General Model Output Discussion

[MR EXTREMES]

The latest Fax charts look very impressive for snowfall potential. Quite a few troughs coming South!

you aint kidding the fax every run absolutely brillant fantastic stuff.

ktom i would not worry from every forecast ive seen 1 or 2c looks likely add on snowcover which some have already then below freezing.

snow will and is and has fallen already them fax charts are superb,

at one stage it looks like the greenland high is sinking into the north alantic but then it seems to move back up there.

im getting more and more excited atleast 7day coldspell on the way cant grumble at that.

Edited January 1, 2010 by badboy657

[Iceberg]

Good new year all, since the kids have got me up, I thought I might as well have a quick blury eyed look at the models, hopefully my blury eyes are not deceiving me with ECM bringing in a thickness of 502 into the south onthe 10th of Jan. A Complete Turnaround from the 12Z, (BTW the 12Z was at the top of it's ensembles at the end and it's ensembles were getting milder).

I am still not totally brought on the transformation to the high to the east, but it's looking better.

GFS Ensembles are fantastic as well Keeping even the south in the -5 until the 14th of Jan.

UKMETO another peach of a run as it brings more organised snow across England (particularly the south at the 144 mark).

GFS is less keen onthis, ECM more keen and extends the snow.

NAE and GFS bring the saturday night band south, GFS brings it further south than NAE, but neather have much precip on it once it gets out of the Midlands.

Basically very nice models still.

[Frosty.]

HAPPY NEW YEAR ALL

The UKMO 00z T+144 is sensational, even better than the gfs & ecm in the same timeframe. The good news for cold fans is the ecm is back on track after it's 12z wobble, both the gfs and ecm agree on an anticyclonic outlook beyond next week and remaining very cold with severe frosts and probably widespread freezing fog as winds fall light. Much of next week could produce some large snowfalls in the form of frequent snow showers and widespread persistent, severe frosts, as a bitter outbreak of Arctic air sweeps south which will just enhance the cold air already in situ, the snow will probably be the powdery variety.

[Methuselah]

Looking at the fax's it does look promising for some snow, what is slightly worrying is that the met are still talking about the prospect of a mixture of rain/sleet and snow showers. If we can't get 100% snow in this set up we are in trouble!

The real cold air always seems to be around 3 days away, temps for tomorrow look to be around 4c for most...not far of average. I'm not moaning before I get shot down, just stating the facts.

That's the rub though, KT...If it's precipitation we want, then (unfortunately) it's not all going to be of snow? If it weren't for the temperature/moisture contrasts, there wouldn't be any precipitation at all...

IMO, the beauty of today's Faxes lies in two things: firstly, there's a lot of entrenched cold air ahead of the system; and, secondly, the air following on behind is even colder?

[KTtom]

That's the rub though, KT...If it's precipitation we want, then (unfortunately) it's not all going to be of snow? If it weren't for the temperature/moisture contrasts, there wouldn't be any precipitation at all...

IMO, the beauty of today's Faxes lies in two things: firstly, there's a lot of entrenched cold air ahead of the system; and, secondly, the air following on behind is even colder?

I guess you're right there, it would be great for once to have a nailed on snow event without having to jump into the car and head up the nearest hill

This is a great chart, as you say the air behind is bitter and I wouldn't have thought there would be too much rain in that front as it moves south.

[Iceberg]

They should hopefully be updating those faxes as I think they are from yesterday looking at the date/time and the t120. Shame though as they have a L just offshore from me.

I rather like this chart from the ECM showing -12 850s across alot of England down to -13 in the south, in a strong easterly wind, that will feel truely bitter. !

[Glacier Point]

Happy New Year to you all!

Nice to see the general concensus in the modelling this morning takes along the lines of the evolution anticipated. ECM has predictably backed off its 12z solution.

A couple of things to note:

The GFS ensemble mean comes up with a parcel of extremely cold air over Europe in the medium to long term with 850 values of up to fifteen degrees below average:

http://raleighwx.eas...nomalyNH216.gif

That is going to be very difficult to shift and would I think more or less lock in a pattern over Europe for a considerable period.

The ECM evolution intoduces sub -10C 850 values with anticyclonic conditions in the longer term.

http://www.vedur.is/...01_0000_240.png

That would result in brutal cold for the UK, not experienced by many of the younger generation.

The GFS ensemble mean is also hinting very strongly at a reload as an upper trough slides underneath the cold block over Europe forcing height rises to the north.

http://raleighwx.eas...nomalyNH360.gif

Keep an eye on the progression of the MJO as this is the best indicator of when or of this third pulse of cold is due - entering phase 5, 6, 7 is the trigger.

http://www.cpc.noaa....O/foregfs.shtml

Edited January 1, 2010 by Glacier Point

[Methuselah]

Not a bad chart, Ice...That HP would give me another freezing-fogfest if it came-off...I wonder how much they'll all change today??

