Model Discussion And Chat 19th Feb.2012

[Nick F]

Interesting 8-14 day prognostic 500mb chart this evening and ties in with what the 12z GFS and ECM operationals are showing, -ve anomaly over northwest Europe and +ve anomaly over Norwegian/Barents Seas. a chilly start to March in the offing?

Long way to go to get into this position and it could go wrong along the way, but winter may not be done with us until the fat lady sings ...

[legritter]

anything is possible gang . looking at present data ie modells plus generall weather chat across northern hemisphere things could kick of in about a week . dont write off march , if we can get record snowfalls in aprill , ok 1908 i grant you ,we could certainly get some fun in march . i like ECM later output .also GFS keeps on putting in some fun , if we can get some good upgrades soon im sure this forum will be in full winter mode in EARLY SPRING /lets just hope our friend azores goes to sleep and drifts off ,hopefully way south ,perhaps tonights GFS ,will firm up abit ,cheers legritter

[damianslaw]

Reliable timeframe - very mild with the azores ridging north into southern parts maintaining very mild south/southwesterly flow. All models are showing some pressure height rises to our NE by the end of the week with a deep longwave trough becoming anchored over the mid atlantic - what happens next could be very interesting, if those heights to our NE are joined by strengthening heights ridging SW further to our east - we could see the trough dropping over the country and pulling in much colder air - the set up would then be ripe for 'undercutting' and a very robust high to our NE.

So whilst the winter looks like ending on a very benign mild note, the start of spring could see winter returning again.

ECM is suggesting a set up of these sorts, and GFS wants to bring in an easterly the week after next. An alternative scenario could develop and that is for a similiar set up to what we saw in early feb - less cold overall though. Meto update suggests a NW flow for early March which doesn't seem to back up the ECM and GFS offerings - I have a feeling it will change its outlook in tomorrows update to something much chillier..

[nick sussex]

Very quiet in here considering both the ECM and GFS evenings outputs are the best we've seen for many weeks for cold and wintry potential. It's probably understandable though that people are somewhat model fatigued after an overall very disappointing winter.

In terms of the trend to drop low pressure south with ridge backing west over the top, it's not a pattern that happens all that much and its quite complicated hence it's still quite a hurdle to overcome.

Some uncertainty with how much cold will be available to tap into and whether this could produce a rain to snow event if it managed to verify.

In terms of the ECM ensemble maps, some interesting options at 168hrs:

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

If the trend is maintained tomorrow then perhaps we can look forward to something colder with even chances for some snow for favoured areas but given the winter best to keep expectations low until we see that low drop south within a closer modelling timeframe.

[davehsug]

It's modelling some impressive uppers Nick, but we all know, even if it gets the synoptics broadly correct, we never get those uppers. December 2010 is the only time when anything approaching the uppers modelled has actually come to pass.

[karyo]

Very quiet in here considering both the ECM and GFS evenings outputs are the best we've seen for many weeks for cold and wintry potential. It's probably understandable though that people are somewhat model fatigued after an overall very disappointing winter.

In terms of the trend to drop low pressure south with ridge backing west over the top, it's not a pattern that happens all that much and its quite complicated hence it's still quite a hurdle to overcome.

Some uncertainty with how much cold will be available to tap into and whether this could produce a rain to snow event if it managed to verify.

In terms of the ECM ensemble maps, some interesting options at 168hrs:

http://www.ecmwf.int...t!2009112700!!/

If the trend is maintained tomorrow then perhaps we can look forward to something colder with even chances for some snow for favoured areas but given the winter best to keep expectations low until we see that low drop south within a closer modelling timeframe.

Yes, I am trying not to get carried away to avoid another disappointment!

Has anybody heard from GP and his thoughts for March? I haven't been here much and may have missed his post.

Karyo

[Zakos]

If I recall correctly the early feb cold spell started in a very similar fashion to this chart -

Interesting.

Despite the easterly on this run, The cold never makes it to the UK. This is due to the Siberian air taking a detour through the Mediterranean

Wouldn't take much tweaking of this chart to bring in a bitter easterly

Interesting times ahead I believe. Only one week outside of winter, so no reason we cant see cold and snowy conditions.

Once again,absolutely no sign of any wet weather to alleviate the drought. We have seen some very warm, and extremely cold weather these last 12 months. But the only remarkable thing to me has been the lack of rainfall for the south and east.

