Model Output Discussion - 05/01/2016 18z onwards

[Fingers]

A question to ask. I know it's only one run but the jet stream charts below show the stronger reds over us from t120 to t144 and increasing further so we are on the wrong side of the jet and the boundary between the cold and warm. Surely we need the jet dig a lot further down towards Africa to be in the true grip of cold weather? 

 

[bluearmy]

29 minutes ago, IDO said:

 

It looks like the ECM has lots of entropy with respect to it's members and spread by D7 is amazing. This shows with the op being the coldest run at D9 in the De Bilt graphs:

Looking at it's members it does appear that many are dry but milder so I suspect a good cluster in line with the GEFS mean. Would not rule out anything from the ECM tonight with that spread!

 I find the tweet a bit overdone.  The spaghetti spread is wide with all 51 members included. Take out the clear outliers and that 800 miles becomes 400.  For day 8, not unreasonable. The actual spread on heights across the conus isn't too big at day 7 although uppers is, which reflects the depth of cold that could dig into the USA if the jet amplifies that bit more than the mean shows and drags the chunk of vortex further south. 

[IDO]

7 minutes ago, bluearmy said:

 I find the tweet a bit overdone.  The spaghetti spread is wide with all 51 members included. Take out the clear outliers and that 800 miles becomes 400.  For day 8, not unreasonable. The actual spread on heights across the conus isn't too big at day 7 although uppers is, which reflects the depth of cold that could dig into the USA if the jet amplifies that bit more than the mean shows and drags the chunk of vortex further south. 

 

Sorry I was assuming the green line was the op and that falls well into the outlier territory if that was the case? Which one is the op. I assume the orange is the mean? Thanks.

[Backtrack]

In my opinion, both the ECM & GFS 12Z runs today are the most important. It's getting into the range now where the larger scale is pretty much nailed. It's the fine-tuning that's to be confirmed. Short-term upgrades would be fantastic. This allows a larger margin for error in the short term. 

[Timmytour]

9 minutes ago, bluearmy said:

 I find the tweet a bit overdone.  The spaghetti spread is wide with all 51 members included. Take out the clear outliers and that 800 miles becomes 400.  For day 8, not unreasonable. The actual spread on heights across the conus isn't too big at day 7 although uppers is, which reflects the depth of cold that could dig into the USA if the jet amplifies that bit more than the mean shows and drags the chunk of vortex further south.

Could be the outliers not taken out because they are the  OPs?

[bluearmy]

Looking at the mean and op ECM over the USA, they look reasonably in line with each other in their track. The op not an outlier.

[nick sussex]

Looking across all the outputs currently the GFS looks like the flattest solution for the key timeframe in the USA, so it has less dig of cold air heading south.

Putting aside the GFS victory over the Icelandic shortwave we are dealing with a different synoptic here and going on the last divergence with the dig of cold air into the central USA the GFS had to backtrack.

Currently the GFS/ECM/UKMO go from flattest to most amplified, if the models meet somewhere in the middle then a GFS edge towards the ECM and a UKMO edge towards that aswell.

Unfortunately NCEP have not come down definitely one way or another yet but simply stress the complex pattern over there. Just going on the GFS/GEFS flat bias then it would be more surprising if that didn't add a bit more amplitude upstream.

Anyway we'll see in about an hour.

[Banbury]

Haven't posted on here for a while as I'm over on the other side (TWO) , what a mad week of model watching it has been , I can't quite remember one like it . We started off with a GH only to be dumped , wrist slashing , WIO posts etc and it seems to have turned around in the last 36 hours or so with UKMO 144 looking great , obviously it has to verify but one thing is it will be a cold week, some harsh frosts in places even Snow around.

ECM looks cold under the HP at the end with the possibility of linking to another HP to the NE, of course it could spin around again this evening , after the woeful December we have had the lower temps will be very welcome.

[gottolovethisweather]

On 06/01/2016 at 4:25 PM, gottolovethisweather said:

The perfect cold spell for me would consist of an increasing risk of UK wide snowfall and then a drier big freeze some days later. Maybe, just maybe, this might become a reality.

