Model Output Discussion - moving into Winter

[Kasim Awan]

Just now, Catacol said:

OK - that makes sense to my small brain - and presumably then with less of a vertical temperature gradient the required 850s for snow (assuming low dew points) also become less important. -2 up above with 0 at ground and snow still possible. 

inland in this set up if winds are light u only need uppers of 0C because the surface layer and low heights reduces the >0C layer aloft

[Penrith Snow]

1 hour ago, MattH said:

Simply this...

This place never changes, unfortunately, despite some really great input from pro's and amatuers alike. It's really off putting, especially to those who want to contribute and learn.

Cheers.

I agree with you Matt, however, like you I have been on these forums since the early days of TWO 20 years ago and it was always thus.

It's part of what makes our hobby (or in winter curse) fun, I wouldn't want a forum devoid of emotion, this is where we share our mutual interest and without emotion we just become robots.

In pre TWO days there was a flatform called Science Weather or something like that and man was it boring to read.

Andy

[The Northern Ramper]

16 minutes ago, Nick F said:

Don't think any model has the synoptics resolved past mid-week just yet, that upper low / cold vortex doesn't exit the observation-sparse arctic/north pole until early next week before dropping south across Svalbard then Norway / Norwegian Sea. The shape of the upper low when it reaches UK /North Sea will determine where surface features develop and move around its circulation. Still to be determined

But yesterday's 12z EC det. suddenly shifting the southerly-tracking Atlantic jet stream north towards the UK towards the end of the run looked rather suspect, given the cold air advection from the arctic, compared to this morning's cross-model consensus of keeping the jet stream tracking west-east way to the south at the latitude of the Azores and Spain.

The models seem to be converging on the idea of an upper low dropping down across Scandi, North Sea and northern UK. Low heights (low freezing level) will compensate somewhat for what look like mediocre T850s, albeit generally staying below -5C. However, marginality may occur in places, depending on where shallow surface lows track under the circulation of the upper low, if the flow is from the southwest across the south it could bring in less cold maritime air. The kind of slack surface pattern that will bring forecasting headaches from later next week!

 

You say headaches, I’d say wintery delights

[Johnp]

1 hour ago, Kasim Awan said:

Personally i cant see yesterdays outlier repeating. too much support towards the solution shown currently.

You must admit last night you said the momentum *never* stops once a model trends away from cold . Thankfully ECM has smelt the coffee and proven that theory wrong! 

[Tim Bland]

40 minutes ago, Kasim Awan said:

yeah tbh i admit i overreacted. was having one of those days and carried it onto the forum, blinded my judgement a bit. i did however say that cold was still on, snow would come from troughs rather than showers - and the atlantic lows provide a further snow risk. why this was perceived as downbeat by others im unsure.

its clear now with retrospect that the ecm 12z progression was an outlier that had not fully resolved handling of the atlantic energy. this seems to be better resolved this morning and therefore we see stronger cross model agreement. output is prone to this over progressive teething phase prior to cold spells when modelling of atlantic energy changes. the energy is now properly integrated as an iberian jet - provides a new snow opportunity.

Fair play for admitting it was an overreaction.

I think you appeared downbeat in general and seemed to dismiss the cold spell completely after the ECM.  just to confirm last night you said “ there are too many basic synoptic mechanisms powering up the Atlantic for anything special just yet.”

And this seemingly wasn’t referring to the ECM but the pattern overall. Are you taking this back after seeing this mornings runs ? 

[bluearmy]

As has been said for a while now, getting the cold trough across the country is paramount for this initial cold to extend into a sustained spell. 
whilst this remains uncertain as to depth and how far south it gets, offering views in what follows is a little irrelevant. Safe to say that it looks more than interesting if we do clear south into France with a strong southern arm forecast to sustain and further waxing and waning of heights to our northwest. 

[Hotspur62]

Well what a last 24 hours on this forum!I have been a lurker on here for last 10 years and love this forum and have learnt so much (I think!) from everyone which I am grateful.When last nights ECM came out I thought it was odd and feared it was going to be a case of That ECM but it just seemed out of kilter and I thought let’s see where we are in 24 hours.I don’t think we will have a repeat of December 2010 that was a one in a hundred year event and am so grateful to have experienced that but I do think we have be on the cusp of a cold spell not seen in the U.K. since 2012/3 which was the last colder than average winter.

Fwiw I think this cold spell will be a blend of UKMO,GFS and last nights ECM( I know I know).No model will ever nail things in this type of set up and history tells us that we will get a hybrid of sorts.If that’s the case then we should all see cold temperatures and snow for some but as ever that will come down to the high resolution models(ie Harmoine etc).

 

Enjoy the ride folks,we haven’t been in this good a position for a long time.Just keep perspective on things and in the words of JB “Enjoy the weather as it’s the only weather you’ve got”

[mbrothers]

3 minutes ago, Johnp said:

You must admit last night you said the momentum *never* stops once a model trends away from cold . Thankfully ECM has smelt the coffee and proven that theory wrong! 

There’s an lot of folk backtracking today or not appeared this morning. 

