Model Output Discussion - 05/01/2016 18z onwards

[chris55]

ECM looks great this morning. Thursday's little low has the potential to deliver snow on its northern edge and this feature has bee relatively consistent. Thereafter into the weekend it would be very cold with hard frosts and crisp sunny days.

GFS was a mild outlier and that signal, although possible looks less likely.

[The PIT]

Hopefully GFS is an outlier but the general trend is still towards a less colder outlook than originally thought.  The  Beeb forecast this morning also had a subtle change of wording as well.

[snowblizzard]

8 hours ago, nick sussex said:

Sadly the second one is yesterdays! The first one isn't too bad but when the new T120hrs updates that will probably look more like the UKMO raw output. Anyway given the UKMO performance over the last few days the less said about it the better!

Last nights forecast charts with Helen Willetts looked very similar to the fax Nick!

She mentioned it will be notably colder next week with some sleet or snow showers in places and Scandinavian block should stop moisture laden lows from Atlantic , so hopefully drier for flooded area's!

Jet digging South!

Much uncertainty about track of mid-week low to the South of UK but computer showed it tracking through Dover Straights into North Sea.

Could be further North or South!

But, It all looks further West on the latest Fax charts this morning.

Perhaps not game totally over just yet?

Edited January 9, 2016 by snowblizzard

[Duane S.]

Some of the chart ouputs are hilarious, especially the GFS. I have never seen such an incoherent mess. Mesoscale systems popping up here there and everywhere and ambling off in various directions, others lingering like a bad smell.

The FAX charts are probably going to be best guidance but even these are going to be far from infallible with the start data issues being reported at the moment.

The ECM catches my attention with the low approach from the SW next Thursday. If that theme continues, it will get very interesting as in amongst the variations on exactly how that would play out is a massive snow event for anywhere in the UK.

 

[IDO]

Well we have resolved the Greenland High longevity with the slow learners (UKMO and GEM) getting on the right page.

The next question is the high that develops from the WAA coming from the ex-Bermuda LP? How strong will this be and how slow to push east. The GFS op is very progressive and in normal circumstances I would call it out, but the OP has indeed led the way with the changes over the last few days so hesitant to do that at the moment. The GEFS mean is supportive of the ECM op:

ECM D10 T850s  GEFS mean at D10: 

Best to favour cold hanging on till D10 but caution as to how the GEFS develop next few runs.

That spin off low around D5-6 was first spotted by ECM and the GEFS had little support yesterday, but there is now 50% support, though track and snow potential vary at this range. It can now be seen on the mean at T114 just to the SW:

  

^^^ Snow chances in the south peeked at 30% but are rather mute on the 0z, though early days, but a trend would be nice.

So temps wise in the south (ignoring the GFS op) would be max's around 5c for a week or so, but colder than that for most of the day and night with variations within micro-climates. Certainly no ~ice age~ but will be a bit of a shock from December's warmth!

From D10 its difficult to know, the ECM NH profile is promising with a hint of a 3 wave attack (D10 so usual caveats) and with background signals likely to appear on the radar, best leave that to the experts. Again some warming in the strat, but this is way out in FI and at the moment never really gets closer, so an SSW looks like for March rather than Feb IMO, if it happens:

Hopefully today's runs will confirm at least a week of cold.

Edited January 9, 2016 by IDO

[bluearmy]

Still no faith in the operational output. 

Note that ecm from day 6 through 10 has the main chunk of vortex over the pole. This at a time when the AO is supposed to be neg 4/5 rising slowly to neg 2 on the ens. Technically, the op still has a neg AO through that period but no sign on the ens mean that we should see that vortex astride the pole for 5 days. 

Best to ignore the macro scale post day 5 on this run IMO and given that the micro scale isn't worth analysis on ops post day 6, not sure what purpose this op serves (other than to show decent snow over across the east of the country)

Edited January 9, 2016 by bluearmy

[Frosty.]

 The models are showing gradually colder weather next week with showers and longer spells of rain with snow on hills and to lower levels at times, especially after midweek. The risk of ice and frosts increases too, especially through the second half of next week with the Ecm 00z indicating there will be some very frosty nights towards the end of next week and particularly early into the following week as high pressure becomes centred over the UK. There is a lot of uncertainty in the outlook from midweek onwards but in our current position I would happily take what the ecm is showing but whatever happens, next week will become colder than most of us have seen so far this winter and lots of options are still on the table as we look further ahead...hopefully the wintry kind will win!!

 

 

Edited January 9, 2016 by Frosty.

[Man With Beard]

Amidst all the chaos, one theme is gaining traction - Thursday looks like a good day for a snowfall. Almost all models have some sort of feature crossing the UK at that time, and few have the mild sector anymore (though of course that could reappear yet). 

