Model Output Discussions 18z 31/01/2016

[Gustywind]

No 216 is horrible but FI by then and the transition from 192 looks odd - too progressive. Let's hope 120-144 upgrades again as that's the real disappointment this morning.

[NorthYorksWeather]

Latest NMM for Europe just out and this is looking very much like GFS. All lows heading into France with a cold easterly setting up. 

UKMO is somewhere between GFS and ECM but still looks to have the slider and an easterly flow for the majority of the UK.

 

Really is a fine line between rain and snow, another behind the sofa moments when opening the Euros later for the 12z. 

[Gustywind]

Yes the NMM and UKMO has the little Icelandic wedge, this is absent on the ECM.

[Purga]

Where's Steve Murr??

[johnholmes]

beyond the next 3-4 days and the anomaly charts have over the past 36 hours or so all started to show a marked rifge-trough situation in the UK area with the 500mb flow from n of west. No direct arctic flow, it comes via the Atlantic, but colder rather than milder would be the outlook just using their data.

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

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

[nick sussex]

Is there a wall I can bang my head against!

Its always the same drama when theres a sniff of snow for the UK. The problems all start from shortwave modelling south of Greenland.

Indeed today we can say that unbelievably FI starts before T72hrs which is about as rare as snow for the UK.

The ECM postage stamps at T72hrs onwards don't fill me with much confidence as theres far too many different solutions from there.

The ECM ensemble spreads at T72hrs clearly show the issue:

Its very unusual to see that level of spread at only T72hrs.

Given the timeframes involved the extra 6 hours of newer data on the GFS 06hrs run will be crucial.

 

[Ali1977]

Hopefully the ECM was a big outlier within its ensembles, are they out yet?

[nick sussex]

Just now, Ali1977 said:

Hopefully the ECM was a big outlier within its ensembles, are they out yet?

You can see the ECM postage stamps here which go upto T120hrs. Given the importance of the earlier timeframe what happens upto T96hrs will set the tone.

http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!96!pop!od!enfo!enplot!2016020800!!/

[feb1991blizzard]

Just now, nick sussex said:

You can see the ECM postage stamps here which go upto T120hrs. Given the importance of the earlier timeframe what happens upto T96hrs will set the tone.

http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!96!pop!od!enfo!enplot!2016020800!!/

I think the ECM 12z will be the one that resolves the issue, if its the same as the 0z then its game over, not necessarily for the 10+ day timeframe but for our chance of any low level widespread disruptive snowfall in the short term.

[Summer Sun]

6 minutes ago, Ali1977 said:

Hopefully the ECM was a big outlier within its ensembles, are they out yet?

They are out now yes

 

[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 MONDAY FEB 8TH 2016

THE CURRENT GENERAL SITUATION  Storm 'Imogen' will move slowly away NE later today and the severe gales across the South will steadily ease later though leaving a legacy of strong Westerly winds with showers across most areas.

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

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the British Isles will remain around 4000ft across the UK falling a little across Northern areas later with the snow risk level falling to lower elevations in the North and West by 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  Mostly unsettled and very windy with rain or squally showers. Fluctuating temperatures with some snow at times over higher ground especially in the North.

THE GFS JET STREAM FORECAST  The Jet Stream remains very strong over the next 14 days. The flow remains to the South of the UK encouraging Low pressure to centre close to the UK for most of the time. Later in the period the flow moves slightly further North for a time.

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

GFS OPERATIONAL The GFS Operational Run today maintains a very unsettled and turbulent period with rain and showers and some hill snow at times through this week. Some snow on lower ground at times could develop over the North at times as Low pressure aims further South than recently with a cold East flow over the North for a time. Then through the second week the weather becomes somewhat less volatile with longer dry spells between the rain bands with temperatures mostly close to average in the South especially.

