Model Output Discussion 12z 03/04/13

[davehsug]

You should only give up when they're not showing the outcome desired by the cold obsessives John , but then you already know that!

Edited April 4, 2013 by davehsug

[Captain Shortwave]

The eastern seaboard low is back

Previous run

The low is a few hundred miles further south this run anyway.

Edited April 4, 2013 by Captain shortwave

[SP1986]

There does seems to be a definite trend away from milder weather now, well there is a slight warming up with double digit temperatures, but still below average.. with night frosts. I can't say what the future holds, but I think we have to entertain the possibility that below average temperature might be here throughout this month, and beyond.. it's a reasoning that is right to be criticised however, it is not being challenged by the unravelling season at the moment.

if we continue with frosts throughout the rest of the month, then Spring growth may be as late as its ever been.. bare trees into May would be a record I think?

Anyway musing aside below average for the forseeable future is the headline I think.. and I did suspect this may be the case after the models did something similar in mid-late March. I would expect similar FI warm ups to be discarded for a colder regime this month, we're just on the wrong side of the jet streams and undercutting is rife as had been said in previous posts!

[Chris K]

not true and I have 3 years watching them to believe otherwise, and there are 30+ charts over 12 months that prove as my other post suggested that they are correct for the upper air on about 70% of occasions.

Maybe I should just give up on trying to plug this idea of 500mb anomaly charts, when they are consistent over a 3 day period and have the backing of data available for further out ideas on major pattern evolvement?

I enjoy your input regarding the 500mb anomaly charts...extremely useful for amateur learners like me and in my opinion, whilst I enjoy reading everyone's interpretation of model outputs... you're one person whose posts I always read because they are level headed, unbiased and actually, the outcome is either as you presented thoughts on, or close.

Plus, if they have ever been a bit off you often explain why.

They aren't the only tool by any means, but I'd always recommend people to read your posts and PDF notes found here and in the in-depth model discussion thread.

[Guest pjl20101]

Have retweeted a lot of matt hugo's tweets and yes an improvement is on the cards. Next week however we will have a trough to contend with. Also I looked on CFS on the CPC site and it does look currently like April will be a drier than average month, despite it not being too brilliantly warm at times.

[IDO]

The GFS 0z run continues with the end of the blocked cold pattern. It takes till mid next week before all the influence of the high is pushed east:

Wet for all and a return to closer to average temps for the southern UK.

On this run the Iberian/Euro high fails with its attempt to push north and the UK ends in a zonal flow with the jet traversing the country. So by D12 still in a zonal flow:

The south now average temp wise.

Late in FI the Euro high drags in some warm air:

So on this run any warm weather is delayed and we look like having a spell of cool wet cyclonic westerlies.

The GEFS pressure charts suggest a split as to the influence of the mid latitude HP: so still possibilities for an earlier taste of above average warmth.

Edited April 5, 2013 by i'm dreaming of...

[ANYWEATHER]

Gfs model showing milder weather the ecm showing the colder option right out to t+168, Both models though show us entering unsettled conditions, mainly of rain from the gfs, something like rain,sleet and snow from the ecm...

[Frosty.]

A very nice end to the Ecm 00z op run, becoming anticyclonic and slowly turning warmer. As for next week, the track of the low is still uncertain, the gfs 00z takes it further north which eventually brings milder air to the whole of the uk whereas the ecm 00z takes it further south which keeps northern britain in the colder air throughout next week with a wintry mix, one thing is for sure, next week looks very unsettled with low pressure over the uk with bands of cold rain and showers, or if the ecm verified, a mix of rain, sleet and wet snow, the snow risk mostly for hills and especially for scotland but then there are signs of pressure rising and hopefully mid april onwards will become dry, sunny and eventually warmer but the gfs 00z op run is a mixed bag in FI with colder and milder intervals, some settled weather but unsettled at times.

[mushymanrob]

As we don't know what is happening beyond 5-days any kind of chart prediction beyond this is a lottery.