[Penrith Snow]

24 minutes ago, MattStoke said:

There have been a few model runs that bring in more of a north westerly. Depends on orientation of the trough. With such low heights, cold air/low thickness over warmer than average sea, and the trough looking rather disorganised (wavey isobars suggesting instability in the flow), there should be some decent snow chances, anyway, regardless of exact orientation.

My thoughts exactly.

Normally higher SSTs would be a real cause for concern but get the air cold enough and the warm sea will trigger copious instability.

Prime example was late November 2010, north sea temperatures were still at their autumn high and somewhat above average but the intense cold just prevented the low level air rising above freezing and produced massive amounts of instability and snow. 

NE England became like Buffalo under Lake Effect snow and Depths reached 40cms in parts of Northumberland.

Although nice who wants a bone dry northerly?

Andy

[Bats32]

Who is all ready for the GFS6z? 

[Kasim Awan]

1 minute ago, Tim Bland said:

Fair play for admitting it was an overreaction.

I think you appeared downbeat in general and seemed to dismiss the cold spell completely after the ECM.  just to confirm last night you said “ there are too many basic synoptic mechanisms powering up the Atlantic for anything special just yet.”

And this seemingly wasn’t referring to the ECM but the pattern overall. Are you taking this back after seeing this mornings runs ? 

In regards to the quoted statement, I was referring to the dropping of the screaming convective easterly which now appears unlikely. This still seems to be the case, and instead we see a slow yet highly unstable easterly flow. So rather than widespread showers in the usual prone areas, we see trough related snowfalls which do not follow a predictable trend.

[Nick F]

9 minutes ago, Ramp said:

You say headaches, I’d say wintery delights

Could become a postcode lottery though for wintry delights.

Personally I prefer a clean deep cold northeasterly or easterly that brings convective snow showers with no worries over marginality, though I appreciate western areas can be dry unless troughs bring showers well inland. The setup on the table from most models. for now, becomes a slack and cold pattern when it becomes embedded from late next week. Showers generally around coasts and dry inland - so will need to rely on small lows or troughs rotating around the upper low circulation to bring snowfall inland. But there is the marginality risk depending which side of these lows - especially near coasts - with an onshore flow introducing less cold air from warmer SSTs. So coastal areas at greatest risk of being snowless, unless the flow is offshore. 

[ScottSnow]

One thing that I have noticed is that as the evolution has came into the closer timeframes the 850 temps seem to have got colder. If you look at Tues/Weds next week they are pretty cold now. It seems like they have upgraded which holds us in good stead for the rest of the cold spell.

As for yesterdays ECMWF 12z, I never worry unless you start to see two bad runs in a row. There are going to be good runs and bad runs but the overall pattern is strong. The pattern does remind me of March 2013, I have always said that if that happened in winter then it wouldn’t have just been the higher areas that got buried.

From a personal standpoint I am starting to get confident that I will at least get a covering here in the north east of England.

Edited December 3, 2022 by Snow White

[The Northern Ramper]

2 minutes ago, Nick F said:

Could become a postcode lottery though for wintry delights.

Personally I prefer a clean deep cold northeasterly or easterly that brings convective snow showers with no worries over marginality, though I appreciate western areas can be dry unless troughs bring showers well inland. The setup on the table from most models. for now, becomes a slack and cold pattern when it becomes embedded from late next week. Showers generally around coasts and dry inland - so will need to rely on small lows or troughs rotating around the upper low circulation to bring snowfall inland. But there is the marginality risk depending which side of these lows - especially near coasts - with an onshore flow introducing less cold air from warmer SSTs. So coastal areas at greatest risk of being snowless, unless the flow is offshore. 

Just having a ticket is a result these days

[Frigid]

What a horror show last night's ECM was, devoid of any proper cold.. glad it's backtracked on that idea. GFS 0z possibly the best in terms of prolonged cold.

Next week looks great throughout

And as for the ECM..

[Weathizard]

1 minute ago, Kasim Awan said:

In regards to the quoted statement, I was referring to the dropping of the screaming convective easterly which now appears unlikely. This still seems to be the case, and instead we see a slow yet highly unstable easterly flow. So rather than widespread showers in the usual prone areas, we see trough related snowfalls which do not follow a predictable trend.

I’m not sure there was ever a screaming convective Easterly on the agenda though, normally an Easterly is a result of a trough dropping south as we are seeing.

I think at this point Northerly into into some kind of Easterly wind would seem the form horse, but as always, there’s still many stumbling blocks, a cold trough dropping over us as a starting point will be fine by me, and I say that as the southernest of southerners

[Spah1]

Just a word on people’s criticism of members reaction to each op run. I thinks it’s unjustified and misses the points of why some people post on this thread. 
 

There are some members here who have professional knowledge and are interested in the weather patterns over weeks and months and that’s fine and their contribution is valued however I would suggest the majority reading this are looking  for a snow flake In their back yard. 
 

For those who get annoyed with members over reaction to each op run I say this. Weather model watching is like supporting a football team. At the start of the season you roughly know where your team will finish in the league but you hope for more. We know winter will bit a bit mild and wet with the odd bit of cold interest but we hope for more. 
 

