Model Output Discussion 18th Nov.2013-12z onwards.

[bluearmy]

signs that the cold few days could spring some surprises - a secondary dropping low just to our west is not unusual in this set up. sustained or a blip ?  if it is to be sustained then the ops must become consistent around a different evolution to the ens post day 10. lets see how ecm op handles its fi's over the next few runs. 

[Frosty.]

If Carlsberg did weather maps, it would look like the last few frames of the Ecm 00z op run, look at those thicknesses, 522 dam..510 dam..........EPIC I just exploded   

Edited November 27, 2013 by Frosty.

[legritter]

Morning Gang ,just crawled out of bed and some nice charts to set me up for the day .this is what i like and even if its only short cold blasts ,they CAN DELIVER IF SYNOPTICS ARE OK .all eyes now on tonights runs to see if consistancy creeps in with our hunt for that magical four letter word ,I half expect a big Ramp from  FROSTY soon ,catch you all up later .

[The Northern Ramper]

The downside I see to these charts is the timescale and the differences we will most likely have at this range.

It would not take a huge shift for it to miss or clip the Uk. Give me the ECM at t72 and I will be happy, positive but tentative steps this morning.

[snowice]

Well the profile over the pole is there in the ECM0Z AT 240HRS NOW. I bet Nick Sussex eyes will pop out when he looks at the ECM What a turn around from the ecm in 24hrs still long way off but some excitement in here today i bet! 

Edited November 27, 2013 by snowice

[R.P. McMurphy]

Morning Gang ,just crawled out of bed and some nice charts to set me up for the day .this is what i like and even if its only short cold blasts ,they CAN DELIVER IF SYNOPTICS ARE OK .all eyes now on tonights runs to see if consistancy creeps in with our hunt for that magical four letter word ,I half expect a big Ramp from  FROSTY soon ,catch you all up later .

 

Morning Legritter,

 

Yup, some stunning charts to feast our eyes upon this morning & last night. **IF** the charts come off as they are now for 4/5th December, it would be something quite special for some areas.

 

Albeit, I would prefer something more sustained in terms of cold, but a short cold blast of snow & ice is sure to wet the appetite of some members!

 

528 Covering the majority of the UK, with a nice brisk NW Flow, heavy risk of snow showers.

 

[bluearmy]

Well the profile over the pole is there in the ECM0Z AT 240HRS NOW.I bet Nick Sussex eyes will pop out when he looks at the ECM What a turn around from the ecm in 24hrs still long way off but some excitement in here today i bet!Well the profile over the pole is there in the ECM0Z AT 240HRS NOW.I bet Nick Sussex eyes will pop out when he looks at the ECM What a turn around from the ecm in 24hrs still long way off but some excitement in here today i bet!

If you are to take the NH profile day 10 ECM then you have to ask yourself where the depression headed across the top of the Aleutian ridge is going. that will probably take the low heights back into n America to join the vortex back together. At ten days, individual features cannot be relied upon so little point dissecting. It's just nice to see a trop chart like that as we enter dec. approaching the anniversary of our 'lost easterly'!

[That ECM]

If you are to take the NH profile day 10 ECM then you have to ask yourself where the depression headed across the top of the Aleutian ridge is going. that will probably take the low heights back into n America to join the vortex back together. At ten days, individual features cannot be relied upon so little point dissecting. It's just nice to see a trop chart like that as we enter dec. approaching the anniversary of our 'lost easterly'!

If you look at the NH profile day 10 of ECM and GFS then there is a lot of differences. Much talk of consistency in the output but I would suggest that low dropping in from the north is one of not many commonalities.

[winterof79]

I am likeing the trends today.

http://www.meteociel.fr/modeles/ecmwf/runs/2013112700/ECH1-216.GIF?27-12

http://modeles.meteociel.fr/modeles/gfs/runs/2013112700/gfsnh-0-264.png?0

http://modeles.meteociel.fr/modeles/gem/runs/2013112700/gemnh-0-240.png?00

http://modeles.meteociel.fr/modeles/bom/runs/2013112700/bomnh-0-240.png?00

And JFF CFS from Boxing day http://www.meteociel.fr/modeles/cfse_cartes.php?ech=720&mode=0&carte=1&run=10

[johnholmes]

for what it is worth these are my thoughts based on the usaul close scrutiny over each day of the 500mb anomaly charts with links to them below

 

Wed27nov

Ec-gfs

Both show some degree of merdionality (!) over the states and +ve areas east of the states with the main trough north of the uk tending to edge west; this does look on balance as if the flow at 500mb into and over the uk is going to veer to n of west, but it is not a done deal as yet. The noaa outputs also show some degree of meridional pattern over the states and the +ve area over the atlantic (it was close by the sw of the uk) is moving west, quite high values on the 6-10.

