Model Output Discussion - 23rd Jan - 12z onwards

[snowangel32]

Could someone please highlight that shortwave at the crucial time period i just cant see wich one it is lol.

[nick sussex]

Come on nick - you can sacrifice a biscay low for a part of the uk to get a proper dumping! (As long as it 'blows up' closer to Spain than the uk!)

as nick L has said, that ECM run delivers a proper fall to the sw quadrant (inc wales)

Lol!  as you know I come out in hives if I even see any low pressure in that area. Down here even a squirrel jumping about on a power cable is enough to turn the lights off!

 

As an aside we have those lovely red squirrels down here, no sign of those American grey ones , I've even seen a black squirrel here. Anyway enough of WinterWatch! lol You won't believe the looks I got when I asked in the garden centre if they had some specialized squirrel food, in France if you can't eat it then its not worth bothering about,one of  the funniest things I've  seen was one of those re-location programmes, the people were rearing Alpacas and the French villagers wanted to know what the meat tasted like!

 

If its going to deepen then a track into northern France gives you snow and keeps the strongest winds further north away from me, the ECM looks interesting with that shallow feature.

 

I love shallow features!

Edited January 28, 2015 by nick sussex

[East_England_Stormchaser91]

Well, this is it! What we've all been waiting for.

That potential Channel low is the one catching my eye in the medium term getting closer. If that blows up over biscay, then it really could be a significant event for the south with driving blizzards. We'll see how it pans out as it gets closer to the more reliable timeframes.

Also the end of ECM shows real potential for a reload from the north with a displaced Atlantic ridge heading up towards Greenland. The lack of blues and purples W of Greenland look encouraging too.

Meanwhile, hope everyone in Northern and western areas enjoy the first snows of today and tonight

[Dr. Astro]

Great charts this morning, big upgrades for early next week too, the -10C 850's reaching down the Western side of the UK and into South Wales, a lot of places could see snow from this:

 

 

 

Brrrr:

 

 

A very cold run overall from the GFS, all the way out into deep FI.

 

[starstream]

Someone asked yesterday for paint jobs,as someone who isn't skilled in any way at reading the models,and relies on clear interpretation from the main posters in here...... Can we have some more piccasos please?

It really does make things so much clearer for a visual learner like me.

I do know it's time consuming.

Thanks in advance guys.

[carinthian]

Guten Morgan all, wonderful winter charts this morning for much of Europe, especially The British Isles. Also , a bonus of a cold spell extension now likely. GFS have put back the Atlantic flow again and more likely now to come on board with ECM and UKMO with its later runs.

C

[West is Best]

 

Good morning all,

 

I've spent a few days watching the medium term patterns, in other words from the critical point of 3rd Feb onwards. The 2-3 day colder spell Thurs-Sat is fairly nailed on, although there remain issues about the uppers, it's what comes after that has been of interest to me. The GFS op has consistently been progging a northerly reload, but it is also consistently lacking in support. At times the scatter has been tighter, but in the last two runs the op has been very much on the colder side: the 18z was an outlier altogether.

 

My point here is that once the arctic sourced westerly, then eventually northerly sets in, beyond that (Sunday onwards) remains unclear and far from certain. We watch with all due caution. The operational has been below the ensemble mean in every single run for the past 48 hours. So I would temper understandable medium term enthusiasm and make the most of the next 2-3 days. Beyond that still looks precarious from these ensembles and the toppler scenario is likely to emerge at some stage in an operational if this much scatter persists for much longer:

 

 

 

 

 

 

 

 

 

 

In the meantime this colder blast should be fairly interesting.

 

Returning to this point, looking at the panel maps for the individual runs shows really remarkable variation in options for next week. There's everything from the scenario people are fixing on here through toppler high and zonal: and we're only talking 7 days away. My advice is to make the most of the cold snap between now and Sunday, enjoy it for what it is, and stay slightly cool about next week. It's not unusual to have some scatter, but this is quite considerable and as I mentioned the op has been below the mean every run for the past 48 hrs. So next week's embedded cold is far from nailed on if these ensemble scatters are an indicator (which I think they are). Panels for 7 days time:

 

https://forum.netweather.tv/gallery/image/20793-/

https://forum.netweather.tv/gallery/image/20794-/

https://forum.netweather.tv/gallery/image/20795-/

https://forum.netweather.tv/gallery/image/20796-/

https://forum.netweather.tv/gallery/image/20797-/

https://forum.netweather.tv/gallery/image/20798-/

https://forum.netweather.tv/gallery/image/20799-/

https://forum.netweather.tv/gallery/image/20800-/

Edited January 28, 2015 by West is Best

[ITSY]

A rare IMBY post from me coming up. Great looking short-medium term charts for the nation as a whole, with a lot more optimism in the long run too, this morning. Lots of opportunities coming up of this mornings big 3 operationals are to be believed. Biggest concern for me is the lack of said opportunities for the eastern side of the country - still time for that to change though. Eyes should really be peeled to the faxes who will show in more depth the small features expected by The MO. The control seems pick of the long term bunch this morning - ECM the pick of the short-medium term if you live out West.

