Model Output Discussion 1200 hrs 15/11/14

[knocker]

The GFS ops is quite interesting this morning. At t192 it has a deep low SW of Ireland which has ridden along on the strong jet that has turned SE to the west. The jet being just a reflection of the 250mb contour chart and in this respect the disposition of the upper highs and lows. It continues to travel SE into Europe which sets up an easterly regime over the UK as it also allow the Azores high to ridge from the SW. This diverts the main arm of the jet NE with a branch nipping south over the UK which is in the warmer air although this will turn cooler later. This essentially is the set up until the end of the run with the jet becoming weak and very meridional around the HP systems in the Atlantic and to the east.

Charts courtesy weatherbell.com

Edited November 20, 2014 by knocker

[IDO]

This flip flopping for the next undercut potential is a replay of the last event. The GEFS are doing there thing now where they start throwing in MLB and HLB from around D9-10: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

 

It looks like, again, the flow from the NW is being modified somewhat, enough for the Atlantic to be repelled within many members. So we get some sliding potential. The last effort was blocked due to the phazing of the low heights with the Azores/sceuro upper ridges, As the ECM, GFS and GEM D10 chart shows, at the moment both upper ridges are better placed for the disruption of the UK trough rather than another pulse of higher heights being pushed SW to NE like last time:

 

  

 

If that remains the status quo, unlike last time when the upper level low sunk south, any lower anomaly looks like going SE. 

 

So although only a subtle swing in output over the last few runs, and obvious caveats re uncertainty, there is a better background for lower heights to move into the MED area.

Edited November 20, 2014 by i'm dreaming of...

[BlueHedgehog074]

The models do show some interesting battles this morning: The 00z GFS, for example, seems keen to bring a bit of an Atlantic influence for the UK in the next few days as Atlantic Lows try to smash through further East. Being a bit of a wimp, the High Pressure to the East doesn't do much about this. The North-West, however, looking to see the most disturbed conditions for a time. The South probably likely to see much drier conditions being more at influence from High Pressure to the South or South-East. But all of a sudden, the Scandinavian High Pressure system starts getting really mad at the Atlantic Lows... so it comes back ready to pounce on the Atlantic. It's a success. The Atlantic Lows to the West surrender and drop to the South of the UK against the mighty block to the North-East. Right out to the end of the run, the Scandinavian High proves victorious.

The GFS 00Z Parellel exhibits similar traits to its brother, although the Atlantic Lows struggle to make as much of an impact for the UK, with only really North-Western areas seeing any affect of it. Again, the Low Pressure systems to the West start loosing the fight against the block to the East and so they drop to the South of the UK with High Pressure building to the North. Easterly flow establishes. But I'm afraid it's just not enough as a monstrous Atlantic Low comes rolling back through towards the island at the end of the run. The Europeon block loses!

One thing I will say is that with mild 850 hPa Temperatures wrapped around the Easterlies on both these models in FI, this is probably likely to translate to damp, cloudy conditions for the UK. Though would still be very cool with the flow coming off the continent.

Finally, the ECMWF shows the Atlantic lacking the strength to beat up the block to our East (so kinda similar to the GFS Parellel run) while the GEM gradually eradicates the block to the East - the Atlantic Lows gain the upper hand. And it's 1 - 0 to the Atlantic Lows.

The Low that drops to the South of the UK in FI on the ECMWF, though, fills quite quickly. Nonetheless, the European/Scandinvaian block is waiting their at 240 hours ready for the next Altantic Low to fall prey to the High Pressure system's mighty powers...

While the block to the East may have just about won the battle on most of the model runs, can it win the war?

[MR EXTREMES]

Nothing exciting from the models ok we have the se diving low but we need retrogress to Greenland iceland area for better shot at colder conditions.

Although the lower heights make inroads into Europe we need more cold into Scandinavia area in afraid the se driven low is only one part of the puzzle although the North of the uk could well have a shot at colder conditions and snow even to lower ground if the low makes it far enough southeast to draw in easterly.

But remember this is all fi and is unlikely to happen.

As some of the top posters have suggested recently dec jan is more likely to deliver the goods than anytime soon.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY THURSDAY NOVEMBER 20TH 2014.

