Model Output Discussion - 14th Jan 12z Onwards

[Bristawl Si]

This is more than likely to change tomorrow and then maybe different areas will be favoured or maybe not.

After viewing on here for a number of years i'm well aware of that.

Par for the course in this type of situ.

Will we be on the 'right' side of the trough for snow or on the 'wrong' side for rain?

Place your bets!

[SMU]

So going on from the post about 'shallow low'

 

The mean at 120 is a good indicator.

ECM DET 850's at 144

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/ECU0-144.GIF?14-0

 

ECM MEAN 850's at 144

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/EDU0-144.GIF?14-0

 

That's some 3 degrees colder- backing up the theory of the ECM DET being to deep.

 

The 500 track on the mean-

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/EDU1-144.GIF?14-0

 

that's about as Positive as it gets in terms of widespread snow.....

 

best regards

Steve

Edited January 14, 2015 by Steve Murr

[Weathizard]

So then, we arrive somewhat disjointed at a potent cold snap.- which has the potential to last 8 days ( day 1 is T48)  - possibly longer.

 

Since March 2013 there haven't been ANY HLB synoptics, with just very short NW transitional Pm flows last winter. - so of course we can all understand the desire for our own 'imby' to come up trumps in next weeks scrum of low pressure drifting / sliding SE.

 

My thoughts thus far is that as we home in on the slider low the track & intensity probability wise do NOT favour snow for the following areas.

 

SW - South of M4, southern England- again along the south coast & the shires more so & also the SE corner like Kent & Essex / sussex. ( if the PPN makes it at all)

 

Why? If we look at the information available from UKMO & ECM we see the tracks:

 

ECM-

 

120-

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/ECU1-120.GIF?14-0

144-

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/ECU1-144.GIF?14-0

 

The ECM tracks the low across Ireland towards wales & then into the channel & deepens it to 976MB, which is far to deep for a slider.

 

This sort of depth - creates turbulence & forces milder TM saturated air ahead of the system, because of the turbulence the slightly milder uppers & indeed a increased 'melt layer' in the column of air from cloud base to ground mix ahead of thee frontal zone NE wards- so your surface cold is all gone by the time the PPN arrives.

 

remember 'Deeper the low = further NE milder penetration', so along the lows track you would need to get into the midlands to find the snow line.

 

UKMO is better because the intensity is shallow- which is likely to be the form horse- However the track is flatter & less acute.

 

120-

http://www.meteociel.fr/ukmo/run/U120-21UK.GIF?14-18

 

144

http://www.meteociel.fr/ukmo/run/U144-21UK.GIF?14-18

 

Track is through Ireland across the central belt, meaning again you can forget snow for the south, its reserved for the North along the line where those tight easterly isobars are.

 

So of the Euros overall neither paint a great signal for the UK, however the ECM does look good for snow further North.

 

Whats going to change? well the optimum for retaining snow prospects was the NAVGEM

http://modeles.meteociel.fr/modeles/navgem/runs/2015011412/navgem-0-132.png?14-17

 

low mixing from the warmer air & a very shallow system.

 

So as it stands based on a blend of ALL tracks & intensity + the fact there's no HLB directly to the east enforcing a deep SE flow out of the continent theres is MINIMAL slider snow prospects for the SE / SW / South- but please reflect on the high uncertainty allowing for some adjustments that could suit these areas ( the most likely adjustment is the PPN doesn't even reach these SE / E areas. )

 

Once again areas in the firing line seem to be the central / North midlands & areas possibly further North which if you catch the slider right, will see continuous snowfall as PPN arrives then slides east & stalls before pulling away south.

 

Prior to the slider, A potent storm- followed by Squally Wintry showers in the NW when eventually becomes Northerly -

 

As the wind swings closer & closer to the North so this flow becomes very cold  & associated dew-points will drop out sub zero. I have highlighted an embedded trough swinging SSE through the UK on Sunday, however again the south & SE may not have sufficient depth to the cold ahead of it at that point to support snow. - so what appears as snow in the midlands may end up a sleety mess in the E/SE corner.