Central areas currently the main target, but far too early for such details. 

Runs such as ECM 00Z would probably allow any snow cover to remain on the ground for a few days after.

[Severe Siberian icy blast]

33 minutes ago, s4lancia said:

Some of the chart ouputs are hilarious, especially the GFS. I have never seen such an incoherent mess. Mesoscale systems popping up here there and everywhere and ambling off in various directions, others lingering like a bad smell.

The FAX charts are probably going to be best guidance but even these are going to be far from infallible with the start data issues being reported at the moment.

The ECM catches my attention with the low approach from the SW next Thursday. If that theme continues, it will get very interesting as in amongst the variations on exactly how that would play out is a massive snow event for anywhere in the UK.

 

Absolutely agree . Anything after t120 just for speculation . And perhaps trends . 

A much better UKMOand ECM this morning . The high pressure on the ecm moving north certainly has the 'potential' to drift  northwards  . Whether that's east/west/ or directly above us remains to be seen . Or if at all . Very scatty across the board for the last 3 days or so . So let's enjoy next week . Poss snow event on Thurs.  Plus any disturbances/troughs in the flow before then have the potential to be wintry.  Particularly at night . 

[Polar Maritime]

Here's the NetWx - MR model for Thursday, Snow showers over the Spine of the country into the North Midlands with -7 850 uppers over the UK. It really will feel cold to what we have been used to of late with a biting Northerly wind-chill, And night time temps falling to -5/-6c and even colder in rural areas. Wrap up warm!

Edited January 9, 2016 by Polar Maritime

[northwestsnow]

Some really excellent posts this morning

As others have said, its so complex i really dont know what to think moving forward.

As it stands some will see snow next week, ecm offers the best hope i would have thought,and if ecm is anywhere near the mark the snow should hang around through the weekend as we get trapped under a cold high.

Im wary of GFS though, it takes an age to get the colder uppers in and then sweeps them away rapidly,err, no thanks GFS.

Buzzword at the moment though has to be shannon, there must be high entropy at the moment with all the bits of energy flying around FI is till 96 imo.

[Liam J]

1080mb over Greenland @ T84 on the JMA @Greenland1080

[northwestsnow]

6 minutes ago, Polar Maritime said:

Here's the NetWx - MR model for Thursday, Snow showers over the Spine of the country into the North Midlands with -7 850 uppers over the UK. It really will feel cold to what we have been used to of late with a biting Northerly wind-chill, And night time temps falling to -5/-6c and even colder in rural areas. Wrap up warm!

Nice post PM- looks similar to ECM op i suspect.Certainly thursday looks the more promising day/night but im not entirely sure i trust anything post 72hrs at the moment

[Cloud 10]

5 minutes ago, *Sub*Zero* said:

1080mb over Greenland @ T84 on the JMA @Greenland1080

 

 

Well done Sylvain!

 

 

GFS 00z op run is a huge outlier especially the further north you go.

 

[West is Best]

There are, indeed, many very good posts this morning and it's great that we have waited for the ensembles. Otherwise the mystery of GFS vs UKMO / ECM et. al. would be deeper. As it is, the GFS operational is an outlier. That doesn't mean it's wrong but at least it means we can hold onto  hope that the European models have this right.

Sometimes GFS ops in these scenarios gets it spot on. Other times the GFS fails to pick up the signals for blocking pattern changes. It's a very west-to-east dominated model still, which is fair play as that's the norm, but doesn't always handle these setups. It'll be interesting to see if it throws an operational into the mix that are opposite to the 0z. It wouldn't surprise me.

Game still on for something fairly prolonged. Meantime, a colder snap including some potential fun on Thursday is fairly locked in.

Edited January 9, 2016 by West is Best

[snowice]

12 minutes ago, *Sub*Zero* said:

1080mb over Greenland @ T84 on the JMA @Greenland1080

Well that would be close to a world record! 1084.4 in Asia in 2001?

[bluearmy]

Ecm control is close to the op - even with the small shortwave dropping down the east in fi. high pressure dominated through to day 15.  No cold easterly develops but likely to be surface cold. 

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON SATURDAY JAN 9TH 2016

THE CURRENT GENERAL SITUATION   A deep and complex area of Low pressure will move slowly east into the British isles today and tomorrow with bands of showery rain  circulating North and East across the UK at various times through the period.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the British Isles lies between 1700ft asl over Scotland to nearer 5000ft across Southern England. Snow is expected across Scottish and Northern English hills today, tonight and tomorrow.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE  Becoming colder and still rather unsettled with some rain, sleet or snow at times and frost at night.

