Model Output Discussion 1200 hrs 15/11/14

[knocker]

Weatherbell's licence with ECM precludes re-distribution except for WMO-Essential. They haven't complained according to Ryan Maue when I asked for clarification on the issue.

Edited November 27, 2014 by knocker

[Ali1977]

FI has no raging PV. no cold in the next few weeks but much to play for mid dec onwards.

[bluearmy]

Weatherbell's licence with ECM precludes re-distribution except for WMO-Essential. They haven't complained according to Ryan Maue when I asked for clarification on the issue.

Interesting knocker - I just assumed that their notice re posting must have had a catalyst ? Maybe they didn't complain but reminded their license holders in general about reproduction of restricted output. that's more subtle!

[knocker]

Interesting knocker - I just assumed that their notice re posting must have had a catalyst ? Maybe they didn't complain but reminded their license holders in general about reproduction of restricted output. that's more subtle!

 

I think it did. I don't remember the details but some wag in the States produced some of the charts on his web page and made some erronius forecast that caused a certain amount of mayhem. There was more to it than that but those are the bear bones. RM was not amused but he seems a very easy going and helpful guy whenever I have emailed him. I did ask him why not the METO global. Answer quite simple. Cost.

[Barry12]

FI has no raging PV. no cold in the next few weeks but much to play for mid dec onwards.

Highs of just 4C possible on Tuesday widely, which is cold. Could also be snow for Scotland.

[Frosty.]

Very pleasing to see a dig of cold pm air early next week before pressure rises sharply, The first and long overdue cold incursion of the season with hopefully much more to follow it. A seasonal early winter is on the way...hooray

[East_England_Stormchaser91]

One thing that is very good to see, is the imminent looking cold that looks to set in stone over Europe in the coming week or so. 

In the next few days, we could see massive changes/swings in the models in handling the high pressure close by to the UK. One slight shift Northward could place us in a cold frigid Easterly flow, 500 miles further South, then it could be nothing! 

Things can change ever so quickly though. 

One minute you can have as mild as this :

 

 

 

 

 

To this:

 

 

 

All in the space of a week! Which then went on to bring the most snowiest winter on record! 

 

 

Edited November 28, 2014 by East_England_Stormchaser91

[EmmaF]

Looks like Shannon is still with us, quite big changes at day 6 on the 18z

 

 

Much better for coldies!

I'm sorry what is a "Shannon" ?

[Mucka]

Morning all.

 

GFS at least firming up on a double dip with cold PM air albeit they are fairly brief affairs.

 

 

That would at least provide something worthwhile for high ground in the North and give a seasonal feel to the weather with more settled weather and night frosts possible in between.

 

 

No doubt the GEM run will be the real eye opener though with a prominent Atlantic ridge forming up with the Arctic high which has come from nowhere really and seems unlikely but the possibility of such changes does exist while an Arctic high is in the mix as the models have difficulty with them. Also though the upstream pattern being so amplified has also not been modeled before so we will have to see if any of the other models hint at such an outcome or if it appears in the ensembles.

 

 

EDIT

 

Just had a browse through GFS ensembles and the vast majority have the Azores high ridging in over the UK though one or two do go with Atlantic ridge but not to the same extent as GEM. The only one that resembles it with similar amplification upstream was p1.

 

Edited November 28, 2014 by Mucka

[Captain Shortwave]

Day 6 charts

UKMO

GEM

GFS

Parallel

The UKMO and certainly the GEM try to attract that Arctic high towards Greenland with a potential extended ridge allowing colder air to try and shift south west from the pole. The GFS and parallel are not interested in this. The key seems to be how amplified the upstream ridge is.

The GFS ensembles tend to favour the high staying towards Siberia with an associated ridge, this isn't ideal for us as the polar vortex just spins around to the north/north west of us with pressure remaining fairly high, especially so in the south. Lets see what the ECM can chuck out.

[Ali1977]

I think this forum may wake up much happier this morning, GEM and now ECM pushing WAA up towards Greenland meeting with the Arctic high. ECM showing straight Northerlies by day 8.

[winterof79]

Day 6 charts

UKMO

GEM

GFS

Parallel

The UKMO and certainly the GEM try to attract that Arctic high towards Greenland with a potential extended ridge allowing colder air to try and shift south west from the pole. The GFS and parallel are not interested in this. The key seems to be how amplified the upstream ridge is.

The GFS ensembles tend to favour the high staying towards Siberia with an associated ridge, this isn't ideal for us as the polar vortex just spins around to the north/north west of us with pressure remaining fairly high, especially so in the south. Lets see what the ECM can chuck out.

Welcome back winter

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014112800/ECH0-192.GIF?28-12

http://www.meteociel.fr/modeles/ecmwf/runs/2014112800/ECH1-192.GIF?28-12

 

We have sorely missed you.

[Captain Shortwave]

ECM shifts the Arctic high in a similar manner to the GFS (drains it towards Siberia), but it does offer enough upstream amplification to deliver a brief northerly. Day 9 looks like a toppler but I suspect the next low will dive south east as the high retreats westwards.