Since they use the same data as the NWP models but simply represent it in a different format they are as prone to change as the models and often do. Furthermore there is often somewhat of a lag before they catch up with changes or trends that the medium term models pick up quicker.

as you quoted my post i was going to answer these, but i see jh has. as i listen to what the more experienced suggest, ive found that jh's interpretation is well worth noting .

the current synoptics arent just a random set of events, the synoptics we get or are likely to get are driven by many 'upstream signals'. the anomaly charts are an early indication as to what the overall pattern might be, and they take into account the many factors that drive out weather.

oh, and this mornings runs suggest that they will be correct!

not true and I have 3 years watching them to believe otherwise, and there are 30+ charts over 12 months that prove as my other post suggested that they are correct for the upper air on about 70% of occasions.

Maybe I should just give up on trying to plug this idea of 500mb anomaly charts, when they are consistent over a 3 day period and have the backing of data available for further out ideas on major pattern evolvement?

dont you dare give up plugging this ! its very useful to those of us with less knowlege/time to get a realistic idea of what the furture might hold.

well we do seem to be drifting slowly into a less cold pattern, the threat of a re-load has diminished and even a possible warm up in fi makes yet another appearance. but there are differences, the gfs has the trough further north then the ecm and ukmo into next week. if the gfs is correct, itll be milder, if the ecm and ukmo are correct, itll be cooler, especially the further north you are.

but we have to go through this transition, as the block breaks, hopefully by this time next week we will be turning our heads towards the prospect of warmth as opposed to losing this deep cold. unbiasedly as we can of course! :lol:

[Captain Shortwave]

It's as you were again from the models this morning.

ECM/UKMO take the low through southern England and follow this with a brief northerly before high pressure builds. Yet again ECM suggests Arctic oscillation will go negative with northern blocking re-establishing to our north though nothing cold yet (notice the cold uppers creeping back into Scandinavia though)

GFS continues its campaign of establish rather more normal conditions for the UK, unfortunately it's add odds still with the Euros here and frankly given the situation, one could easily think the GFS is on a mild at all costs run.

GEM is the middle ground sending the low slightly further north but also suggests heights rebuilding to the north (over Greenland instead of Svalbard in the ECM run).

In the end it's not over us that the GFS is at odds with, it's all the profile over Canada and the Northern states showing lower pressure, yet again though it seems to be developing a deep low pressure over Canada (backed up by the NAVGEM at T168, ECM/GEM have no low pressure system whatsoever, so one to watch as this will directly affect the profile over the pole)

[johnholmes]

The NOAA output and the ECMWF-GFS this morning, not totally similar but sufficient to suggest that milder air at 500mb is going to be with us by about the middle, possibly Thursday of next week. Just what the surface pattern will be is not too clear. It could be that pressure rises to the SE of the country and gives a more settled feel for many by the following weekend with a respectable rise in temperatures and with overnight frosts disappearing. I would still expect some unsettled weather before this and again afterwards-it is April after all.

Funnier things have happened!

thanks for the kind comments about 500mb anomaly watching-they will continue.

Edited April 5, 2013 by johnholmes

[Gibby]

Hi folks. Here is this morning's take on the 00z output from GFS, UKMO, GEM and ECM for today Friday April 5th 2013.

All models show the rather cold conditions persisting for the time being. Through today the semi permanent NE flow over England and Wales should blow itself out today with the rather cloudy skies and the odd snow flurry giving way to brighter conditions later. Elsewhere away from Northern Scotland where a weak trough brings some light rain and hill snow today and the weekend sees a lot of dry and bright weather by day and frosty nights and daytime's will feel warmer with the lack of breeze aiding the process. Through Monday and Tuesday of next week a depression slides ESE into NW France increasing the pressure gradient over the UK with a fresh and cold ESE wind developing with some outbreaks of cold rain spreading NE into Southern and western areas.

GFS then shows the midweek period as becoming milder with rain spreading North and East over remaining areas with bright and breezy, showery weather following in much less cold air. A sustained period of Westerly winds carrying troughs of Low pressure in association with Atlantic depressions to the North of Scotland is then shown with spells of rain and showers for all in temperatures close to average for mid April. Late in FI. Late in FI pressure builds from the South and a first spell of settled warm weather looks possible at the edge of FI with above average temperatures and warm sunshine.

