Model Discussion - 16th January

[Stuie]

I think I have been blinkered here Nick and sorry for being naive but the runs from the eg: The ECMWF are world wide weather forecasts? Hence your NOAA posts?

[Tim Bland]

Hmm, I think the ECM has become demented judging by the 12Z! What HAVE we got? Arctic front activity? Sure looks like it.

Massive upper trough covering most of the N Atlantic and UK, and how about that intense HP over N Canada!

It seems a bit of stretch to say the least for such an amplified development to happen from T144 to T240 - a mere 4 days.. If such a pattern did, by some remote chance verify, the resulting actual weather would be interesting indeed - certainly cold enough for widespread snow - and such a trough would take some dislodging.

I await with great interest subsequent runs!

Do you rally believe the ECM would give widespread snow? Uppers look v marginal to me away from highest ground. I expect the ECM to be a mild outlier and think the GFS 12z will be closer to the mark. If I lived on low ground south of Leeds I wouldn't be holding my breath for snow (in the next 5 Days) other than a snow shower on Fri

[Gibby]

Hi there. I have stayed away from this thread both here and on TWO recently. Nothing personal but I don't enjoy the hype that many posters on both forums submit about pending snowmageddon etc at t180hrs+. I will return with my daily summaries when the winter snow posters hibernate for the summer probably about March. In the meantime just a brief look at the models as they currently stand. We have seen various output over the past week or so which has suggested wintry weather could arrive soon and apart from our current frosty high pressure we are still waiting. The main culprit which has prevented this is the Azores High which has been responsible for driving the UK's weather this entire season so far. On tonight's output it remains the dominant feature for some considerable time yet. There is a flirtation with cold and maybe a little snow for higher elevations in the North and East at the weekend before a warm sector replaces it with mild and damp conditions again. Further out the operationals look far from convincing from a cold perspective with the ensembles not reflecting anything much better than cold zonality in the majority of recent runs. The Atlantic remains very much alive over the next week or so though with the proximity of the Azores high to the SW this doesn't necessarily mean copious rainfall. Instead in summary tonight I would say that things remain unexciting weather wise with fluctuations in temperature just either side of normal over the output period and no severe weather likely anywhere.

[nick sussex]

I think I have been blinkered here Nick and sorry for being naive but the runs from the eg: The ECMWF are world wide weather forecasts? Hence your NOAA posts?

The reason I look at the NOAA discussions is that what happens in the USA and Canada has ramifications for the downstream pattern in Europe.

[OldMetMan]

Well we're doing again aren't we getting the prozac out because of one run. :blink:

From a personal viewpoint and from over 40 years of weather watching experience I believe that this weekends progged cold /cooler spell is the start of a gradual transition to a real piece of winter as we go through february and only part one of the transition at that. We should remember from GP'S forecast that mid january would be our first window of opportunity not our only window of opportunity.

In reality if the models were to serve up and and verify on a 2 week cold and snowy spell with a northerly outbreak becoming an easterly one just about every cold/snow lover would be happy. I would point people in the direction of the winter of 77/78 when naff all happened until the last week of Jan for Scotland and the second and third weeks in Feb for the rest of us. but when it came it was certainly worth having waited nearly all winter for it.

With the waning PV coming under continuing and further attack pretty much anything beyond 144 on any of the models is little more than speculation. Such volatile condtions are going to mean rapid changes in output as varing ideas are picked up because of this I think we will find that when our piece of winter arrives it will do so at relatively short notice.

Well said Mcweather! We must be of a similar vintage - I became interested in weather in 1967!

I too remember Feb 1978 - 12 hours of continuous snow even on the Isle of Wight where I lived at the time.

Yesterday, I suggested the possibility of an abrupt upper wave amplification. Today it looks more like a gradual transition as you say, but I also agree that the coldness itself could arrive quite suddenly - I have seen such events in the past - but having just been rude about the latest ECM, I can't envisage quite such a rapid change as THAT shows!

It's all fascinating stuff!

