Model output discussion 25th Jan onwards

[keithlucky]

Not much has been discussed about the snow potential for the UK today looks looks good for a short sharp Arctic blast,With colder air after the rain moves through,later today and tonight

Tonight:

From the met office A few showers this evening, with some more persistent showery rain during the middle part of the night, falling as snow to low levels for a time. A chilly night. Minimum temperature 0 °C.

.

Edited February 11, 2014 by keithlucky

[IDO]

The GFS op continues the theme of a more refrained zonal flow from week 2, with the flow still having a propensity to edge north. This allows for ridging between the next lows. But more rainfall looking likely and no respite despite the slacker westerly flow.

 

The GFS op appears to be more progressive on this run with the ridges more transient compared to say the GEM at T192:

 

GFS  GEM

 

At T240 on the GEFS again only one member showing last night's ECM scenario with nearly all showing a zonal flow but the variance is on its energy and latitude. The mean:

 

 

ECM this morning closer to GEM at T192:

 

T216:  T240: 

 

Closer to the GFS synoptic compared to last night and I suspect they will edge closer as we near D7+. Nothing cold on the London GEFS for the next 16 days apart from a very small risk of snow later in FI:

 

 

 

 

 

[Jason M]

Yes, poor GEFS suite this morning. The opp run seems well supported.

ECM is okay and I've seen worse METO runs. I think tonight's runs will be key but I'm not optimistic given that GEFS have failed to develop yesterday's trend any further. The smart money now is presumably on standard zonality through the back end of the month.

Maybe time to put up the white flag this evening but you never know :-)

[Frosty.]

 

 

Wax that sledge ........

 

S

 

00z model runs....To wax or not to wax..that is the question

[weather eater]

Here's my post from yesterday for the period following the wind and rain of this week.

 

"My punt would be for still a relatively flat pattern but much less intense in terms of wind and rain than the last couple of weeks, I would not expect the GFS 12z to be a million miles out from the general pattern at 200hrs." 

 

I pretty much think the model suites this morning reflect that this is still a reasonable call.

Edited February 11, 2014 by weather eater

[Frosty.]

Yes, poor GEFS suite this morning. The opp run seems well supported. but I'm not optimistic given that GEFS have failed to develop yesterday's trend any further. 

I thought the GEFS suite was poor yesterday with temps trending upwards from the south through FI..how could it be any worse today? 

[bluearmy]

Not bad and here's the GFS for the 21st November, 12z on the on the 10th Nov, the GFS picked it up earlier and was more consistent, I would say for 11 days out pretty good. I would recommend looking at the archives for the GFS 12z run for 11th 12th and 13^th Nov 2010, all pretty good given the range, some myth BA

The myth being that the ECM flip flopped on it. All the models dealt with the onset of the 2010 freeze like clockwork.

Anyway, a more realistic take on the possible undercutting, given the upstream profile from the 00z runs.

[Jason M]

I thought the GEFS suite was poor yesterday with temps trending upwards from the south through FI..how could it be any worse today?

Fair question.The ensembles in graph form can be misleading. Despite the 850 graph not looking too special there were some pretty good set ups and better good have developed if the trend was maintained. This mornings set are largely zonall. They could flip tonight but tbh most of the signals are pointing towards a toned down version of what we currently have. Last weekend I'd have given a 20% chance of an easterly, now maybe 10%. All my view of course. ....Edit - I also don't pay much heed to deep FI unless there is a very strong signal. 192 hours and 240 hours are the timescales I look at. Edited February 11, 2014 by Jason M

[Gibby]

Good morning folks. Another wet morning here in the West Country and another poor set of charts to whiz through this morning as I look at the outputs of the big 5 this morning for today Tuesday February 11th 2014.

 

All models show a squally trough and outbreaks of rain, heavy in places swinging East across the UK currently followed by a cold and windy Westerly flow with wintry showers later with some snow on all high ground. Tomorrow shows showers dying down early in the day as winds back SW and strengthen to gale or severe gale in the SW as another deep and powerful depression sweeps NE over Ireland and the North through the day with another spell of very heavy rain and snow in the North followed by showers, wintry again over hills. Thursday sees a strong Westerly flow as the Low moves away with further wintry showers and this goes into Friday too in the North before the South clouds over again late in the day as yet another deep Low moves up into the South with widespread heavy rain and gales. As this engages with colder air in the North a spell of snow is possible, perhaps disruptive in places before Sunday returns the rather cold and showery pattern once more.

