Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[SMU]

Morning WIB

The guys are right ever since 2 days ago where the 12z suite all switchef to a track over holland ( remember the ukmo ) they have all been bending back west

So much so the overnight ECM is pretty much back to where my original forecast line was-

The ECM at 144 is now at a point where the track is as good for snow as the first 2 sliders & the cold had been extended out to 192 with the potential here for another repeating pattern -

The last 4 consecutive ECM runs have all been upgrades as have the GFS& UKMO all be it not quite as acute as the ECM ....

S

[nick sussex]

WIB unfortunately we don't have 12hr steps so the easiest comparison in terms of trend is to use yesterdays UKMO 00hrs and todays 00hrs.

 

I'm looking more at the impact of how the pattern could develop to wards next weekend and whether the cold can get extended, as for the slider that's giving me a headache and I still don't think that's sorted out.

[Snow Grain]

As I said yesterday, the lack of continental feed makes any snow prospects marginal.

There needs to be a (Real) shift west for any snow chance improvements but as it stands this is an over rated cold spell. This mornings charts see a north west type influence so a wintry mix generally is this weeks offer. Maybe the Scandinavian high can save the day on future runs.

[chicken soup]

Morning WIB

The guys are right ever since 2 days ago where the 12z suite all switchef to a track over holland ( remember the ukmo ) they have all been bending back west

So much so the overnight ECM is pretty much back to where my original forecast line was-

The ECM at 144 is now at a point where the track is as good for snow as the first 2 sliders & the cold had been extended out to 192 with the potential here for another repeating pattern -

The last 4 consecutive ECM runs have all been upgrades as have the GFS& UKMO all be it not quite as acute as the ECM ....

S

does this mean your snow forecast map from the other day still stands steve....ta

[bluearmy]

.

Decent agreement between gefs bias corrected and ECM ens at day 10

Just to say that the extended eps show a change in nuance on the 00z suite post day 10 as the Azores upper ridge looks to be a bit more influential and any disruption would seem to be weaker and more likely to our east. It could be the start of the model trending towards a different evolution completely. As it's one run, best not to dissect it without any clusters to support.

Edited January 18, 2015 by bluearmy

[SMU]

does this mean your snow forecast map from the other day still stands steve....ta

Yes all be it slightly further ene - maybe more for NI as well -

S

[Geordiesnow]

Got to say I find the charts quite underwhelming, the cold uppers are just getting mixed out with each run and any PPN coming in from the West is more than likely will lack any real intensity to try and compensate for the mixed out cold air.

 

I also don't think an easterly will float my boat, cold, raw, mainly dry weather does not float my boat and will the Scandi high really come into play much? I very much doubt it, models are clearly saying it will head back towards Russia and the UK will eventually be back in the milder Atlantic air. 

 

Whilst it good people have got some snowfall, this cold period could easily be more memorable but sadly what could wrong has gone wrong but thats the weather for you. 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SUNDAY JANUARY 18TH 2015.

NEXT UPDATE MONDAY JANUARY 19TH 2015 08:00

THE CURRENT GENERAL SITUATION A slack and cold Northerly airflow lies across the UK today. A frontal trough will clear the SE this morning and a showery trough over the North will dissipate as it moves South.

MODELS-2 WEEK HEADLINE Rather cold and unsettled with rain or snow in places. Frost at times.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow rather weaker than o flate though sufficiently strong to maintain a generally Atlantic driven pattern of cold zonality with the positioning of the flow remaining South of he UK and troughed down over Europe towards the Meditteranean.

GFS NEW OPERATIONAL The GFS operational today maintains a generally rather cold and unsettled picture across the UK. The first week is dictated by disrupting Low pressure troughs as they slide SE across the UK in cold air. All areas will have a mix of rain and snow events through the week punctuated by wintry showers and some frosts at night. The deveil remains in the detail again though and this morning's run has continued this rather cold theme through week 2 as further Atlantic Low pressure becomes blocked near the UK by the cold pool still lying close to the UK, especially the South with further sleet and snow risks at times almost out to the end of the run.

 

THE GFS CONTROL  The GFS control run also shows this extension to the cold and in places wintry theme with disrupting Low pressure continuing to be forced SE through the second week too as the cold pool over and near the UK lies in situ with no real push of Atlantic Westerlies until the very last few frames of the run.

THE GFS CLUSTERS The GFS Clusters continue to project the most likely scenario remaining in this cold and slider territory for the next 10 days or so with 40% of clusters still showing at least cold zonality under Low pressure still dominant in two weeks time.

UKMO UKMO this morning also shows slider Lows moving SE from the NW but has their axis somewhat further East to those from GFS bringing their bands of rain and snow East before clearing them to scattered wintry showers in a NW flow later in the week.

THE FAX CHARTS The Fax Charts illustrate a complex pattern developing over the UK through the week as elongated troughs lie NW to SE down the spine of the UK and the North Sea. Lying in cold air they will bring snow or rain at times clearing to wintry showers in a chilly NW flow in the West at least later.

