SMU

Cheers Steve 168 may look a toppler @ first but keep an eye on the blocking over Western Greenland redeveloping as the low slides south http://www.meteociel.fr/modeles/ecmwf/runs/2015012712/ECH1-168.GIF?27-0

Because the troughs are a link in the flow as a opposed to a closed system we will probably get minimal onshore flow from the east - so minimal mixing- although extreme NE coastline may be effected. 144 chart - very good but not quite as good as UKMO http://www.meteociel.fr/modeles/ecmwf/runs/2015012712/ECH1-144.GIF?27-0 S -EPO ridge is just a teleconnective pattern that has high pressure over Alaska into the pole. ( a bit like say the -NAO) The more blocking into the pole the weaker the westerlies become..

A band of snow moving down the east on day 4-5 on the ECM with the very cold uppers penetrating south behind it http://www.meteociel.fr/modeles/ecmwf/runs/2015012712/ECU0-120.GIF?27-0 -9c in the north chasing the -6c line that's exiting the south. Dewpoints subzero everywhere- 516 DAM thickness touching Shetland 520 DAM in the NE 524 DAM in the South. all parameters condusive to snow. S

Wow - UKMO 144-!!!!!!! Where did the EPO- ridge appear from !!!!!! Surprised no one has noticed- UKMO ! GFS The UKMO would certainly slow the eastward progression down due to the 2 wave pattern being progged.- the UKMO is the best run thus far- S

Ive just revisited the thread - why is everyone suicidal- its looking very good, initial flurries tomorrow night then potentially the main event for the weekend-! S

Morning all Fantastic looking charts for the short & mid term today - However the trending past 168 hasnt been so kind to as overnight- Still plenty of wiggle room for those to change A high expectation of most seeing some of the white stuff this week & if the fronts become a little slow moving then maybe even some covering! Fingers crossed for better updates on the 12s S

Found this on YT http://www.youtube.com/watch?v=XGopWqBzpCs&spfreload=1

Just tapping away on phone ECM 144 looks potentially great with the icelandic shortwave looking alligned SSE to crosd the uk with ridging behind Could be good.....

good stuff- We should start seeing some pinks across the SE on the Euro 4 from the 00z run.... ECM to 72 has -6c uppers remaining in the SE http://www.meteociel.fr/modeles/ecmwf/runs/2015012612/ECU0-72.GIF S

& its back in the regional thread... so when the front clears weds eve- expect a dramatic drop of air & dewpoint from +8c to -3c 12pm Weds http://modeles2.meteociel.fr/modeles_gfs/runs/2015012612/48-101UK.GIF?26-12 15PM Weds http://modeles2.meteociel.fr/modeles_gfs/runs/2015012612/51-101UK.GIF?26-12 overnight temps plummet in clear air before a period of snow moves in http://modeles2.meteociel.fr/modeles_gfs/runs/2015012612/60-779UK.GIF?26-12 May well give a dusting- at least the first meaningful snow falling for 2 years. Post that, UKMO brings us a potent arctic blast that would certainly again see snow falling across the region.- At that point we need a bit of timing & luck to see snow cover- The best 850 GFS chart for some time http://modeles2.meteociel.fr/modeles_gfs/runs/2015012612/198-7UK.GIF?26-12 deep cold uppers ( -11c) spreading south- very negative dewpoints- so any PPN falling would be snow. Looking nice at this stage... S

Yep pretty poor overnights its got to be said ( away from the mid term excitement from the UKMO et al) So some potential within the week with varying degrees of intensity, & still of course the chance of upgrades down the line 192-216 although the jet allignment doesnt look ideal. Chances of a greenland high almost zero.- as has been from the start, the only chance of anything sustainable is from the North East. S

