]

Do you mean Siberia?

yes lol|!!!!!

[Cecil Hogmanay Melchett]

We need to be realistic here.This cold spell is at an end.Massive thaw going on today with a 1040mb scandy high and a contiental feed.

Anyone else noticed the AO/NAO profile in a weeks time,looks very very positive to my eyes.why is this happening i thought it was supposed to be negative! :lol:

[Thundery wintry showers]

True enough, but the mean is still below zero.

Again a different between the GFS and NAE at short range, which could make a big difference in the outcome for Tuesday. Again the GFS has this further north the NAE (up to Tues 12 Hz, keep it further south. The UKMO different again keeping it further south, and with a much smaller milder sector, right in the centre of the low. Much more snow in teh UKMO evolution compared to teh GFS version.

Did we actaully declare a winner in relation to the event before Christmas.

ECMWF was the most consistent regarding the pattern for 24-26 December and latched onto the correct evolution once it got to within T+144. GFS and to a lesser extent UKMO were too progressive, the UKMO brought mild south-westerlies in on a few of its runs while the GFS often vastly overdeepened the Christmas Eve low, resulting in the event being projected to be more marginal in the north and east than actually transpired.

Embarrassingly I don't know where to get access to this "NAE" model- where is it?

All you guys are a lot more experienced than me but for the life of me I can only see milder southerlies on the charts at the end of this week. There is a lot of uncertainty though and the track of this low coming in is very problematic.

SS2

The southerlies on the GFS are blowing off a cold continent so would most likely translate to temperatures near freezing. Such a southerly flow introduces the possibility of some sunshine coming through in places, which tallies well with the GFS's projections of some cold nights returning towards the end of the week.

[cyclonic happiness]

I see that right at the end of FI there is the traditional winter chart of a major hurricane on the way here and Greece going into a major freeze lol!

Dustbinland starts at 144+ before that it's just a bit hazy still.

[johnholmes]

Quite amazing differences at such a short range.

you said it Nick

It really is a nightmare for any forecaster

and as someone has just posted-back to the 'old winters'-prior to computer models as well when wondering if the TV or radio forecast that evening really would be what one saw the following morning.

nowt had changed when I first started forecasting and I suppose some might say not a lot has even today.

Fascinating-I know I keep saying bit it is.

[Nick F]

GFS is very very similar to feb 6 1996- although the trough was more elogated to the south then

http://www.wetterzentrale.de/archive/ra/1996/Rrea00119960206.gif

could be very good for someone..... Im surprised you said only IOW- gfs has PPN all the way to London- but the core of the PPn in your zone-

Sorry Steve, meant areas east of line from Liverpool to IoW would remain as snow (though not reaching E Anglia and E Kent), by GFS progs, while areas west of that line would see snow initially before turning to sleet/rain.

All fantasy this far off, of course!!

[ANYWEATHER]

I see that right at the end of FI there is the traditional winter chart of a major hurricane on the way here and Greece going into a major freeze lol!

Dustbinland starts at 144+ before that it's just a bit hazy still.

I would go as far to say that "dustbinland" for any finer detail is probably less than 24hrs The theme continues though, major blocking to our East so slightly less cold conditions for a while but will the deep cold be back soon after,?? in my eyes its certainly more probable than the Atlantic winning out... :lol:

[SMU]

Sorry Steve, meant areas east of line from Liverpool to IoW would remain as snow (though not reaching E Anglia and E Kent), by GFS progs, while areas west of that line would see snow initially before turning to sleet/rain.

All fantasy this far off, of course!!

I guess like me you have bitter memories of that spell- front stalled in a line that was literally in throwing distance from my house- I imagine the front wasnt that far away from you-

S

Edited January 10, 2010 by Steve Murr

[West is Best]

We need to be realistic here.This cold spell is at an end.Massive thaw going on today with a 1040mb scandy high and a contiental feed.

Anyone else noticed the AO/NAO profile in a weeks time,looks very very positive to my eyes.why is this happening i thought it was supposed to be negative!

