Model Output Discussion 1200 hrs 15/11/14

[blizzard81]

Given both GFS's 18hrs and the ECM I think the UKMO solution is looking very unlikely, whilst both the ECM and UKMO might look similar at T144hrs there is a small but critical difference over in the ne USA which means the ECM will not be able to develop the more favourable trough disruption at T168hrs.

 

The divergence begins within T120hrs and so its very unlikely that with an extra 6hrs worth of data that both the GFS and GFS P have called the pattern incorrectly.This is in relation to shortwave phasing and timing issues.

 

I hope I'm proven wrong in the morning but the evidence suggests that the UKMO, GEM and JMA are barking up the wrong tree. The UKMO is generally known for being the dream killer in here as its often the one that harpoons an easterly by refusing to come on board, I've yet to see it pull out a colder solution against the other major models at the T144hrs timeframe that verified.

 

The GEM regardless of its upgrade and the JMA are basically cat litter and not to be trusted, the performance of the UKMO has been dismal over the last week, we saw from it Scandi high, a refusal to develop shortwave energy to the ne etc etc.

 

The ECM which I have criticized frequently over the last few weeks may have been all over the place at T168hrs onwards but sadly in this case is likely to be right at the key T120hrs timeframe.

 

The models may all still have the pattern too far east but even allowing for that the PV over ne Canada is just sending across too much energy to realistically see the high backing west at this stage , it may happen later.

 

Much talk of jam tomorrow which is understandable as there are better background signals this winter and we're not yet even into December but I think I speak for many when I say we're bored and we want jam now!

Best post of the day in my opinion. The dye is cast as far as I am concerned for at least the first third of Dec for cold & snow.

This comment may sound rather rash and full of impatience, wishing for something resembling winter weather but as Nick has put so elequently above,

we want some form of jam now. This is because last winter was a total write off for cold lovers in the UK and therefore it feels like

an eternity since we experienced anything like winter weather.

Polar, there's nothing good about this chart. The gfs has the tendency to overdo the coldness of the uppers at this range when the wind comes from the west/northwest which we also saw last winter.

Totally agree, from a coldies perspective, we do not want to see anything like the said charts verifying!!

[Barry12]

Finger crossed for the GFS P to verify!? Awful NH profile and snow restricted to the mountains.

[blizzard81]

Finger crossed for the GFS P to verify!? Awful NH profile and snow restricted to the mountains.

The run goes against many of the teleconnections so if it is proved wrong then it will go a long way to proving that this upgraded version

is as bad as it's older brother!

Edited November 22, 2014 by blizzard81

[Nick F]

Not a great pub run pushing the jet north ete.Could i just ask you guys a question?Keep hearing comments that fi is generally about 5 days

.Why are people pinning there hopes on strat conditions,mjo,enso ete when they are generally forecast weeks away?Are they not way in fi and subject to the big changes just as the model output is.Thanks in advance

ENSO fluctuations are a lot more gradual than changes in the synoptic patterns we see with every model run, tropical SSTs fluctuations which control the ENSO state, can be predicted well in advance - thus a signal for an El Nino developing can be picked up months in advance of it occuring - so then these gives a lead time of weeks or even months of predicting its effect on extratropcal or mid latitude areas.

Again, the MJO progression over the tropics can be tracked over 30 to 60 days, so offers a longer lead time than simply waiting and guessing the next changes in the model ouput. The MJO movement can be linked to changes in the upper flow patterns over the NE Pacific or west side of N America, which in turn effects the pattern downstream eventually.

The behaviour of the stratosphere can often be predicted for a particular month or even season, based on the long term impact of tropospheric waves over a period of time, such as recently, where waves are tending to distort or split the polar vortex. These continued upwellings from the trop can eventually lead to a SSW and collapse of the PV. Eurasian snow extent, biggest for years, also having a long term impact by causing wave breaking.

So hence the ability to look ahead of the model output for clues of what may lie ahead and current optimism longer term, despite the lacklustre model output for now.

Edited November 22, 2014 by Nick F

[knocker]

Just a couple of charts from the (P). No great significance in the long term

charts weatherbell.com

 

[Captain Shortwave]

Just seem the ECM, the Azores high looks very much overplayed in the scheme of things and this skews the run as you link the Azores/Scandi anticyclones and eventually end up with a UK high. The mean follows the same pattern but the watered down ridge from the Azores gives a different solution later on.

That said again we have 2 issues, one the Atlantic westerlies have trended to break through the UK and secondly we have little or no cold to pull in from the east. The GEM is the perfect example, by day 10 we are still struggling to give an air frost in Germany, let alone the UK.