THE GFS JET STREAM FORECAST  The main theme of the Jet Stream today shows the Jet Stream continuing to stream East across Southern England and France over the first week before slowly returning to a more Northerly latitude later, still in a generally West to East movement.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows unsettled conditions throughout the period this morning. The Low pressure complex currently to the West of the UK will move East across the UK through the weekend and the first half of next week. Colder air will seep South to all of the UK with a mix of rain, sleet and snow at times for all, the snow chiefly over the higher ground and in the North. Then late next week and through Week 2 a more changeable but less cold period develops as winds turn back to a west or SW direction with rain at times and temperatures returning to near average or somewhat above at times.

GFS CONTROL RUN The theme of the Control Run is very similar to the Operational run with the first week seeing some chilly weather with rain at times, turning to snow over higher ground. Then on this run the second half of the run will see more changeable conditions with temperatures near to average and dry weather outweighing occasional wet spells as High pressure areas close to the South at times interrupt the passage of Low pressure.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

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

UKMO The UKMO today shows Low pressure remaining in control of the UK weather next week, largely positioned over the UK with showers or longer spells of rain and colder air too will see this turning to sleet and snow at times especially on the higher ground and in the North.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show complex Low pressure and troughing slow to clear to the east of the UK early next week with rather cold and unsettled weather with rain and snow at times almost anywhere.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM this morning brings colder conditions across the UK next week too behind complex Low pressure moving East out of the UK early in the week. The theme then is for a very slow transition to drier weather as High pressure edges across from the SW before things become less cold and changeable again over next weekend and the start to the second week as winds turn more Westerly across the UK.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM keeps rather cold and showery weather next week with some snow showers over higher ground almost anywhere through the week. High pressure gradually builds across the UK by next weekend with frosts at night in places..

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM today shows unsettled and relatively cold weather next week with showers or longer spells of rain, sleet or snow as Low pressure continues to meander around over or close to the UK before slowly shifting away East later next week and next weekend as High pressure builds strongly later in the run leading to a change to fine, cold and frosty weather to end the period.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The 10 day mean chart shows a fairly slack pattern overall with the highest pressure near the UK suggesting a drier spell developing next weekend with fine weather and frost at night with daytime temperatures just a little below average at worst.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme of the output shows a slow transitions to drier conditions later next week with less cold conditions returning later in the extended outlooks.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO  and GFS at 96.5 pts respectively.  At 3 days ECM is leading with 97.6 pts to UKMO's 96.8 pts while GFS lags behind at 96.4 pts. At 5 days ECM leads with 90.2 pts to UKMO at 88.0 pts then GFS at 87.6 pts. Then at 8 Days ECM still leads at 66.7 pts over GFS's 64.1 pts. Finally at Day 10 ECM is ahead of GFS at 48.7 pts to 47.6 pts respectively. 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS   Evolutions between the models continue to differ somewhat in the longer term outputs this morning although there is some common ground showing up in amongst the differences. Firstly the heights over Greenland shown strongly earlier this week have all but vanished by later next week and which means to maintain cold across the UK we have to rely on the very cold conditions currently over some of Europe warding off the Atlantic. In the short term we still have several days of unsettled and often wet weather with snowfall restricted to the higher Northern elevations and flooding remains an issue I'm afraid for a while yet. Through the early days of next week the Low pressure complex across the UK delivering all this rain will edge away to the east but it looks a slow and arduous process keeping unsettled conditions for many right out towards next weekend. With winds flowing down from a more Northerly sourced direction more and more of us will see some snow in the precipitation and while Southern parts should not see to many problems from this Northern high ground and perhaps very locally in the South may see some lying snow and as the week progresses frosts at night will become more coherent for many. Then by next weekend it looks like High pressure will develop close to or over the UK with a welcome change to fine and dry conditions with sharp overnight frosts and a chance for the wet areas to dry out. Longer term models then show the most favoured option is for milder Atlantic winds to move back across the UK from the west with rain at times but I should note that while Europe remains cold any milder weather may have a job to fight through the cold air to our East and I expect more developments for this period of time to be toyed with in the models over the coming days. So summarising finally we should still be seeing some cold and unsettled conditions next week and many will see a little snow before things dry out and gradually become less cold again thereafter, all this a marked improvement on the extremely mild and wet conditions a while ago.

Next Update on Sunday January 10th 2016 at 09:00 approx 

[Nick F]

Plenty of snow potential from the 00z ECM high res on Thurs/Fri/Sat next week, even in the south, as a low moves SE across the north on Thursday dragging in cold air with it and merges with the low coming up from the Azores, snow potential becoming confined to the east Fri/Sat as low pressure slides into the Low Countries and another low slides down the east coast.