Edit: also agree with above post on not taking the long term candy as gospel. Don't be lead astray into thinking it is nailed only to reach for the pills if it vanishes - it is still an option but only that at this point! Fingers crossed and all that

Edited January 28, 2015 by ITSY

[TEITS]

I shall have to disagree with you Richard (WIB).

 

Firstly you refer to this cold spell being Thurs-Sun when the evidence strongly suggests until at least next wednesday. The scatter you refer to in the ensembles does not really being until the 4th Feb.

 

http://max.nwstatic.co.uk/ensimages/ens.20150128/00/t850Cambridgeshire.png

 

I agree the GFS OP has consistently been much colder than the mean but as we all know when this happens and is supported by the control we take more notice. Now along with the UKMO/ECM the evidence suggests we take more notice of the operationals than the ensembles.

 

Personally I feel the outlook for next week continues to be cold but the uncertainity for me is whether the cold N,ly will veer towards an E/NE,ly.

Edited January 28, 2015 by TEITS

[Jason M]

Yes the GEFS are not great tbh. That said, they are really struggling at the moment and have been for a couple of days. It's one of those situations where you generally go with the opp runs as we have good inter run and cross model agreement.

Depth of cold and duration have steadily increased. The GEFS struggling is just a sign that it's no ordinary toppler (if it even does topple).

It makes sense that the flow eventually takes on a NE component. This will be good as it adds interest in the SE which is the least favoured area in the initial stages.

Edited January 28, 2015 by Jason M

[carinthian]

Well, this is it! What we've all been waiting for.

That potential Channel low is the one catching my eye in the medium term getting closer. If that blows up over biscay, then it really could be a significant event for the south with driving blizzards. We'll see how it pans out as it gets closer to the more reliable timeframes.

Also the end of ECM shows real potential for a reload from the north with a displaced Atlantic ridge heading up towards Greenland. The lack of blues and purples W of Greenland look encouraging too.

Meanwhile, hope everyone in Northern and western areas enjoy the first snows of today and tonight

Yes, the snow chase starts today. As soon as the cold flow become entrenched ,The Met 25Km Model ( snow prediction computer ), similar to what we use here in the Alps for snow prediction with-in a specified area, provides significant detail for the forecaster, however, it is important for local knowledge input be be added. Daily fax updates should now show areas/ regions of potential snowfall over the come days. There is always a surprise element, so accurate prediction will never occur. Finally, check the precipitation radar on here and have fun chasing and wishing snow in your direction and remember the surprise can be an added bonus. Enjoy the cold and snow, you lot really deserve it !

C

Edited January 28, 2015 by carinthian

[West is Best]

I shall have to disagree with you Richard (WIB).

 

Firstly you refer to this cold spell being Thurs-Sun when the evidence strongly suggests until at least next wednesday. The scatter you refer to in the ensembles does not really being until the 4th Feb.

 

http://max.nwstatic.co.uk/ensimages/ens.20150128/00/t850Cambridgeshire.png

 

I agree the GFS OP has consistently been much colder than the mean but as we all know when this happens and is supported by the control we take more notice. Now along with the UKMO/ECM the evidence suggests we take more notice of the operationals than the ensembles.

 

Personally I feel the outlook for next week continues to be cold but the uncertainity for me is whether the cold N,ly will veer towards an E/NE,ly.

 

Splitting hairs Dave, but it isn't a northerly until Friday/Saturday (it's westerly veering nor'west) and even then most of it is to our west with much of the UK under less cold uppers. Nevertheless, the overall source is arctic so we can probably let that pass http://www.weathercharts.org/ukmomslp.htm. Some of southern Britain should see some sleet and snow showers from tonight.

 

We shall see re next week. I remain of the opinion that the jet is still belching out of the US, albeit slightly more amplified for a time, but it lacks bifurcation and that spells the way back to zonal to me. With that much ensemble scatter I would encourage folk to focus on the period 0-T96. Anything beyond that is uncertain.

Edited January 28, 2015 by West is Best

[Jason M]

Hi West

Maybe.

48 hours ago I'd have put the odds on you being right at 75% (25% difference being the fact that we kept seeing those outliers that i and others were posting).