[Stuie]

I understand Nick, I was just curious when the NOAA mention models is it just continental runs or worldwide.

[ANYWEATHER]

Hi there. I have stayed away from this thread both here and on TWO recently. Nothing personal but I don't enjoy the hype that many posters on both forums submit about pending snowmageddon etc at t180hrs+. I will return with my daily summaries when the winter snow posters hibernate for the summer probably about March. In the meantime just a brief look at the models as they currently stand. We have seen various output over the past week or so which has suggested wintry weather could arrive soon and apart from our current frosty high pressure we are still waiting. The main culprit which has prevented this is the Azores High which has been responsible for driving the UK's weather this entire season so far. On tonight's output it remains the dominant feature for some considerable time yet. There is a flirtation with cold and maybe a little snow for higher elevations in the North and East at the weekend before a warm sector replaces it with mild and damp conditions again. Further out the operationals look far from convincing from a cold perspective with the ensembles not reflecting anything much better than cold zonality in the majority of recent runs. The Atlantic remains very much alive over the next week or so though with the proximity of the Azores high to the SW this doesn't necessarily mean copious rainfall. Instead in summary tonight I would say that things remain unexciting weather wise with fluctuations in temperature just either side of normal over the output period and no severe weather likely anywhere.

At Last .....A Realistic Post!! Seems that anyone new who comes on here, would be thinking we are in for some serious Winter Weather! Too many "Cherry Picking" and " HopeCasting". Im sure the Synoptics will eventually change and I may not score many points with this post, but the post above is "Realistic" and patience is required "to" and "if" we get any real Winter weather this year!

[nick sussex]

I understand Nick, I was just curious when the NOAA mention models is it just continental runs or worldwide.

They use the main global models ECM/GFS/UKMO/GEM.

But their discussions are primarily aimed at the CONUS, the 48 US States south of the Canadian border.

[egret]

Well said Mcweather! We must be of a similar vintage - I became interested in weather in 1967!

I too remember Feb 1978 - 12 hours of continuous snow even on the Isle of Wight where I lived at the time.

Yesterday, I suggested the possibility of an abrupt upper wave amplification. Today it looks more like a gradual transition as you say, but I also agree that the coldness itself could arrive quite suddenly - I have seen such events in the past - but having just been rude about the latest ECM, I can't envisage quite such a rapid change as THAT shows!

It's all fascinating stuff!

I agree entirely - remembering last year when there was an exceptional turnaround on about a three day timeframe. I shall be watching with interest how the models behave after Wednesdays weather moves through.

[OldMetMan]

Do you rally believe the ECM would give widespread snow? Uppers look v marginal to me away from highest ground. I expect the ECM to be a mild outlier and think the GFS 12z will be closer to the mark. If I lived on low ground south of Leeds I wouldn't be holding my breath for snow (in the next 5 Days) other than a snow shower on Fri

Hi Tim, I have seen such a pattern in the past, albeit rarely, produce snow, where there are LPs revolving with a broad and deep upper trough, but I really don't think such a pattern as the ECM shows will come about. I was just astonished at the ECM for coming up with such a solution!

[Isolated Frost]

I expect many people to be disappointed with the De Bilt ensembles, why?

Here's why:

Temperatures at De Bilt will be very similar to recent outputs, the source is the only difference... the continental cold was NOT that significant on previous runs and therefore a cold Pm airmass will deliver similar temps. Don't read too much into the ensembles.. the control and mean synoptic pattern is more important.

[snowray]

Model watching here with even more than the usual level of interest.

We have been staying in Nice, France for a few days but have to drive to Villars Sur Ollon nr Lake Geneva by the end of the week 1800m asl. We were planning to leave on Thursday morning to beat the snow and were looking forward to the weather there at the end of the week. However, we have been completely thrown by the pesky ECM run. It better be an extreme outliner!