But as others mention, low confidence over detail from mid-week, as the models disagree so much over the low coming across the north Thurs/Fri and that low coming up from the Azores.

00z EPS mean has high pressure signal for the UK in the extended, the control also has HP building NE across the UK.

Edited January 9, 2016 by Nick F

[nick sussex]

I should add to my previous post NCEP have commented on a lot of uncertainty regarding northern and southern jet stream interaction in the USA.

In our case we want that interaction near the eastern USA, its this which is different between the ECM versus the GFS/UKMO. The former interacts those the latter don't.

[northwestsnow]

2 minutes ago, Nick F said:

Plenty of snow potential from the 00z ECM high res on Thurs/Fri/Sat next week, even in the south, as a low moves SE across the north on Thursday dragging in cold air with it and merges with the low coming up from the Azores, snow potential becoming confined to the east Fri/Sat as low pressure slides into the Low Countries and another low slides down the east coast.

But as others mention, low confidence over detail from mid-week, as the models disagree so much over the low coming across the north Thurs/Fri and that low coming up from the Azores.

Thanks Nick 

ECM looks really good for some snowfall almost anywhere, a good shout of snow sticking around through the weekend  and i would suggest some really cold minima under the high across the snowfields, my non expert stab for sweet spot, the midlands

[Singularity]

I do think we need to be careful what we assume to be resolved. Unreliable probably starts as early as +72 and perhaps before than for GFS if it's still doing that weird MJO flip. The AAM outlook certainly hasn't got up to speed yet as of the 00z update. Each day GEFS projects that it will start moving through phases 7 then 6 then 5 etc. over the following few days, only for the update the next day to show almost no movement at all from its current 6/7 position. Look at the plot points for the past few days and you can see how the AAM is locked in almost as high as the scale will allow:

The thing about this is that it's pretty much a new phenomenon to the models for it to display such behaviour at such a high sigma (over +3.5). I wish I could see AAM plots for the ECM ensembles because I suspect they will struggle to capture its behaviour entirely.

Having said that, ECM and its ens. have been staying away from the burst of momentum that GFS/GEFS keep producing, and this reflects an outlook where the AAM doesn't drop away as GEFS keeps showing. This is tied in with the MJO movement; a sudden drop in phase 8 as GEFS shows is a recipe for a falling AAM, while steady propagation to phase 1 as ECMF has consistently predicted is a recipe for holding it up high. I think that amplification bias is the reason why ECM took a bit longer to change the upstream pattern with respect to the initial WAA, as opposed to handling of tropical forcing.

 

So, the theory plus recent history suggests that the jump in momentum shown by GFS/GEFS is likely to prove erroneous, with ECM's more amplified mid-and-longer-term favoured. So it is that we face the question again as to whether ECM is over-amplifying through its bias... in theory yes, meaning it might be moving things along too fast, BUT I can see plenty of credence to its attempts to bring about another round of WAA in the N. Atlantic. With this new attempt appearing further east, the room for adjustments without thrashing our chances is larger than before - but we have a way to go before we can start looking at that attempt without way too much uncertainty surrounding it.

The huge uncertainty in the short to mid range is the reason for my lack of discussion over that - for all we know what we see for Tue-Thu for example will end up being quite some distance from the truth, especially with respects to the mid-Atlantic ridge. I just can't say with any confidence where we're most likely to go with that!

One of the biggest issues at the mo is the behaviour of those heights over the N. Pole. The very much expected route, with a neg. AO locking in, seems to have been thrown out of the window for some reason.

Again I must ask whether GP's vision involved a sustained neg. AO followed by a neg. NAO developing as the 'torpedo lands', or the re-emergence of a neg. AO as the neg. NAO establishes? Thanks in advance to whoever responds 

Edited January 9, 2016 by Singularity
only human

[Ali1977]

JMAs chart for Tue is up there with the ones from a few days ago....any chance this happening??

[nick sussex]

2 minutes ago, Ali1977 said:

JMAs chart for Tue is up there with the ones from a few days ago....any chance this happening??

The JMA still has the shortwave stuck out west into the Atlantic at T84hrs. At this point we're going to have to make the best out of the current situation. Theres very little chance now of a strong block to the nw. After yesterdays traumas if offered and in the UK I would accept the ECM. Its at least got some snow chances and some good frosts. The GFS would be an insult too far given what was projected a few days back, its dire to be honest.

[Singularity]

3 minutes ago, Ali1977 said:

JMAs chart for Tue is up there with the ones from a few days ago....any chance this happening??

Glancing through GEFS postage stamps for that time, there are some with a stronger ridge from the Atlantic, but very few have that strong linkup with the Arctic High.

Yet given the uncertainties at play, that JMA outcome can't be ruled out at all!