Watching an op is like watching a game. One week it’s fantastic and you win 3-0, next week rubbish lose 3-0. The emotion of the ups and down is what football fans love but it doesn’t take away the fact they know they will probably finish mid table at the end of the season. 
 

We get excited at the 7 day cold snap and sledging with the kids then sad at the mild SWly’s the week later. 
 

So the point is it’s the thrill of the ride, the chase, the expectation and I for one am all in favour of toys in and toys out just like your football team is brill one week and crap the next. 
 

And every now and then that 10 day magical op run is slowly supported by other op runs and it’s ens and 2010 happens or Leicester put together a few excellent and unexpected results …… it can’t happen, it may happen, it could happen, it did happen they won the league !!!!!

[Ali1977]

As the icon is now rolling out I’d thought I’d put up the 120 from the 00z, let’s see if we have any changes for the better here

[chris55]

As soon as I saw last nights ecm on wetter last night I thought it prob best to avoid the MOD thread till this morning

Glad I did lol. 
 

Much better run from ECM this morning, and all models continuing the theme of the cold trough dropping down. 
 

Beyond mid week still a lot to be decided on depth of cold, any potential snowfall and longevity of the cold. 
 

ideally we want a clean drive of the coldest uppers possible, then a slack trough, followed by a channel low then a cold surface high to set up………

Plenty more ups and downs to come.

 

[Mike Poole]

31 minutes ago, sheikhy said:

Now mike u say theres uncertainty as early as 72 96 hours!!now is that uncertainty for the better or for the good!!?as long as you say there is some uncertainty for the better i be happy lol!!

Not sure @sheikhy, think it is probably good as it is evidence against yesterdays ECM 12z!  Just to follow up on my comment on the clusters about the early uncertainty at T96, I’m talking about whether the flow south of the cold from the trough between the Greenland high and Russian heights continues or quickly gets cut off.  GFS shows it continuing as per T96:

Now look at the GEFS ensembles - all of them - at the same time:

Most of them follow the op and maintain the flow south.

Now look at the ECM ensembles - all of them (2 screens!):

Most of them cut the flow off and leave a cut off low which then goes on to supply our cold air.  I would much prefer the GFS/GEFS solution at this point, as it would continue the NE flow of cold to the UK for longer, but here’s the point:

If the 2 main ensemble suites are completely at odds on this key point at T96, it is almost pointless analysing anything later until this is resolved.

And don’t just discount the GFS here.  Yes, the ECM performed much better in the run up to this.  But that was the run up, it is a new game now, and GFS has good form for handling Greenland highs, it is one of its strengths.  

[Lloyd1]

1 minute ago, Mike Poole said:

Not sure @sheikhy, think it is probably good as it is evidence against yesterdays ECM 12z!  Just to follow up on my comment on the clusters about the early uncertainty at T96, I’m talking about whether the flow south of the cold from the trough between the Greenland high and Russian heights continues or quickly gets cut off.  GFS shows it continuing as per T96:

Now look at the GEFS ensembles - all of them - at the same time:

Most of them follow the op and maintain the flow south.

Now look at the ECM ensembles - all of them (2 screens!):

Most of them cut the flow off and leave a cut off low which then goes on to supply our cold air.  I would much prefer the GFS/GEFS solution at this point, as it would continue the NE flow of cold to the UK for longer, but here’s the point:

If the 2 main ensemble suites are completely at odds on this key point at T96, it is almost pointless analysing anything later until this is resolved.

And don’t just discount the GFS here.  Yes, the ECM performed much better in the run up to this.  But that was the run up, it is a new game now, and GFS has good form for handling Greenland highs, it is one of its strengths.  

The Polar Vortex looks close to splitting on all, could that well happen? 

[Lord Baltimore]

15 minutes ago, Weathizard said:

I’m not sure there was ever a screaming convective Easterly on the agenda though, normally an Easterly is a result of a trough dropping south as we are seeing.

I think at this point Northerly into into some kind of Easterly wind would seem the form horse, but as always, there’s still many stumbling blocks, a cold trough dropping over us as a starting point will be fine by me, and I say that as the southernest of southerners

Not quite the southernest of southerners

[northwestsnow]

Chart for 6pm  Wednesday acc to EC 00Z det the cold air is in 5 days time..

[Liam Burge]

ECM just wanted every to have a mild heart attack for a couple hours... bit of a delayed April Fools prank I think. Anyway, beautiful set of 00zs and some good conditions for snow for most of the country! Can't wait to see what 'fun' (or horror) we'll be put through today!!

[snowsummer]

2 hours ago, northwestsnow said:

I can't cope

I don't know whether to order a sledge or a canoe !!

Ive ordered a canoe but have my grandsons sledge runners ready to attach. Ive got some flip flops but got larger size snow boots that they can fit inside. Im going wearing a t-shirt under my knitted jumper. Gloves where you can pull the finger part off ( also handy for scrolling down your phone to check the latest model  output!) The fan is positioned next to the radiator.  Oh, and did i tell you? I was drinking baileys in my coffee at 3am this morning waiting for Crews updates! Come on models! Through your best at me!