SMU

http://www.meteociel.fr/modeles/ecmwf/runs/2013120912/ECH1-240.GIF?09-0 The best ECM @ day 10 for some while - although day 10 a long way away!! At least something promising though.. S

Evening All- A disappointing few days model watching, what seemed so promising a week ago actually landed nothing more than a fleeting visit from old man Winter & Jack frost. We did get the scandi heights, but not the Scandi High- which sadly for us is a different scenario for the UK, with mild SW winds on the western flanks. Its going to be a while before we see any cold into the UK... S

When I first presented the Idea of a scandi high around a week ago, then over the few days leading up to that long post Monday the proposal was a ridge thrown into Scandi that gets cut off with undercutting, well I think that we do get the scandi high, however as MANY will agree, sometimes to get the cold to the UK ( Upper cold ) it sometimes takes 2 even 3 attempts & the third one is often linked in with a polar high- It seems that many may be looking at the wrong place on the maps - in terms of the azores low to undercut- Please remember this straight forward bit of info to get deep cold into the UL ( not just surface cold) you will only ever get undercutting & a sustainable high If there is a polar high to force a split in the jet ( or a Siberian high ridging west) to join the ridge in the atlantic moving NE- No polar high usually = a high that meanders around as a sceuro high- here are some examples of what to look for- Svalbard is the focal point. then the following charts http://modeles.meteociel.fr/modeles/reana/1947/archivesnh-1947-1-21-12-0.png http://modeles.meteociel.fr/modeles/reana/1947/archivesnh-1947-1-22-12-0.png http://modeles.meteociel.fr/modeles/reana/1947/archivesnh-1947-1-23-12-0.png Also, http://modeles.meteociel.fr/modeles/reana/1956/archivesnh-1956-1-28-12-0.png http://modeles.meteociel.fr/modeles/reana/1956/archivesnh-1956-1-29-12-0.png http://modeles.meteociel.fr/modeles/reana/1956/archivesnh-1956-1-30-12-0.png & finally http://modeles.meteociel.fr/modeles/reana/1987/archivesnh-1987-1-7-12-0.png http://modeles.meteociel.fr/modeles/reana/1987/archivesnh-1987-1-8-12-0.png http://modeles.meteociel.fr/modeles/reana/1987/archivesnh-1987-1-9-12-0.png So we shouldn't be looking SW we should be looking NE for the key indicators: Vertical ( or near vertical) ridging towards Svalbard Energy diving S/SE over scandi whilst the ridge builds on Northwards Polar heights ridging OVER the pole or from Russia to support the block & cut the atlantic off The ECM shows SOME of the signals tonight especially at 216 & 240 - but it does require that element of vertical advection Possibilities on the cross polar ridging. If you look at our chances they come at intervals 192 & 240 for better chances of deep cold. In summary tonight- A week of meandering southerly / SE flow with generally cold conditions at the surface especially for the England- My projected 'fun' maps were 13/14- but maybe it will be 14/15. The key being persistent spells of ridging up to the pole looks to be the start of the domino effect to cold down the line. However the stumbling block being if the advection is not quite northerly & any low moving up the blocking cuts off the conjoined highs by 'getting through the gap' & moves ESE into any wave of energy trying to come SW over scandi then its not going to happen..... S

Slowly but surely the models are backing North & Slightly west- We started 2 days ago with mostly a Euro high with the odd Sceuro block- now we have mostly Sceuro blocks with a few Scandi highs in the mix ( like GEM) THe models do not resolve energy moving SE through Scandi very well & usually catapult them towards Greece, then as T144 arrives the see less movement SE & start moving things SW- Can we get the full bifta full easterly- Possibly not, but remember the forecast is for a Scandi block- which if we get the right shape has the chance to retrograde back. Im sure of note tonight is the gradual moderation of warmer temps forecast- The Theta E charts show this well with the cold surface continental air trying to feedback in westwards http://modeles.meteociel.fr/modeles/gfs/runs/2013120418/gfs-6-138.png?18 - not quite getting there though. Also the Berlin ensembles beginning to create large scatter- once on the very Western periphery- now all of a sudden in the mix http://www.wetterzentrale.de/pics/MT8_Berlin_ens.png Poor ECM tonight & poor recent form, which now we are 24 hours away seemingly the GFS was closer to the mark, which is surprising but undeniable from the predicted outcome...... S