Edited February 26, 2012 by Zakos

[nick sussex]

It's modelling some impressive uppers Nick, but we all know, even if it gets the synoptics broadly correct, we never get those uppers. December 2010 is the only time when anything approaching the uppers modelled has actually come to pass.

Yes the infamous GFS 850's predictions!

I think the ones upto 240hrs look okay but the ones right at the end of FI look a bit far fetched! Certainly the GFS overdoes the southwards extent of cold when theres no proper Greenland high, so that ties in with your thoughts regarding December 2010, with the rare Greenland high visitor you've got several days to get the cold uppers down.

I think it would need a lot of good fortune to just get the first low dropping south with ridge backing west within 240hrs.

[on the coast]

Very quiet in here considering both the ECM and GFS evenings outputs are the best we've seen for many weeks for cold and wintry potential. It's probably understandable though that people are somewhat model fatigued after an overall very disappointing winter.

In terms of the trend to drop low pressure south with ridge backing west over the top, it's not a pattern that happens all that much and its quite complicated hence it's still quite a hurdle to overcome.

Some uncertainty with how much cold will be available to tap into and whether this could produce a rain to snow event if it managed to verify.

In terms of the ECM ensemble maps, some interesting options at 168hrs:

http://www.ecmwf.int...t!2009112700!!/

If the trend is maintained tomorrow then perhaps we can look forward to something colder with even chances for some snow for favoured areas but given the winter best to keep expectations low until we see that low drop south within a closer modelling timeframe.

Just when spring looks like its coming the cold appears?

[snow drift]

The ECM is an interesting run but the differences between GFS and ECM at T 144+ are big. UKMO is sort off in between perhaps nearer to ECM output. Had this been showing six weeks earlier, there would have been much excitement on here. For what it is worth, I feel that everything will move slightly north as we get nearer the time and the interesting weather will be for the North of the UK.

Still, interesting model viewing for awhile before I put it down and come back later in the year. Summer months have little interest for me and I will need a rest after this winters viewing.

[mikeocarroll]

ECM this morning looks interesting to say the least:

[Nick F]

Yes, divergence between GFS and ECM after t+144. ECM keen to split a cold pool SEwards over the UK from the Greenland Vortex, with a trough eventually sinking SE over western Europe with a cold (though not especially deep cold) NE flow setting in behind.

00z GFS ens show about half the members supporting the split with trough sinking SE into Europe:

[snow drift]

Yes, divergence between GFS and ECM after t+144. ECM keen to split a cold pool SEwards over the UK from the Greenland Vortex, with a trough eventually sinking SE over western Europe with a cold (though not especially deep cold) NE flow setting in behind.

00z GFS ens show about half the members supporting the split with trough sinking SE into Europe:

I so look forward to be able to add the detail that you have demonstrated to illustrated the differences between the two runs. This winter has been great for learning and my goal for next winter is to be able to post in away which is similar to the way you have demonstrated. Thanks to all posters who have posted in away which adds to learning and is also informative.

[Alex95]

Whoa, almost a snowy NE'ly on the ECM - where did that come from?! It wouldn't quite get cold enough for significant snow from North Sea snow showers, but it gets quite close. These charts are 9 days away though, and as the ECM and GFS are so far apart we can't really talk about the change with confidence, but I think we can be fairly confident that there'll be a change of sorts from the constant high pressure we've had lately.

Fwiw, the GFS post +300 would be ideal for snow I think at this time of year.

[Frosty.]

The latest models in FI are looking cold and wintry, nothing like the mild unsettled meto outlook update yesterday!

I still prefer the ecm solution with it's quicker transition to cold and unsettled with widespread -5 850's for the uk but the gfs 00z shows quite a potent arctic blast with reload potential as the jet becomes aligned nw/se but the week ahead is going to be very mild although probably cooler in most areas by friday and some unsettled weather arriving by next weekend.

Edited February 27, 2012 by Frosty039

[johnholmes]

The output from ECMWF-GFS on the 500mb anomaly charts continues to show some divergence on how the upper air pattern may turn out. The ECMWF is perhaps a bit closer to the NOAA issue last evening, see the charts below,but if it is correct then a colder outlook seems to be developing after the first few days in March. Less anticyclonic and more cyclonic perhaps. Certainly the flow is suggested, especially by ECMWF, to be north of west and it also lowers contour heights which again suggests turning less mild possibly rather cold?

