Jump to content
Sign in to follow this  
DiagonalRedLine

Model Output Discussion - The Run In To Christmas

Recommended Posts

Amazing difference between JMA and ECM really re upstream shenanigans. 

 

JN192-21.GIF?21-12

 

Now that is much more like it. Maybe we have tapped into that parallel universe.  :w00t:

Well that's interesting, especially as the MetO have the JMA as a well respected model.

 

Who knows what going to happen on 27/28th, never mind getting on towards the end of the month and the new year!

 

It's a very interesting, if frustrating spell of model watching!

Share this post


Link to post
Share on other sites

What do you mean fad? have you looked at the differences over the USA between the UKMO and GFS's between T96 and T144hrs.

 

It's hard to miss the huge difference caused by the models handling of the shortwave which the last time I looked was a meteorological term!

 

In the real world if the UKMO verifies there won't be a cold set up that's why the shortwave is crucial.

 

In the real world Nick UKMO goes out to T144, and that T144 chart is an exciting setup. Anyone coming on here for the first time could have been misled by your post especially as you give no explanation or backup for what you're talking about with your shortwave. Where is this mysterious missing shortwave? Why? When? Perhaps you could back it up and post a raft of charts to show your setup is the only means to cold in the UK, that there could be no other way to have an exciting and interesting setup occurring in the festive period?

 

 
There could be a reason that the experienced forecasters at the Met Office don't go beyond T144 my friend …? ;)

Share this post


Link to post
Share on other sites

This is what I mean, best shown by the ECM. As I say, a it's as though a switch has been flicked off. I'd be interested to know what particular signal that is being sent from today's data as opposed to the same time yesterday. 

 

ECM 12z yesterday

 

ECH1-240.GIF

 

ECM 12z today - same timeframe

 

ECH1-216.GIF?21-0

 

 

The sudden lack of variation only makes sense if there is some incredibly strong signal overriding everything else so that nearly all models (GEM, UKMO, GFS, ECM) are compelled to follow (looks like JMA is the only one bucking the trend)

There is undoubtedly conflicting signals, ergo the insane model volatility over the past 5 or so days. I think that we won't see a middle ground here in all honesty; it'll be all or nothing as we enter January. I say this because working against the strat signals seems to be something which relates to a strengthening vortex and a lowering of polar heights. I'm at a loss to what this could be though, given the seemingly favourable stratospheric state and NH profile I.e QBO etc.

Share this post


Link to post
Share on other sites

So the ECM doesn't back the UKMO and doesn't back the GFS's either! It's really utter chaos with two issues, one to the sw which the ECM disagrees with both GFS's by not splitting that energy and unfavourable phasing, it disagrees with the UKMO on both fronts and backs the GFS's with the shortwave over in the USA.

 

Its a total mess and we're none the wiser this evening.

 

 

The setup is becoming a lot clearer: an intense low at or around 27/12 (a day later on ECM) bringing a powerful storm surge and biting cold northerlies off the western flank.

Edited by Osbourne One-Nil
Erm....

Share this post


Link to post
Share on other sites

Day 6 charts

ECM

ECH1-144.GIF?21-0

Slow moving low moving east, mild south-westerly flow for the UK.

UKMO

UN144-21.GIF?21-17

Polar maritime flow, but the pattern is flattening upstream so a mobile westerly flow would follow.

GFS

gfsnh-0-144.png?12

Deep low to the north east of the UK, cold northerly flow establishing (duration up for debate).

Parallel

gfsnh-0-144.png?12

Similar to the GFS is surface conditions

GEM

gemnh-0-144.png?12

Quite similar to the ECM with a mild south-west flow and a slow moving trough.

 

Overall the best we have is a northerly which might last a day or so, or we could get near enough nothing. Potentially Christmas/Boxing day could potentially be the coldest days in the next 7-10 which I have to admit even I am surprised with.

Edited by Captain shortwave

Share this post


Link to post
Share on other sites

Some daft reactionary posts this evening. Whats wrong with the ecm? It suggests high pressure being much more dominant then previously and the gfs is toying with mid latitude high too. Forget these quick fix northerlies, they arent going to amount to much. Get high pressure in contention then watch where it drifts too.

I dont relish the cold, and so far its failed to fulfil any potential. But mid latitude high holds the future promis of better cold potential as it blocks the jet across us and might end up to our northeast.

On the other hand things are so turbulent we might just get another freezeless winter lol.

Share this post


Link to post
Share on other sites

ECM fi nonsense. jma - a day behind the other models with its output! ECM 'reliable' timeframe is like a dog with a bone.

Just won't let it go.

Gem looks like something one of those monkeys with their typewriters came up with. Looks Implausible.

maybe we're all in a parallel universe ............ Especially when it's gfs which shows some consistency.

Share this post


Link to post
Share on other sites

Very underwhelming output this evening. We've gone a long way back in the hunt for cold. As CC eluded to, cold charts could start appearing in the mid term out of nowhere but for now patience is required.