The GFS Ensembles show the warm up well under way over the coming days though it takes a while longer before average uppers are achieved when normal values are sustained from then on through the run with some rain at times for most areas in the process. Things become rather more settled again at the end of FI though the high temperatures shown by the operational are not supported.

The Jet Stream continues to blow in more Southerly latitudes currently but it shows signs of pulsing further North with time towards Southern England next week.

UKMO today shows Low pressure over the UK midweek drifting out into the North Sea allowing a cold and cloudy North or NE flow down over the UK later in the week with rain at times and some hill snow still possible in the North.

GEM gives a rather complex pattern of Low pressure over and around the UK later next week with rain at times before it trends towards a settling down later next weekend on a Southerly flow with warmer temperatures and rather breezy conditions with fronts edging in from the West at the end of the run with some rain.

ECM shows a wet period midweek as Low pressure exits East out of the UK with a cold northerly giving way to settled and dry conditions next weekend as high pressure builds over the UK, extending North later. On its 240hr chart it shows yet another blocking situation with High pressure to the north and a cool Easterly breeze developing over the South making North Sea coasts very chilly.

In Summary the current cold weather is scheduled to last until midweek next week although the weekend will not feel at all bad in the sunny spells and the absent cold wind. The cold wind will pick up again early next week before a wet and windy spell midweek ushers in divergence between the models with the models from the States keeping things more unsettled with rain at times in milder conditions while ECM brings a quick return of a High pressure block close to the UK and settled fine weather with sunny spells but a frost risk at night. Despite few signs of warm conditions shown this morning things should trend more normal once we leave the unsettled and rather cold patch of weather early and midweek next week.

[bluearmy]

I havent commented much recently as i dont feel too confident in the nwp. having seemed bullish about the demise of hlb, the ecm is now trending back towards it after a brief respite. I would caution too much optimism/pessimism. It could easily stay on the cool side last third april.

[Summer Sun]

If the ECM monthly forecast for Birmingham is right temperatures would stay well below normal into May

[Frosty.]

This weekend looks dry and bright with lighter winds but with overnight frosts apart from the far north which looks a bit more unsettled, into next week the Ecm 00z op run shows cold uppers only slowly retreating northwards through the week, even by midweek the 528 dam line is still across central uk and the 522 dam line across the far northeast of scotland but the ecm shows warmer uppers encroaching into the south and southeast later next week, the ecm run ends with a nice looking warming trend in a settled looking pattern which would be very welcome following the expected cool and very unsettled spell next week, coldest further north with hill snow. There are signs of a more anticyclonic spell mid month or soon after and slowly becoming warmer, but it remains well into FI.

Edited April 5, 2013 by Frosty039

[Guest pjl20101]

Have to say that the ecm is right on the money as its been very accurate about today and this week. I don't see a sign of a let up as the trough is likely to happen next week followed by something better. The question is whether it can last? Probably not but who can tell at the moment.

[West is Best]

OK I may be misreading this completely and I desperately want warmer weather, but next week looks far from clearcut to me. Indeed there looks to be the potential still for further disruptive snowfall in the north (probably only the north at the moment) on the boundary lines between mild and cold. The 06z actually has a channel low and whilst by that stage the coldest -5 850hPa will have shifted north, as the fronts stall and the leading side pulls easterlies back in, I'm far from convinced it won't bring another bout of white stuff.

I really hope I'm wrong and we see an Atlantic onslaught. I have a nasty feeling from these outputs that it's not going to happen without a fight that could see further snow.

[SP1986]

OK I may be misreading this completely and I desperately want warmer weather, but next week looks far from clearcut to me. Indeed there looks to be the potential still for further disruptive snowfall in the north (probably only the north at the moment) on the boundary lines between mild and cold. The 06z actually has a channel low and whilst by that stage the coldest -5 850hPa will have shifted north, as the fronts stall and the leading side pulls easterlies back in, I'm far from convinced it won't bring another bout of white stuff.

