General Model Output Discussion

[Shiny_Bottom_1]

there no sign of any snow coming our way, then you watch BBC weather this evening on there they saying the band going to fizzle out

but on the gfs maps they saying the battle Field further north!!!

I would have caution with the GFS ppn charts, even at this range. I've said before, they have been quite inaccurate, however, typically its when the Op run (which is used quite often when posting the maps) has been somewhat higher than most ensembles.

Whilst I still would stick more with the likes of the BBC TV and the METO charts at this range, I would say the GEFS 12z op does not seem to be an outlier nor one the 'higher' solutions for ppn amounts. Certainly will be interesting.

One change on the UKMO Fax chart for the 12z, is that the front is not showing as a decaying front. I still wouldn't expect anything massive for the west midlands, north eastwards, and also wouldn't guarantee snow (although sleet is perhaps the worst solution away from the coasts), but the s/w and south wales could take a hammering.

[nick sussex]

Nick

I think the hurdles will have to be cleared through to end of Jan...BUT there are signs that

a] this pattern doesn't want to shift

b] When it does it will want to repositon, regroup and come back.

Its what used to happen in the 60s and 70s...what is apparent.. and for me is the ovewrriding factor/influence is the southerly tracking jet. With that in place retrograde and northern blocking is almost 'encouraged'....actually like am right now with todays output.

BFTP

Yes i agree with you, it's like the pattern is just determined to stay and with the PV set to take up residence over the pole then given the upstream pattern and with a split flow a good chance the high will ridge westwards. The ECM De Bilt ensembles certainly throw up some interesting members. Would be nice to see the synoptics for the control run!

http://www.weerplaza.nl/15daagseverwachting/default_pluim.asp?r=midden

Edited January 11, 2010 by nick sussex

[meerkat63]

A very interesting aside to the here and now is how well the various models have coped with northern blocking so far this winter.

I made reference to this briefly in questioning yesterdays output (and several other far more experienced posters than I guarded against taking the models then at face value). By and large I would say that ECM has dealt with blocking consistently better than its counterparts - and of course there has been the odd blip - however it does remain the model of choice imo. To that end, tonights output (by the aforementioned ECM) has to be a step in the right direction - for cold lovers anyway!

[conor123]

The 18z has the main part of the precipitation not even reaching most of the Midlands tommorow, looks like it will slide across into the South East as usual...

[chionomaniac]

Looks like rush hour chaos for the south on Wednesday morning.

[gottolovethisweather]

The 18z has the main part of the precipitation not even reaching most of the Midlands tommorow, looks like it will slide across into the South East as usual...

Indeed, although I haven't looked at the said model what if...... the low pressure went steaming along the channel or even dived south-eastwards into France, just like some of often talked winter synoptics of the past.

Why do I mention the above, well having read Robert Stirling's book of British Weather, many episodes of a similar breakdown event have down just that in the past. The models aren't getting a grip so the next 24-36 hours at the ones to watch short term, methinks

Pure guesswork on my behalf, what do the top guys think, GP, TEITS, JH, anyone?

I reckon we should have a Tracking the Low thread for tomorrow.

Whatever, the past few weeks have been interesting and unusual, the future looks interesting too.

STORMBOY

[Tim Bland]

Is there supposed to be a shortwave / front ahead of the main Low? If you look at this frame - http://www.netweather.tv/index.cgi?action=nwdc;sess= the whole Uk if covered in percipitation which is heavy in the East at midnight tommorow?

[chionomaniac]

Looks like rush hour chaos for the south on Wednesday morning.

NAE very similar:

[Nick F]

Indeed, although I haven't looked at the said model what if...... the low pressure went steaming along the channel or even dived south-eastwards into France, just like some of often talked winter synoptics of the past.

Why do I mention the above, well having read Robert Stirling's book of British Weather, many episodes of a similar breakdown event have down just that in the past. The models aren't getting a grip so the next 24-36 hours at the ones to watch short term, methinks

Pure guesswork on my behalf, what do the top guys think, GP, TEITS, JH, anyone?

I reckon we should have a Tracking the Low thread for tomorrow.

Whatever, the past few weeks have been interesting and unusual, the future looks interesting too.

STORMBOY

GFS, NAE and UKMO/UKMet Fax output this evening take the low NE across the SE corner then swing it north up the east coast ... following the 500mb flow like all surface lows. Don't think there is too much uncertainty where it'll go now ...

