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

[Liam J]

Great ECM 00z! the second half of next week gets colder and colder with increasing risk of snowfall (too early to say where) & harsh overnight frosts for many, looking at the 2m T's overnight temps -3 to -6c quite widely and parts of Scotland -9 to -12c some nights with definite ice days to follow, the last few frames under that high pressure the midday temps are widely sub zero away from the far south and south west but even here 0 to 3c max temps. 

[Severe Siberian icy blast]

26 minutes ago, IDO said:

A move towards the GFS by ECM this morning. It has downgraded the Atlantic High from 1040mb to 1030mb (it's propensity to blow up highs in high entropy situations). It has also changed the position and influence of the Azores Low, now much closer to the GFS take:

T144:     GFS: 

The net effect is that the high is not sustainable with respect to a Greenland connect and gets pushed away, as GFS have been showing in the last few runs; where the Azores low phases with the US trough to push the pattern east.

D7 ECM:   GFS: 

Very similar, though ECM remains better for cold for longer (is it over amping still?), though with its run to run changes I would expect ECM 12z to be different again tonight, where as GFS has been consistent.  There is a cluster of about 25% that support the ECM evolution by D8 on the 0z GEFS, so an evolution that is feasible now that ECM has stepped towards the GFS with respect to earlier developments. As for who is correct (post D7), I am as flummoxed as most on here.  All fluid and best to watch and learn so we can gauge what model is better in such future circumstances. Cold High on ECM from D7-10.

As for the UKMO it phases the Atlantic high into the Greenland High and that doesn't look likely from what the GEFS show. GEM decouples the Azores low with the US trough around D7 as further HP moves in (similar to ECM yesterday and now binned by the ECM 0z).

The gfs has a deep trough north of Norway.  The ecm doesn't.  

The gfs has blew up a massive low in the atlantic with pressure down to 960mb . Where as the ecm has it at 990/985 with an undercut.  They model things quite differently but the one similarity they both have is low pressure in Europe. 

With that there the high can't sink so that in itself will keep things interesting.  

I'l challenge what you say and say it looks better this morning for a long cold spell .

Edited January 10, 2016 by Polar Maritime
To move discussion on..

[That ECM]

I understand that we look west on most occasions to see what is happening as this effects us later but I would be interested in comments around the ridge out east which is there on all 3 @ t144. Ukmo goes no further but ECM goes on to build this yet gfs flatterns it out. 

My thought is that if it remains would this not have the effect of slowing everything down and allowing more heights to build over or near to us?

hope this makes sense but genuinely interested in thoughts.

[Weather-history]

38 minutes ago, IDO said:

A move towards the GFS by ECM this morning. It has downgraded the Atlantic High from 1040mb to 1030mb (it's propensity to blow up highs in high entropy situations). It has also changed the position and influence of the Azores Low, now much closer to the GFS take:

 

 

Hmmm.

If anything I would have said GFS op run has been moving more towards ECM.

This was yesterday's GFS 0z run for Saturday 1am

and look at it now

 

ECM yesterday's 0z for same time

and today's

[Abyss]

 So to my untrained eye is it possible the ECM could deliver snow to more northern areas before high pressure moves in so therefore frosty with snow?

Edited January 10, 2016 by Polar Maritime
Deleted quote box.

[IDO]

9 minutes ago, Severe Siberian icy blast said:

The gfs has a deep trough north of Norway.  The ecm doesn't.  

The gfs has blew up a massive low in the atlantic with pressure down to 960mb . Where as the ecm has it at 990/985 with an undercut.  They model things quite differently but the one similarity they both have is low pressure in Europe. 

With that there the high can't sink so that in itself will keep things interesting.  

I'l challenge what you say and say it looks better this morning for a long cold spell .

Your assuming that ECM has the Arctic profile correct. ECM has a vortex parked over the pole from D5-D10 where neither GEM or GFS do. Downstream the ECM is blowing up the Russian upper high at D10 where as GFS does not. That Russian High acts as another block to prevent the UK high and Euro trough being pushed east. These are text book ECM failings at that range, and although they could be right, I suspect that ECM is playing catch up and will correct in due course. If you have a bias to over amplify, that means by D10 it is can have a totally blocked pattern when in reality it is far from that. So if the Russian high is over done then the pattern will be more mobile. I have been watching similar ECM D10 charts for years and nearly all of them backtrack, statistically they are due one to verify so this may be the one, but all I am saying is don't bank on it.

Last night's ECM D10 mean which I find hard to believe at the moment:  

[Polar Continental]

18 minutes ago, Weather-history said:

Hmmm.