 

GFS then takes us through next week showing a broad flow of Westerly winds and rain at times as fronts from depressions to the North of the UK cross East in the flow. Pressure will be higher to the South and SW of the UK than of late so the emphasis of the most rain should shift away from the SW to the NW with some drier and brighter intervals between the rain bands. Temperatures will recover to near average values after the weekend.

 

UKMO today closes it's run at the start of next week showing Low pressure near Southern Ireland moving ESE and delivering another spell of heavy rain in the South and West. However, this Low may bring a spell of snow for some especially in the North and East as it engages cold air on it's Northern and Eastern flank.

 

GEM shows a rather cold and quieter period next week under a weak Northerly. Wintry showers could occur in places and frosts at night. Further rain at times look possible again later as fronts disrupt somewhat over the UK with no doubt some further snowfall towards the NE.

 

NAVGEM shows weak ridging for a time early next week with more scattered possibly wintry showers before Atlantic fronts return rain to most areas by this time next week.

 

ECM shows brief ridging too early next week but it all seems very tentative with troughs also in the mix continuing the risk of wintry showers or rain early next week before a new surge of the Atlantic is shown towards the end of next week with more widespread rain and showers once more.

 

The ECM 9 and 10 Day Mean Charts are still very poor this morning with the general theme likely to remain one of Low pressure to the NW of the British Isles continuing to steer spells of wind and rain in a typical WSW flow with the heaviest rains perhaps more likely towards the NW though the SW will still get a fair amount should this pattern verify. With winds likely to be from the West or SW temperatures should pick up a bit from those of this week, especially in the South.

 

http://www.wetterzentrale.de/pics/Reem2161.gif

 

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

 

The GFS Ensembles today show strong support for a rise in temperatures later in the run as High pressure creeps up closer to Southern Britain. However, with rain still shown scattered about between the members it looks unlikely it will get close enough though the heaviest deluges look less likely than those of the upcoming 4-5 days.

 

http://www.null/two/ensembles/

 

The GFS Jet Stream Forecast indicates the flow maintaining it's current status South of the UK for a while yet before it's orientation shifts more towards the NE over the Atlantic and the UK in response to pressure rises to the South.

 

In Summary today there is still no definitive end to the current spell of wet weather with all models toying around with a weakening Jet flow and it's final resting place. As it is this morning all models do hint at some changes likely next week though they all show very tentative solutions which don't underline any significant dry and fine spell with High pressure struggling to take overall control. The most likely solution that I can see today is that after this weeks terrible weather again things will moderate into next week with the emphasis of rain shifting more towards the NW and away from the SW which is a positive in it's own right and it maybe that the South in general sees some drier interludes and less frequent and heavy rain. In addition the rather cold weather of this week could well give way to something rather milder at times later in a SW flow.

[johnholmes]

that summary seems fine to me with no sign of any blocking developing that some keep mentioning.

[weather eater]

The myth being that the ECM flip flopped on it. All the models dealt with the onset of the 2010 freeze like clockwork.Anyway, a more realistic take on the possible undercutting, given the upstream profile from the 00z runs.

Looking at the archives, it is better than I thought although some runs appear to be missing, so maybe flip flopping is a phrase too far, although it does not alter the fact that the GFS was very good with its modelling of that spell. It also doesn’t alter the point I was actually making, which was that despite the ECMs better verification stats it is foolish to dismiss the GFS on every occasion as the GFS does better than the ECM some of the time. An open mind is always a useful tool provided it’s not so open that your brains dribble out of your ears and as I have said many times I do not rate the GFS over the ECM. In my view the best thing the could happen with the GFS is a dropping of the 06z and 18z runs as IMO they make the GFS look poorer than it actually is.

[weather eater]

Just seen the BBC forecast and some reasonable cheer for some of us who are looking for a drop of the white stuff, a possibility of snow later today across parts of the midlands and up into EA, we have a rain snow mix here at the moment, mainly snow. Tomorrow very strong winds especially for the midlands north, very heavy rain for all parts followed by the prospects of what looks Blizzard conditions for parts of the North by tomorrow evening.