Share this post


Link to post
Share on other sites

Some daft reactionary posts this evening. Whats wrong with the ecm? It suggests high pressure being much more dominant then previously and the gfs is toying with mid latitude high too. Forget these quick fix northerlies, they arent going to amount to much. Get high pressure in contention then watch where it drifts too.

I dont relish the cold, and so far its failed to fulfil any potential. But mid latitude high holds the future promis of better cold potential as it blocks the jet across us and might end up to our northeast.

On the other hand things are so turbulent we might just get another freezeless winter lol.

 

 

It suggests the opposite of high pressure being more dominant.

Between your and West is best's posts I fear my head may explode.

Edited by Mucka

Share this post


Link to post
Share on other sites

So ECM/ UKMO/GEM and GFS parallel pretty poor for any chance of decent cold but GFS 12z Op and JMA especially giving hope all is not lost.

If ECM had backed JMA I would have been optimistic for something much better tomorrow but it goes the opposite way unfortunately.

 

Let's   hope ECM has been on the eggnog and is currently doing the equivalent of photocopying its backside and forwarding it to all via the internet. :smiliz39:

Ha ha ha! That last sentence is so funny :smiliz19: On a serious note, I note Ian F mentioning on more than one

occasion that the Meto have great respect for JMA :smiliz39:

Share this post


Link to post
Share on other sites

Ha ha ha! That last sentence is so funny :smiliz19: On a serious note, I note Ian F mentioning on more than one

occasion that the Meto have great respect for JMA :smiliz39:

 

Yeah it is definitely not cannon fodder and it actually came up with something very similar yesterday evening so at least it has some consistency (for now)

 

Yesterday/today comparison.

 

JN192-21.GIF?21-12JN168-21.GIF?21-12

Edited by Mucka

Share this post


Link to post
Share on other sites

Day 6 charts

ECM

ECH1-144.GIF?21-0

Slow moving low moving east, mild south-westerly flow for the UK.

UKMO

UN144-21.GIF?21-17

Polar maritime flow, but the pattern is flattening upstream so a mobile westerly flow would follow.

GFS

gfsnh-0-144.png?12

Deep low to the north east of the UK, cold northerly flow establishing (duration up for debate).

Parallel

gfsnh-0-144.png?12

Similar to the GFS is surface conditions

GEM

gemnh-0-144.png?12

Quite similar to the ECM with a mild south-west flow and a slow moving trough.

 

Overall the best we have is a northerly which might last a day or so, or we could get near enough nothing. Potentially Christmas/Boxing day could potentially be the coldest days in the next 7-10 which I have to admit even I am surprised with.

Yes, makes a mockery of Darren Bett's forecast a couple of days ago stating that Boxing Day will be mild.

It will possibly be the coldest day of the winter so far lol. :w00t:

Share this post


Link to post
Share on other sites

I've never known the 'well respected' jma to ever 'rescue' any situation. If it's at odds with the other output, that's because it's wrong. Bit like when posters start putting up ensemble members to illustrate a cold solution. It means coldies are in trouble!

I will add that I find most of today's modelling very unconvincing but then we can't really start to imagine what the NWP could or should be showing. Where would that end? We can only comment on what it is showing.

Share this post


Link to post
Share on other sites

Having a glance at the GEM (Canadians should know about the vortex) and I have to say, what`s happened to it, it`s in bits. Is this the first signs of the SSW?, hmm

gemnh-0-186.png?12

Share this post


Link to post
Share on other sites

Yeah it is definitely not cannon fodder and it actually came up with something very similar yesterday evening so at least it has some consistency (for now)

 

Yesterday/today comparison.

 

JN192-21.GIF?21-12JN168-21.GIF?21-12

Great post Mucka. Either the JMA is bang on the money or it is a little late smelling the coffee lol.

When the models are like this, who knows?

Share this post


Link to post
Share on other sites

1. Transient snow is fine if you would like to see a White Xmas - better to have it fall fresh on the day than be sticking around from a week before looking rather tired and dirty as was the situation in December 2010. The trend within 5 days appears to be to improve the snow potential - with this as the latest Xmas Eve fax chart:

post-992-0-26804900-1419189267_thumb.png

I wonder how the T+96 Fax chart for Xmas Day might look?

 

2. There is cross-model agreement on that intense cut-off low pressure system developing, but there is disagreement on the track it will take. This is not unusual. There are enough options GFS/GFSP/JMA (and even UKMO to an extent) on the table to suggest that this could cross the UK with wintry weather on its western flank. Again, only a transient situation, but nonetheless a situation not experienced during last winter.

 

3. The N-W seasonal forecast is for a cold-hearted winter. We haven't reached that period yet. If models can't reach agreement at T+132, it is not surprising that there are wild variations at T+200. Statospheric/Polar vortex forecasts are just that and are subject to change. I hear the same mundane predictions of "four weeks of mild weather" at this time of year when inevitably the Xmas period doesn't look like being exceptionally cold and snowy. If it was that easy to predict, there would be no need for this forum.