[gottolovethisweather]

GFS, NAE and UKMO/UKMet Fax output this evening take the low NE across the SE corner then swing it north up the east coast ... following the 500mb flow like all surface lows. Don't think there is too much uncertainty where it'll go now ...

Hi Nick,

In my stupidity I believe I am actually about 1000 miles out with my interpretation of the track of the low according to the MO sequence I've seen, so still learning here.

Can you post a couple of charts for us please.

Cheers

STORMBOY

[igloo]

a horror story from tonights pub run lets all hope it doesnt happen a real nightmare

[cold snap]

Oh dear.

18Z is a nightmare so much so im not even going to look at the rest of the run.

Easterly has been forgotten about and the block just goes up in smoke.

Awfull run.The 12Z is superb compared to this

Edited January 11, 2010 by cold snap

[Nick F]

Hi Nick,

In my stupidity I believe I am actually about 1000 miles out with my interpretation of the track of the low according to the MO sequence I've seen, so still learning here.

Can you post a couple of charts for us please.

Cheers

STORMBOY

If you are refering to the low that develops in the Channel tomorrow night, the fax charts below track the shallow low up the east into Thursday, the frontal snow moving N with it:

http://cache.netweather.tv/fax/PPVI89.png

http://cache.netweather.tv/fax/PPVJ89.png

http://cache.netweather.tv/fax/PPVK89.png

Well GFS not keen at all on following the 12z ECM and doesn't develop the -NAO with the retrogressing high and undercut of lows, instead it looks rather mild in outlook in FI. Will ECM in the morning stay with or back away from its idea of developing an easterly next week? All will be revealed in around 8 hours time!

[Snowyowl9]

The atlantic really is being tested out big time here,always a south or cold SE-ly surface wind.

http://www.wzkarten.de/pics/brack3.gif

http://www.wzkarten.de/pics/brack4.gif

[yamkin]

The 18z has the main part of the precipitation not even reaching most of the Midlands tommorow, looks like it will slide across into the South East as usual...

Precisely what PJB has indicated on the UKweatherworld website

[Great Plum]

It does appear that the models are really struggling at the moment - they seem to wildly flip flop between one extreme to another - this is one of those times I am pleased I am not a meterologist... to find out what will happen next week it seems easier to look at a crystal ball, or tea leaves or count the number of terns flying south for winter then rely on the models at the moment!

[snowmadchrisuk]

Well have just got home , and have been looking back through this evenings posts , you all seemed happy with the 12z GFS and even more so with the 12z ECM , If I was you I wouldnt let the pub run ruin everything . ECM has been pretty persistent over the last few days , it has to be said.

[johnholmes]

One of the major differences in the next week as compared to the week past is the position of the two main troughs-west of and east of the North American continent.

Both are about 30 degrees further east on the predicted NOAA 500mb anomaly charts. This, in turn, means the upper ridge is that much further east; its over the far NE of Norway or north Russia as opposed to being over the UK, or a touch NW of the UK. The pattern, of each of those wavelengths is fairly slow moving. However, the one now and the past week means the UK on the cold side, the predicted pattern suggests on the warm side (warm being a very relative term), thus no deep cold and a more unsettled spell of weather, or perhaps more accurately a more Atlantic type pattern. Mainly Pm or rPm but not true Pm or even less Am (Arctic).

Just how the Pacific jet will react in all this is unclear but it seems to be defaulting, as NOAA comment, to the position in late November. This MAY mean a return is on the cards, as per the post in the Technical thread by GP, or it may not. On a differing time scale the AO has today shown a signal for falling again. Perhaps this is linked to the teleconnections which GP refers to as a 'reload' for the third week in January.

Very interesting model watching at whatever time scales one chooses.

In the short term its still a forecaster's nightmare for this week with the models now making more of the 'wave' or whatever breaking east along the Channel ahead of the main low.

The whole thing for several days has been on a knife edge-more snow for areas with height and only a slowish thaw for most areas away from south and western coastal areas, and to a degree this applies to eastern coastal zones where the thaw has been a touch faster.

An overall temperature of just 1C lower and many more would have seen more widespread snow, but the very cold 850mb air could not last forever without any new influx and that was absent.