Before a plethora of comments about the 12zs arrive and further to some recent postings by one or two of our more experienced members, I can't help but reminisce on the above as it seems to correspond with their current thinking. The reality of this dream scenario will be proven over the coming days of course but I can't help but feel we could be on the cusp of something special. I don't want to get into the specifics of when and how much snow falls and precisely where, as this will chop and change. However, I do advise folk to keep watching as the daily details will change and I suggest that they follow the relevant threads. Intriguing times ahead and overall this is a very encouraging read for coldies from weatheronline as well. 

Edited January 10, 2016 by gottolovethisweather

[khodds]

9 minutes ago, gottolovethisweather said:

Before a plethora of comments about the 12zs arrive and further to some recent postings by one or two of our more experienced members, I can't help but reminisce on the above as it seems to correspond with their current thinking. The reality of this dream scenario will be proven over the coming days of course but I can't help but feel we could be on the cusp of something special. I don't want to get into the specifics of when and how much snow falls and precisely where, as this will chop and change. However, I do advise folk to keep watching as the daily details will change and I suggest that they follow the relevant threads. Intriguing times ahead and overall this is a very encouraging read for coldies from weatheronline as well. 

But is it though? I'm reading so many mixed signals from people here, as someone who has only a small understanding of what's been said, it feels quite a damp squib to me? Or am I just being pessimistic?

[Methuselah]

Righto everyone - it's toys (I mean eyes) down, the GFS is about roll. Let's get ready to rumble!

[Banbury]

3 minutes ago, khodds said:

But is it though? I'm reading so many mixed signals from people here, as someone who has only a small understanding of what's been said, it feels quite a damp squib to me? Or am I just being pessimistic?

It depends what you were expecting really , for me just a lowering of temps day and night will do for starters . Fax charts are always a good indication and 'live' weather forecasts too

[nick sussex]

Unusually NCEP in their short term discussions used quite a lot of the NAM the mesoscale model for the USA. They were fine with its Pacific flow, the GFS was seen as a little faster than the other guidance. With that in mind heres the latest NAM 12hrs run to T84hrs:

Heres the GFS 06hrs run to T90hrs:

You can see the GFS flatter over the central/west USA.

Lets hope this is a good sign for its 12hrs run coming out soon.

 

[Nouska]

42 minutes ago, IDO said:

 

Sorry I was assuming the green line was the op and that falls well into the outlier territory if that was the case? Which one is the op. I assume the orange is the mean? Thanks.

The coloured lines are all detailed below the graphic on the tweet - op/det run is in white.

[gottolovethisweather]

32 minutes ago, khodds said:

But is it though? I'm reading so many mixed signals from people here, as someone who has only a small understanding of what's been said, it feels quite a damp squib to me? Or am I just being pessimistic?

Yes, by way of longevity it is looking nailed for seven days at least and I anticipate a much longer spell of cold weather. Initially a wintry mix is a good description of what we can expect but eventually deeper cold will filter through as well. I'm just cherishing the thought of it being perishing and wishing for some drifting of snow in bitter winds in the days ahead. Banbury provides some sound advice there too. Eyes down then. 

Edited January 10, 2016 by gottolovethisweather

[Methuselah]

1 minute ago, Greenland1080 said:

GFS coming into line with the UKM an ECM is my call...oh an Leicester to beat Spurs 3-1........an with NAO AO negative some mid term upgrades an eye candy......

 

2 minutes ago, Greenland1080 said:

GFS coming into line with the UKM an ECM is my call...oh an Leicester to beat Spurs 3-1........an with NAO AO negative some mid term upgrades an eye candy......

It could be more marginal than that, Greenland. Though, going by what all the models suggest, Wednesday may well be less so?

[IDO]

8 minutes ago, Nouska said:

The coloured lines are all detailed below the graphic on the tweet - op/det run is in white.

Thanks. So the OP (546 dam) swings into outlier territory at least twice  compared to the mean and main clusters! Certainly has little support on that chart.