 

4. Although I favour cold and snowy weather, the current pattern of alternating between tropical and polar air sources is perhaps the fairest to all parties. It really doesn't have to be all or nothing.

Edited by The Enforcer

Share this post


Link to post
Share on other sites

The 20 GFS perturbations seem to divide into three camps. About five (only) give any real support to the deep North Sea low on 27th, the most intense is number 15. About five more seem to agree more with the ECM or even the GEM in terms of a slower moving low hanging back to the west. The rest would be less intense versions rather similar to the GME 132h. For that reason the GME has backed into a position of being the least offensive looking compromise of all available solutions.

 

I think the most likely outcome is going to be less intense than the worst case GFS and possibly a bit less intense than the UKMO, but would take the GME and intensify it by 10 mb. There will be a bit of everything in the mix, a spike in temps late 26th and early 27th near 8 C, moderately strong westerly winds, a modified cold shot, snow on higher terrain in the north, brief and transient snow in some lower areas too, and a somewhat messy return to milder westerlies. Blizzards, wind damage and storm surges are all possible but I feel they will all be largely avoided by the actual outcome. It will be a rather close-run thing as they say however.

 

Ice and freezing fog on Christmas morning and again late evening into Boxing Day morning might be the highest impact weather event of the period despite all the isobars on display.

Share this post


Link to post
Share on other sites

ECM has gone from hero to zero in 24 hrs and joins the GFS brethren in very underwhelming prospects for any lasting cold until month end at least.

Some confusing differences up stream but apart from the JMA the common theme is to reduce the ridging across the Atlantic.

I think a brief pm shot seems the best we can expect after Christmas but I don't think we should assume the return of the Atlantic considering the mixed and volatile outputs we are seeing currently.

Share this post


Link to post
Share on other sites

Tonight's GFS shows a northerly kicking in on the 27th, and winds are still from a northerly quadrant on the 31st. That's 4 days worth of an air mass coming from a non-mild direction.

 

The 31st is 228 hours away and anyone on here knows that is "FI". Only by T+252 does the wind start to veer around to the west. Now I'm not betting man, but who can honestly say anything after T+252 is worth worrying about?

 

Until then the weather is pretty interesting and it's all on a knife-edge, and after that who knows? Keep the faith - it's hardly a 2012/13 scenario.

Share this post


Link to post
Share on other sites

1. Transient snow is fine if you would like to see a White Xmas - better to have it fall fresh on the day than be sticking around from a week before looking rather tired and dirty as was the situation in December 2010. The trend within 5 days appears to be to improve the snow potential - with this as the latest Xmas Eve fax chart:

attachicon.gifXmas Eve4.png

I wonder how the T+96 Fax chart for Xmas Day might look?

 

2. There is cross-model agreement on that intense cut-off low pressure system developing, but there is disagreement on the track it will take. This is not unusual. There are enough options GFS/GFSP/JMA (and even UKMO to an extent) on the table to suggest that this could cross the UK with wintry weather on its western flank. Again, only a transient situation, but nonetheless a situation not experienced during last winter.

 

3. The N-W seasonal forecast is for a cold-hearted winter. We haven't reached that period yet. If models can't reach agreement at T+132, it is not surprising that there are wild variations at T+200. Statospheric/Polar vortex forecasts are just that and are subject to change. I hear the same mundane predictions of "four weeks of mild weather" at this time of year when inevitably the Xmas period doesn't look like being exceptionally cold and snowy. If it was that easy to predict, there would be no need for this forum.

 

4. Although I favour cold and snowy weather, the current pattern of alternating between tropical and polar air sources is perhaps the fairest to all parties. It really doesn't have to be all or nothing.

Another great post. Sometimes we are trying to look too far in to the future and we miss what is

right under our noses.

Edited by blizzard81

Share this post


Link to post
Share on other sites

I don't like all these personal digs creeping in again tonight, I was one of the victims last night for being positive / optimistic and I still think we could get something out of this but let's show respect to others opinions even if you strongly disagree and don't let it spoil Christmas.

In fairness I think most folk are just pointing out inaccurate reading of the charts. It's not meant to be personal.

There are nearly 600 people reading this thread and when someone makes inaccurate or misleading comments it's only fair and right that they are pulled up. I think the more experienced chart readers have actually shown great restraint to be honest as there has been some crazy and completely unjustified ramping in recent days (and that's a general observation and not targeting anyone in particular).

It was only yesterday that I got pulled up for saying there was nothing massively snowy in the outlook by someone quoting four charts showing 'blizzards'. The slight issue was they were not showing blizzards and were actually showing 2 days of heavy rain!

Edit: country file has just said only snow over Christmas Day will be on high ground in Scotland and perhaps over North york moors. Dry and sunny for most. Boxing Day sees rain moving into the NW with potential for some snow in Scotland for a while. Temps average to just below. Great uncertainty thereafter re path of low pressure system. Sorry mods as forecast related but in view of wider discussion in here I do think this has relevance on this occasion.

Edited by Jason M

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×
×
  • Create New...