Edited February 11, 2014 by weather eater

[bobbydog]

Looking at the archives, it is better than I thought although some runs appear to be missing, so maybe flip flopping is a phrase too far, although it does not alter the fact that the GFS was very good with its modelling of that spell. It also doesn’t alter the point I was actually making, which was that despite the ECMs better verification stats it is foolish to dismiss the GFS on every occasion as the GFS does better than the ECM some of the time. An open mind is always a useful tool provided it’s not so open that your brains dribble out of your ears and as I have said many times I do not rate the GFS over the ECM. In my view the best thing the could happen with the GFS is a dropping of the 06z and 18z runs as IMO they make the GFS look poorer than it actually is.

 

i think its worth noting though, (despite a certain poster mistakenly claiming i "inferred" that the GFS was better than the ECM) that the GFS model is undergoing a major overhaul with the help of the staff at the ECMWF. apparently to be 'unveiled' in the spring. it has recognised faults which are being rectified. hopefully we will find out soon enough

[Polar Maritime]

Snow prospects have been showing in the models for the last few days with far better scope over 150m Midlands North over the next 48hrs and Friday.

Already a slight covering here and snowing heavy.

Edited February 11, 2014 by Polar Maritime

[Nick L]

Please keep snow reports to the relevant threads folks.

[phil nw.]

Off topic posts such as snow reports or stuff that can be done by PM have been removed.

Model discussions only in here please folks.

 

Thank you.

[Mucka]

that summary seems fine to me with no sign of any blocking developing that some keep mentioning.

 

Ah, but did you see any signs in yesterday evenings output?

Certainly much flatter output today than yesterday evening but personally I expected that, well I expected ECM to be flatter at least.

It is all a matter of perspective and one should always be ambiguous when talking about possible pressure patterns setting up in FI.

 

I can't talk for others but my opinion way back was that the pattern would become more amplified around mid month as the Canadian PV moved East and the jet slackened behind with the slim possibility of an Atlantic ridge and Scandinavian trough setting up dependent on how quickly the PV to our West could reorganise or be resupplied. I think we have seen this to some extent but although we saw a decent ridge modelled in the ensembles and occasional operational (around 50% or so at one stage) there was never really that much support for it and where there was the pattern was often quickly overrun by the jet returning North over the top.

 

Even so we have seen increased amplification modelled for mid month onward and that has occasional thrown up better charts where we have managed some undercut but now we are looking out into the last 3rd Feb for the next opportunity which comes on the back of any increased amplification. We have almost always had to play the long game when looking for cold opportunities this year and if I were simply giving 7 day forecasts cold would very rarely have entered my summaries - indeed I personally have never stated it WILL be blocked or WILL be cold at any particular time-frame 10 days+. Only that there may be an increased opportunity for blocking and how that may develop over a certain time-frame and almost always I remind people that the usual caveats apply at those time-frames.

 

Yes the endless search for cold patterns in winter does niggle some people when all they see in the charts for the next 7 to 10 days is wind and rain but it shouldn't.

As I always say folk have the power of discernment and can take or leave the more speculative and long range model output discussions for the more reliable time-frame and/or actual forecasts for the UK.  Personally I read it all because it all has value to me.

Just so long as people are not making definitive statements of incoming big freezes based on a single 384 chart. Speculating over the future output is a big part of this thread and so it should be because the output changes day to day so it would be more foolish to assume any particular output was set in stone at the longer ranges.(FI)

 

On that note this mornings output is disappointing after last nights glimmer of hope and the ensembles also do not suggest any kind of blocking so it is understandable that people would want to write off the rest of February, especially given the Winter we have had. 

I certainly wouldn't want to suggest there is anything in the long range ouput this morning where any kind of blocking is suggested as taking hold except perhaps the azores high ridging over the UK, which I guess we would all take, but at least there is still the suggestion that we will see ridges being thrown up from around mid month in the Atlantic and while that is the case there will be the opportunity for one of these ridges to force low pressure SE rather than NE and that could easily show again in tonight's output though as I said yesterday this is more for around 10 to 15 day time-frame (now 9 to 14) - it was just the ECM over-egged the pudding,

Anyway the more amplified pattern is around 4 or 5 days away with the first ridge worthy of the name being around 7 days away - that won't be enough but it will keep the pattern amplified upstream and it will only take a little less forcing from the PV as it reorganises and drops SW to get a stronger ridge thereafter capable of disrupting the Atlantic flow to the point where a MLB could take hold so I think we will at least see this modelled again even if ultimately the Atlantic proves too strong yet again.