Post the slider event may well be the chance the NE/E & SE have been looking for with a backing west of continental cold, this all depends on the ridging NE of the altantic high cutting off the trough feeding the sliders from SE Greenland.

The immediate upper air profiles to the east wont be 'that' cold so 24 hours of flow at least will be required before any deep cold may arrive. ( triggering convection )

 

What's not been mentioned to much thus far is the potential for a very low CET period spanning 7 days for Scotland & the North. The central belt of Scotland could see overnight lows approaching the magical -15c & with that depth of cold the recovery across the snowfields may only see maxima -5cs returned. - so low single digits of negative CET could be the order of the day.

Frozen rivers & lakes etc could be common place by next weekend.

 

In summary then a bit of a messy pattern, - Messy usually means lots of snow & if I was located in the central / northern belt as it stands I would be satisfied that I have the highest probability of frontal snow.

 

For the snow starved elsewheres in the south its a case of wait & see with baiting breath but as it stands the initial set up & prognosis doesn't look 'that great'

 

regards

S

Really appreciate how much effort you go to Steve to summarise not only your own area but everyone else's also.

The south are always going to struggle in these setups, that being said Jan 2013 slider was fantastic down here so anything is possible, looking for exact nuances at day 5/6/7 when it comes to slider lows is fraught with danger though, incredibly hard to predict correctly. Let's hope things fall into place for everyone to get a bite of the cherry!

[bluearmy]

 

wonder where that NH profile is headed ..........................

 

wonder if the extended will continue that evolution ?  it hinted at similar a few runs ago. too crazy to contemplate

[Midlands Ice Age]

Whilst in a quiet period.

 

OPI seems to have gone  very quiet on this subject.

 

But I seem to remember that Cohen actually said that a normal 'lateish' winter was his favourite for  most of Europe.

Presumably if this does come off as the charts suggest  and is continued then he will be able to chalk off another notch on his bedpost.? Would that be 12 out of 13 correct?

 

Or would it all be down to good luck?

 

By normal I would mean going back to the 60- 70 period where late january february cold was fairly common.

 

     

 

MIA

[shaky]

So going on from the post about 'shallow low'

 

The mean at 120 is a good indicator.

ECM DET 850's at 144

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/ECU0-144.GIF?14-0

 

ECM MEAN 850's at 144

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/EDU0-144.GIF?14-0

 

That's some 3 degrees colder- backing up the theory of the ECM DET being to deep.

 

The 500 track on the mean-

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015011412/EDU1-144.GIF?14-0

 

that's about as Positive as it gets in terms of widespread snow.....

 

best regards

Steve

thats a beauty of a mean steve and that would could give frontal snowfall pretty much every where across the south! !

[ItNeverSnowsInWindsor]

Just got home and will view the ecm behind the sofa by reading the posts here! :-)

Edited January 14, 2015 by prolongedSnowLover

[Severe Siberian icy blast]

EDH1-240.gif

wonder where that NH profile is headed ..........................

wonder if the extended will continue that evolution ? it hinted at similar a few runs ago. too crazy to contemplate

Il contemplate it for you !

A coupe of possibilities here , both include a cross polar flow , I think the Atlantic ridge looks like been part of the mega block over the pole. With a chunk of very cold uppers and associated chunk of the vortex slips casualy into Siberia , marching west aided by the low in Southern Europe which looks quite deep actually , either way the Atlantic looks blocked ! Any ideas most welcome

Edited January 14, 2015 by Severe Siberian icy blast

[Jason M]

Although I agree with BA in thinking that it's pointless looking at detail over 5 days away, if the slider scenario verified I suspect Steve Murr will not be far out with his prognosis. This is really just based on experience. As TEITS will no doubt testify in these scenarios it's either dry and cold or rain / sleet in EA and the far SE. I'd say essex, Kent and Suffolk are the places not to be. Depressing for me but that's life.