I'd say the chances of a quick return to zonal are now no better than 50 50.

 

Edited January 28, 2015 by Paul

[southbank]

Some better charts this morning from a coldies point of view , but I'm with WIB , until we see the MO\IF latest thinking then view the NWP outputs with caution

Also a concern we have had some solar energy this week ( minor Storm and 2 m flares) which had been typical all winter , the moment we have had promising charts at D5 + the sun throws energy our way

[Captain Shortwave]

Looking at the ECM ens, it still seems to be around Wednesday when we start to lose the convective potential from the northerly as high pressure builds eastwards.

That said even the Thursday chart might still see some showers in the south east. But splitting hairs there. 

 

Again the potential on Monday keeps cropping up in one form or another.

Clearly shown on the ECM mean

The track of this has great uncertainty and I'm sure there will be differing opinions on how people would want this to pan out.

 

How do we push on from the middle of next week? Perhaps signs of an easterly trying to establish. ECM anomaly is pretty similar to the GFS surface set up around day 9/10

More runs needed on this.

From a personal viewpoint, I thought the ECM op was very wild in its output this morning. Seems to be a lot of mixed signals at the moment. Something is telling me though that the low heights to our north west in week 2 are being overplayed somewhat and a more meridional pattern may be the way forward.

Edited January 28, 2015 by Captain shortwave

[shaky]

Yes, the snow chase starts today. As soon as the cold flow become entrenched ,The Met 25Km Model ( snow prediction computer ), similar to what we use here in the Alps for snow prediction with-in a specified area, provides significant detail for the forecaster, however, it is important for local knowledge input be be added. Daily fax updates should now show areas/ regions of potential snowfall over the come days. There is always a surprise element, so accurate prediction will never occur. Finally, check the precipitation radar on here and have fun chasing and wishing snow in your direction and remember the surprise can be an added bonus. Enjoy the cold and snow, you lot really deserve it !C

gota give it to you carinthian!! You mentioned a couple of days ago that the model that you were looking at is showing the cold to last a lot longer and now the other model outputs are following suite!!

[BLAST FROM THE PAST]

Guten Morgan all, wonderful winter charts this morning for much of Europe, especially The British Isles. Also , a bonus of a cold spell extension now likely. GFS have put back the Atlantic flow again and more likely now to come on board with ECM and UKMO with its later runs.

C

Hi Carinth

Of note has also been your background drum beating of such an outcome, thanks too for sharing the longer forecast thoughts of the weather professionals in Austria...been very interesting seeing their views

 

BFTP

[MR EXTREMES]

Splitting hairs Dave, but it isn't a northerly until Friday/Saturday (it's westerly veering nor'west) and even then most of it is to our west with much of the UK under less cold uppers. Nevertheless, the overall source is arctic so we can probably let that pass http://www.weathercharts.org/ukmomslp.htm. Some of southern Britain should see some sleet and snow showers from tonight.

 

We shall see re next week. I remain of the opinion that the jet is still belching out of the US, albeit slightly more amplified for a time, but it lacks bifurcation and that spells the way back to zonal to me. With that much ensemble scatter I would encourage folk to focus on the period 0-T96. Anything beyond that is uncertain.

i think theres really no better way of putting this other than the breakdown if you can call it that only shows from the 4th feb by this time we would have very cold surface air across the entire country.

when the high topples over the uk there for very cold nights bright crisp days with the eastern side hold onto the cold and wintry weather longest.

 

but even then hints of another rerun of whats coming over the next 5 6 days so perhaps settled cold then west northwest flow then heights building again up towards greenland maybe again not making it but with the same effect as were getting now.

 

the most certain thing i can see from the models is that theres no mild sw flow on any of the models.

 

but the ukmo and gfs vs the gem gefs and ecm and jma but all the latter models progress the alantic heights topple quicker than the rest but all have very cold surface air.

 

as the gfs and ukmo have a northerly still in place and fair slack flow with enriched deep cold with hints of a north east to east flow mostly on the gfs.

i dont think the background feedbacks have done the complete job,

 

and in anycase once cold is set in then its a bugger to remove and to be honest its only warmed up here in the south over the last few days so that was a longer spell than orinally projected by the models.

 

i posted the charts earlier today but didnt get to see the ecm until later but even the mild sectors shown through the ecm run are subject to changes.

but the overall setup is the best in years and now casting will be a certainty.