GFS CONTROL RUN The theme of the Control Run is also very unsettled with rain and showers around on most days with snow on hills and while gales or even severe gales are likely through Week 1 the theme of a slow transition to less stormy weather is looking possible in the second week. Nevertheless, the weather remains mobile throughout the run with spells of rain and temperatures near average alternating with sunshine and showers and colder conditions with some snow on the hills.

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

GFS ENSEMBLE DAY 14 DATA  The GFS Clusters today once again show the Atlantic in total domination of the UK weather in 14 days. Winds all blow from between SW and NW with a bias towards a more unsettled theme rather than a drier one as only a handful of members suggest enough influence from High pressure to the South and SW to have a meaningful effect.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO The UKMO model this morning shows a continuing picture of Low pressure based near or over the UK across the week to come. While the early severe gales die away by midweek fronts associated with the Low pressure will bring further wind and rain later in the week and with some colder air in place this week it looks like some snowfall can be expected on modest hills at times away from the far South.

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

THE FAX CHARTS The Fax Charts today maintain an unsettled pattern this week though with winds decreasing from current levels. Quiet weather with showers near coasts midweek give way to renewed Low pressure into the SW again by the end of the week.

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

GEM GEM today shows Low pressure maintained across the UK throughout the coming week with rain or showers at times and snow on hills and while winds remain strong they are shown to become less strong after today. Then early next week a marked ridge moves East and settled the weather down for a time with some night frosts but pleasant days before cloud, rain and wind move back down across the North and West of the UK from the NW by the end of the run.

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

NAVGEM NAVGEM today also shows Westerly winds and unsettled conditions with showers through most of this week with some snow at times on the hills of the North. then over next weekend another storm system is shown to move across from the West bringing spells of strong winds, cold rain and hill snow for many before quietening down again at the very end of the run as a ridge moves in from the West.

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

ECM ECM today also shows a very unsettled week to come with today's severe gales subsiding leaving a legacy of unstable and cold air across the UK with showers, some heavy and thundery with snow on hills. Then later this week a new deep Low brings renewed gales and rain with possible snowfall for the North. then towards the end of the run a pattern shift towards better weather is shown with a short spell of Northerly winds and snow showers in places ahead of a ridge bringing frost and a return to milder SW winds for many again at least for a time at day 10.

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

ECM 10 DAY MEAN The 10 day mean chart today shows the same theme as recently  with Low pressure to the NW and the Azores High at home with a West or NW flow across the UK with rain at times and snow possible on Northern hills at times.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The models continue to maintain volatile and windy Low pressure based conditions across the UK with just slight hints towards Low pressure moving further North later in the period.

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 at 99.5 pts and GFS at 99.4 pts.  At 3 days ECM is leading with 97.6 pts to UKMO's 97.0 pts while GFS lags behind at 96.6 pts. At 5 days ECM leads with 90.6 pts to UKMO at 88.7 pts and GFS at 88.1 pts. Then at 8 Days ECM has the leading spot from GFS with 67.0 pts to 64.5 pts. Finally at Day 10 GFS leads today at 49.9 pts to ECM's 48.7 pts.

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   The models continue to show a very mixed pattern of weather over the next few weeks with the most stormy weather likely over the next week while in Week 2 things may turn somewhat less volatile with a more traditional Atlantic pattern returning. Currently Storm 'Imogen' is rattling a few panes across the South  but this will ease down by tomorrow with the mix of rain and showers continuing for many. Then a quieter midweek period with showers restricted more towards windward coasts is replaced by another deep Low pressure area towards the weekend. This Low looks like travelling ESE across the heart of the UK and could give some significant snowfall to it's North so it's track is crucial on who gets snow and who gets cold rain. However, I don't see this as a major wintry outbreak away from the highest ground of the North and following a colder and more showery period late next weekend when snow could reach the hills of the South as well it looks like a strong ridge could build across the UK for a time with frosty nights but a couple of bright and dry days. Thereafter it is likely that Atlantic depression return but more towards the NW setting up a strong Westerly but milder flow with rain at times for many but less intense weather events in the South and East. That's the way I see it this morning. For those who see snowfall in a big way this morning I would urge caution as there is not a lot of cold air to tap into and cold rain to me looks the more favoured option for much of England and Wales under next weekends storm system though I would happily be proved wrong. thereafter it looks like standard Winter fayre of wind and rain at times under an Atlantic flow.       