Hopefully the pay off will come for the South and southeast with a cold easterly down the line, which brings these areas into play. Further complications will arise anyway as the models will begin to pick up on warm sectors nearer the time.

To me this looks like a standard winter cold spell. Looking at the bigger picture though there may be room for better down the line. Maybe a 50 50 chance of a full on easterly in the next 15 days.

All of that said, given how the charts have changed in the last 3 days, who knows what we will be seeing in 5 days time.

Given that at the weekend it looked like January was a write off, next week is a bonus.

Edit just seem SMs last post, can't argue with the mean chart!

Edited January 14, 2015 by Jason M

[EML Network]

I know that everybody is excited, but I must be missing something. 

 

The pattern to me seems to flatten out very soon after an all too brief NE' sterly and we look to be back to square one all too quickly. 

 

 

 

Not only that but the ''slider'' isn't far enough West, you end up with a one or two day window , very similar to what happened over XMas and boxing day

 

.

 

I'm sure those in the usual places will get a pasting whilst us in the snow starved south will get naff all

 

Enjoy it whilst it lasts because if you ask me it aint gonna last long

[Cloud 10]

EDH1-240.gif

 

wonder where that NH profile is headed ..........................

 

wonder if the extended will continue that evolution ?  it hinted at similar a few runs ago. too crazy to contemplate

 

Yes,would be interested to see where it goes from there...

 

[Man With Beard]

EDH1-240.gif

wonder where that NH profile is headed ..........................

wonder if the extended will continue that evolution ? it hinted at similar a few runs ago. too crazy to contemplate

I'm intrigued BA. Are you thinking split vortex, leading to direct northerly?

[Severe Siberian icy blast]

Yes,would be interested to see where it goes from there...

 

EDH101-240.GIF

See my annalysis lol iv worked it all out !!!

[snowking]

Yes,would be interested to see where it goes from there...

 

EDH101-240.GIF

Repeat after me...

 

 

Boom.

 

SK

[nick sussex]

I know that everybody is excited, but I must be missing something. 

 

The pattern to me seems to flatten out very soon after an all too brief NE' sterly and we look to be back to square one all too quickly. 

 

 

 

Not only that but the ''slider'' isn't far enough West, you end up with a one or two day window , very similar to what happened over XMas and boxing day

 

.

 

I'm sure those in the usual places will get a pasting whilst us in the snow starved south will get naff all

 

Enjoy it whilst it lasts because if you ask me it aint gonna last long

Oh dear did the dog eat your winning lottery ticket? You've picked one output from the GFS at day ten and the slider is still 5 days out so that might change.  In terms of length who knows, just try and chill out you never know it might work out alright. I understand your frustration and I'm sure that's shared by many who haven't seen a snowflake yet but its too early to tell whats going to happen, if a east/ne sets up you'd be in a decent location for that.

Edited January 14, 2015 by nick sussex

[Cloud 10]

Repeat after me...

 

 

Boom.

 

SK

 

Very tasty and looks very OPI-ish.

[chionomaniac]

Repeat after me...

 

 

Boom.

 

SK

Glad you put that up because you saved me a job - and I believe that the EPS ensembles are showing another strat warming. This cold spell could turn into something more meaty as the background winter teleconnections are finally starting to show.

[West is Best]

Richard, I think it's

http://www.wetterzentrale.de/pics/Rgfs1442.gif etc

 

Thank you so much. Not sure that's now working though actually?

[damianslaw]

All three main models in strong agreement now for a slider low of sorts early next week bumping into cold uppers thanks to this weekend's northerly drift. Yes there are variances with the track and depth of the low as expected, but there is now increasing confidence of a more sustained cold attack taking place after the marked swings from very mild to something chilly that have dominated the winter so far.

 

ECM northern hemisphere profile painting a very cold outlook - PV moved to Siberia and blocking to the north.

[Weathizard]

I know that everybody is excited, but I must be missing something.