I can't see from your details whereabouts you live, so am assuming from your post it's probably somewhere like the Canary Isles or perhaps Marrakech? Am I close? Here in the hitherto mild hinterland of north Devon we had 10-15cms of snow overnight and this morning, and it hasn't stopped sending down flakes of snow all afternoon.

As for the 12z GFS run, well that most certainly is not an end to the cold spell. From that run there are still -5C 850hPa uppers appearing a week hence. The sort of extremely low temperatures we have experienced could not last all winter, but that a thaw does not make.

The degree of childishness from one or two people this winter has taken my breath away even more than the extreme cold. There has been complete disregard for wise and experienced posters; the actual conditions; the national perspective and finally what the models are really showing.

[Avain]

In keeping with what was predicted yesterday it snowed continuously here from 10 AM till 3:30PM mostly fairly heavy with largish flakes, yet even on top of existing snow only about a half inch accumulated, on clean areas such as roofs, branches etc, nothing remains.

Unless the air on the incoming LP for Tue/Wed is a colder surely, Particularly as a lot of the air seems to be sourced more from the bay of Biscay rather than the continent, for this section of the country we are looking at a thaw rather than a freeze again? (I don't mind that, it would give the smaller country roads a chance to clear some.)

[Eugene]

What massive thaw happy days, all the snow still in place here in warwickshire with a town max of 1C and countryside max at least a few Celsius colder than that, feels freezing still.

Latest BBC forecast going for cold all week, so obviously they aren't taking much notice of the UKMO 12Z run which looks too progressive to me and to them.

[J10]

ECMWF was the most consistent regarding the pattern for 24-26 December and latched onto the correct evolution once it got to within T+144. GFS and to a lesser extent UKMO were too progressive, the UKMO brought mild south-westerlies in on a few of its runs while the GFS often vastly overdeepened the Christmas Eve low, resulting in the event being projected to be more marginal in the north and east than actually transpired.

Embarrassingly I don't know where to get access to this "NAE" model- where is it?

Within Weatheronline - Expert Charts

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=dldl&MODELL=nae&MODELLTYP=1&VAR=pslv&HH=0&BASE=-&WMO=&ZOOM=0

[markg]

hate to bring bad news but i went to glasgow early this morning and the temp was -5 when i left here but zero in glasgow, when i left glasgow at 2.30pm the temp was+6*c and all the snow was melting fast ,that alone leads me to believe that any front coming in from the south west is only going to give snow on high ground as the forecast for tomorrow on the bbc stats also, after that if the GFS is to be believed it is definetly looking less cold 3-4*c is still cold, weve just been spoilt the last 3 weeks :lol:

and after 144hrs is anybodys guess!! <_<

[paul tall]

What massive thaw happy days, all the snow still in place here in warwickshire with a town max of 1C and countryside max at least a few Celsius colder than that, feels freezing still.

Latest BBC forecast going for cold all week, so obviously they aren't taking much notice of the UKMO 12Z run which looks too progressive to me and to them.

There is a massive thaw in the North. Temperatures are hardly high, 3-4º for most, but the snow is disintegrating quickly.

We have had though, 25 consecutive snow lying days and were up to 24cm depth two days ago where I live, so mustn't grumble!

[PB22]

We need to be realistic here.This cold spell is at an end.Massive thaw going on today with a 1040mb scandy high and a contiental feed.

Anyone else noticed the AO/NAO profile in a weeks time,looks very very positive to my eyes.why is this happening i thought it was supposed to be negative!

Yes, been a big thaw going on here since yesterday evening, I'd say we have now lost half of our original snowcover - which stood at 15cm.

UKMO 12Z certainly turns the UK much milder by the end of the week:

http://www.wzkarten.de/pics/Rukm961.html

http://www.wzkarten.de/pics/Rukm1201.html

http://www.wzkarten.de/pics/Rukm1441.html

At odds with GFS somewhat, but I'd think the milder air will win out for most by the week's end.