GEM GEM today shows generally rather cold and unsettled conditions through the next 10 days with winds predominating from a NW point. Low pressure troughs slide SE throughout this week with a mix of rain and snow followed by wintry showers seeming most likely with further opportunities for more sliding troughs through the latter part of the run most likely slightly further East later keeping rain and sleet bearing spells short ahead of rather chilly and wintry showery NW wind spells following.

NAVGEM NAVGEM also shows rather cold and unsettled conditions through the week with troughs and Low pressure slipping SE through the middle of this week before a more definitive Low pressure sits on top of the UK next weekend with rain or wintry showers at times in chilly and blustery west or NW winds.

ECM ECM this morning too maintains a rather cold outlook with the weather powered by successive pushes of Low pressure down over or just to the East of the UK, each bringing their own version of unsettled conditions with showers or longer spells of rain, sleet and snow in strong and blustery winds from the NW at times. At the end of the run it looks like a push of milder Atlantic Westerly winds take hold with temperatures recovering to average for most.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart shows a very similar image to the ones of recent days, made up of options of cold zonality under NW winds and a trough over Europe. There are also a few milder options on the plate to complete an unclear progression of where we may be synoptically in 10 days time.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The main differences indicated from this morning's output is an extension of the rather cold period with a longer run of disrupting Low pressure near or down over the UK, possibly extending into the second week.

MY THOUGHTS The most interesting part of this morning's output is the extension to the cold period that most of the output shows this morning. nearly all models show several slider type scenarios crossing down or just to the East of the UK, each bringing their own brand of spells of rain, sleet and snow followed by wintry showers. Ideally the axis remains too far East for Southern and Western Britain to see much more than transient sleet and snow from these disrupting features as they weaken and pull SE but Eastern and Northern areas could see some significant snowfall at times. In the wake of the troughs NW winds would bring wintry showers and frosts at night look very likely under the clearer periods through this week. We then come to where we go from the end of this week on and the jury still remains very firmly out on what happens synoptically then as it all depends on the axis position and method that the Low pressure areas exit Britain to the SE and the legacy of cold air that remains. However, I wouldn't be surprised to see some output beginning to lean towads a more coherent pressure rise to the NE in the coming days and if that occurs that would of course enhance the risk of much of the UK remaining cold through the second week too or of course we have to cater for a push of milder Atlantic winds eventually pushing the cold air further away to the East, something that is again hinted at this morning in some output. However, while Low pressure is maintained near the Meditteranean Sea then the chances of coldish weather for the UK remains likely as Atlantic Low pressure to the NW of the UK will continue to be sucked down towards it giving rise to at least cold zonality conditions with wintry surprises for many continuing at times. Fnally the one constant in this morning's output is the continued absence of the word 'mild' within the projections and this is in itself a step towards a more seasonal feel to things this January compared to last.

Edited January 18, 2015 by Gibby

[Severe Siberian icy blast]

image.jpg. image.jpg

Decent agreement between gefs bias corrected and ECM ens at day 10

Taking this on face value that's got sliders written all over it , infact one would say looking at that alone that's a very snowy set up for the uk? As they drain into europe the key will be weather we can get any separation of the sliders , if we can then you would think we will pull these colder uppers from over eastern Europe over us , which will obviously hold us in good stead for the next slider ?

But even if not , I'm sure we'r sitting in negative uppers , we just hope the atlanitc doesnt move milder uppers over us , if we can sit with uppers of maybe -3 with a gentle southern/southeasterly wind before the event then fun and games will ensue ! But that's a strong anomaly over Scandi showing its hand .

Blue army I'm just a bit puzzled because with the vortex taking a trip to Siberia in 10ish days , that doesn't realy promote a Scandi high does it? Maybe it can retrogress west ??

Edited January 18, 2015 by Severe Siberian icy blast

[Eugene]

Got to say I find the charts quite underwhelming, the cold uppers are just getting mixed out with each run and any PPN coming in from the West is more than likely will lack any real intensity to try and compensate for the mixed out cold air.

 

I also don't think an easterly will float my boat, cold, raw, mainly dry weather does not float my boat and will the Scandi high really come into play much? I very much doubt it, models are clearly saying it will head back towards Russia and the UK will eventually be back in the milder Atlantic air. 

 

Whilst it good people have got some snowfall, this cold period could easily be more memorable but sadly what could wrong has gone wrong but thats the weather for you. 

 

 

It only started yesterday and you are already writing an Epitaph, when are you going to realise snowfall in this country is a nowcast.

 

Very encouraging runs this morning for a continuation of this beautiful cold spell, lovely blue skies right now.

Edited January 18, 2015 by Eugene

[kev238]

Well I thought the westerly regime was likely yesterday for the weekend onwards- now it looks like that is on shaky ground.