If anything I would have said GFS op run has been moving more towards ECM.

This was yesterday's GFS 0z run for Saturday 1am

and look at it now

 

ECM yesterday's 0z for same time

and today's

Exactly my thoughts this morning, the GFS has prolonged the cold spell with a cold high developing around 150 hours and is beginning to track ever north with each run. The UKMO and to a certain extent the ECM have remained more solid. From my observations it is the GFS which is subtly changing its projections. 

[Frosty.]

I'm really excited about the week ahead, just taking the Gfs 00z shows progressively colder conditions through next week with showers and longer spells of rain turning to snow on hills and then gradually to lower levels so I think quite a lot of the UK could have a covering of snow towards the end of the week. Nights and early mornings look increasingly frosty and icy, indeed there could be some severe frosts, especially by the end of the week...so I'm delighted to say winter is set to arrive shortly...

[Polar Maritime]

Yes Frosty, It will feel bitter by the end of the week. A snapshot of Thursday's snow 'potential' from the NetWx - MR Model. All subject to change..

Edited January 10, 2016 by Polar Maritime

[Bolton67]

6 minutes ago, Polar Maritime said:

Yes Frosty, It will feel bitter by the end of the week. A snapshot of Thursday's snow 'potential' from the NetWx - MR Model. All subject to change..

Basically over high ground on Thursday. The Pennines taking a good hit.

[Nick F]

Looks like the more nationwide snow potential begins from Thursday, as an area of low pressure moves E/SE across the UK, though at this stage no agreement on exact track or timing. EC takes the low across central/northern England then out into the N Sea from Lincs, it shows rain turning increasingly to snow across northern England, Midlands and Wales during Thursday, then across E Anglia and SE England by evening. GFS further north with the low, but has a frontal system crossing east over all parts and with some back edge snow.

00z GFS high res has a secondary wave run SE across southern parts on Friday, bringing a spell of heavy snow across Wales, Midlands and southern England ... BUT, EC doesn't have the feature, rather it's cold and dry in a raw northerly flow bar sleet/snow showers around coasts.

So, plenty of potential wintry weather for all later in the week, though what's currently showing isn't necessarily what will happen, plus  for the UK, forecasting where and when it will snow this far ahead away from higher ground is often difficult, as quite often temperatures and dew points are very marginal – which means a subtle change in either in a borderline set-up can make a difference between rain or snow falling.

Edited January 10, 2016 by Nick F

[Kentish Snowman in Yorks]

15 minutes ago, Polar Continental said:

Exactly my thoughts this morning, the GFS has prolonged the cold spell with a cold high developing around 150 hours and is beginning to track ever north with each run. The UKMO and to a certain extent the ECM have remained more solid. From my observations it is the GFS which is subtly changing its projections. 

Yes I have been studying the GFS Ensembles for a few days now and the point where the massive scatter starts in terms of the 850 temperatures is always stuck around T144 with the cold spell being prolonged within that timeframe in the meantime.

It seems to me that the GFS is being persistently overly progressive with the pattern but at the same time it refuses to do a full backtrack just to extend the drama day by day which always seems to be around the T120/144 mark.

Still great to see how it all unfolds though.  Cold and snow for many this week that is for sure.....

[Frosty.]

Poor daffs are in for a shock, there could be some severe frosts as well as a covering of snow, even the south and southeast has a good chance of snow later in the week and the gfs is not even the best output for wintry weather so the coldies are finally going to have frost and snow to talk about in the days, weeks ahead.

[Ali1977]

FRI looks like better potential for a decent accumulation down south, colder air than in place on Thursdays potential.

[carinthian]

Nice to see the UKMO extend the cold spell and even intensifies it. ECM also a cold run. The difference being the location of the high pressure, ECM wants to move towards a very cold continent and UKMO looks like retrogression with mostly Arctic Feed. GFS still seems to progressive to the change to mild. This weeks snow forecasts probably hard to pin point as Nick F has reported this morning. Best now follow UKMO updates and fax charts. Its in the range of our snow portal service, I will get an up date in the morning and relay back, but seems they were correct to keep the potential channel low move a more southerly track. Bags of potential for blighty and will be pleased for you very patient cold fans to get some snow and at worst a protracted colder spell in the offering. Had about 10 cm fall overnight here, sparkling sunshine this morning, may even get my skis out today.

 C

[Iceberg]

Ecm is slightly above avg re temps on Thursday/Friday but has considerable snow for the east and the wash/Lincs on Thursday then snow on Friday for the west I.e Cheshire Wales and a little for the sw going from precip charts

a long way down the road, but areas of snow potential for certain. Wider possibilities for snow on Thursday are much more uncertain. 