Who remembers the OLD days of forecasting Easterlies VIA the GFS ensembles Warsaw, Berlin, Copenhagen > London. You used to start with the Warsaw ensembles dropping through the floor & so on. Lets start with the Warsaw & Berlin Ensembles from 12z. Berlin- MEAN after the cold 3c. http://www.wetterzentrale.de/pics/MT8_Berlin_ens.png Warsaw- MEAN after the cold rising to 0c. http://www.wetterzentrale.de/pics/MT8_Warschau_ens.png Lets see what the 00z & 18z throw up- at least 1 will be cold. http://modeles.meteociel.fr/modeles/gens/run/gensnh-16-1-252.png?18 S

I must admit for me today has meant nothing- I expect a BIG swing towards more inflection in the atlantic tomorrow & a better Scandi high- Remember more inflection in the Atlantic will ensure more if not all energy goes under Scandi not over... just like the NAVGEM 18z has started http://www.meteociel.fr/modeles/navgeme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0 S

Good post GF- Look where the main clustering is- & the angle of the wind a you've done..... UKMO has classic split flow @ 144 & would see the ridge shooting towards Scandi @ 168.. S

Evening All- Missed all the days runs but I haven't missed much- ECM & OP at considerable odds with the MEAN clustering post day 10. I suggest that the models are being over generous with the zonal flow- http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=12 Its unusal to see the operational such a wild swing away from the MEAN> Best run of the day UKMO 144. http://www.meteociel.fr/ukmo/runs/2013120312/UN144-21.GIF?03-18 with the blue hole suddenly to become a yellow ridge over scandi. S

Cheers John - Et al for the comments- Finely poised tonight- fingers crossed for upgrades tomorrow- although probably a few pots of gold in the 18z runs- Who wants to start ensemble watch for -5c from the east for London!! Cheers Steve

Thanks for the comments ( around 2 hours for the post) Anyway- changes afoot on the GFS- Major- the jet looks like going over the Scandi low as opposed to under it this time around.... It will alter the post 192 projections - but possibly still to flat for a big easterly.... S