Edited January 10, 2016 by IDO

[Captain Shortwave]

1 hour ago, IDO said:

Looking at it's members it does appear that many are dry but milder so I suspect a good cluster in line with the GEFS mean. Would not rule out anything from the ECM tonight with that spread!

*Cropped the quote to avoid making this post too large.

It's fair to say that we are not going to see eye to eye over the coming set up going into the mid-range, well until the models agree of course.

Unfortunately no MJO update from the GFS and ECMWF so I will just use the MJO predictions from the pair as it does kin of explain some of the divergence.

GEFs and ECM

  

The GFS signal weakens quickly before re-amplifying in week 2. The ECM and other parts of the ECMWF climatology (Seasonal models included) all go for the MJO to move swiftly into phase 1 before the signal weakens with some members going into phase 2.

Looking at the MJO composites.

Phase 8 and 1

  

As we see phase 8 puts us under a a strong upper ridge which could be mild if we see a strong enough south westerly flow. Phase one puts heights just north of the UK with colder and more unsettled weather to our south, this puts us in the risk of developing an easterly flow.

Until this is resolved then it is a little hasty to regard the output as a simple return to a more westerly type pattern, especially given the ECM's bullishness at keeping the UK cold and settled at the surface comfortably until day 10 and also keeps us very close to sound very cold air to our east. At least we have lost the strong manipulation of the longwave pattern by the strong El Nino event with frequent pulses of high heights reached the pole which at this present time I do not expect to cease. Any model output suggesting the reformation of a strong tropospheric vortex should be treated with caution given that new amplified ridges could easily appear over the coming days.

So the breakdown, the models are more in support of a gradual loss of the cold air first at 850 level and then finally at the surface, especially so the GFS suite. That said there is a good signal that we could see the ridge over us amplified enough to keep the UK cold and settled for the foreseeable. There are two other options which are of a lower possibility. The first could be a re-shuffle of the northern hemispheric pattern which could allow heights to retrograde back towards the north west to allow another northerly plunge, the second is that the high could build far enough north around day 6/7 where we could feasibly build the ridge to our north/north east and allow a north east or easterly flow to develop, add to that we see heights continued to be modelled over central and north Russia that means there is a possibility that we could even link those heights to our ridge cutting off the deep trough over eastern Europe which could really set up a bitter easterly. The odd of these events are in my view 50%, 30%, 10% and 10% going by statistical evidence.

My one concern about the GFS is of course that it is modelling the Atlantic pattern differently to the other models by persistently forcing a weak low through the Atlantic hitting some areas of the UK on Friday, no other model wants to do this (The NAVGEM 06z does however). This shows a continued presence of the jetstream across the Atlantic through the day 4-7 range where the other models (UKMO/ECM/GEM) do disrupt the jetstream which allows a renewed push of heights northwards in the Atlantic. The second concern is of course whether the GFS is currently modelling the MJO signal correctly, if it suddenly tracks into phase one then the eurotrash high signal could quickly disappear in the longer term trend. Of course the reverse could occur.

So as the models come out this evening, I am going to take a bit of a punt here that we will see a prolonging of the cold signal pushing to the middle of next week with the potential to develop an easterly flow, albeit probably quite a slack one which will affect more southern areas. Hopefully the ECM and GEM will show something like this and the GFS will continue to move towards a solution where the upper ridge is squeezed further north west by strengthening the cold trough signal over central and eastern Europe, and the trough over the western Atlantic. Something near the UK between day 8 and 10 will be fine and the loss of the signal for a south westerly flow before low resolution (day 10). Of course the first hurdle will be seeing the GFS stop pushing shallow areas of low pressure across the Atlantic around day 4/5.

Can we build on charts like these this evening.

Just my take on things and I am hopeful for something better than what is currently modelled at the moment, especially the GFS. Of course I could be wrong and the models could backtrack to a milder solution for week 2, if so I think a change of profile picture might be in order. Something like this....

The 12z suite is about to come out so fingers crossed on improvements in our chances for cold and snowy weather.