IF these things continue as they seem to be proceeding over the last 2-3 days for the next 2-3 and with a meridional flow looking more coherent over the states with a subsequent effect down wind over the atlantic towards the uk then a colder spell would develop. To me it would be a fairly short lived spell 2-4 days perhaps, unlikely to be a week or so. Why? The +ve areas show little if any sign of migrating into the Greenland/Iceland areas but stay over the atlantic south of 60n. This rarely leads to anything more than a shortish cold spell.

Timing currently IF all the pieces fall into place would be about 10 days from now?

 

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

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

Edited November 27, 2013 by johnholmes

[Cloud 10]

ECM operational at t240 looks fairly in-tune with the ensemble mean regarding the main 

anomalies across the NH.

 

op run..  ens..

 

 

 

Incidentally,that ECM op run would provide some brutal cold for parts of

the Northern USA.

 

[Tim Bland]

For those in the north it could be a 4 - 5 day shot at wintry weather. All i see for the south is 24-36 hour window of opportunity before the high topples. Hope i'm wrong and it does develop into a more prollonged spell. Just being realistic for those who are south of the midlands and are reading this thread and waxing their sledges

[johnholmes]

Just to back up the two posts above this about being realistic.

Go to the free data area and 'play' the GFS 500mb and isobar chart through. Watch how the cold comes in ONCE the surface high (it is under the upper ridge) moves west next week but also how GFS shows it moving back close to the UK and stopping deep cold remaining.

Until the upper ridge and its surface feature beneath it remain well west of the UK then disturbances running around its northern flank cannot, no matter how much folk may hopecast, affect the UK for other than brief shots. The post I made above is about IF the upper ridge because of the northern hemisphere long wave pattern is able to establish a ridge north of 60N is the only way, in the current set up, that deep and longer lasting cold can affect the UK.

hope this helps those not able to work out the charts and perhaps puzzled by some posts suggesting more cold than some others are suggesting.

Edited November 27, 2013 by johnholmes

[SMU]

Thanks GOTTO-

 

Also the temperature anomaly from the ECM would show a very uniform cold departure over the entire united states which is very rare- usually they have a big  anomaly in one half & a very opposite anomaly in the other

 

In terms of the ECM ensembles they have trended lower today ( sub 5 now past day 8/9)

http://www.knmi.nl/library/php/resample_image.php?filename=/exp/pluim/Data/pluim_06260_0_00_60.png&width=692

 

Also a very interesting control with 15cm of snow then a sharp warm up- indicates some sort of atlantic feature moving through.

 

Mere speculation at the moment in terms of the use of the word snow- lets get the height anomalies correctly located first - especially the pole-

I wouldn't be forecasting a toppler just yet- topplers come from atlantic ridges with no height support over the pole- this pattern & forecast is being driven by the wave of cold being forced out of the pole from the High over the other side ( Aleutian)- so there is support for something more sustained due to the amplification of the pattern & cross polar flow 60N blocking is the key...

 

 

S

Edited November 27, 2013 by Steve Murr

[Severe Siberian icy blast]

I am likeing the trends today.

http://www.meteociel.fr/modeles/ecmwf/runs/2013112700/ECH1-216.GIF?27-12

http://modeles.meteociel.fr/modeles/gfs/runs/2013112700/gfsnh-0-264.png?0

http://modeles.meteociel.fr/modeles/gem/runs/2013112700/gemnh-0-240.png?00

http://modeles.meteociel.fr/modeles/bom/runs/2013112700/bomnh-0-240.png?00

And JFF CFS from Boxing day http://www.meteociel.fr/modeles/cfse_cartes.php?ech=720&mode=0&carte=1&run=10

having just had a flick through the cfs it doesnt get much better than that. Certainly very cold xmas and behond with a good easterly flow into jan with undercutting lows. Quite a lot of long range models at the min routing for scandi highs dominating the winter months. Time will tell of course .