NEXT UPDATE FRIDAY NOVEMBER 21ST 08:00

 

THE CURRENT GENERAL SITUATION A slack airflow over the UK will strengthen somewhat as troughs of Low pressure move up from the SW later today, tonight and tomorrow.

 

MODELS-2 WEEK HEADLINE Slowly becoming windier and more changeable next week and beyond with rain or showers and strong winds at times moving down from the NW. Temperatures near or a little below average.

 

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the split in flow currently running East both to the North and South of the UK becoming ill defined and slack for a period early next week before it strengthens markedly close to Southern Britain later next week while maintaining it's tendency to divert both North and South around the mainland of Europe as the High pressure block over Eastern Europe persists.

 

GFS OPERATIONAL The GFS operational this morning shows a trend towards deep Low pressure gradually moving SE over the UK later next week setting up a spell of wet and very windy weather for all areas. Temperatures would be average at best and it will feel cold in the rain and wind. Later in the run the weather settles down somewhat as the Eastern European High makes a comeback in the form of a ridge stretching West across the UK from Scandinavia bringing cold and drier weather with some frost and patchy fog in the Easterly drift. Weak troughs coming up against the block could give a little rain at times still chiefly in the far West which may fall as snow over Northern high elevations.

 

THE GFS PARALLEL RUN The GFS Parallel run is broadly similar to the operational this morning through the first two thirds of the run but it brings an even colder Easterly flow for a short while later with a better orientated ridge from Scandinavia allowing East winds and wintry showers near the East coast before the power of the Atlantic ratchets up a major storm cell to the NW at the end with Westerly gales and spells of rain affecting all areas before the end of the run.

 

THE GFS ENSEMBLES Putting all the GFS members together the ensembles are in unity over bringing the deep Low pressure down across the UK later next week with all it's attendant wind and rain. However, the majority of members want nothing of an attack from cold to the East with the general consensus being a ridge from the SW on the backend of the departing depression to the SE before the Atlantic wins through with more deep depressions close to or over the UK and wind and rain for all in average temperatures to end the period.

 

UKMO UKMO today shows a very slack period next week as the early week front finally clears the SE. The air will be chilly and probably filled with a lot of mist, low cloud and fog with frost too for some which if persists could give some very cold days for a time otherwise the weather looks fairly benign at the end of run stage.

 

THE FAX CHARTS The Fax Charts show a marked complexity of the frontal system affecting the UK from late today until late Monday when it looks like finally clearing the SE. As a result there will be a zone of wet weather across the UK only very slowly clearing SE as the higher pressure and chilly air across the NW eventually makes it's way down to the SE at some point early next week.

 

GEM GEM this morning shows the quiet beginning to the week with the weekend trough only barely having cleared the Southeast early in the week before it moves back North at the same time as being injected by falling pressure from the West. This then strengthens the slack flow across the UK early in the week to much stronger one with eventual Westerly gales and heavy rain for many as on this run Low pressure is held furhter to the North than is shown by other output but meaning little difference in surface conditions to what is being shown by the others.

 

NAVGEM NAVGEM this morning makes a much cleaner break and clearance of the weekend trough with High pressure covering Southern Britain early in the week with bright days but frost and fog issues likely by night. Later in the week pressure falls from the NW slowly but only the North looks like being affected by wind and rain from Atlantic depressions while the South holds on to something of a ridge with dry and bright weather maintained rather longer as a result.

 

ECM ECM this morning shows a quiet start to next week as the trough over the SE decays at the start of the week leaving behind a rather cold and potentially frosty and foggy period before the Atlantic winds up by midweek with a deep Low heading SE just to the West of the UK with a strong and cold SE wind bringing rain in across principally Southern and Western areas and as that moves away and decays a new surge of Atlantic energy pushes more Atlantic troughs into the UK with attendant wind and rain especially in the West. Through all of the period the block of High pressure to the East of the UK over Eastern Europe is maintained.