Edited January 10, 2016 by Iceberg

[nick sussex]

I see the UKMO is back to its old tricks! I was thinking we might have less drama but oh no!

The differences start early upstream around T96hrs with how the models handle shortwaves running in from the Pacific, the net result is the UKMO develops this shortwave it runs across the Canadian/USA border and helps to sharpen up the troughing to the west as it interacts with the PV lobe.

Downstream the more sharpened up troughing helps to develop the ridge further north. The GEM shows something similar in terms of a favourable interaction between the PV lobe to the nw and shortwaves running east.

Hopefully NCEP will have some thoughts on these interactions, we'll see whether its a case of the UKMO/GEM leading each other up the garden path or whether theres something to their different view.

Well I think this says it all, the WPC extended outlook:

MEDIUM RANGE GUIDANCE REMAIMS IN LARGER SCALE AGREEMENT WITH THE IDEA OF STEADILY PROGRESSIVE PACIFIC ENERGIES RIDING INTO THE LOWER 48 UNDERNEATH MORE BLOCKY NRN STREAM FLOW ACROSS THE HIGHER LATITUDES. HOWEVER...AMPLE DETERMINISTIC MODEL AND ENSEMBLE MEMBER FORECAST SPREAD AND RUN TO RUN VARIANCE ISSUES WITH FLOW EMBEDDED SYSTEMS AND STREAM INTERACTION EMPHASIS SEEM TO SUGGEST PREFFERENCE FOR A MORE CONSISTENT/SMOOTHED ENSEMBLE MEAN BASED FORECAST APPROACH. ACCORDINGLY...WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS WERE PRIMARILY DERIVED FROM THE REASONABLY COMPATABLE 18 UTC GEFS MEAN AND 12 UTC ECMWF ENSEMBLE MEAN. MANUAL FORECASTER ADJUSTMENTS WERE ALSO APPLIED TO MAINTAIN WPC CONTINUITY IN A COMPLEX PATTERN WITH SEVERAL INTERESTING WINTERY SYSTEMS WITH BELOW AVERAGE PREDICTABILITY.

Edited January 10, 2016 by nick sussex

[iand61]

46 minutes ago, Polar Maritime said:

Yes Frosty, It will feel bitter by the end of the week. A snapshot of Thursday's snow 'potential' from the NetWx - MR Model. All subject to change..

The Pennines look to be in line for a pasting if that comes off but, as is often the case, altitude is key and most on here will be looking at a sleety mess, at least until the colder air digs in.

i just hope that we can get get some widespread cold and snow from this upcoming spell so, for a short while at least, white can replace wet across the country and not just be a high ground affair.

[liam300]

16 minutes ago, Ali1977 said:

FRI looks like better potential for a decent accumulation down south, colder air than in place on Thursdays potential.

This is very marginal. It seems anything south of London has temperatures round 4-5 degress

[kumquat]

Sub zero 850s for ALL of the UK for ALL of the  ECM run. Winter doth cometh.

Disturbances running South East:

 

[Polar Maritime]

Just a heads up re-'Snow potential' It's difficult to forecast snow even a few hours out.. So don't get to hung upon detail as Nick F explained a few posts up. Every single model run will vary over the next few days, With just a degree of difference leading to big changes in local areas.

Edited January 10, 2016 by Polar Maritime

[bluearmy]

 

this NH profile from UKMO day 6 of 'a bird' is reminiscent of some previous charts I recall seeing in the past on ens means so I expect it teleconnects quite well.  The animal lovers should cover their eyes - we need to sever that bird right through the middle whilst needing it to keep its wings out.  unlikely!

[Ali1977]

14 minutes ago, liam300 said:

This is very marginal. It seems anything south of London has temperatures round 4-5 degress

Timings may be critical, temps will quickly fall after dark so as long as precip coincides with this , we may have a chance.

[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 SUNDAY JAN 10TH 2016

THE CURRENT GENERAL SITUATION   An increasingly cold and unstable and showery Westerly flow will affect Southern Britain throughout the next 24-48hrs while Low pressure moving into the North of the UK ensures cloudy weather with some rain or snow in lighter winds.

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 ridging strongly North in the second week as High pressure builds near the UK.

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

GFS OPERATIONAL The GFS Operational Run today shows unsettled and cold conditions throughout the first week this morning as complex Low pressure across and near the UK make day to day differences in weather hard to pin down. However, rain, sleet and snow looks possible for all. Then High pressure slowly makes more inroads across the UK in the second week drying things up with quite chilly conditions maintained for the most part with frost at night as High pressure builds across the UK from the East.