Too early in my view but look for an evolution similar to this later in December.

Edited November 28, 2014 by Captain shortwave

[knocker]

A general comment on the ECM monthly update keeping in mind MH's previous comments.

 

T240 has the Atlantic HP dominating and extending upstream into N. America with a trough pole/Scandinavia/Europe. HP over the Pole and trough eastern Pacific and NE Canada. It should perhaps be noted the sub-tropical jet has put in an appearance in the eastern Pacific at the moment for the first time for four years.

 

The next week amplification of the HP N. America and the opposite for the Pole. Zonal Atlantic flow with a trough north of the UK and removal of same Scandinavia with an increase in heights north eastern Europe.

 

Thisis  basically the scenario for the last two weeks, remembering that detail is missing.

 

On the surface this translates to a lessening influence of the Atlantic HP, a zonal flow with depressions centred Greenland.Iceland area.

 

Temps hovering around the average and no sign of any cold incursion.

[knocker]

A quick look at the GEFS anomaly. Chart shows T144 and from then onwards a flattening of the Meridional flow, and removal of the NE European trough.leaving the N/S Atlantic split. Essentially this a continuation of tha Atlantic HP with depression nipping around it to the north on the jet.

Chart courtesy weatherbell

 

Edited November 28, 2014 by knocker

[Essex winter]

Hi all, newbie here.Have no idea on reading weather charts but hope to gain some knowledge from your excellent informative posts on here.thanks in advance.E.W.

[nick sussex]

The ECM shows an improved picture upstream with just enough amplification to make things a bit more interesting, however the GFS and GFS P are flat and even flatter with troughing over the ne  USA .

 

It's quite a hard slog really to get from T168 to T192hrs on the ECM, however at face value it could get even a bit more interesting if we could squeeze just a little bit more amplification at that timeframe but theres always that nagging doubt with the ECM and this more amplified scenario .

 

At T144hrs it does have some upstream support from the UKMO  but the key really is what happens between T168hrs and T192hrs.

 

More amplified the ridge topples even more favourably, flatter the energies phase to the north so its very much on a knife edge.

 

PS just seen the GEM which even me the optimist can't see happening! Of course I'd love to be  wrong but I have little faith in the GEM operational output.

Edited November 28, 2014 by nick sussex

[EML Network]

I tend to look at the ensembles to get some sort of consistency at this time of year, I've noticed that after a slow decrease in the 850 Uppers, they are starting to trend back upwards again. 

 

Below is the ensembles for Derbyshire, which is about as close as you're gonna get to ''Middle Britain'' , why people are forever posting the London ensembles and thinking it's indicative of the rest of the UK i'll never know. 

 

So after a short time of a few days of below average temperatures, presumably as transient north westerly's fall on the leading edge of any incoming High pressure cells.

 

Worth looking to see where the Jet stream is too, and not surprisingly it's well North of the UK from early next week onward and tends to stay that way throughout the run, going over the High pressure(s). 

 

So more seasonable next week for sure and finally some respite from the rain...that will do me for now. 

[ItNeverSnowsInWindsor]

A fairly typical setup showing on most models with low pressure crossing well to the North of UK leaving us in a Westerly flow with brief colder incursions. The only glimmer of hope being offered is on the GEM model at T192. The ECM brings a brief Northerly but this relies on sufficient amplification upstream which needs to be shown on other models too in the next few runs.

Edited November 28, 2014 by prolongedSnowLover

[BLAST FROM THE PAST]

 

Spot on!  Just as an aside, this is kind f what I envisioned ......and believe may still happen 

 

BFTP

[knocker]

But of course if you move on a tad you get this. Odd little fella mid Atlantic.

Chart courtesy weatherbell

Edited November 28, 2014 by knocker

[johnholmes]

Hi all, newbie here.Have no idea on reading weather charts but hope to gain some knowledge from your excellent informative posts on here.thanks in advance.E.W.

welcome and don't be afraid to ask questions, also have a look at the Net Wx Guides area, lots of information in there

[Ali1977]

Still no indication from the METO of any potential Northerly blasts so I'd be surprised if the next run of ECM or GEM show this. I wonder if the early snow cover and strat warming may be starting to effect the Northern hem though, rapid changes in charts/medium term forecasts can happen at this time of year.

[Paul_1978]

I'm sorry what is a "Shannon" ?

Shannon Entropy - it's basically a measure of confidence.

High Shannon Entropy values = low confidence.

There's a really complicated Wikipedia article about it but that's the gist of it.

Anyone please feel free to correct me if I'm wrong!

[Gibby]

HERE IS WHERE I  GIVE MY TWICE A DAY ANALYSIS OF THE OUTPUT FROM  5 OF THE MOST POWERFUL WEATHER COMPUTERS IN THE WORLD AND GIVE AN INSIGHT AS WHAT WEATHER MAY BE UP AND COMING ACCORDING TO THESE SUPERCOMPUTERS.

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY FRIDAY NOVEMBER 28TH 2014.

NEXT UPDATE SUNDAY NOVEMBER 30TH 08:00

THE CURRENT GENERAL SITUATION A weakening Easterly or SE flow across the UK will back ENE tomorrow and decrease.