Next Update Tuesday February 9th 2016 from 09:00 

[chris55]

So GFS and UKMO take the slider south with colder air filtering in. ECM pushes everything further north and east leaving us less cold and wetter.

im praying for some dryer and slightly more settled weather as we have just taken the roof of off a house we are renovating !! And all these storms are starting to annoy me. 

Cold and dryer PLEASE!! 

Lets pray ECM reverts to the GFS solution on the 12z.

[nick sussex]

In a desperate effort to find something upstream from NCEP to count against the ECM solution.

There is this , its the low that phases with the shortwave near southern Greenland. The GFS has a deeper initial low and this phases earlier, the ECM doesn't really absorb this shortwave into the main low circulation.

In the short term NCEP discussion:

07Z UPDATE:  THE 00Z ECMWF CONTINUES TO PERFORM CONSISTENTLY
FURTHER TRENDING TOWARD THE GFS COMPROMISE BUT REMAINS SLIGHTLY
WEAKER AND SOUTH WITH THE COASTAL DEVELOPMENT COMPARED TO THE GFS
AND 00Z UKMET.

 

[Polar Maritime]

The GFS again continues to show 'wintry' cool to cold conditions from Northerly type flows over the next 10 days. With -10 850's shown pushing into England it will sure be a shock to the system compared to what we have endured all Winter, With some hard frost especially for the North. 

Edited February 8, 2016 by Polar Maritime

[feb1991blizzard]

4 minutes ago, Polar Maritime said:

The GFS again continues to show 'wintry' cool to cold conditions from Northerly type flows over the next 10 days. With -10 850's shown pushing into England it will sure be a shock to the system compared to what we have had all Winter.

Indeed and a very nice shock too, but not sure its very likely to verify, at least not to that extreme anyway.

Edited February 8, 2016 by Polar Maritime
To tidy quote up.

[Nick F]

00z ECMWF the spoiler this morning, though at least the high res does bring some light snow to the Midlands, E Anglia and parts of SE England Tuesday night as an occluded front drops SE in the cold NWly flow. 

Quite marked differences in the 500mb pattern t+120 to 144 between the GFS and EC operationals - GFS builds 500mb heights over Norwegian Sea to Iceland area, which has the effect at stopping lower heights and the strong jet streak coming out of N America pushing further northeast as per ECM.

t+120

t+144

On the plus side 00z UKMO does take low pressure across the far south between t+120-144 rather than across central parts as per 00z EC det.

The ECM does redeem itself by disrupting the deep trough over Europe into a cut-off low with high pressure linking in between the Atlantic and Russian ridges, so we get a Nly veering NEly, though it remains to be seen how cold the air will be tap into.

Certainly plenty of drama ahead to look forward to from the models!

[carinthian]

Morning all. looks like a wet end of the week for Southern Britain with a serious of lows passing through on Friday and into Valentine weekend. Upper air profile advects some cold air into the North on this latest UKMO run. So snow potential for Northern England and possibly Central regions. Should be a good week for weather watching, especially more of a wintry feel. Expecting some heavy falls in the Alps with the alignment of the jet .

 c

[moffatross]

30 minutes ago, nick sussex said:

today we can say that unbelievably FI starts before T72hrs which is about as rare as snow for the UK.

The ECM ensemble spreads at T72hrs clearly show the issue:

Its very unusual to see that level of spread at only T72hrs.

Not meaning to be too parochial, but I'm sure when you said UK, you maybe meant the south of the UK ? I'm in the South of Scotland, and only at 150m ASL, but even I've already seen a few snow falls that have settled and stayed around for a few days so far this winter.