[gottolovethisweather]

Thanks GOTTO-

 

Also the temperature anomaly from the ECM would show a very uniform cold departure over the entire united states which is very rare- usually they have a big  anomaly in one half & a very opposite anomaly in the other

 

In terms of the ECM ensembles they have trended lower today ( sub 5 now past day 8/9)

http://www.knmi.nl/library/php/resample_image.php?filename=/exp/pluim/Data/pluim_06260_0_00_60.png&width=692

 

Also a very interesting control with 15cm of snow then a sharp warm up- indicates some sort of atlantic feature moving through.

 

Mere speculation at the moment in terms of the use of the word snow- lets get the height anomalies correctly located first - especially the pole-

I wouldn't be forecasting a toppler just yet- topplers come from atlantic ridges with no height support over the pole- this pattern & forecast is being driven by the wave of cold being forced out of the pole from the High over the other side ( Aleutian)- so there is support for something more sustained due to the amplification of the pattern & cross polar flow 60N blocking is the key...

 

 

S

 

Indeed, some hope but not a whole lot more than that yet, I like yourself and others certainly don't see a SWr'ly dominant regime setting up anytime in the near future, so for coldies, that is one large piece of the puzzle in place. I was one of the first in fact, to highlight the NW flow as the place to start things off, albeit it maybe short-lived. Whether we can get something more exciting might start getting nailed later this week, for later next week, if you understand my meaning is the next piece of the puzzle.  JH is right as such in that nothing EPIC is likely to arrive over shores for the next seven days or so.

Edited November 27, 2013 by gottolovethisweather

[tight isobar]

Lots falling intoplace now regarding a decent shot/ shots of cold as we head into December. Will most models begin regression of HP, where most would like to see it. And large hints neg AO..think Dec could be intresting!!!

[Nick F]

Does look increasingly like there's a more potent surge south of cold arctic air brewing towards the end of next week, as the core of the cold vortex/low heights in the arctic circle is suggested to shift southeast and eastwards to form a deep long-wave trough to the E and NE of the UK next week - while heights rise over the NW Atlantic. The 00z EC ensemble mean suggests this by t+240 as did yesterday evening' sCPC 8-14 day 500mb outlook update:

 

 

As John H alluded to earlier though, no strong +ve heights indicated over the Greenland area yet, so this may be a cold snap rather than a cold spell. Also secondary lows forming on the jet, picked up nearer the time, may dilute the cold surge towards southern areas. But, besides the usual flies-in-the-ointment to watch out for, perhaps the most potent northerly outbreak potential of the season thus far maybe evolving.

Edited November 27, 2013 by Nick F

[Catacol]

Based on what *May* happen though the opportunity for a northerly with deep low heights (unstable) seems to be presenting itself and more importantly some signals that a disconnect between the stratospheric vortex and tropospheric pattern may be in the offering-

 

 

Not sure about that - the strat forecast shows moderate wave 1 and wave 2 warming up to day 8 at the moment, centred over Asia. That is exactly why the aleutian ridge develops and the vortex is dropped further to our side.

 

 

 

Trouble is - it is just a wobble because mean zonal wind speeds remain high and are forecast to remain high, and so anything cold that occurs is transient. 

 

The worst news this morning is that at day 10 wave 1 and wave 2 warming starts to decline according to the forecast, so IanF's call of a short snap seems even more likely as the wobble in the vortex wont be sustained and at best we will return to a NW air flow thereafter.

 

We need something far more aggressive to be thrown at the vortex if we are truly to unlock the cold. If we get ridging into the arctic without any warming episode occurring then a disconnect would be more obvious... but to be honest since following the Strat thread carefully I cant remember seeing such a disconnect at any stage. December 81 isnt a great example to use because December strat temperatures bottomed out at -70 (we are close to -80 now) and there was a Canadian Warming that month that will have helped the development of a blocking pattern downstream. So the strat and the trop on that basis were very much connected.

 

Following that train of thought what we really need to see therefore is a Canadian Warming and we need to see it soon otherwise nothing remarkable this side of Xmas remains likely.