As usual my caution as the trend is only 2-3 days in progress so another couple of days to see if it is maintained.

[No Balls Like Snow Balls]

I am very happy that the models (especially the ECM) seem to be suggesting a change to more unsettled conditions by this time next week. Really need some rain and wind to entertain me, not a great fan of mild and benign conditions. ECM also sugeesting not only will it be much more unsettled but also much colder, whether it will be cold enough for snow country wide is another matter. IMO we would really need to see some really cold uppers to make a cold spell of note at this time of year.

[summersnow]

ECM indeed looking to introduce something a bit different - almost bang on time for the beginning of spring equinox. GFS however, still keen to maintain a powerful and dominant Azores HP, which is never too far away. GFS continues in FI, to show he Azores HP sliding further west and orientating itself so that the jet alignment brings about a more polar maritime flow. GFS has been quite consistent with this theme for several runs now, so I'm beginning to suspect something similar will verify. ECM looks to be over doing things a little but it wouldn't surprise me to see a similar set up to this verify later in the month.

Edited February 27, 2012 by summersnow

[KTtom]

http://www.wetterzentrale.de/pics/Rtavn1261.png

Have to laugh, imagine the frontal snow this would have introduced had it been 2 weeks ago with the frozen continent.

[KTtom]

http://www.wetterzentrale.de/pics/Rtavn17417.png

Lol, then we do get snow, and galeforce winds for the south at +174! 06z off on one!

Edited February 27, 2012 by KTtom

[snowmadchrisuk]

http://www.wetterzen.../Rtavn17417.png

Lol, then we do get snow, and galeforce winds for the south at +174! 06z off on one!

Hehe , Yes that would be a beautiful Setup for Some with a Channel tracking Powerful Low Pressure System while under -10 Air , Blizzards M4 Northwards if that happened.

[Brum Watcher]

Wow @ the models, there are showing what we wanted to see all winter. All Fi, even then we had not seen what we are seeing in fi now. With some support from ENS and some cross mod agreement, this feels possible. Nice GFS, classic channel low with low uppers cutting into the system. Ecm/ukmo Also nicely poised with similar setup.

Edit: Ecm/ukmo not far off I meant.

Edited February 27, 2012 by Brum Watcher

[snowmadchrisuk]

Wow @ the models, there are showing what we wanted to see all winter. All Fi, even then we had not seen what we are seeing in fi now. With some support from ENS and some cross mod agreement, this feels possible. Nice GFS, classic channel low with low uppers cutting into the system. Ecm/ukmo Also nicely poised with similar setup.

Edit: Ecm/ukmo not far off I meant.

The Met update Seems to be starting to hint at a change towards what the Current Models are Showing with Snowfall possible on there 6-15... 16-32 dayer is still uninspiring though .

[Zakos]

One trend above all is for a lowering of the heights to our south. This has been a major player in the weather this winter. Yes this pattern would be better in january, but better late than never I say, and it looks like March may well be more wintry than the whole of winter bar early feb.

[nick sussex]

Looking at the overall output it looks like it will be turn somewhat colder towards the weekend with high pressure to the ne and the Azores high displacing nw into the Atlantic.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

If you look at the ECM ensemble maps still alot of variation however with what happens to low pressure near the UK and we're not certain to get that low to head south into France, or whether the outlook would be more in line with the GFS 06hrs which doesn't sink the troughing but takes some energy north clearing the path for that Channel Low.

For this reason prospects in relation to snow are way too far out to have any confidence in. It's a case of interesting synoptics but late in the season and marginality is going to be a problem.

Of course the continent has warmed significantly and it will need a decent injection of cold uppers on the GFS 06hrs there to be advected west to deliver for the UK and even though the GFS progs snow off the northern flank of that Channel low I'm not convinced.

The ECM would take longer to develop any snow chances but has a better ridge to the east and low pressure looks like it could be forced se through the UK later, again though what that produces is hard to say as we just don't know how much cold will be available at the time.

I think for the timebeing we just need to see the pattern remain sufficiently amplified upstream to force the removal of the limpet high to the south, and force heights to drop in central Europe.