Evening All- Ive not replied to anything today- so sorry if ive missed anything important. A juicy post to get your teeth into before the 18z.- An honest evaluation of the model performance this week. So we are there now ( all but) - but the wide variations between the models have been removed & finally we have some unity with the best of it seemingly here at T84. http://www.meteociel.fr/modeles/jma/runs/2013120212/JN84-21.GIF?02-12 http://www.meteociel.fr/modeles/jma/runs/2013120212/JN84-7.GIF?02-12 into 96. Within this short window of 18-24 hours there is the prospect of storm force Northerly winds & heavy snow showers packing into Northern Scotland, western Scotland, NI & possibly NE Scotland- Im sure we will see a line of snow showers glancing the extreme east coast- but all staying offshore. Perhaps now we have allignment of sorts - todays a day to reflect on the Rollercoaster that has been the model output of the last few days. ECM- Very very strong consistency from the ECM, showing the Northerly pattern - in-fact the ECM has had the correct pattern type on Nov 26 @ 00z & 12z - but really got its act together on the 27th- Here are the ECMs for the last 5 days running 216 - 192 - 168 - 144 - 120 00z + 12z 216 chart 27th http://www.meteociel.fr/modeles/ecmwf/archives/2013112700/ECH1-216.GIF?00 SPOT ON http://www.meteociel.fr/modeles/ecmwf/archives/2013112712/ECH1-240.GIF?12 VERY GOOD 00z + 12z 192 Chart 28th http://www.meteociel.fr/modeles/ecmwf/archives/2013112800/ECH1-192.GIF?00 SPOT ON ( 100 miles to far west though) possibly slightly over amplified http://www.meteociel.fr/modeles/ecmwf/archives/2013112812/ECH1-192.GIF?12 EXCELLENT 00z + 12z 168 Chart 29th http://www.meteociel.fr/modeles/ecmwf/archives/2013112900/ECH1-168.GIF?00 V Close but to amplified at the SW Greenland tip http://www.meteociel.fr/modeles/ecmwf/archives/2013112912/ECH1-168.GIF?12 V Close but to amplified at the SW Greenland tip & to far west. 00z + 12z 144 chart 30th http://www.meteociel.fr/modeles/ecmwf/archives/2013113000/ECH1-144.GIF?00 V Close but as above- slightly to amplified & to far west 200 Miles. http://www.meteociel.fr/modeles/ecmwf/archives/2013113012/ECH1-144.GIF?12 V Close but eastward correction 100 miles - still to amplified. 00z + 12z 120 01st http://www.meteociel.fr/modeles/ecmwf/archives/2013120100/ECH1-120.GIF?00 Spot on barring the over amplification http://www.meteociel.fr/modeles/ecmwf/archives/2013120112/ECH1-120.GIF?12 Correction East, angle of amplification more NE instead of North- Looks to be spot on. 00z + 12z 96 2nd today http://www.meteociel.fr/modeles/ecmwf/archives/2013120200/ECH1-96.GIF?00 SPOT ON http://www.meteociel.fr/modeles/ecmwf/archives/2013120212/ECH1-96.GIF?12 12 hours later spot on.... ECM Summary : If you look at the GLOBAL Picture- back across the last 12 runs you will see it nailed it on the 26th - some 9 days out at 216.- that's the ridge in the Atlantic, Deep low digging south over the North sea, Aleutian Ridge moving SE downstream & a split flow over the states with a low in the Midwest. The ONLY area of fault on the NEW updated ECM has come from the area around the SW tip of Greenland & the speed of the solution- being slow & amplified, in-fact its not 'quite' been there & that subsequent swing to a faster solution has taken the amplification past the point when it no longer goes North, but ENE traversing the coast of southern Greenland. HERE What we are talking is an UNDER estimation of the Jet by a maybe a FEW M/S - The net correction is a 'slightly flatter pattern, a slightly eastward jog (200 miles is nothing in weather terms- but Massive for the UK) & of course 1 full less day of cold as there is no high pressure to traverse around the high but through it. We need to be clear though the ECM has never promised sustained HLB, just over amplified the ridge towards Greenland. Incidentally the ECM made a similar mistake the other week, that is- totally lick the GFS in the overall pattern but mistake the over amplification- which again has big repercussions for the UK- this was the model output ECM http://www.meteociel.fr/modeles/ecmwf/archives/2013111412/ECH1-144.GIF?12 Notice ridging into Greenland ACTUAL Varification: http://www.meteociel.fr/modeles/ecmwf/archives/2013112312/ECH1-48.GIF?12 - Notice the flatter upstream pattern- right in the place it hurts for us. What to take away from the ECM for the rest of Winter, ECM is the leading model over the GFS, it licked the 500 MB pattern 9 days in advance & has stuck with it run after run all the way through, however around the Iceland region it 'sees' more ridging than perhaps is going to happen- there's not many places in the globe that the extra amplification matters, however at the southern tip of Greenland there comes a cut off where systems all of sudden STOP going North & suddenly start going East- this through an angle of 90 degrees.- so a SMALL error / bias which would normally swing from say 10 degrees to a ever so slightly flatter 20 degrees to the North is suddenly swung from 0 degrees North to nearly 90 degrees East. This pattern change has a direct impact on the sustainability on UK cold as it shortens the cold & reduces the westerly penetration of cold- This small error is some peoples eyes is a huge error- hence the calls for the ECM being trounced / its failed its followed the GFS etc etc- No the model error is small but the visible impact to the UK is huge.