[carinthian]

Hi Carinth

Of note has also been your background drum beating of such an outcome, thanks too for sharing the longer forecast thoughts of the weather professionals in Austria...been very interesting seeing their views

 

BFTP

Hi Blast, thanks. The professionals here are really on the ball regarding snow forecasting as its a important part of life over here, especially in regards to mountain weather The portal service provides us with a wealth of charts including model variations and includes a chat with a forecaster to exchange thoughts and views. Sometimes they can go on for nearly an hour, such is the insight and enlightenment. Hope you get to see some snow in your parts.

C

Edited January 28, 2015 by carinthian

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS

THE CURRENT GENERAL SITUATION Cold fronts will clear SE out of the UK later today leading into a very cold and strong WNW flow with wintry showers tonight and tomorrow..

MODELS-2 WEEK HEADLINE Becoming colder with snow showers or snow at times before becoming less cold and changeable again beyond next week.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a week long spell with a deep trough over NW Europe keeping the flow well South of the UK in NW winds. In week 2 the pattern flattens markedly over the Atlantic and Europe with the flow then moving in a more traditional and flatter West to East motion over or close to Southern England between High pressure re-established to the South of the UK and Low to the North.

GFS OPERATIONAL The GFS operational today continues to show an extension of the cold theme under Northerly winds throughout much of next week now with various disturbances running SE in the flow to enhance the coastal snow showers into the threat of more organized and widespread spells of sleet and snow at times. Later in the run the cold Northerly or NE feed by then is dislodged in preference to milder or even mild SW winds with rain at times more notably towards the North and West as a ridge collapses away from the UK.

THE GFS CONTROL  The GFS control run is broadly similar in many respects to the operational in the short to mid term but it shows support for cold weather to last for much of the run as High pressure ridging over the UK in 10 days eventually sets up a Scandinavian High pressure with a cold South-East feed developing especially across the South with the threat of snow as pressure falls to the SW.

THE GFS CLUSTERS The GFS Clusters are not much interested in any control developing from High pressure to the East with a 75% to 25% majority in favour of Atlantic Westerlies overpowering our cold North feed by the end of the forecast period.

UKMO UKMO this morning continues to show the UK in a very cold Northerly flow well into the middle of next week and probably longer with unstable air and disturbances running down from the NW next week enhancing the risk of more widespread snowfall for all in the otherwise snow showery type theme with a lot of inland dry if very cold and sunny weather with all areas at risk of sharp night frosts.

THE FAX CHARTS The Fax Charts show an array of fronts crossing South and SE in cold and unstable air for most of the period out to 120hrs. A wintry mix of rain, sleet and snow showers or longer spells of snow for a few is possible from such an unstable airflow.

GEM GEM today also takes until the end of next week to displace the cold feed and in the period leading up to the flattening pattern from the West shows plenty of frontal activity in the cold Northerly airflow to offer many areas at least the risk of snowfall between now and then.

NAVGEM NAVGEM today keeps the cold going over the UK right out to the end of the run with High pressure gradually replacing the cold and unstable Northerly flow across the UK at the end of next week with widespread frosts.

ECM ECM this morning maintains cold weather to right out to the end of it's run today with as per NAVGEM High pressure ridging across the UK by Day 10 to take us out of the cold and unstable Northerly feed with quiet and cold fine and frosty weather by the end of next week. Synoptics shown at Day 10 looks ripe for a repeat of another cold plunge South next weekend.

ECM 10 DAY MEAN The 10 Day Mean this morning has slanted back towards a somewhat colder theme today with the Jet flow positioned further South a still some troughing across Europe. This chart is no doubt made up of colder options mixed with some Atlantic Westerly type scenarios and is not particularly a good guide within this current stand off.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for much colder and windy weather later next week and through next weekend. The longevity of the spell has reverted back to a rather longer period as complications running down from the NW within the cold air extends the cold somewhat.

MY THOUGHTS  Well here we are at the point of entry into the cold spell which has been well handled by all the models in the run up to it with little variation in how we got here. It looks from this morning's output that apart from a slightly less cold interlude on Friday when precipitation could be of rain for low lying Britain that snow will be much more likely at times but it's all a question of where. More about that in a moment. The main talking point for folks as it always has been will be how cold it feels with a strong and locally gale wind feeding across the UK first from the WNW and then the North. The marked windchill that this gives will be of the like not felt so far this Winter. In compensation though there should be some good sunny spells and this should offset the chill to some degree but not much. then we come to the question of snow. This is the hardest nut to crack because as well as dealing with the notoriously variability of showers snow showers are even more unpredictable. The general line of thought is that all Northern, Western and Eastern coasts and hills will fair well with inland areas less likely to see many and for these areas we rely on minor troughs and features running South within the flow to see much in the way of snow here. The fax charts show that there will be some and a more noteworthy risk develops early next week as a small low tracks SSE from Iceland over western Britain. This then leads on to the expected longevity of the spell which has been extended by most output to take us out to the end of next week, mostly due to the Icelandic feature just mentioned early next week. Then at the extreme end of reality it still looks like a relaxation of cold either in the form of High pressure or Atlantic westerlies look likely but even then there is some suggestion of an European high of sorts to keep 'coldies' interested. So all in all a lot to keep an eye on over the coming days or weeks but remember the cold spell is almost here so don't miss it by keeping your heads into your computers all day looking for polar Lows and the likes when the cold spell will be unfolding right before your very eyes outside of your own windows.