Edited November 27, 2013 by Catacol_Highlander

[Summer Sun]

Looks like a 4 day or so cold snap before a return to average or even above average temps according to Ian Fergusson on twitter

 

A short colder phase likely between 8-12 days time but likely followed by a return to average or even above average temps (contra D Express)

 

Latest from Gibby on the 00z models

 

All models show a period of very slow changes in the weather over the UK for the next week or so. High pressure remains stubbornly close to SW England and the weather shows a milder and moister West flow across the UK now with widepread anticyclonic gloom and hill mist and drizzle at times. This weather will likely persist for the next 36 hours or so before brighter and fresher conditions chase the low cloud and murk away on Friday with sunshine and scattered showers wintry on hills in the North briefly. By the second half of the weekend the weather retrns milder and cloudy again as milder and moist air again rounds the Northern periphery of the High still close to the SW and down over the UK. The start of next week looks relatively mild and benign as the High finally starts to relax away SE while maintaining a UK ridge which maintains dry and quiet weather for most.

 

GFS then shows temporary injections of more unsettled weather starting midweek next week firstly over the North, extending to the South too at times. However, any one weather type remains short-lived as milder air quickly replaces any colder weather and there will be rain at times in the second half of the run although amounts in the South look small on this operational run as High pressure remains fairly close towards the SW or South for much of the time.

UKMO shows High pressure over the mid Alantic with a ridge all the way across the UK to Germany next Tuesday. The quiet and benign weather will still be well established next Tuesday with only a slight increase in the Westerly breeze across the North with perhaps a little light rain in the far North and NW. Temperatures would be relatively mild under relatively cloudy skies.

 

GEM today holds quiet and benign conditions right out to the end of next week now as High pressure clings on and only briefly looks like giving way at the very end of next week to a spell of rather colder and blustery NW winds with rain at times and some snow showers for a time on Northern and Eastern high ground before the likelihood of mild and damp weather returns to all over next weekend.

 

NAVGEM closes it's run with a slow deterioration in conditions through the middle of next week as weakening troughs move SE down over Britain with a little rain with the prospect of a phase of more active fronts and wind later in the week but never looking overly cold at any point.

 

ECM this morning shows fine weather still at the midweek point as High pressure clings on over Britain before a pulse of energy pushes a band of rain and colder weather SE over all areas late in the week before conditions gradually turn less cold but still unsettled in the North in time for the weekend while the South would probably become dry and rather cloudy again and less cold to end the run as High pressure is close by to the South.

 

The GFS Ensembles continue to show nothing threateningly cold and wintry over the next few weeks. True, there is a period when below average uppers look likely later next week but coming from the NW things could well become modified at the surface by the North Atlantic when crossing the UK to give no more than the threat of wintry showers for a time over Northern hills. There is then strong support for even this pattern to flatten out later as Westerly winds look favoured to take hold with rain at times, chiefly in the North and temperatures well up to average.

 

The Jet Stream flow remains stubbornly positioned to keep cold weather away from the UK for the reliable future with the main core of the flow well North of the UK. Later next week it does show signs of moving South towards crossing the UK rather than locations to the North but it's orientation remains poor for any sustained cold outbreaks with just transitory NW'lies the only likelihood of anything below average later next week.

 

In Summary the weather remains stubbornly locked into a High pressure based Winter pattern which provides days of anticyclonic gloom and benign weather. As the High shuffles about over the next 7 days there is some opportunity for clearer and cleaner air to flood South towards the weekend before this becomes displaced by Sunday by more of our current weather pattern lasting into the middle of next week.

 

As on previous runs there is still evidence of a change to colder and more unsettled weather from the end of next week but this seems a lifetime away and if anything as been reined back this morning in it's spread and influence on this morning's output to just bring a day or two of colder air before the Atlantic bandwagon NW of the British Isles flattens the pattern to return milder air with rain at times, chiefly in the North.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[gottolovethisweather]

I hope those of you who were interested in hearing the views of Steve Murr and I were quick, as my post has now disappeared into the ether. Hopefully not like this year's wintry weather.

Edited November 27, 2013 by Osbourne One-Nil
It's in the winter discussion thread!

[BLAST FROM THE PAST]

Interesting times are upon us.  After what seemed like an eternity in early Autumn its fair to say since end of October we've had some interesting weather and interesting synoptics trying to force their hand.

As Great Plum mentioned and quoted Lorenzo's [now in my mind fabled 'vortex is all vortexy] it is also IMO significant that we are getting what we are getting and have had.  As big Steve M says there may be a 'disconnect' going on and for me it is the change in Jetstream behaviour which continues to show its hand, it is generally more south and it is generally more meridional.  Steve, 1981 eh?  One idea to keep in the back of the note book.