- so the perception is skewed towards a thought process that the model is rubbish. Its not- its king with a bias just like nearly all the models. In terms of the rest of the Winter wit the ECM I will generally STILL run with this model - why? because the Hemispheric pattern for the last 4 years has been heavily loaded towards Northern blocking so fortunately the ECM bias hasn't been visible due the conditions actually supporting the bias, however this winter thus far that bias has made it look a little foolish - when actually its performed superb. So for Future budding cold spells look towards Southern Greenland to see if there is any low pressure or shortwave action that is the key trigger - as this may be to slow & to far west in the ECMS eyes- then as it corrects east the low slips east of the tip rather than South. SW GREENLAND = CRUCIAL TO THE UK COLD. The GFS model... ( Links are the 12z & 00z model only) What can I say about the GFS ..... well in the name of balance when the ECM at 216 was picking up the pattern for spot on the GFS was here- 216 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112700-0-216.png?0 Very good but to flat with the US pattern http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112712-0-216.png?12 VERY GOOD 192 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112800-0-192.png?0 Pretty good but upstream Midwest low very fast ejecting out to pole http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112812-0-192.png?12 AWFUL AWFUL look at the eastward bias in all its glory our northerly it over into Germany 168 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112900-0-168.png?0 Not bad- pretty close upstream http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013112912-0-168.png?12 POOR AGAIN- look at that bowling ball low to the NE- but like all the other runs to Greenland ridging 144 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013113000-0-144.png?0 V Poor but very flat- +4c isotherm across England some 14 degrees to warm @ 850. http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013113012-0-144.png?12 Poor again- to far EAST - England has zero cold air. - Eastward bias evident again. 120 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013120100-0-120.png?0 Pretty good ticks all the right boxes. http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013120112-0-120.png?12 Slightly to far east again but catching up & westward correcting. 96 00z & 12z http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013120200-0-96.png?0 SPOT ON http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013120212-0-90.png?12 SPOT ON. GFS SUMMARY Why do I personally Hate the GFS- because its always playing catch up to the EUROS, Its always flat when the Euros show an amplified pattern so is wrong nearly every time we get a Scandi or Greenland high. We get 4 runs a day- which If I overlaid all the other 12 runs would show a multitude of scenarios, some at the extreme eastern end of the range, some over amplified ( looks like the 18z is usually the pub run) & some just on some wild tangent- usually the 06z. Should I dismiss it- well I'm going to change my tact on GFS, what the faster flat pattern helps to show is usually the opposite of the pendulum, If the ECM is at the slowest amplified end then you can bet your bottom dollar that the GFS will be the flattest, with this in mind quite often the final solution is a blend of each- the halfway house- but normally not quite halfway to the GFS, more like 1 third to the GFS & 2 thirds of the EUROS- From this you could generate a predicted forecast, but with one very difficult element & that is does the 2 third house create any pinch points that could change the final pattern so drastically for the UK- 2 main areas arise from this- ( For UK cold)- Southern tip of Greenland energy is 1 & the other is when we are setting up Easterlies & low pressures are projected to move south then SW whilst the ridge builds above.- The fast solution ( GFS ) will throw the low pressure further into Europe - but the bigger impact on the long-wave pattern is instead of a Scandi High you see a 'Sceuro' high, with the UK in a southerly or SE flow & the jet to flat on top. Then as the Easterly approaches its how far does the GFS move to ECM where the Sceuro is suddenly a Scandi high again because the solution was in-fact slower. This example is VERY evident tonight. GFS SCEURO HIGH- http://modeles.meteociel.fr/modeles/gfs/runs/2013120212/gfsnh-0-192.png?12 JMA Scandi high -http://www.meteociel.fr/modeles/jma/runs/2013120212/JN192-21.GIF?02-12 This all comes from FAST v SLOW solutions. Anyway, what to take away from the GFS- 12z Eastward bias. IGNORE- if its significantly FLATTER or EAST than the ECM. 6z/18z . IGNORE - if its significantly different to the ECM. 00z- do not discount- I cannot find to many faults with the 00z GFS- not biased in many ways & generally the most consistent. What we can also take away is the GFS will find the weaknesses in the blocking first ( usually) because its primed for a faster solution- so that can support us going forward with comparisons with the ECM. The model that's come out best again is the UKMO- resilient & Smooth, seemless & minimal fuss. In this case it started at 144 with the 2 thirds house & has never changed since. The Scandi High.......... I'm pleased that I presented this idea first ( even Mr Holmes questioned the 500 heights not following ANY ridging to Scandi) The forecast was driven by the angle of the jet coming out of Canada & the subsequent split flow- It is now appearing in the models- So what would be tonights forecast- based on the ABOVE model inconsistencies. GFS- 12z 240- Slight amplification - http://modeles.meteociel.fr/modeles/gfs/runs/2013120212/gfsnh-0-240.png?12 But a Euro high- Mild SW winds for the UK. ECM 240 12z Much better amplification http://www.meteociel.fr/modeles/ecmwf/runs/2013120212/ECH1-240.GIF?02-0 KEEN ESE wind & very cold at the surface, - JMA 192- Run of the day http://www.meteociel.fr/modeles/jma/runs/2013120212/JN192-21.GIF?02-12 Easterly @ 216 GEM 240 - AWSOME http://modeles.meteociel.fr/modeles/gem/runs/2013120212/gemnh-0-240.png?12 But... the Best suite of the day is the ECM 15 day. 00z Chilly http://www.knmi.nl/library/php/resample_image.php?filename=/exp/pluim/Data/pluim_06260_0_00_60.png&width=692 day 11/12 mean around 4c. 12z very much colder http://www.knmi.nl/library/php/resample_image.php?filename=/exp/pluim/Data/pluim_06260_0_12_60.png&width=692 ( swop to 12z) Day 11/12 mean now down to 2.5c & the control + op very cold. Therefor the updated forecast based apon the model bias today is- Northerly toppler, for 24 hours, high pressure ridging over the top but contrary to the GFS no WAA getting into the UK barring the extreme NW - The SE staying cold- day 8 -9 look for Energy dropping south into scandi in the form of a shallow low- with rapid pressure building NE, the UK sitting at the extreme western end of blocking for day 9/10.- light Southerly or SE tug. Then energy getting underneath tugging the winds easterly & increasing day 12. Look out for the Maps for 13/14 December. best regards Steve