Issued at 08:00 Wednesday January 28th 2015

[seaside 60]

Returning to this point, looking at the panel maps for the individual runs shows really remarkable variation in options for next week. There's everything from the scenario people are fixing on here through toppler high and zonal: and we're only talking 7 days away. My advice is to make the most of the cold snap between now and Sunday, enjoy it for what it is, and stay slightly cool about next week. It's not unusual to have some scatter, but this is quite considerable and as I mentioned the op has been below the mean every run for the past 48 hrs. So next week's embedded cold is far from nailed on if these ensemble scatters are an indicator (which I think they are). Panels for 7 days time:

 

What cold snap, the proper cold spell doesn't start till sunday here.

Top temps of 5/6c is average, I cant see any snow here till sunday, maybe some wet snow, as far as I can see its only a NW wind down here.

A bit IMBY however up north it should be good, but looking at any models down here, average temps tilll then.

[seaside 60]

Hi Blast, thanks. The professionals here are really on the ball regarding snow forecasting as its a important part of life over here, especially in regards to mountain weather The portal service provides us with a wealth of charts including model variations and includes a chat with a forecaster to exchange thoughts and views. Sometimes they can go on for nearly an hour, such is the insight and enlightenment. Hope you get to see some snow in your parts.

C

Wouldn't it be good to have a much more detailed service in this country.

Professionals taking time to discuss what the various models show, with longer details.

They get so little time to chat outside the couple of mins they are allowed.

[Eugene]

Fantastic GFS 00Z upto T+240 hrs, laughable how once we enter low res it completely goes pear shape, that run would definately lead to continental blocking, i think we are looking at a two week cold spell maybe longer.

Edited January 28, 2015 by Eugene

[weather eater]

I can't see a quick return to zonal, a MLB over the UK seems far more likely if the high topples  than zonality at the moment. A lot depends on how the models are dealing with the lobe of the PV to our NW, we need it to stay west, if it does so or the longer it does so, then that makes a quick return to outright zonality pretty impossible. If we use the operationals over the last couple of days as an ensemble then the cold looks a good bet until this time next week at least. Thereafter is in the lap of the weather gods because there's an awful lot of synoptic evolving to get through before then and I expect the models to throw out some interesting possibilities over the next few days.

[Nick F]

The ECM low on Monday night brings a lot of precip into Wales, western England, West Midlands and parts of the southwest, with decent cold air too. That would make a good snow event and finally bring something widespread for central and southern areas!

 

Yes, the ECM brings a few disturbances south in the arctic northerly flow that sets in over the weekend and lasts into next week. Though we wont know yet to whether any of these disturbances will verify, such is the difficulty of modelling these features 5-6 days off.

 

Anyway, a northerly, without fronts/troughs/disturbances in the flow will generally create a 'wishbone' effect whereby inland areas stay dry. sunny and cold while northern Scotland, eastern and western coasts see the showers. Trains of showers can set up in certain areas too, such as the 'Pembrokeshire Dangler' which can bring continuous showers to SW Wales and far southwest England, bringing large accumulations if it falls as snow.

 

But, there is potential with the northerly for secondary features to run south in the flow from the weekend, late Sat and early Sun, EC shows a low dropping south down the east coast which may accentuate shower activity:

 

 

Then on Monday, we see a low drop down from Iceland area, bringing a threat of more organised sleet and snow to western Scotland, EIRE/N Ireland. NW England coastal areas, Wales and SW England:

 

 

maybe a little too marginal across the SW though:

 

However, GFS and UKMO a lot further west with this low.

 

Before then, looks like Scotland, N England and N Ireland sees the lion's share of the snowfall, a lot more hit and miss further south, Wales and SW England fairing better exposed to the westerly veering northwesterly wind.

 

Worth keeping an eye on that low moving south down that North Sea early Saturday which triggers the northerly, though again, airmass is marginal then before the colder northerly sets in later in the weekend

 

 

Plenty to look forward too for those south of the favoured north and northwestern areas, but you'll have to wait until the northerly sets in for this better snow potential.

Edited January 28, 2015 by Nick F