 

THE ECM ENSEMBLES  The Ensemble run continues to show a deep trough lying from Southern Greenland through the West of the UK to Italy with cyclonic South or SW winds across the UK with spells of rain and showers for all likely in average tmperatures overall.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend still shows a downhill trend to wet and windy weather though it does look like there will be a lot of disruption to troughs and Low pressure, most likely over the UK as they move up against the persistent block of High pressure to the East.

 

MY THOUGHTS Though nothing very wintry of note is shown in the output today the synoptic pattern could hardly be described as boring as the High pressure block over Europe persists and plays havoc with the models in determining what to do with ever more powerful Atlantic depressions and fronts as we move through the next few weeks. At the current time they mostly all show and agree on the path of the first deep depression as it's programmed to drift down over or just to the West of the UK next week bringing wind, rain and potential gales to places. Once that moves away SE and fills as is currently shown is a window of opportunity for pressure to rise further to the North and NE of the UK and while nothing majorly is shown in this camp this morning look out for the possibility of that happening in future runs over the coming days because if it does I feel it could tilt the balance towards cold reaching our shores soon from the east. As it stands at the moment and bearing in mind we are by then in FI territory the general thrust of thought this morning lies with powering the Atlantic up into a frenzy under a strong Jet flow by then and delivering rain and gales over the UK with a parent and very deep low likely somewhere towards the North and NW. If however, and it is a big 'if' the block to the East proves strong enough the orientation of the second attack from the Atlantic in week 2 could be more favourable under slider Low pressure meaning we might begin to see something more wintry across the UK as we enter December. This is not a forecast from me though and I mention it only as I have seen this setup in many winter's past where projected and powerful storm systems from the Atlantic power up and even strengthen the block to the East. We will need Europe to cool down much more than it currently is though to bring any snow interest into any equation. However, as the ECM Ensembles testifty this morning having a Low pressure belt stretching between Southern Greenland and the UK to Italy with intense High pressure over Russia is not a bad place to be in as we enter December if it's cold weather your looking for later in the season.

 

[knocker]

Nothing exciting from the models ok we have the se diving low but we need retrogress to Greenland iceland area for better shot at colder conditions.

Although the lower heights make inroads into Europe we need more cold into Scandinavia area in afraid the se driven low is only one part of the puzzle although the North of the uk could well have a shot at colder conditions and snow even to lower ground if the low makes it far enough southeast to draw in easterly.

But remember this is all fi and is unlikely to happen.

As some of the top posters have suggested recently dec jan is more likely to deliver the goods than anytime soon.

Agreed a detailed analysis in FI is not going to verify but one has to explore the possibilities. For example the GFS scenario I outlined above is dead in the water with a slight variation of the 250mb chart and the jet a tad further north.

 

As for "As some of the top posters have suggested recently dec jan is more likely to deliver the goods than anytime soon". Well..........................yes.

[BLAST FROM THE PAST]

Well for me I've chosen this still frame in FI just to highlight where I'm coming from.  If blocking was to win should we initially be looking at the block to the NE to be main player or could we see, as this shows, the LP dropping S/SE and Atlantic ridging following behind to ridge towards the ridging over Greenland/Iceland?  An area I'll be watching. 

BBC weather forecasters keep emphasising any 'warming up' and then how any chilly spell is 'expected this time of year'.  Of course it is but whay the 'empahsis' ?

 

BFTP

Edited November 20, 2014 by BLAST FROM THE PAST

[MR EXTREMES]

Agreed a detailed analysis in FI is not going to verify but one has to explore the possibilities. For example the GFS scenario I outlined above is dead in the water with a slight variation of the 250mb chart and the jet a tad further north.

 

As for "As some of the top posters have suggested recently dec jan is more likely to deliver the goods than anytime soon". Well..........................yes.

although this is not a bad look anom chart from the gfs 

ecm 192 and the last fram from ecm

gefs

ukmo has things a little futher east in terms of blocking but still not the worse run.

problem is its so easy to get sucked into the hype just a week ago there was easterly incoming but then backed of but thing thats catching my eye is that its cross model agreement but then we had that to a week ago so im on the fence still.