Northern Alps will get more snow, no doubt about that, Southern Alps particularly Piedmont/Lombardy very little, Geneva region will get snow later this week at 1.800m . The snow has been coming across into Italy but only as far as Aosta in West/ South Tyrrol region in East, anywhere further South has been protected from Northerly incursions. But should we see the trough any further West LP would form around the Bay of Genoa dragging colder air Westwards so the Southern Alps might also get some decent snowfall . This Winter, due to the Influence of our Euro High most of the Southern European Perturbations have formed over the Adriatic and have been fast flowing features producing snowfall in Southern Italy, Greece and Turkey.

[OldMetMan]

You're the only one then!

I think most people are now suffering from model fatigue and just want a resolution to this so we can either throw our toys out of the pram or look forward to something a bit more interesting!

You'd think this modelling lark was rocket science given the inability of the models to just agree on an outcome at 144hrs!

The ECM is my favourite model but even thats getting on my nerves now! In terms of the ECM NOAA have gone with the earlier ECM ensemble mean/operational combo.

BASED ON THESE CONSIDERATIONS THE UPDATED PRELIM FCST WAS BASED ON

A SOLN CLOSE TO THE 00Z ECMWF ON DAYS 3-4 THU-FRI... WITH HALF

WEIGHTING OF THE 00Z ECMWF ENSEMBLE MEAN INCLUDED DAYS 5-7 SAT-MON

TO ACCOUNT FOR INCREASED DETAIL UNCERTAINTY BY THAT TIME. THE 12Z

GFS STILL DISPLAYS A PROGRESSIVE TENDENCY IN GENERAL WITH THE 12Z

GEFS MEAN HEDGING AT LEAST PARTIALLY AWAY FROM GFS IDEAS. OTHER

12Z SOLNS VARY TO SOME DEGREE BUT WITHOUT SUFFICIENT CONSENSUS TO

RECOMMEND MEANINGFUL CHANGES IN THE PRELIM FCST ASIDE FROM A

SLIGHTLY WEAKER TREND WITH THE SYSTEM CROSSING THE NORTHEAST EARLY

IN THE PERIOD.

However I'm not sure if they even included the ECM 12hrs in that discussion, they mentioned other 12hrs solutions but normally they single out the ECM.

Quite agree Nick, I am quite bewildered by the variety of model solutions.

Must be hard going for the "official" forecasters!

[weathe20]

Hmm, I think the ECM has become demented judging by the 12Z! What HAVE we got? Arctic front activity? Sure looks like it.

Massive upper trough covering most of the N Atlantic and UK, and how about that intense HP over N Canada!

It seems a bit of stretch to say the least for such an amplified development to happen from T144 to T240 - a mere 4 days.. If such a pattern did, by some remote chance verify, the resulting actual weather would be interesting indeed - certainly cold enough for widespread snow - and such a trough would take some dislodging.

I await with great interest subsequent runs!

Thank you for your posts OldMetMan. As soon as a model shows a downgrade the mood is 'thats it, all over' or 'downgrade downgrade'. What helps me and what is so good about your posts is that you actually EXPLAIN WHY you think a model could be wrong. This is something many posters cannot do.

[Great Plum]

Correct me if I've got this wrong but:

12z ensemble mean for GFS:

http://www.wetterzentrale.de/pics/Rz500m5.gif

12z ECM at 120 hrs...

http://www.wetterzentrale.de/pics/Recm1201.gif

Spot the (enormous!) differences??

[snowray]

Hi there. I have stayed away from this thread both here and on TWO recently. Nothing personal but I don't enjoy the hype that many posters on both forums submit about pending snowmageddon etc at t180hrs+. I will return with my daily summaries when the winter snow posters hibernate for the summer probably about March. In the meantime just a brief look at the models as they currently stand. We have seen various output over the past week or so which has suggested wintry weather could arrive soon and apart from our current frosty high pressure we are still waiting. The main culprit which has prevented this is the Azores High which has been responsible for driving the UK's weather this entire season so far. On tonight's output it remains the dominant feature for some considerable time yet. There is a flirtation with cold and maybe a little snow for higher elevations in the North and East at the weekend before a warm sector replaces it with mild and damp conditions again. Further out the operationals look far from convincing from a cold perspective with the ensembles not reflecting anything much better than cold zonality in the majority of recent runs. The Atlantic remains very much alive over the next week or so though with the proximity of the Azores high to the SW this doesn't necessarily mean copious rainfall. Instead in summary tonight I would say that things remain unexciting weather wise with fluctuations in temperature just either side of normal over the output period and no severe weather likely anywhere.