Anyway, it seems to me on this rare almost wind-free day, that the increased uncertainty is a function of the slack synoptics that follow a trough digging further south than we have become accustomed to. I know there're primary and predictable interactions aloft further afield but away from the main action, the consequences are secondary. A bit like the eddies that slowly swirl in the northern slack side of a pool on the bend of a river, they're unpredictable, while the raging currents on the gravel bank on the southern side of the bend follow a much more predictable route.

[Singularity]

 

It's the shortwave SW of Iceland on the ECM run (left) that's causing the issues. The GFS version for example (right) has this feature weaker and it basically gets carried away SE by the jet stream. The shortwave west of Iceland is then free to move west toward the upstream Atlantic low, making room for height rises over Iceland => The Wedge Is Born.

ECM's stronger version of the first feature interacts with the second to form a broader low that prevents The Wedge from forming, meaning the jet isn't diverted as far south, and it all goes a bit pear-shaped. Room for recovery days 6-8 should the upstream pattern prove less progressive (a good bet given recent MJO/GWO tendencies), but it would be a shame not to score some snow this weekend, despite the possible interference with Valentines Day plans across the affected regions.

[Singularity]

00z and 06z for +48 hours:

 

So far, no notable changes. LP west of Iceland a tad weaker. Unclear with one to SW... barely any difference.

 

Oh and the GFS 00z parallel supported the det. run:

  

850's are similar too.

[Singularity]

 

The ridge is stronger and the shortwaves near Iceland have cleared more readily. So moving further away from the ECM version - go figure.

I wonder if this run might suggest the weekend precipitation ending up being confined to the Channel. That'd bring nasty flashbacks to March 2013 

[SLEETY]

On 04/02/2016 at 7:26 AM, bluearmy said:

Observation that the upper trough does clear post 10th but as per the late jan potential cold, a hang back beyond  Iceland prevents the potential mid Atlantic ridging that the ens were hinting at.  The result is that we don't force upper cold south and as such the nw euro trough isn't as cold as it was predicted to be.  Looks messy chilly and then beyond that back to zonal average. 

why when cold weather is forecast,the models struggle again,or one model not play ball

[Ali1977]

Poss snow event as early as Fri evening on latest run for the South.

This weekend shouldn't really be FI but it looks like that after the ECM, if anything more potential than the 00z with this GFS run.

Edited February 8, 2016 by Ali1977

[Singularity]

Deeper low for Friday more than compensates for stronger HP wedge. Snow line for midday Friday is Bristol northward on this run but on track to move back south as LP moves to SE. The 00z had the boundary right along the south coast - as was the N. limit of the precipitation.

Funny how you can have so much potential within 4-5 days yet so little confidence in getting anything much out of it, almost entirely down to a single model (inc. its ens.).

Waiting now to see how the weekend pans out on the 06z as that's when the real fun and games happened on the 00z and 18z. Then my dabble in frame-by-frame model watching will be over for 6 hours or so . Basically doing this for a change of theme having focused so much on the longer range of late.

[Severe Siberian icy blast]

1 minute ago, Singularity said:

Deeper low for Friday more than compensates for stronger HP wedge. Snow line for midday Friday is Bristol northward on this run but on track to move back south as LP moves to SE. The 00z had the boundary right along the south coast - as was the N. limit of the precipitation.

Funny how you can have so much potential within 4-5 days yet so little confidence in getting anything much out of it, almost entirely down to a single model (inc. its ens.).

Waiting now to see how the weekend pans out on the 06z as that's when the real fun and games happened on the 00z and 18z. Then my dabble in frame-by-frame model watching will be over for 6 hours or so . Basically doing this for a change of theme having focused so much on the longer range of late.

Lol your obsessed mate never have I saw such an experienced weather enthusiast comment so much frame to frame haha love it