 

[legritter]

Well i,m certainly Sat on the fence ,Emotional Rollercoaster  Post [685] has just said what i was going to say .looking at the Models today one cant escape the fact that beyond about 7 days we could be looking at quite big differences of where we source our surface winds from .I am not hinting at something Bitter or something wet and windy but for us Model watchers theres plenty in todays charts and Data to keep us on our toes .And its certainly all Systems go looking at the Northern Hemisphere at the moment ,But taking all available Data it looks to me that the Atlantic is gearing up for an attack on western europe but as ever the Meteorological battles are prone to big changes on the Battlefield ,In all the posts i,v ever done on this forum i have never posted any charts etc ,but fingers out, i will be trying my hand soon ,Great forum ,  catch up later .

[knocker]

The GEFS and ECM ens anomalies are still consistent this morning with moving the block east and not developing the Azores ridge. The main players are still the Canadian low and the Eastern Atlantic trough.

Edited November 20, 2014 by knocker

[Nick F]

While the 06z GFS trickles out, good see the strong Altantic jet forecast later next week diving SE into Iberia rather than over us, taking low pressure SE into mainland Europe.

 

 

However, the shape of the Russia high is not really conducive to pulling enough cold air into eastern Europe to get anywhere near the UK. Though ECM does show cold pooling developing over Scandinavia and western Russia as a result of the increasingly cold high over Russia. The cold airmass it still kept well at bay.

 

Once the trough disruption occurs later next week, whereby Atlantic trough extending SE into Europe gets 'pinched' by amplifying ridges upstream and to the NE of the UK to form a closed low over western Europe, it'll be interesting to see if the upstream ridge over the Atlantic amplifies enough to allow sufficient pressure rises to our north to stop further Altantic lows from dropping down from the NW. Idealy, the shortwave trough coming out of NE Canada needs to sharpen more as it enters the NW Atlantic, to create stronger amplification downstream, as I've annotated below on the t+192 ECM chart (ECM not keen on this afterwards).

 

 

00z GFS op certainly hinting at this:

 

Edited November 20, 2014 by Nick F

[shaky]

GFS not slipping so far south east on the 6 z but the Parallel   keeps the slip south eastwards still

what are the chances of it looking completely different come 12z this evening! ! 06z is known not to do well in these volatile situations!!

[IDO]

The GFS 06z op is one of the outcomes that kept popping up for this week, the Atlantic bursting through as the PV lobe over Greenland discharges over the UK:

 

 

 

One of the GFS's favourite FI charts with Atlantic -v- E. Block battles. So although a possibility, based on this week's eventual outcome, probably unlikely. The parallel gives another possibility:

 

D10: 

 

The JMA update has just come out and it is as I was expecting, the UK caught in the stand off with the maintenance of the repeating pattern, well into December:

 

Week 2:  Week 3+4: 

 

Having seen that the GFS op is slightly more tempting! However the flip side is the ECM control probably hinting at what some of the MOGREPS ENS were pointing at, and although strictly an outlier, shows that there are background noises again:

 

De Bilt:   

 

So we have a period of good agreement till about D8 then the Atlantic-v- Block saga afterwards and I don't expect that to be resolved till the end of the weekend.

Edited November 20, 2014 by i'm dreaming of...

[Polar Maritime]

I've moved a few posts, Can we please only discuss Model Output in here.

Thanks, PM

[492]

The cooling off in Eastern europe has continued much as shorter term model predictions. Parts of Poland are currently experiencing light snow with temperatures close to 0 C in places. Some of the longer term model predictions were inclined to show more mobility to the north of the ridge encouraging it to collapse southeastwards however is remains in situ feeding colder air into parts of europe from the east albeit tempered at times by the infiltration of some warmer air from the eastern Med.

http://meteocentre.com/analyses/map.php?lang=en&map=eur_full&area=eur&size=large

[IDO]

^^^ The Met's take on things is in their blog and it appears that in this instance there will be no direct response from the US cold to the UK. That is, no cold and no storms: http://metofficenews.wordpress.com/2014/11/20/us-snowfall-and-will-it-impact-the-uk/.

 

The CET now stands at +2c, the third anomalous warm month of this very mild year.

 

As for the weekend, still uncertainty on surface conditions though ECM & GFS now agreeing on a mild day Saturday (13c+) for the south. With the cold front heralding a cooling off on Sunday and a cold Sunday night:

 

 

ECM then goes more average to above for the rest of the month.