Edited January 11, 2010 by johnholmes

[davehsug]

It does appear that the models are really struggling at the moment - they seem to wildly flip flop between one extreme to another - this is one of those times I am pleased I am not a meterologist... to find out what will happen next week it seems easier to look at a crystal ball, or tea leaves or count the number of terns flying south for winter then rely on the models at the moment!

I think that's inevitable Plum. We are pretty much at a crossroads between 2 very different weather types. ECM earlier showed what could happen if the block to the east could move back west & the 18z showed what could happen if it didn't. Both solutions look perfectly valid to me, together with the one in the middle!

ECM has performed much better than GFS recently & it's only the pub run after all, so my money would be on the ECM, but the 18z wouldn't be any great surprise either.

[Liam J]

very intersting looking at the models atm, the amount of chopping and changing is gobsmacking especially the gfs but i put that down to the 4 runs per day it puts out, as we know all 4 runs can vary to some degree as opposed to a model that has 2 runs in which we see 2 seperate outputs per day.

the atlantic is not going to make much inroads for a few days at least, and when the lows bump up against the high to our NE expect some very windy weather at times with the tight pressure gradient, snowfall will most likely be an event for those with elevation tue/wed which could be quite nasty given the wind strength.

hoping the 18z pub run will get the easterly back for next week on the 00/06z runs, however a few days of watching the atlantic try to break back in will be interesting no doubt.

[MP-R]

In the short term, certainly still looking cold for certain until the weekend when everything is up in the air. These charts would suggest some cold nights still to be had, presumably under clearing skies and over snowfields with lows of -5C not far from here actually:

http://www.wzkarten2.de/pics/Rtavn5417.png

The highest temperatures at present seem to be happening at this time, and to me that looks about average for the time of the year and it's not long until the suppressed temperatures arrive back again:

http://www.wzkarten2.de/pics/Rtavn13817.png

[Craigers]

In the short term, certainly still looking cold for certain until the weekend when everything is up in the air. These charts would suggest some cold nights still to be had, presumably under clearing skies and over snowfields with lows of -5C not far from here actually:

http://www.wzkarten2.de/pics/Rtavn5417.png

The highest temperatures at present seem to be happening at this time, and to me that looks about average for the time of the year and it's not long until the suppressed temperatures arrive back again:

http://www.wzkarten2.de/pics/Rtavn13817.png

yep that certainly sums the situation up but ive got to admit that the ECM has been keen on bringing that easterly back in 7-8days and with how this winter has evolved it could happen again, especially with febuary coming closer :wacko:

[gottolovethisweather]

If you are refering to the low that develops in the Channel tomorrow night, the fax charts below track the shallow low up the east into Thursday, the frontal snow moving N with it:

http://cache.netweat.../fax/PPVI89.png

http://cache.netweat.../fax/PPVJ89.png

http://cache.netweat.../fax/PPVK89.png

Well GFS not keen at all on following the 12z ECM and doesn't develop the -NAO with the retrogressing high and undercut of lows, instead it looks rather mild in outlook in FI. Will ECM in the morning stay with or back away from its idea of developing an easterly next week? All will be revealed in around 8 hours time!

Cheers Nick, just what I was after. It certainly appears it can't happen as I hoping as for one thing it's not forecast to be deep enough anyhow.

Many Thanks

STORMBOY

[Optimus Prime]

Evolution looks interesting to me with riding building up from the east and lows developing on it's SE'rn flank. Many classic cold spells develop this way.

To sum up staying very cold (particularly by day) upto Saturday then much uncertainty after a brief 'possible' less cold day Sunday. I would go for ridging to take place and lows developing under it's southern flank dragging back an easterly for next week.

Massive uncertainty at that range as always in these situations. One thing I think we can guarantee - no raging Atlantic for the foreseeable future.

If I was to go for a guess for the end of the month, with the AO and NAO situation developing I'd go for more unsettled finish.

[KTtom]

I'd be inclined to dissagree with the above as looking through all models I think the trend is definately for the Atlantic to win out mid to long term. Even the weekends low is widely predicted to cross the whole country.

High pressure tries to re-establish itself around +162 but the Atlantic storms just look too strong.

In the short term todays 'event' looks to have been blown out of all proportion by the met yesterday, the ppn now looks like its delayed around 6hrs, lighter with the snow confined to hills.