The pattern to me seems to flatten out very soon after an all too brief NE' sterly and we look to be back to square one all too quickly.

Not only that but the ''slider'' isn't far enough West, you end up with a one or two day window , very similar to what happened over XMas and boxing day

.

I'm sure those in the usual places will get a pasting whilst us in the snow starved south will get naff all

Enjoy it whilst it lasts because if you ask me it aint gonna last long

This post comes across very bitter in all honesty and there's no need for it, yes where we are things look dicey but if you're midlands/wales/north then you're bound to be excited by the charts being shown.

We normally get the best of it in the summer when the north get pasted by rain so it's a balancing act, I don't agree with your post anyway as others have said, the uppers are pretty close for us but things can and will change, a shift south/SW a few hundred miles could make all the difference

Edited January 14, 2015 by Weathizard

[barton444]

Hi all, very new to all this and a complete noob but could someone post a chart (historical or otherwise) that would show what I should be looking out for if I wanted to see snow on Anglesey please?  Apart from Dec 2010 and Jan 2013 we always seem to miss out and a better understanding would certainly be more beneficial than the snow dance I do every winter (worries my neighbour something rotten that does!)

[Severe Siberian icy blast]

I know that everybody is excited, but I must be missing something.

The pattern to me seems to flatten out very soon after an all too brief NE' sterly and we look to be back to square one all too quickly.

Not only that but the ''slider'' isn't far enough West, you end up with a one or two day window , very similar to what happened over XMas and boxing day

.

I'm sure those in the usual places will get a pasting whilst us in the snow starved south will get naff all

Enjoy it whilst it lasts because if you ask me it aint gonna last long

Well it seems you have missed very important factors pointed out by many . Firstly why look at a chart 10 days away when you have cold and snow from 48 hrs ?

Secondly you have cherry picked 2 charts when in reality they are just the operational version of a very complex computer model consitsted of 22(?) ens , (gfs).

Re the ukmo , the last chart on the computer model is the most volatile , how many times do you see the 144 hr time frame come into fruition ? At the very best it can give you an idea of a pattern maybe , ie high pressure/low pressure dominating , but even then your asking a lot , many many times we see low pressure systems been over egged , ie , if it's over doing the depth of the low , then it's over doing the northerly/easterly progression of it which also means the warm sectors are over done .

And finally If you take the worlds best model (ecm) and take a look ens and mean on this occasion you will see its over doing everything I mention above , so the likelyhood of a prolonged cold spell has increased dramatically this eve , but for the sake of sanity why don't we focus on the next 7 days first , which includes , cold weather , sever cold over snow fields , ice , snow , a major wind event , with blustery ,wintry ,thundery showers including hail , sleet , snow , and thunder , all within a 24hr period !

Edited January 14, 2015 by Severe Siberian icy blast

[Duane S.]

'Sliders' rarely produce for the majority, Jan 13 was the the exception to the norm. What is more important is what potentially they set up thereafter. They often represent the start of a building cold spell. Look at it as a bonus if lower lying areas in the southern half benefit as energy travels SEwards / Swards towards the continent. It's all about whether, with lower pressure in underneath us and a quiter Atlantic, we can get the real thing with the window of opportunity this affords us, aka a proper cold spell(not snap) for the uk. This is the first time since late winter'13 we have genuine hope!

[Frosty.]

Fantastic ECM 12z ensemble mean tonight for all the coldies, it's trending progressively colder with an increasing risk of snow and severe frosts, it's every bit as good as the 0z and last night's 12z, perhaps even better..turning much colder and more wintry from the weekend onwards..reasons to be cheerful, many :-)

[A.J]

for anyone wondering where their post has gone, there's a very high verification probability that their post just wasn't plausible, the post content synoptics just weren't right, indeed the overall pattern didn't make sense......

 

....in other words, it had nowt to do with the model output discussion........please use the plethora of other netweather threads for non-model related stuff.....sorry to sound like a broken record but it get's frustrating making these requests just to see them ignored by a few posters

 

cheers