Winter Model Discussion 18Z 13/1/13 onwards.

[MR EXTREMES]

So what's happened come back and the whole model forum has gone into melt down....I think the 12z wernt the worst I've seen.

[Captain Shortwave]

The mighty NOGAPS/GEM and a soon to be watered down UKMO (following the FAX) against ECM and GFS - hmmmmm.

Given ECM and it's essembles, I wouldn't put it in either camp, It's certainly not bringing the Atlantic in at a reliable time frame and many members show prolonged cold. Mean temperature for london doesn't rise above 2/3oC

So it's more UKMO/GEM vs GFS

Two models with consistency over the past week against GFS hmmmmmm

[TEITS]

Only just catching up.

Im not surprised the fax backs the ECM/Ensembles but that doesn't mean the UKMO is wrong. I disagree with BFTP about the synoptic evolution that the UKMO shows because it makes perfect sense if you run through all of the run.

Personally I feel members should keep an open mind because just look at the difference between these model runs. I know its the NOGAPS but it highlights the uncertainty.

http://modeles.meteo...0-144.png?13-23

http://modeles.meteo...0-150.png?13-18

These model runs might look vastly different between each other but its only because they cannot decide where all that energy goes from the Atlantic. Some runs have taken this all NE, other runs SE i.e UKMO and then we have an inbetween with the energy being split between N/SE i.e ECM.

My instinct is telling me the UKMO is onto something here whatever the fax charts say!

Edited January 13, 2013 by THE EYE IN THE SKY

[stainesbloke]

Agreed, hopefully we can start looking toward the next cold setup if things progress as discussed in here lately. That's an observation, no charts to back that up, just hours upon hours sitting in here listening to the more intelligent.

Yes, with the SSW still to filter through and another strat temp rise on the cards I'm sure late Jan and Feb could be very interesting Potential for this week not over by any means either, it's more of a wait and see approach because no model seems to be able to predict outcomes with confidence. At least I saw the sun today!

[Nick F]

Very strong 180knt+ jet roaring out of NE Canada and across the Atlantic this weekend on the 18z, so the cold block under a lot of pressure to get shunted east. Still uncertainties on how the models handle this energy and how quickly the cold is pushed back east, though there does seem to be an air of inevitability to how this eventually goes (i.e. return to Atlantic westerlies) unless there is some drastic change in fortunes. Though I guess the door is still open for the Atlantic trough to disrupt against the cold block, a la ECM. So not all hope is lost for me.

Edited January 13, 2013 by Nick F

[Yarmy]

Blimey, a week of cold, plenty of snow potential to come, yet still rampant pessimism. A couple of days ago, there were certain op runs and ens members showing the Atlantic blasting through on Tuesday and a raging PV thereafter. The only trend I can see is the cold spell being extended. Yet just because the UKMO mega blizzard is probably a glitch, it's the end of the world. A quick trawl through the New Year's Day T240 archives will be a salutary reminder of where we could have been.

[Pembroke Dangler]

First post for me, but must have a say on how I think the gfs (and to a certain extent the ECM) are over playing a split jet to occur around the 72-96 hour mark (can't post charts on phone) surely the piece of jet shown to to go north of Iceland is going against the ssw affect, of reverse zonal winds around the periphery of the arctic circle, or has the ssw begun to subside and I'm missing something?

Just my thoughts on the pattern emerging!!!

I for one feel the plausible solution would be for a more powerful nw/se flow to the jet coming out of the eastern sea board hence undercutting potential around 120-144 to occur al a ukmo/gem and the ever more reliable CMA!!

Just a thought from me!!

Thanks

[OldMetMan]

Looking at later runs, I can't add that much more to what I said this afternoon, apart from the fact that the longer term model solutions are even more varied.

One thing of interest is the fact that the GFS are still keeping the Scandinavian block in place, in fact are even intensifying the surface HP right out to T180, presumably in answer to the intense Atlantic LP it is predicting by that time. Thereafter, it goes a bit mad with raging Atlantic storms blasting all cold European air way back to Russia.

Overall, the 500mb pattern is looking a lot more amplified than it has for a while, and I am more inclined to think that the powerful forecast jet will dive ESE or SE, as the earlier GFS run suggested or perhaps even a split stream with more energy heading NE as well. In that event, I think blocking would be more likely to be maintained, maybe the upper high reforming further W near Iceland.

It's interesting too that the latest FAX charts are showing quite a respectable HP to the NE and developing LP coming from the US and Canada looking more like it will head NE.

Lots to keep an eye on in the coming days!

[Jason M]

Very strong 180knt+ jet roaring out of NE Canada and across the Atlantic this weekend on the 18z, so the cold block under a lot of pressure to get shunted east. Still uncertainties on how the models handle this energy and how quickly the cold is pushed back east, though there does seem to be an air of inevitability to how this eventually goes (i.e. return to Atlantic westerlies) unless there is some drastic change in fortunes. Though I guess the door is still open for the Atlantic trough to disrupt against the cold block, a la ECM. So not all hope is lost for me.