GFS CONTROL RUN The theme of the Control Run is very similar to the Operational run though with High pressure setting up shop to the South of the UK in week 2 milder conditions are more likely with rain at times as troughs cross East across the UK with rain at times in temperatures returning to near average.

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 model today shows chances of a much more sustained cold period across the UK, certainly lasting through this week and next weekend and probably longer. With complex Low pressure ensuring a lot of instability in the atmosphere outbreaks of rain, sleet and snow at times look possible anywhere in the UK throughout. 

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

THE FAX CHARTS The Fax Charts show complex Low pressure and troughing across the UK all week with rain or snow at times in temperatures colder than of late and winds still quite strong at times.

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

GEM GEM this morning brings colder conditions across the UK too with complex Low pressure and low uppers aloft ensuring a lot of cold and showery conditions lasting through to next weekend when High pressure to the NW slips SE across the UK with cold, dry, bright days with sharp overnight frosts for all to start the second week as a strong ridge is maintained across the UK by then from the SE.

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

NAVGEM NAVGEM is loosely similar in theme to GEM with showery Low pressure giving way to High pressure slap bang across the UK by the end of next weekend displacing the previous cold and showery weather with some snow in places.

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

ECM ECM today also shows a theme of High pressure developing across the UK next weekend and into the second week bringing fine, cold and very frosty weather to all of the UK following a week of cold and showery conditions with some snow at times over the hills with rain and sleet at lower elevations through the week.

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

ECM 10 DAY MEAN The 10 day mean chart shows High pressure likely to be close to the UK in 10 days time with fine and dry weather with frosty nights the most likely scenario though there is some suggestion of milder conditions for the North and West on a SW flow by the end of the period there.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme of the output shows a slow transitions to dry and fine conditions later next weekend with less cold conditions returning later in the extended outlooks first in the West and NW.

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 respectively.  At 3 days ECM is leading with 97.6 pts to UKMO's 96.7 pts while GFS lags behind at 96.3 pts. At 5 days ECM leads with 90.0 pts to UKMO at 87.8 pts then GFS at 87.4 pts. Then at 8 Days ECM still leads at 66.9 pts over GFS's 63.3 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   The upcoming cold spell has probably been the most difficult thing for the models to get a handle on in recent times and even now there are still plenty of longer term options shown which could change the longevity and the longer term weather conditions across the UK a week or so from now. However, there are a few common themes beginning to emerge between the different models this morning. Whatever happens longer terms all models agree on the UK becoming rather cold this week and with various areas of Low pressure meandering around the UK all week showery conditions look like continuing for many days. As the air becomes colder over the South in the coming days these areas will join the North in receiving a cocktail of precipitation from these showers and almost anywhere could see at least a dusting of snow through the week with frosts at night becoming much more likely. Then by next weekend it looks like High pressure will be building across the UK by one source or another to quieten conditions down and bring a spell of dry and frosty weather across all areas of the UK for a while at least. GFS today then shows it's usual of late return to less cold and unsettled weather with rain at times as things return to a more mobile pattern of Low pressure passing East to the North of the UK but to be honest things could be complicated by all sorts of issues as cold air across the UK and Western Europe could prove more stubborn to shift than is currently shown. So in simplistic terms the weather looks like being rather cold and showery over this coming week before drier and frosty weather maintains a cold theme through next weekend which leads us into a much more questionable period thereafter with plenty of options likely to be thrown up through model runs in the week to come for the period of weather in the second week, not all of them mild.

Next Update on Monday January 11th 2016 at 09:00 approx 

[johnholmes]

Looking beyond this week which is being quite well covered in broad scale by the charts. Detail of where any snow falls will of course keep interest going in here as the models try to get the outcome correct. In terms of 6-10 days from now and possibly further out I see no real change from what I posted last evening, 2 against one in terms of the anomaly charts as below,

Sun 10jan

Ec-gfs

And they continue with two differing ideas around the uk, as before ec shows the ridge Greenland/atlantic with trough over/just e of uk; gfs shows a flatter w’ly type with no ridge of any consequence for the uk.

This leaves noaa and ec similar and gfs differing.

I would think that the two are nearer what will be seen in the upper air in 6-10 days time?

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

For 10-15 days then the NOAA chart suggests that an upper ridge may be around along with its surface cousin, at least at the start of this period. By the end of the period, unless something not yet picked up takes over, then a more mobile westerly looks on the cards. This would give a mix of PM and some Tm air with Tm perhaps more frequent in the far south?

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php