BBC now expecting precipitation to fade-away overnight? So, I'll be very interested in what the models show...

[MR EXTREMES]

thanks for the post gp it would seem that the mjo evolution is in slow mo for now but ofcoarse it will change soon.

although colder air is with us now the models do suggest even colder air is possible but how cold will it go?

Edited January 1, 2010 by badboy657

[Methuselah]

I guess you're right there, it would be great for once to have a nailed on snow event without having to jump into the car and head up the nearest hill

This is a great chart, as you say the air behind is bitter and I wouldn't have thought there would be too much rain in that front as it moves south.

Further to this, the snow in Sneckie has suddenly turned to sleety rain. So, beware of patches of slightly higher uppers hidden in the general flow...According the the GFS, there's a miniscule area of -5C air enclosed in what's otherwise -6...Marginality can, of itself, be quite interesting!

[nick sussex]

Morning all and happy New Year and very nice to see the ecm back on board after that little wobble yesterday. Generally we see good agreement across the board for the pattern.

I would say theres just one more little hurdle to overcome before we can call a cold first half of January thats around 144hrs as we see the next stage to possibly even colder air heading west along the southern flank of the high in association with high pressure transferring just to the north, here you need the right balance of energy going into the northern and southern arms of the jet.

Because of the pattern the set up is likely to eventually settle things down to the north closest to the centre of the high, where as southern and se areas are most likeliest to keep the coldest upper air and snow chances.

Before then there are likely to be several snow chances as troughs are likely to head sw in the ne flow so hopefully these can share the snow around.

[yamkin]

Not a bad I'm not happy, in fact I'm quite sad run- operational only has -14c's into the SE in FI now-

http://91.121.94.83/modeles/gfs/run/gfs-1-252.png?0

ensemble mean now -11c at 168- an upgrade on the 18z

http://91.121.94.83/modeles/gens/run/gens-21-0-168.png?0

S

The Ensemble Mean remains under 0c up to 'OFF THE SCALE' Incredible

Thought I'd attach the Moscow Ensemble too

[johnholmes]

yes Happy New Year all

after a December that broke most 'wintry' type numbers for here it is looking like the first 10-14 days, at least, of January are going to be NOT mild, indeed mainly cold or, at times, very cold.

As to snow, then with a flow down the North Sea, already places are showing a covering and with the probability of troughs then this must extend further inland over the next few days. I've noticed various posters with photos of snow cover, even near Dublin as a line of showers came off the Irish Sea, similar in parts of Kent and then from Lincs northwards-sunny and frosty here.

If the cold does last at least 14 days, however little snow falls then on temperatures this winter would, for most, be into the category of at least the coldest in 10 probably 20 years if not longer for some parts of the country.

So, come on folks, its a New year, all the coldies enjoy what seems in store for this week anyway.

[Tom Montalbano]

A very Happy New Year to you all.

Some tremendous runs overnight then with the prospect of some very wintry weather in the next week.

Would expect some more roller coaster stuff, it wouldnt be the models otherwise!

The feature that drops south on Saturday does have some slightly milder air wrapped in it, so some will have a wintry mix, while others will get lucky and have just snow.

A long way off still but if we can keep the PV away from Greenland and to the north of Scandinavia, we have a stab at an easterly, perhaps followed by another rise in heights over Greenland/Iceland, which was alluded to by some of the guys yesterday. A couple of models that go out that far are now toying with that scenario.

ECM. http://charts.netweather.tv/ecmimages/20100101/00/ecm500.192.png

http://charts.netweather.tv/ecmimages/20100101/00/ecm500.216.png

GFS. http://charts.netweather.tv/ecmimages/20100101/00/ecm500.216.png

An example of what can happen if the PV stays north of Scandinavia and away from Greenland and remember we'd be tapping into entrenched bitter cold over E.Europe.

JAN 1987. http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870112.gif

A long way off of course and plenty to enthuse about in the coming week or so.

Regards,

Tom.

[swfc]

Goodmorning and a happy new year.Great output this morning and all pointing to an extended cold spell of weather.The fax charts worth keeping an eye on or maybe local tv regarding snow showers ete.Big downgrade on the bbc regarding yesterdays predicted snow showers for today but i guess its a complicated set up.Bone dry here but anywhere could catch a rogue shower i guess.Ecm as got over its hangover and the ukmo looks on song.Happy days so far.