 

I will just add that there is indeed no sign of a deep cold pattern setting up in the output but there is plenty of wiggle room for something more seasonal to show up last 3rd of February - we can but hope.

Edited February 11, 2014 by Mucka

[phil nw.]

What we are seeing this week is a notably cold westerly flow sourced from the Upper Canadian trough.

Owing to the sheer strength of the current jet this has meant the really cold uppers of -20C off the Eastern seaboard have had less modification than normal with quite cold air still reaching across to the UK-hence the back edge snow at quite lower levels some of us have seen.

 

Gradually as the Canadian vortex eases back we will lose this effect so the trend would be to confine the Wintry stuff to higher levels again as successive lows mix out the colder air,especially away from the far north of the UK.

 

still an unsettled pattern going into next week but with the sting taken out of the jet somewhat as the thermal gradient reduces across the Atlantic the flow starts to show signs of buckling and ridging here and there so hopefully longer drier interludes and less ferocious storms should result.

The Day 10 means

 

far from settled but just an easing of this current strong cyclonic setup as the vortex,especially those very low heights to our nw, start to show signs of waning.

Edited February 11, 2014 by phil nw.

[Bobby]

Signs of the Canadian cyclone cannon and the jet weakening into late February but still not looking especially settled nor cold. Perhaps a watered down version of the current pattern, generally unsettled with wind and rain at times just not to the extremes of the winter so far is the most likely medium range outlook.

 

ECM ens mean at day 10

 

 

NAEFS and GEM ensemble mean at +300

 

 

The most unsettled weather perhaps for the NW, so something more traditional for this time of year.

[johnholmes]

Ah, but did you see any signs in yesterday evenings output?

Certainly much flatter output today than yesterday evening but personally I expected that, well I expected ECM to be flatter at least.

It is all a matter of perspective and one should always be ambiguous when talking about possible pressure patterns setting up in FI.

 

I can't talk for others but my opinion way back was that the pattern would become more amplified around mid month as the Canadian PV moved East and the jet slackened behind with the slim possibility of an Atlantic ridge and Scandinavian trough setting up dependent on how quickly the PV to our West could reorganise or be resupplied. I think we have seen this to some extent but although we saw a decent ridge modelled in the ensembles and occasional operational (around 50% or so at one stage) there was never really that much support for it and where there was the pattern was often quickly overrun by the jet returning North over the top.

 

Even so we have seen increased amplification modelled for mid month onward and that has occasional thrown up better charts where we have managed some undercut but now we are looking out into the last 3rd Feb for the next opportunity which comes on the back of any increased amplification. We have almost always had to play the long game when looking for cold opportunities this year and if I were simply giving 7 day forecasts cold would very rarely have entered my summaries - indeed I personally have never stated it WILL be blocked or WILL be cold at any particular time-frame 10 days+. Only that there may be an increased opportunity for blocking and how that may develop over a certain time-frame and almost always I remind people that the usual caveats apply at those time-frames.

 

Yes the endless search for cold patterns in winter does niggle some people when all they see in the charts for the next 7 to 10 days is wind and rain but it shouldn't.

As I always say folk have the power of discernment and can take or leave the more speculative and long range model output discussions for the more reliable time-frame and/or actual forecasts for the UK.  Personally I read it all because it all has value to me.

Just so long as people are not making definitive statements of incoming big freezes based on a single 384 chart. Speculating over the future output is a big part of this thread and so it should be because the output changes day to day so it would be more foolish to assume any particular output was set in stone at the longer ranges.(FI)

 

On that note this mornings output is disappointing after last nights glimmer of hope and the ensembles also do not suggest any kind of blocking so it is understandable that people would want to write off the rest of February, especially given the Winter we have had. 