Indeed- ^^ UKMO Tops there better than ECM over the last 31 days however it is HN... Anyway heres the blocker to the Northerly deep cold on the GFS which isn't on the euros- http://modeles.meteociel.fr/modeles/gfs/runs/2015012512/gfs-0-102.png?12 note the 960 low over Scotland - what this does is - in its position west of Scotland it blocks the cold air from flooding south & forces it away south West into the atlantic- The ECM & UKMO are cleaner, keeping it east of the UK http://www.meteociel.fr/ukmo/runs/2015012512/UW120-21.GIF?25-17 So if your looking for why / If the deeper cold is coming look in that area!! S & yes RJBW great reference post to this chart- http://modeles.meteociel.fr/modeles/reana/2010/archives-2010-12-18-12-0.png

Just one to add - When we saw the PPN in the cold air last week we were really scratching around with dewpoints @ between -0.5 & +0.5 / +1 making it very marginal- The depth of the cold front clearing through weds night has a clear deep polar signal with a strong cold dewpoint line all the way from the south coast to the North! - its clearly visible here http://modeles2.meteociel.fr/modeles_gfs/runs/2015012512/78-101UK.GIF?25-12 This very dry air will help quickly reduce surface temps to freezing- Theta chart http://modeles.meteociel.fr/modeles/gfs/runs/2015012512/gfs-6-90.png?12 10c & uppers http://modeles.meteociel.fr/modeles/gfs/runs/2015012512/gfs-1-84.png?12 -6/-7 At T90 a band of SNOW - not rain & sleet looks to slide across the south. In terms of probability of falling & possible settling snow- its the south of englands best chance this winter ( also the showers piling into the NW as well- which of course will be snow ) ENJOY- S He needs to lower it a few DAM for the UKMO 144!!!

SK -that's the 06z 850 thicknesses - was awaiting the 12z to see if they were sub 1290 D S

Edit : UKMO 144 http://www.meteociel.fr/ukmo/runs/2015012512/UW144-21.GIF?25-17 A Marked trough over the UK bringing very wintry conditions- very similar to the thundersnow event in terms of synoptics S

GFS hinting at some snow even into the south west overnight weds with the parameters staying on the right side of marginal.... I will update what they show when the Hi- Res updates shortly... Post that- this is a very very good chart for a multitude of reasons- http://modeles.meteociel.fr/modeles/gfs/runs/2015012512/gfsnh-0-144.png?12 * Easterly undercut into the Low * Very low heights - @ 500 MB * Thickness circa 528 DAM * Better alignment of ridging towards Greenland! *A possible snow event for the South & SW- S

A quick entry from me- more later The ECM today portrays a scenario of getting colder & colder across the UK, I suspect the temps across the days will mean out about 3-6 at day 5, & then drop off around a degree or so each day, so by day 8 on the ECM the UK looks more like -1C to 3C across the PISTE... Certainly upgrades in the prognosis over the last 36 hours, MAINLY due to the 2 day toppler suddenly becoming something more substanstial with the first toppler low missing the UK & the flow behind it becoming more amplified. Now that things are coming into view- probably the best chance of a more widespread snow event across the UK with trough features coming down from the North- Again though- not for the first time this year - it looks great for the far north- I imagine parts of scotland still have reasonable snowcover from the last event- Can we get to day 10 today on the 12's & see the cold extended further with the high ridging over the top.... S PS lets see of we can get a better alligned flow at 192 -216 today to drag the -10c line across the UK...