Edited November 22, 2014 by Captain shortwave

[Jason M]

I think Captain makes the key point about the current set up, which is a total lack of cold 850s to draw on. GEM gets close, but there is still the matter of the missing cigar!!!

Take ensemble 13 from the 18Z GFS suite as an example (link below). Lovely synoptics from 192 all the way out to 384 andthe lowest 850s are -4C on the last chart (albeit proper cold would probably arrive a couple of days later).

http://www.meteociel.fr/modeles/gefs_cartes.php?code=13&ech=384&mode=0&carte=0

If the Russian high ridges west we wont get the colder uppers into Europe because the ridge itself blocks off any cold from the north. We need a favourably aligned Scandi High to form in situ as a separate feature.

Its frustrating but not that unusual as its been a mild autumn in NW Europe and its still very early so will inevitably be hit and miss (more 'miss' in this case) re cold uppers.

[lorenzo]

MJO providing a mixed lead wrt IO cyclone devel. MJO due to dissipate, yet after strong phase 3 damage is done. This phase has great analog for trop precursor to strat effects within 30 days.

 

Hellish NAO in the interim and horrible on models, but the future results are spectacular...

[Geordiesnow]

First time I seen the output and I wish I hadnt, the medium term looks increasingly likely the Atlantic will come back and with a poorly orientated block in Scandi, then mild southerlies and increasingly wet weather looks like the form horse.

 

It is really one of the worse types for those wanting even just wanting genuinely chilly weather(by that i mean in terms of upper air temps, not surface cold), mild southerlies being pumped up into the Arctic regions but far enough east to not really disturb the PV and as you see, a lot of Scandi is mild for their standards, mild in Svalbard and the jet is in a poor position to deliver any polar airmasses from the West and North West.

 

Of course a bartlett is probably worse but at least there is a chance of some brief polar airmasses coming in from the Atlantic... we have had so little chilly air its unbelievable as we are nearing the end of November. 

 

On the other hand, we could head into a wet and windy period so we could see the other aspects of Autumn and winter, unfortunately we seen that type far too much last winter and lets just hope it is not going to be a repeat. 

[kumquat]

Yes BB but, of course, everybody's looking at the here and now. It would be lovely to write to my mum in Northampton and tell her if the big freeze is on the way. It certainly isn't but we're all gearing up for the middle of December.

 

That Azores High is being a right pain in the bum. I can see how it goes hand in hand with the PV segment over Greeny. Those two ride together well. Their little spawns along the jet can also be vicious and a couple are starting to be modelled now. It's funny when you look around the globe at HP below the jet, you couldn't get it any stronger than in our neck of the woods. Typical.

[TSNWK]

GFS 00z more progressive with Atlantic around D6 onwards, towards the end of HiRes the high to our east has retreated noticeable, with Atlantic driven weather making progress over scandi, this low presure supported underneath by a high pressure cell centered over Germany AKA as the euro high....

[TSNWK]

GFS 00z more progressive with Atlantic around D6 onwards, towards the end of HiRes the high to our east has retreated noticeable, with Atlantic driven weather making progress over scandi, this low presure supported underneath by a high pressure cell centered over Germany AKA as the euro high. Low res is very for coldies as well.
 

Edited November 23, 2014 by Polar Maritime
to remove double quote.

[Eugene]

GEM 00Z is fantastic with cold easterlies towards the end, UKMO 00Z at T+144 hrs has potential, just need the azores high to not ridge our way and that approaching atlantic low to dive southeastwards.

[Polar Continental]

Looks like the Gem and the UKMO are going down the same route at T144 

The UKMO has the low further south. The continued evolution from the GEM eventually sets up a cold easterly over the UK. The GFS and ECM continue to play the Atlantic scenario.  

[Captain Shortwave]

GEM

Deep disrupting trough with a negative tilt.

UKMO

WAA vertical, low pressure over south Iberia is going to become cut off with the Azores high building over the top.

 

ECM

To be honest the UKMO is much much closer to the ECM chart this morning. So we pretty much have the GEM as the only model showing a decent block which can push in even some remotely cold air (-8C Isotherm is just off the coast of Kent).

So I would put an Atlantic breakthrough as the more likely option, though I suspect that it won't be long before the eastward progression of low pressure will start to struggle.

[Nick F]

Bit of a horrow show from GFS op + P for coldies at first glance, with a strong westerly jet ploughing across the UK as we start December, the only positives from it would be transitory cold Pm incursions from the west which would bring temporary snow accumulations across northern mountains. ECM appears to have the jet further north still, but this would allow high pressure to build in from the SW.