[TEITS]

Very nice runs once again this morning with the ECM +144 being a particularly nice chart with plenty of snow showers being blown in. However I shall remain cautious until the E,ly is at +72 for the simple reason is I wouldn't want the HP to be centred further S because it would kill any convection for my location. I believe beyond the +240 chart we would eventually see the HP move back NW.

The ECM ensembles have actually prolonged this cold spell compared to yesterdays 0Z.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Happy New Year by the way.

Edited January 1, 2010 by THE EYE IN THE SKY

[beng]

Those ECM ensembles are mighty! It's not uncommon IMO for the block to be nudged a bit further North as we get closer - that would be the coldest scenario for all as it would produce lower 850s and more widespread snow. We'll have to watch the trends on the next 48 hours of runs to see whether the block is shifted slightly north or south then.

[weather eater]

A cold New Year from the High Peak area, certainly a very hard frost to greet the New Year in. I see the ECM has backed away this morning from yesterdays 12z, as I thought it would. This just goes to show, that one run even with support from its ensembles is not indicative of a new trend. If fact I'd rather make a judgement based on a range of recent operational runs and ignore the ensembles altogether, mainly they indicate to me that modelling past the 120-144hr mark is largely a waste of computing power. This mornings ECM is a case in point, as beyond that 120 - 144hr mark its not just a bit different from last night 12z, its nothing like it.

[kev238]

I think the outline for the next five days or so is clear. However, the specific detail is likely to vary. GFS brings more precipitation down tomorrow afternoon/ evening. Will it be correct?

Anyhow, if this morning is any indication then just look out of your windows--- how can anyone not enjoy sparkling sunshine and glistening frost on the ground??!!

[bluearmy]

this is becoming ever more interesting. the ecm ens for holland show just how dry the next fortnight is likely to be. however, the trick for us will be the onshore flows and how the deeply cold uppers interact with the sea.

as GP alluded, some cold coming up, the like of which hasnt been seen for a long time. even if the block were to settle closer to us, the temps would still be absolutley frigid.

[TEITS]

this is becoming ever more interesting. the ecm ens for holland show just how dry the next fortnight is likely to be. however, the trick for us will be the onshore flows and how the deeply cold uppers interact with the sea.

as GP alluded, some cold coming up, the like of which hasnt been seen for a long time. even if the block were to settle closer to us, the temps would still be absolutley frigid.

If I was to sum up next week then I would say I have high confidence of remaining bitterly cold but low confidence of a classic snowy E,ly. My confidence isn't low because I don't think it will happen but due to the timeframe.

At the moment I would say the further SE you are the better your chances of a snowy E,ly. Whereas locations such as NE England, Scotland will need to hope the HP is further N.

[Geordiesnow]

Really good 06Z imo still, theres bound to be loads of snow from that set up i would of thought and the good thing is that unlike this set up, there won't be much high cloud around and instability should be lower so more widespread showers i would of thought.

Not too fussed about any potential breakdown at the moment, for the foreseeable future, it's looking cold and rather snowy for some.

[johnholmes]

Its pleasing to see the return of optimism amongst the cold brigade this morning and the next 7-perhaps 14 days looks like staying cold or even very cold.

However, I would just add a word of caution about the far synoptic outlook as suggested by ECMWF 12z Thursday.

As most know I produce a commentary on the T+240 outputs from ECMWF and GFS in my lrf issues. When I look closely at the past 5-6 days it has shown similar ideas on most days. Nor is that at total variance with some other indicators.

All very confusing as I trot off to work out the lrf for the period 11-21 January?

[nick sussex]

Another good gfs run here, some slight differences with how the Scandi high builds but to be expected at that range, what does stand out from this run is the slackness of the flow and because of this coupled with the very cold upper air there could be some extremely low night time temps, IMO if the flow remains slack for several days then favoured areas with snow cover and clear skies for example east Wales, west Midlands could easily approach -15c, for further north Scottish glens could hit -20!

Remember here you don't need extremely cold upper air to hit extreme cold nighttime temps , basically no mixing, clear skies, snow cover for several days will suffice.

[TEITS]

what does stand out from this run is the slackness of the flow and because of this coupled with the very cold upper air there could be some extremely low night time temps, IMO if the flow remains slack for several days then favoured areas with snow cover and clear skies for example east Wales, west Midlands could easily approach -15c, for further north Scottish glens could hit -20!

Sod the slack flow, give me a gale force E,ly.

Very important Met O 6-15 day forecast coming up today. The reason I say this is we shall find out how many of those ensemble members opt for the HP over the UK bringing very cold surface temps or further N bringing a snowy E,ly. Lets hope its the latter and the forecast mentions heavy snow showers especially in E districts.