Looks Nice tonight - ECM Reminds me of jan 2004 IIRC- thundersnow lol In terms of the ECM, it manages a fine balance ( very rare in the UK ) of established Northerly winds & a jet that stays attenuated enough to keep us in the cold air for more than 2 days. It does still feel a little 'optimistic' especially after 168 with 2 reloads & no eastward progression from the Atlantic however a couple of amazing charts... one for the UK- http://www.meteociel.fr/modeles/ecmwf/runs/2015012412/ECU1-144.GIF?24-0 possible frontal snow- rare as turkey teeth http://www.meteociel.fr/modeles/ecmwf/runs/2015012412/ECU1-216.GIF?24-0 More frontal snow for the NE however this all superseded by the bowling ball cold cover the Whole eastern seaboard of America... day after tomorrow stuff!!!! http://www.meteociel.fr/modeles/ecmwf/runs/2015012412/ECH0-240.GIF?24-0 Certainly an uptick in optimism tonight- although still 'noise' around longevity -- however all models have hinted that a reload of some sorts is likely with the first atlantic attack taken away to the SW of the UK S Not quite conceding defeat, however the angle of the low & shape was preventing any true cold air coming south- luckily the ECMs view today has certainly sharpened up the flow to suitable levels- IE sub -6c S

Reviewing the ECM 144 it has * A trough moving south over the uk ( look at the kink ) * low heights - circa 500mb thickness ~ 524 dam * low uppers over england - as low as -8c in the SE Thats certainly has wintry potential!! s

The thickness is related to the pressure contours so whilst the heights are lower ( ECM + GFS look around 512 ) once you calculate the fact thats along the 985 MB line- tthickness usually evens out to around the 524-528 line as we would expect. Not much support for the ECM operational along the MEAN with a flatter pattern @ 240 over Greenland- so I suspect that will be the order of play- however not conclusive at this stage- S

Morning A better ECM today- however we have been here before this winter- almost the exact same synoptics that failed to land- The model trying to deliver a wave 2 pattern, however with modest heights over greenland there isnt enough blocking to sustain a Northerly, but with the 552 Line making it to Greenland, toppling High pressure towards Scandi might be an option. Not overly cold on the ECM however an improving picture as at least the higher pressure is driving more CAA- In terms of Omega block, im afraid not & still unlikely with no blocking over GH.] S

Ha ha the turkey teeth is certainly present in the GFS 18z tonight as we see the -10c line arrive in the uk in FI If we look close the GFS follows the ECMs lead at 240 with ridging north - west of greenland , which I do believe I did comment on in the original post S

Ha Ha Chiono I remember that - i think 2+ years ago now - i think id just given up. Maybe end feb 13- Anyway gfs out to 180 only -4 across the UK Remember no blocking high = limited scope of CAA Maybe things will develop favourably in FI S

I think some need to temper their expectations from what the models are showing, thus far there is certainly no nationwide event progged, the reality is if your just taking a snapshot of the uppers you will see that 5 days of cold air looks great- However once you take out the 2 days for mainland UK that it takes to mix the cold air down to the surface ( & it isnt true polar fed air ) its moderated polar air- hence the slightly higher uppers - Also the instability window will be eroded away from the west as we progress - So essentially 3 days of potential, mainly focussed on the NW & of course Scotand....- Perhaps the NE as well- also the cheshire gap etc etc As for temps- no chance of ice days- people in the SW will probably still return up to 5c & for most of england 3-4c which is warmer than its been in the last cold spell. The ECM offers the best 'get out of jail card' at day 10 another surge of heights alligned to western greenland, with ridging over the pole & Russia all could allign favourably- however as it stands I wouldnt bother getting excited just because theres some dark blue over the UK... its a mainly scotland & northern england event..... S there is no link, as you can see the residual jet flow across that gap.

Hi Tamara - A nicely put post, however this winter thus far hasn't delivered ANY of the expectation laid out by the winter forecasts of indeed any of the hype / analysis presented in the stratosphere thread either- A few flirts with a 2 wave pattern in December which didn't land either- A lesson to everyone that the modelling of the stratosphere & even then the downwelling & coupling of Strat V trop doesn't always deliver. Also I don't think barring maybe 1 or 2 runs that the GFS has modelled any Greenland heights this winter, its been 100% mobility all the way- The OPI has been wrong & along with it Cohens forecast, ( & of course mine + NW & the idiot Madden who forecasts the same thing every winter ) A very muted signal for Northern blocking which may improve into Feb, although its not the favourite as it stands... S