Same thoughts from me really. Not quite a done deal yet, but the smart money goes on Atlantic westerlies from here. For the first time in days GFS has shown a degree of consistency today and a clearer signal from the ensembles is emerging.

I bet it all changes in the morning now :-)

Jason

[Carlrg]

Am i right to say the BOM keeps the Atlantic at bay right up to the 22nd of Jan with only the odd incursion into Wales,Ireland and far west.

http://www.meteociel.fr/modeles/bome_cartes.php?&ech=6&mode=1&carte=0

Don't know how reliable the Bom is though.

[Roy]

The way the models have changed with nearly every run in the last few days, you can be rest assured that this is not the end of the story. And still potential this week for snow events to occur almost anywhere, esp as the cold is in place.

[Buzz]

Blimey,22 acronym's in one post.

And what's most worrying is that I understood every single one of them. Must be something wrong with me .............

But back to the models ........ well, as myself and others keep saying, don't take too much notice of anything past 72 hours. Oh yes, and roll on the cold NNW!

[Weathizard]

Some very good posts on here this evening if I may say so!

Jason M, I have to say I respectfully disagree though, the ensembles especially have switched wildy recently and I think no clear trend can be seen from the GEFS, also for us to see there is a certain degree of agreement I think there needs to be clear evidence from multiple ensemble suites, which we clearly don't have because the ECM is still pretty cold after days 6-8 with a large scatter. We also have several different models showing varying scenarios. I think this all goes back to what Ian said a few days ago, the models are still finding it difficult manifesting the SSW exact effects into output. I think it could go either way but I certainly wouldn't be putting my chips on the table yet. I'd still favour a NW/SE tracking jet personally, maybe not as soon as the UKM shows but within 10 days.

Anyway evening guys, been good reading your posts in here this evening, which makes a change to the normal mass hysteria and toy throwing!

[Timmytour]

Well. we're finally well and truly in the cold spell...seems an eternity since it was first appearing on the models radar!

What a rollercoaster it's been. Some highs and lows all the way through. At this moment in time it's probably more of a low, for two reasons.

1/ The potential for snow has declined in the short-term... high points were seeing charts from a few days ago which looked like delivering upto a foot of snow! Now it's more like dustings before it dries up

2/ The cold spell itself looks like it will struggle to make it through next weekend, whereas some model runs delivered the hope it would run into february!

Of course not all models are seeing things this way....and as things overall seem to have downgraded, there's every chance upgrades are just around the corner. I think we did have GFS and ECM in step for a couple of hours just three days ago delivering quite superb charts. But things seemed to change with every run, like we were told would happen with the SSW.

So a new working week is almost upon us. I wouldn't be surprised tomorrow to wake up and find that GFS and ECM have delivered substantial upgrades and put us on a high again....but I must say, through all this, it's been hard to fault the steady cautious approach undertaken by Ian Ferguson and his colleagues.

Edited January 14, 2013 by Timmytour

[Just Below Zero]

Well. we're finally well and truly in the cold spell...seems an eternity since it was first appearing on the models radar!

What a rollercoaster it's been. Some highs and lows all the way through. At this moment in time it's probably more of a low, for two reasons.

1/ The potential for snow has declined in the short-term... high points were seeing charts from a few days ago which looked like delivering upto a foot of snow! Now it's more like dustings before it dries up

2/ The cold spell itself looks like it will struggle to make it through next weekend, whereas some model runs delivered the hope it would run into february!

Of course not all models are seeing things this way....and as things overall seem to have downgraded, there's every chance upgrades are just around the corner. I think we did have GFS and ECM in step for a couple of hours just three days ago delivering quite superb charts. But things seemed to change with every run, like we were told would happen with the SSW.

So a new working week is almost upon us. I wouldn't be surprised tomorrow to wake up and find that GFS and ECM have delivered substantial upgrades and put us on a high yesterday....but I must say, through all this, it's been hard to fault the steady cautious approach undertaken by Ian Ferguson and his colleagues.

Have to agree with that.!

They been trying to pin the tail on a donkey and generally got some where near its hindquarters whereas some models have been a bit ass.

Edited January 14, 2013 by Just Below Zero

[davehsug]

We should be approaching D day in the next couple of days with regard to the SSW starting to show it's hand fully in the ECM modelling? Is it around the 25th when the consensus is that it will really start to have an effect?

[Wadey]

Has anybody got precipitation charts they can post for the morning please

[OldMetMan]

Just out of interest, these are the kind of max temps currently across Europe, not excessively cold until you get to Poland although Germany has cooled down a bit in the last few days.

I think this highlights the difficulty in the next few days of determining where, or indeed even if, the snow will fall. Successive model runs have increased thickness values over the UK. Overnight Monday/Tuesday would be my best guess for any significant snow, but in these situations it can sometimes happen that a trough, even a small LP can move W in association with the lowest thickness values.