I really hope I'm wrong and we see an Atlantic onslaught. I have a nasty feeling from these outputs that it's not going to happen without a fight that could see further snow.

I'm in full agreement with you here, the models are consistently pushing the milder outlook back into the unreliable timeframes, and it seems at the moment any milder weather coming is akin to chasing a rainbow. The GFS 6z certainly latches onto the idea of prolonging the cold spell, with perhaps, as you say some frontal boundary snowfall, which could be fairly intense and heavy across parts of Northern England, should precipitation come into the mix later on. It does look like frosty nights for the forseeable future, perhaps severe in places where snow settles..

Only in the far southern fifth of the UK do I see anything akin to Springlike, or anything vaguely resembling mid-April.. To my eye, if we discard the usual overly progressive warm ups, the outlook is still decidedly wintry for most.

So of course personally, I'm very sceptical that there will be any truely average Spring weather in April, I'm not sure when that will come in all honesty.

[Captain Shortwave]

The only consistency with the GFS output is that it somehow manages to manipulate the lows in such a way to pretty much bring the same result by about day 7 which is a mild southwesterly flow. Between days 3 and 7 it's all over the place and frankly the fact it comes up with near enough the same result by the end of high resolution for the UK looks highly dubious. The trough is centred pretty much between northern Scotland and Iceland every run.

Edited April 5, 2013 by Captain shortwave

[Purga]

A southward shift from GFS 06z

If it continues there could be some interesting weather for central and northern parts.

[Frosty.]

The Gfs 06z shows a very slow change to milder/average temps next week, at least for southern britain, the north of the uk staying cool/cold for most of the week but then turning much milder nationwide for a few days before we are plunged back into winter with an Arctic blast with strong height rises to the northwest and pressure falls dramatically to the northeast, so could we be soon entering a spell with wild swings between cold and mild in the next few weeks or a more stable benign further outlook as the ecm 00z shows.

[Tim Bland]

I think it could be too marginal for most lower ground to see any meaningfull snowfall from the breakdown. If these synoptics had occoured 6 weeks ago then it would be a different story. Even with the Channel low temps are still into double figures in the Midlands.

As a snow lover this has been a fantastic winter with snow observed every month for 7 months (starting Oct) My only gripe is that the best synoptic patterns occoured 6 weeks too late. Lets hope for a breat winter next year... March is similar to 1962 this year so lets hope we get a repeat of the winter that followed

[Summer Sun]

GFS 06z is performing its usual tricks this morning well away from the 00z runs

GFS 00z

ECM 00z

UKMO 00z

[Purga]

I think it could be too marginal for most lower ground to see any meaningfull snowfall from the breakdown. If these synoptics had occoured 6 weeks ago then it would be a different story. Even with the Channel low temps are still into double figures in the Midlands.

As a snow lover this has been a fantastic winter with snow observed every month for 7 months (starting Oct) My only gripe is that the best synoptic patterns occoured 6 weeks too late. Lets hope for a breat winter next year... March is similar to 1962 this year so lets hope we get a repeat of the winter that followed

Absolutely Tim that would be fantastic. Not bad this last season snow falls OKish and great about the falls occuring throughout 7 months but a bit disappoiniting with no decent frost or any frozen lakes or canals etc. 1963 the ground froze to 12" in parts of the West Country where I was.

[Frosty.]

It sounds like we are heading for a NW / SE split in the uk weather beyond next week with pressure rising to the south and southeast but remaining generally low to the northwest/north with unsettled weather at times for scotland, n.ireland and nw england, some fine spells too but the best of the dry and bright weather and also the warmest temps further southeast. That's still a long way off though and next week looks like becoming unsettled just about everywhere as the week goes on, and also trending milder for the south of the uk but the change from cold to milder will be a painfully slow process across northern britain and there is a risk of snow in the north next week, mostly for hills/mountains, by the end of next week we are likely to see pressure rising across the uk but fine conditions for the north/nw will probably be shortlived before atlantic systems take control.