I certainly wouldn't want to suggest there is anything in the long range ouput this morning where any kind of blocking is suggested as taking hold except perhaps the azores high ridging over the UK, which I guess we would all take, but at least there is still the suggestion that we will see ridges being thrown up from around mid month in the Atlantic and while that is the case there will be the opportunity for one of these ridges to force low pressure SE rather than NE and that could easily show again in tonight's output though as I said yesterday this is more for around 10 to 15 day time-frame (now 9 to 14) - it was just the ECM over-egged the pudding,

Anyway the more amplified pattern is around 4 or 5 days away with the first ridge worthy of the name being around 7 days away - that won't be enough but it will keep the pattern amplified upstream and it will only take a little less forcing from the PV as it reorganises and drops SW to get a stronger ridge thereafter capable of disrupting the Atlantic flow to the point where a MLB could take hold so I think we will at least see this modelled again even if ultimately the Atlantic proves too strong yet again.

 

I will just add that there is indeed no sign of a deep cold pattern setting up in the output but there is plenty of wiggle room for something more seasonal to show up last 3rd of February - we can but hope.

 

to answer your post briefly and in one word your first line no

a longer reply below

 

I use the 500mb anomaly charts as a guide not a be all and end all for what the vagaries of the weather may be in the 6-15 day time scale.

They do not and have not shown anything more than the probability, as the intense Atlantic flow eases off (something else they showed consistently and some time before the vagaries of synoptic models) of brief Arctic but more likely Polar Maritime bursts behind individual low pressure systems.

The 30mb Stratosphere charts, which I use as a basic guide for even further down the road, coupled with the MJO (and not very much on this actual or predicted really) does show the probability of northern blocking being more in evidence from about early March.

So 6-15 day time scale=no blocking, brief colder ridging behind surface lows, snowfall on low ground in the southern half of the UK very problematical and only improoving as one heads well north. Snow at times, as per this morning, on higher ground from north Midlands northwards.

Edited February 11, 2014 by johnholmes

[Mucka]

to answer your post briefly and in one word your first line no

a longer reply below

 

I use the 500mb anomaly charts as a guide not a be all and end all for what the vagaries of the weather may be in the 6-15 day time scale.

They do not and have not shown anything more than the probability, as the intense Atlantic flow eases off (something else they showed consistently and some time before the vagaries of synoptic models) of brief Arctic but more likely Polar Maritime bursts behind individual low pressure systems.

The 30mb Stratosphere charts, which I use as a basic guide for even further down the road, coupled with the MJO (and not very much on this actual or predicted really) does show the probability of northern blocking being more in evidence from about early March.

So 6-15 day time scale=no blocking, brief colder ridging behind surface lows, snowfall on low ground in the southern half of the UK very problematical and only improoving as one heads well north. Snow at times, as per this morning, on higher ground from north Midlands northwards.

 

Fair enough but JMA, ECM and GEM all showed potential for a strong ridge to develop around day 9 yesterday evening but I guess it depends what one means when they say "no sign of blocking" and also the time-frames involved. Unfortunately that wasn't built upon in this mornings output but I dare say the models will toy with that some more over the next few days.

 

Tomorrow looks horrendous for NW England but many other regions as well, it really will be case of checking to see if the garden fence or shed roof are still there tomorrow.

 

[nick sussex]

Although we saw a climbdown from the ECM this morning theres still some possible interest as some shortwave energy might run se into the UK with snow on the northern flank.

 

The UKMO 00hrs run has this at T144hrs and theres still a chance a stronger ridge to the ne could help put some more forcing on troughing to the west.

Edited February 11, 2014 by nick sussex

[bobbydog]

GFS 12z showing saturdays low as much stronger and organised like the UKMO and ECM

 

 

here we go again........

 

 

and this will be as welcome as a punch in the face

 

Edited February 11, 2014 by bobbydog

[Mucka]

UKMO 120/144 has more in common with last nights ECM than this afternoons GFS.

 

[SMU]

Afternoon All-

 

 

For those that cannot spot potential in these charts ( & modest blocking ) they need to at least review some historic charts-

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014021112/gfsnh-0-168.png?12

 

http://www.meteociel.fr/ukmo/runs/2014021112/UN144-21.GIF?11-17

 

at 144 UKMO has snow for Northern England with -8 c uppers tucking into the northern flank-

 

The key is whether that model higher pressure can hold in site over Iceland & deflect the jet south long enough to link into the Svalbard high-

 

For JHolmes

 

John the only fault I can pick in you using the 500 Anomaly charts is in scenarios like this when very modest 500 blocking ( or highs that distort the overall flow) are located over Svalbard & Greenland...

 

Certainly not huge upper level highs but none the less can be effective...

 

S

Edited February 11, 2014 by Steve Murr