MODELS-2 WEEK HEADLINE Becoming mostly dry with just a little rain chiefly in the North at times. Some frost and fog patches in variable temperatures.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast shows the flow undulating North and South across the UK over the next week on the Northern flank of High pressure to the SW. In Week 2 a flat West to East flow over Scotland will persist with little change through that period between High pressure to the South and Low to the North of Scotland.

GFS OPERATIONAL The GFS operational this morning shows that High pressure firstly to the SW and later to the South of the UK ensures the UK lies in a broad and eventually quite mild Westerly flow with little significant weather features affecting the UK. Some rain from fronts to the NW will undoubtedly affect the North and West at times but the South will see a lot of dry and potentially mild if rather cloudy weather with very minimal amounts of frost and fog.

THE GFS PARALLEL RUN The GFS Parallel run is broadly similar in structure as it moves through the period with the caveat that High pressure slips further away to the South later in the run with more influence of cloud and rain off the Atlantic and the hint of a pattern change from the North right out at the extremities of the run.

THE GFS CONTROL The GFS control run mirrors the operational well this morning with mild Westerly winds affecting all of the UK with the North seeing some rain at times while the South stays fairly dry and benign day and night.

THE GEFS ENSEMBLES The GEFS Ensembles show that the most likely scenario over the next few weeks is covered well by the operational, control and parallel runs in that there is strong agreement from most of the members that mild Westerly winds on a flat West to East pattern will become dominant through the period covered with limited amounts of fog and frost.

UKMO UKMO today shows a belt of High pressure stretching from the Azores to SW England by next Thursday with most of the UK dry and bright with patchy frost and fog but temperatures close to average outside of where any fog lingers. The NW will be rather cloudier and breezier but milder than elsewhere.

THE FAX CHARTS The Fax Charts show a weak cold front clearing SE through the middle of next week as pressure then builds from the SW. A lot of cloud at times will clear midweek to a chillier period with frost and fog patches in the South in light winds.

GEM  GEM is the shining beacon for cold lovers this morning as it replaces quiet and benign High pressure based weather through much of next week with a plunge of cold Arctic air and Low pressure next weekend with spells of rain and showers falling as sleet and snow to quite modest levels anywhere in the UK under cold and fresh NNE winds.

NAVGEM NAVGEM shows High to the SW and Low to the NE by next weekend with a chilly and fresh NW flow with colder weather with a few wintry showers across the North and East for a time soon to be replaced by a cold and frosty ridge moving in from the West next weekend.

ECM  ECM this morning is not without interest for cold fans as the High pressure remains a little further out in the Atlantic and with lower pressure towards Scandinavia the tendency for cold fronts to cross South over Britain later next week is high with wintry showers flooding South briefly later next week before milder air topples over the top of a ridge crossing SE over the weekend.

THE ECM ENSEMBLES High pressure towards the SW of the UK remains the powerhouse within the 10 Day ensemble chart with Westerly and relatively mild weather engulfing the UK with limited rainfall for the NW and even more limited amounts of frost and fog across the South.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The theme remains for the UK to lie under the influence of High pressure most likely positioned just to the SW of the UK over the period with a variety of long term solutions shown.

MY THOUGHTS The weather patterns shown by the models all hinge around the positioning of High pressure close to the South or SW of the UK and the resultant weather brought about by that positioning. The one certainty is that nowhere is going to see much in the way of rain over the next two weeks with the main thrust of Atlantic depressions held well away to the North. GFS this morning has Black Friday fever and is a horror show on all sets of it's output this morning showing a very flat West to East Jet flow over Scotland and keeping High pressure over France with resultant mild and benign conditions for much of the UK. Conversely GEM is the bright light for cold fans illustrating a plunge into a wintry scenario with cold and wintry North winds and snow for some as Low pressure develops and plunges SE across the UK then NW Europe next weekend. ECM this morning has some interest in that field too as it brings a brief Northerly late next week with enough potency to deliver some wintry showers and some sharp night frost before the inevitable toppler ridge follows a few days after. What all this means is that the models are struggling to handle how and where High pressure is likely to sit later next week and small synoptic differences in positioning can have major impacts on surface conditions across the UK. From what I can see there are three options on the table. 1. The High takes a GFS storyline with benign and mild Westerly winds taking precedence with limited weather features of any kind. 2 The High centre sits over the South of the UK with more in the way of frost and fog as a result in the Southern half of the UK or 3 the High sits out further into the Atlantic with a trend for pressure to be lower over Scandinavia helping as a catalyst to aid cold Northerly winds to cross down over the UK albeit briefly before a toppler ridge follows. The Jury is out on which of these options will actually verify but I will say the GEM operational though mouthwatering for many is probably a little extreme but nice to see anyway. So despite a lot of disappointing and benign looking conditions borne out of a flat Westerly pattern is shown this morning there is some more interesting  output on offer and as I indicated a day or so ago I wouldn't mind placing a wager on our best chance of a first taste of winter will come from the North, something akin to ECM or GEM this morning given time.