For me I think at present 00z GFS looks more plausible than 18z GFS as I think we may well continue to see Atlantic influence cutting off sustained cold but I maintain the thoughts of plenty of pM air source so seasonal at least.

Looking at ECM and GFS even at 240 there are similarities although the angle of attack from the secondary LP on ECM is a corker with it running into cold air. I still can't post a link but have a check.  My chart of the day that, will it be close though ? .....I love the build up and anticipation more.

 

 

BFTP

Edited November 27, 2013 by BLAST FROM THE PAST

[Catacol]

Interesting times are upon us.  After what seemed like an eternity in early Autumn its fair to say since end of October we've had some interesting weather and interesting synoptics trying to force their hand.

As Great Plum mentioned and quoted Lorenzo's [now in my mind fabled 'vortex is all vortexy] it is also IMO significant that we are getting what we are getting and have had.  As big Steve M says there may be a 'disconnect' going on and for me it is the change in Jetstream behaviour which continues to show its hand, it is generally more south and it is generally more meridional.  Steve, 1981 eh?  One idea to keep in the back of the note book.

For me I think at present 00z GFS looks more plausible than 18z GFS as I think we may well continue to see Atlantic influence but I maintain the thoughts of plenty of pM air source.

Looking at ECM and GFS even at 240 there are similarities although the angle of attack from the secondary LP on ECM is a corker with it running into cold air. I still can't post a link but have a check.  My chart of the day that, will it be close though ? .....I love the build up and anticipation more.

 

 

BFTP

 

Yes - my last post was a bit glum and I hope Steve didnt take it as an attack - but actually I also remain optimistic going forward. The very fact that the pattern keeps returned to an amplified state even given the strength of the vortex is good news. Models are not always reliable as we know - even the strat models regarded generally as more accurate than the trop ones do occasionally get things wrong as they did earlier in November when they incorrectly forecast a vortex split - so there is lots of stuff to look at and pour over.

 

I've been mentioning Canadian Warming over and over again this autumn, hoping and searching for it. For me it would unlock a special weather event when combined with the strong ridging prevalent in the north pacific so far this autumn/winter. It is this year's Holy Grail... but even without it I think we can get some cold at some point as seasonal warming will start to loosen the vortex naturally anyway past Xmas. And a northerly toppler can produce some special weather for 24 - 48 hours. Perhaps we should all not be so greedy. :-)

[Captain Shortwave]

Interesting that this mornings ECM run again created that Canadian Uberblock which is putting most of the central and northern states into the freezer. There seems to be little support from other models including the GEM which tries to create a cross polar flow further east which might have our name on it. 

The GFS is still very bullish about transferring the polar vortex across the pole to sit more on the Canadian side with this process beginning at about day 9, which of course completely contradicts the ECM op. 

One thing I will say is the GFS is wanting that northerly, impressive day 10 mean

-4C isotherm covering the entire UK, suggesting this has a good shout of occurring.

Will have to see how things develop in the afternoon runs. If the ECM Canadian block shows up again then maybe there is a chance of it occurring.

Edited November 27, 2013 by Captain shortwave

[syed2878]

haven't we been here before with the ecmf just over a week ago? Although the ecmf showing epick charts lets keep our feet on the ground. These charts r stil 240h away.

Morning, So ECM produces a stella run- just trumped by the GEM at 240 which is similar to last nights control run.Some disparity between the ECM & GFS this morning though - GFS not seeing much in the way of polar heights where as the ECM solid in the formation ( again 3rd run on the trot ) of a significant -AO index.The ECM at 240 sees a polar low zipping SE which would bring snow for many - but at this mere conjecture-Based on what *May* happen though the opportunity for a northerly with deep low heights (unstable) seems to be presenting itself and more importantly some signals that a disconnect between the stratospheric vortex and tropospheric pattern may be in the offering-Still similarities to the start of Dec 81 which has been regularly dismissed, but I will keep posting it as its my idea-SPS a comment on ian fs twitter ( I havent read it ) that the DECIDER models have been pretty wrong thus far in there assessments of the pattern returning to all things normal which is rather like the volatile nature & inaccuracies of the ECM DET 32