Edited November 20, 2014 by i'm dreaming of...

[nick sussex]

Not much change today in the outputs, the Atlantic hits a brick wall with the jet running se through the UK.

 

There is however a big difference of opinion between the ECM and the GFS/GFS P later towards day ten over in the USA with the ECM holding the more amplified ridge, in turn this means that more energy is likely to be pulled away from the PV chunk which feeds energy into the UK troughing.

 

Both the GFS and GFS P flatten the pattern, the outlook really depends on which model is correct. The ECM day ten looks like developing much more favourably for cold, the GFS not so.

 

Of course we have been here before with the ECM over amplifying patterns past day 7, on the reverse side its by far the best normally at these types of shortwave/PV interactions.

 

The original deep low shown over the USA which we see now within the T144hrs timeframe was first picked by the ECM, it had one run which had a less developed low but overall it has been solid on this.

 

If it's right with its upstream pattern at day 10 then there could be some much more interesting output for coldies coming up, if not it looks like the stalemate will continue for a while longer.

[nick sussex]

For some reason it won't allow me to edit the above post with an image without logging me out so below is the ECM day ten:

 

 

You can see how important that ridge running into Alaska is as this amplifies the down stream flow over the central USA, the red arrows show the direction of energy transport taken a step forward.

 

The deep low upstream as it phases with the PV chunk will pull some of that nw, the shortwave you see at the base of the main trough will run ese, as this happens it will start shearing some of the energy away from the trough nw.

 

You'll see some WAA heading nw ahead of the UK troughing and the suggestion of a cross polar flow, as the upstream transportation of energies occurs high pressure will develop further nw as the UK troughing weakens.

 

The red hump is where you need to see a lobe of high pressure develop to slow the next phasing of energy with the UK troughing.

Edited November 20, 2014 by nick sussex

[Polar Maritime]

I've had to remove yet another off topic post again, Please only discuss what the 'Models' are showing in here. It's very simple..

 

Thanks, PM.

Edited November 20, 2014 by Polar Maritime

[knocker]

I'm not sure whether this of interest or relevance in this thread but Michael Ventrice posted this on his blog.

 

Sub-Seasonal U.S. Temperature Outlook through mid-December

• Massive Indian Ocean MJO event on the horizon; Favors warmer than average weather to begin December.
• Evolving signal that suggest another period of increased arctic air mass intrusions across the U.S. and higher than average U.S. heating demand during the latter half of the month.
• ECMWF Weeklies could be suffering from snow-cover feedback issues during Weeks 3 & 4.
• Primary Weather Drivers: Tropical Convection (i.e., the Madden Julian Oscillation)

[Barry12]

12z GFS is looking better already at 96 hours, higher heights over Scandi, and everything has backed slightly further west

 

[gottolovethisweather]

One thing is for sure in the early timeframes of the GFS (P) 12z run is that the NH Jetstream is under assault over Europe and the North Atlantic and in complete tatters, it looks very odd. One thing I'm unsure of as this run unfolds, is just how long it will be before it gets to its more rampant organised self and then attempts to unleash itself on us.

 

 

Is the PV causing the Jet to react like this or does it work the other way around.  Can anyone help me with my query? 

 

And by t+111 (borderline FI) -5 uppers coming in towards the West of Ireland from off the Atlantic.     Saw this a lot last year in fact, weird weather to say the least. Looks likely to be a fascinating weather watching week next week that's for sure as I'm mentioned a few times previously and could the first proper upland snowfalls finally be heading our way if the GFS 12z is to be believed, albeit temporarily. 

Edited November 20, 2014 by gottolovethisweather

[Duane S.]

Wow, that is some disagreement, anywhere between +6 and -3 then!

[MR EXTREMES]

image.jpg

Wow, that is some disagreement, anywhere between +6 and -3 then!

Although the majority go for plus ao

[nick sussex]

It's hard to have too much faith in the GFS when it goes from this jet stream pattern over the USA on its 06hrs run at T168hrs:

 

 

To this at T162hrs on its 12hrs run:

 

 

It's more amplified on the 12hrs.