 

The more mobile Atlantic regime doesn't really set in until past t+168, so there's the usual caveat that the models are being too progressive, particularly given the blocking to the east which should mean lower confidence in model guidance past day 6. But you can't help feel that the combined presence of low heights over Greenland/Iceland and strong westerly jet will eventually bring in the Atlantic rot.

 

But, often we've endured bouts of Atlantic mobility for a week or a few weeks in winters past which have incorporated good cold/snowy spells too, so nothing to worry about for now, unless you are desperate for cold and snow.

Edited November 23, 2014 by Nick F

[bluearmy]

Again the ECM looks progressive but as the run continues, it still doesn't get any low heights into scandi. Infact, by the end, the Siberian high is headed sw toward Eastern Europe with some low uppers which would drop further by the day. Given the repeated output of the gfsp, I would be surprised if the apparent mobility in out longitude didn't verify however, how much it impacts on us is questionable. We look to remain in a broad ' no mans land' - moreso the further se as the Icelandic lows impact the nw to a degree.

Will be interesting to see if the extended ens restrengthen the block to our ne again.

[Polar Maritime]

The GFSP this morning continues to show some good reloads of Pm air towards the end of the run, With bands of rain spreading S/E pulling down colder air from the N/W giving chances of snow, Especially for elevated locations but not exclusively. A much cooler more seasonal feel for the start of Winter, With daytime temps around 3/4c in places and a biting wind chill.

 

Edited November 23, 2014 by Polar Maritime

[mushymanrob]

 

Neither this nor colder fi charts have greater or lesser chances of varifying. they are just options in fi based on current data.

Edited November 23, 2014 by Polar Maritime
To remove off topic comment.

[IDO]

The GEM mean at D10 followed by the control:

 

 

 

No support for the op again this morning. ECM mean this morning similar to the battle we have been seeing, the Azores trying to move NE, the block over sceuro regions and the lower heights in the NW. None of these appear to be able to dominate the other. The GEFS at D10 is not dissimilar:

 

 ECM at D10: 

 

Just flatter and that is a trait of GFS. The following bias shows a continued trend even at D7 for low heights to be over emphasised to our north:

 

 

So the GEM & ECM mean at D10 is looking the direction of travel and ties in with my thoughts over the last week or so. We remain stuck in the rut but it is only just approaching December so rather now than in a month's time. Background signals remain very promising so assuming the strat goes to plan an interesting mid to late December beckons.

Edited November 23, 2014 by i'm dreaming of...

[knocker]

GEM 00Z is fantastic with cold easterlies towards the end, UKMO 00Z at T+144 hrs has potential, just need the azores high to not ridge our way and that approaching atlantic low to dive southeastwards.

 

I see what you mean.

Charts weatherbell.com

[Polar Maritime]

Rtavn2882.gif

 

Neither this nor colder fi charts have greater or lesser chances of varifying. they are just options in fi based on current data.

 

Taking aside the obvious comment related to Models in general, As it's no big secret.. What are the options showing Mush? 

Edited November 23, 2014 by Polar Maritime

[johnholmes]

Until the trough shifts considerably from its position as shown on the anomaly charts then there is little change in terms of deep cold weather affecting the UK for at least 2 weeks in my view.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

[mushymanrob]

Taking aside the obvious comment related to Models in general, As it's no big secret.. What are the options showing Mush? 

 

in laymans terms

 

the ecm suggests a continuing stalemate

 

 

so generally a long drawn out rather quiet spell, rather damp at times, rather gloomy at times, but the uppers suggest itll be on the milder side of average.

 

the gfs however (both @ t240 )

 

 

suggests a more progressive atlantic to 'win out' giving us the usual unsettled but average regime, some cooler pm days, some milder tm days .

thats basically what the big 2 are currently showing as options, of course we are likely to get something in between.

but going into the fantasy land of conjecture, it is possible for a cold spell the emerge, IF pressure over southern europe gives way and allows the atlantic systems to take this southern track eastwards. that would then allow for an increasingly cold easterly across the uk.

Edited November 23, 2014 by Polar Maritime
To remove unnecessary comment.

[bluearmy]

differences at day 10 between NAEFS and ECM wrt the azores anomoly. (ecm keener). until thats resolved, going to be tricky to work out much detail.

 

the only thing i'm confident about is that the euro high upper anololys are disappearing. 

 

the atlantic trough is getting closer over time as the scandi ridge is allowed to edge east with the movement of the siberian vortex that way. this goes against the backgorund of slow retrogression but may fit into a general sinking of the atlantic trough (extending into europe) whilst the week 2 northeast american anomoly eventually builds across the top of the trough to find the scandi/nw russian one. that will take well beyond two weeks and relies on the canadian vortex relaxing its extension towards s greenland.