Thanks you for that post Gibby, sounds about right.

The cold prospects for the UK are always turning up at 5+ days out, but not getting any closer, seen this all before many times.

The strat warming event might bare fruit in the end though for us snow freeks around Mid feb.

[Isolated Frost]

A fantastic ECM 240 at 500mb. Copyright ECMWF.

[LomondSnowstorm]

Correct me if I've got this wrong but:

12z ensemble mean for GFS:

http://www.wetterzen...ics/Rz500m5.gif

12z ECM at 120 hrs...

http://www.wetterzen...cs/Recm1201.gif

Spot the (enormous!) differences??

You're absolutely right, massive differences, especially considering the differences between yesterday's http://cdn.nwstatic.co.uk/gfsimages/gfs.20120115/12/144/h500slp.png and today's http://cdn.nwstatic.co.uk/gfsimages/gfs.20120116/12/120/h500slp.png output for Saturday.

Even the UKMO has made not insignificant adjustments since yesterday http://www.meteociel.fr/ukmo/runs/2012011612/UW120-21.GIF?16-17

http://www.meteociel.fr/ukmo/runs/2012011512/UW144-21.GIF?16-17

[Grimsby Snow Lover]

A fantastic ECM 240 at 500mb. Copyright ECMWF.

Would you mind explaining why that chart is fantastic please IF, thanks GSL

[OldMetMan]

Thank you for your posts OldMetMan. As soon as a model shows a downgrade the mood is 'thats it, all over' or 'downgrade downgrade'. What helps me and what is so good about your posts is that you actually EXPLAIN WHY you think a model could be wrong. This is something many posters cannot do.

Thank you Weath20, I appreciate it. I expect some would argue that the reasons I give aren't exactly scientific at times. I am always willing to hear from those far more knowledgeable than me if I am talking nonsense!!

[Cloud 10]

If ever there was a run that i would want to see verify,then this would be it!

http://www.meteociel...rte=1&runpara=1

[nick sussex]

A big switch in the ECM ensemble maps from this morning, and even bigger from yesterday evening:

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

It's very strange the chopping and changing of the GEFS versus ECM ensembles.

For several days the GEFS was completely against any colder solutions with the ECM members more bullish, now the reverse has happened.

The ensembles seem just as volatile as the operational runs.

[bluearmy]

a poorish looking ecm ens run. the vortex lefts out into n canadian arctic bit then drops back into n greenland 10. (with wide spread so not desperate). what i did note on the 850's spread is a wave of cold spreading west from the urals day 6, through se europe and then swinging nw into scandinavia, germany, eastern france. we are too far west at this range but it wouldnt take a big change in the overall pattern (remember GP has kept on saying that things are backing west) for this to have our name on it aswell. it may be gone tomorrow but then again ...............

[Summer Sun]

A fantastic ECM 240 at 500mb. Copyright ECMWF.

Could you please explain why its fantastic? As an amature i'm struggling to work it out.

[Frank Trough]

Would you mind explaining why that chart is fantastic please IF, thanks GSL

i think because it's showing a massive high pressure shifting eastwards towards greenland, amongst other things. But, as usual for this winter, it is in FI. Another ECM tease.

i'll be interested to see how this all pans out at the end of the month in terms of model verification. The GFS has taken a lot of stick while the ECM has been lauded at times. However, there is still no sign of any country-wide "cold" in the reliable timeframe.

it's been a bit disappointing so far, but interesting to follow. In the end, the METO forecasts appear to have been the best guide to this point.