There really is very little detail over what is likely to happen in the next 72 hours let alone by the weekend.

I don't see a signal for heavy snowfall this week- light patchy snowfall yes but not widespread heavy disruptive falls.

[john mac]

Well I thought the westerly regime was likely yesterday for the weekend onwards- now it looks like that is on shaky ground.

There really is very little detail over what is likely to happen in the next 72 hours let alone by the weekend.

I don't see a signal for heavy snowfall this week- light patchy snowfall yes but not widespread heavy disruptive falls.

Like you say, it's too early to say. Things can develop at very short notice in an unstable airflow. Edited January 18, 2015 by john mac

[Snowyowl9]

Where have seen this before on yesterday`s chart for Tuesday.

http://www.wetterzentrale.de/pics/Recm1441.html

[bluearmy]

Taking this on face value that's got sliders written all over it , infact one would say looking at that alone that's a very snowy set up for the uk? As they drain into europe the key will be weather we can get any separation of the sliders , if we can then you would think we will pull these colder uppers from over eastern Europe over us , which will obviously hold us in good stead for the next slider ?

But even if not , I'm sure we'r sitting in negative uppers , we just hope the atlanitc doesnt move milder uppers over us , if we can sit with uppers of maybe -3 with a gentle southern/southeasterly wind before the event then fun and games will ensue ! But that's a strong anomaly over Scandi showing its hand .

Blue army I'm just a bit puzzled because with the vortex taking a trip to Siberia in 10ish days , that doesn't realy promote a Scandi high does it? Maybe it can retrogress west ??

Shaun, not sure where this story about the vortex headed to Siberia has gained traction. There is a split but the Siberian side is not strong. Thereafter, the Siberian side becomes absorbed into the Canadian. That's the mean viewpoint. the Siberian vortex in the mid/upper strat week 2 is perhaps where the confusion has come.

The latest eps extended keeps a split of sorts though the Siberia segment very flaccid and not influencing our part of the N.H. there is plenty of room for a ridge to our east but how far north that can get is open to question unless that split becomes more defined, nw Russia into scandi seems reasonable, given the location of the vortex.

Edited January 18, 2015 by bluearmy

[fergieweather]

UKMO-GM has been modified to slow Fri frontal advance by 9-12 hrs.

[shaky]

UKMO-GM has been modified to slow Fri frontal advance by 9-12 hrs.

that 9-12 hours could make all the difference to what happens after that lol!!! Anyways ian latest gfs has a slacker flow and everything further west aswell!! One thing of note is the scandi high is becoming a big player now in extending this cold spell!!

[snowfish1]

Ukmo 00z is not bad at all!! Its a brilliant start to the day peeps!! Compare yesterday's 00z to todays on ukmo and everything is being pushed westwards and there more trough disruption going south east than east!! Compare yesterday's 120 hours to todays 96 and thats potentially another snow event for England! !

Parts of England but model does not show se in that set up. Unfortunately.

Edited January 18, 2015 by snowfish1

[Fozfoster]

UKMO-GM has been modified to slow Fri frontal advance by 9-12 hrs.

Sorry but what does this mean.anyone. Thanks.

Edited January 18, 2015 by Fozfoster

[chicken soup]

UKMO-GM has been modified to slow Fri frontal advance by 9-12 hrs.

do you not mean tue frontal advance.

[IDO]

Sorry but what does this mean.anyone. Thanks.

Block -v- Atlantic. UKMO model maybe too progressive with the westerly encroachment on Friday. Ergo cold lasting longer.

[mushymanrob]

whats needed to prolong the cold spell and turn it into a proper event is for pressure to build and sit over scandinavia, the azores high is largely immaterial in such situations . theres time yet for pressure to anchor over there, but its not expected to.

 

......... and this morning the mood must be one of optimism (for cold lovers). i havnt read all the posts, so sorry if im duplicating anything (time restraints).

with the now significant downgrade of the mild rescue expected next weekend, for me, its a significant shift. the great cold beasterlies of 85 and 86 were brought to us via a strong scandinavian high (as were other cold spells) and these freezes often come off the back of a messy synoptical mess beforehand. just like the weak indistinct mess we have now. and with the return to westerly atlantic zonal pattern now downgraded, theres a far greater chance of high pressure building and sticking over scandinavia.

high over scandinavia... thats the key to a freeze (for the less experienced, obviously the 'big guns' know that).

[Snowman.]

GFS Sending more SE.

 

 

0z

 

[bluearmy]

do you not mean tue frontal advance.

]

Nope - I think Ian knows what he means

[Skullzrulerz]

GFS Sending more SE.

 

 

0z

 

What will this mean then for us?

[Snowman.]

What will this mean then for us?

Possibility of another slider scenario but due is unlikely to produce any potential snow in the south.

 

If the GFS keeps us with the trend of edging west + sending energy SE then there could be more snowfall and prolongs the current colder scenario we're in.