[Thundery wintry showers]

Potential for some moderate to heavy snow over much of the UK tomorrow, but temperatures will be pretty marginal due to a pool of warmer air with 850hPa temperatures around or above the -5C mark, especially the further south and west you are, so it is doubtful as to how much of it will settle on low ground. The GFS is suggesting that north-east England is most likely to be heaviest affected:

http://cdn.nwstatic..../uksnowrisk.png

We have seen a significant toning down of the subsequent easterly- many earlier runs would have seen a fair number of snow showers come in off the North Sea, particularly for SE Scotland, NE England, Lincolnshire and Norfolk, but it has now been slackened somewhat. The ECMWF and UKMO versions are a little less slack than the GFS and more in line with what the FAX charts show, and thus would bring snow showers further inland than the GFS precipitation charts are suggesting, but if the GFS version comes off then it will only be coastal fringes that will see any showery activity.

The easterly flow is likely to slacken off almost completely by Thursday with snow showers restricted to coastal fringes, but there is considerable potential for classic "frontal battleground" snowfalls as Atlantic weather systems struggle to make much headway against the Scandinavian blocking high and also bring some fairly potent polar maritime incursions in behind the fronts, causing cold air to meet slightly less cold air. A fast breakdown from the west is not implausible as we saw the models overdo Scandinavian blocking as recently as mid-December, but at the other end of the spectrum, nor is something similar to the 5th-7th February 1996 when some parts of the UK had a sizeable dumping.

Edited January 14, 2013 by Thundery wintry showers

[Pembroke Dangler]

We should be approaching D day in the next couple of days with regard to the SSW starting to show it's hand fully in the ECM modelling? Is it around the 25th when the consensus is that it will really start to have an effect?

I thought we were already under the influence of it with the current Synoptics appearing and with the bbc weather guys saying that too! So if its still warming up in the strat we should feel the effects longer then maybe?

Think the Atlantic will be siping some San miguels for a month if this is true

[stainesbloke]

Potential for some moderate to heavy snow over much of the UK tomorrow, but temperatures will be pretty marginal due to a pool of warmer air with 850hPa temperatures around or above the -5C mark, especially the further south and west you are, so it is doubtful as to how much of it will settle on low ground. The GFS is suggesting that north-east England is most likely to be heaviest affected:

http://cdn.nwstatic..../uksnowrisk.png

We have seen a significant toning down of the subsequent easterly- many earlier runs would have seen a fair number of snow showers come in off the North Sea, particularly for SE Scotland, NE England, Lincolnshire and Norfolk, but it has now been slackened somewhat. The ECMWF and UKMO versions are a little less slack than the GFS and more in line with what the FAX charts show, and thus would bring snow showers further inland than the GFS precipitation charts are suggesting, but if the GFS version comes off then it will only be coastal fringes that will see any showery activity.

The easterly flow is likely to slacken off almost completely by Thursday with snow showers restricted to coastal fringes, but there is considerable potential for classic "frontal battleground" snowfalls as Atlantic weather systems struggle to make much headway against the Scandinavian blocking high and also bring some fairly potent polar maritime incursions in behind the fronts, causing cold air to meet slightly less cold air. A fast breakdown from the west is not implausible as we saw the models overdo Scandinavian blocking as recently as mid-December, but at the other end of the spectrum, nor is something similar to the 5th-7th February 1996 when some parts of the UK had a sizeable dumping.

A sizeable dumping is always most satisfying Interesting week to come model watching, must be record uncertainty?!

[metrosnow]

not meaning to be downbeat but today has been a day of pretty much constant downgrades both in the short and medium terms. The only ray of light was the ukmo at 120 and ian says that has been disregarded by the met. So where does that leave us?

Another day of downgrades tommorrow and i think we can call the end to the cold spell fri or sat. What has been particularly dissapointing is the complete downgrading of our midweek easterly from something special to a calm but cold spell of weather.

I dont think the jet will undercut as people are hoping!!

Probable cause of our demise low heights around greenland and that big hunk of vortex in eastern canada.

Yep. As much as at pains me to say it, I couldn't agree more. My only positive is that there's been so much chopping and changing over recent days that it could all be different later!

That UKMO T120 was something to cling onto earlier, but now Ian has told us it has been modified, I see little from the current charts to keep me upbeat. A real shame as there was huge potential a few days back.

[Met4Cast]

00z corrects that low Southwards

Excellent!

[Matty M]

GFS looked better initially with heights but in reality Atlantic further east compared to q8z at T18z.

[The watcher]

GFS looked better initially with heights but in reality Atlantic further east compared to q8z at T18z.

The output has been terrible in terms of Ireland for cold and snow this season and continues to do so. We just don't do well very often on an Easterly. Battle sets itself up in the Irish Sea around days 4/5 on this run.