Morning Mucka the wave at 168 on the ECM is perfectly placed as it becomes the trigger low as pressure builds on its northern flank- Should be a great run this morning- S

If they didn't make a difference they wouldn't have made a whole page about it!!! I don't know why they haven't rectified it- however the bias DOES make a big difference in amplified situations especially for the NW part of Europe- Perhaps NCEP don't care about the UK, or possibly rather than fix it they just buy the ECMWF package for around 50k.... Its cheaper. I hope they finish with it soon- I will buy it off ebay S

LOL- I will take the ECM!! So 18z- who can spot the trough at T90.... http://modeles.meteociel.fr/modeles/gfs/runs/2013120118/gfsnh-0-90.png?18 S

Eastward bias my friend- ..... So before any one else thinks I make it up- whos got the link to the NCEP model bias page- S

http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/EDM1-216.GIF?01-0 ECM Mean @ 216 a lot more Scandi blocked than the 00z- Expect more runs to drop after day 12 in the ensemble suite.... S

http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/ECH1-240.GIF?01-0 So then, close but not quite- however working in the right direction- All in all satisfied with tonights outputs V prediction- PLENTY of time for that high to be further North rather like the UKMO projection. S

http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/ECH1-168.GIF?01-0 Ridging into Scandi @ 168 with the -4c line just holding in kent- S

ECM @ 144 identical to the UKMO Downstream but a few upstream discrepancies- However 850s @ day 3 of the cold. http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/ECF0-144.GIF?01-0 Still -9c for England with -10c in Scotland.... Can we get enough orbit of the high to keep the -5c line in the SE at 168 as that the first step forward!S

UKMO & ECM identical @ 120 today- so we are more or less there now- http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/ECF0-120.GIF?01-0 A light edge off the base uppers now @ -9c, however 144 will see similar values over the UK. IF ECM looks like the UKMO 144 tonight expect to see a big fat Scandi high at 240.......... S

Ian Any chance of the UKMO 168 snippet tonight-/ Image- or commentary whether the ridging is looking good for Scandi heights- thanks Steve

http://www.meteociel.fr/modeles/ecmwf/runs/2013120112/ECH1-96.GIF?01-0 ECM 96 - still on track. Remember the northerly will be VERY cold- but mainly dry away from the North. Lets get the cold & frost in & then something more wintry from the East hopefully... Small nuances between UKMO will impact the OVERALL pattern very little- East / West doesn't really matter- infact all it means NET is that the SW wont be as cold. S

Not so good 12z UKMO- could be a good METO call on the slightly faster solution- which is around 200 Miles further East http://www.meteociel.fr/ukmo/runs/2013120112/UN144-21.GIF?01-17 Nice 144 sees scandi Ridging still evident, Huge pool of cold air just over to the continent. http://www.meteociel.fr/ukmo/runs/2013120112/UN144-7.GIF?01-17 S

People can I just comment- The MET office will go with the data they have, which as highlighted by Ian at this early stage they highlight a NW/ SE split in the day 10-15 Means, this is all you can expect- They will not go on record at day 10 & say the beast from the East is going to arrive... Remember the models are just getting to grips with the speed of the first solution, which has a net effect on the wave amplitude on the second possible ridging towards scandi Get phase 1 sorted first & then the next phase will evolve- * IF* the wave is significant enough the MOGREPS / EC/ GFS ensembles will gradually swing to a more substantial cold outlook- just like the GFS ensembles have ( NB: ensemble watch) this week... S

They are referring to the speed of the solutions to change and the amplitude of the wave.Slow = win.ECM operational expected to resolve this better-Terrier as ever your barking up the wrong tree