Edited January 10, 2016 by Captain Shortwave

[IDO]

Thanks Captain, hope you are right. Knowing our luck we will all be fist thumping as GFS does a U-Turn and then ECM will flip to a GFS solution!

[SLEETY]

8 minutes ago, Captain Shortwave said:

*Cropped the quote to avoid making this post too large.

It's fair to say that we are not going to see eye to eye over the coming set up going into the mid-range.

Unfortunately no MJO update from the GFS and ECMWF so I will just use the MJO predictions from the pair as it does kin of explain some of the divergence.

GEFs and ECM

  

The GFS signal weakens quickly before re-amplifying in week 2. The ECM and other parts of the ECMWF climatology (Seasonal models included) all go for the MJO to move swiftly into phase 1 before the signal weakens with some members going into phase 2.

Looking at the MJO composites.

Phase 8 and 1

  

As we see phase 8 puts us under a a strong upper ridge which could be mild if we see a strong enough south westerly flow. Phase one puts heights just north of the UK with colder and more unsettled weather to our south, this puts us in the risk of developing an easterly flow.

Until this is resolved then it is a little hasty to regard the output as a simple return to a more westerly type pattern, especially given the ECM's bullishness at keeping the UK cold and settled at the surface comfortably until day 10 and also keeps us very close to sound very cold air to our east. At least we have lost the strong manipulation of the longwave pattern by the strong El Nino event with frequent pulses of high heights reached the pole which at this present time I do not expect to cease. Any model output suggesting the reformation of a strong tropospheric vortex should be treated with caution given that new amplified ridges could easily appear over the coming days.

So the breakdown, the models are more in support of a gradual loss of the cold air first at 850 level and then finally at the surface, especially so the GFS suite. That said there is a good signal that we could see the ridge over us amplified enough to keep the UK cold and settled for the foreseeable. There are two other options which are of a lower possibility. The first could be a re-shuffle of the northern hemispheric pattern which could allow heights to retrograde back towards the north west to allow another northerly plunge, the second is that the high could build far enough north around day 6/7 where we could feasibly build the ridge to our north/north east and allow a north east or easterly flow to develop, add to that we see heights continued to be modelled over central and north Russia that means there is a possibility that we could even link those heights to our ridge cutting off the deep trough over eastern Europe which could really set up a bitter easterly. The odd of these events are in my view 50%, 30%, 10% and 10% going by statistical evidence.

My one concern about the GFS is of course that it is modelling the Atlantic pattern differently to the other models by persistently forcing a weak low through the Atlantic hitting some areas of the UK on Friday, no other model wants to do this (The NAVGEM 06z does however). This shows a continued presence of the jetstream across the Atlantic through the day 4-7 range where the other models (UKMO/ECM/GEM) do disrupt the jetstream which allows a renewed push of heights northwards in the Atlantic. The second concern is of course whether the GFS is currently modelling the MJO signal correctly, if it suddenly tracks into phase one then the eurotrash high signal could quickly disappear in the longer term trend. Of course the reverse could occur.

So as the models come out this evening, I am going to take a bit of a punt here that we will see a prolonging of the cold signal pushing to the middle of next week with the potential to develop an easterly flow, albeit probably quite a slack one which will affect more southern areas. Hopefully the ECM and GEM will show something like this and the GFS will continue to move towards a solution where the upper ridge is squeezed further north west by strengthening the cold trough signal over central and eastern Europe. and the trough over the western Atlantic. Something near the UK between day 8 and 10 will be fine and the loss of the signal for a south westerly flow before low resolution (day 10).

Can we build on charts like these this evening.

Just my take on things and I am hopeful for something better than what is currently modelled at the moment, especially the GFS. Of course I could be wrong and the models could backtrack to a milder solution for week 2, if so I think a change of profile picture might be in order. Something like this....

The 12z suite is about to come out so fingers crossed on improvements in our chances for cold and snowy weather.

ecm wasnt far off from developing a bitter easterly at the latter stage of its midnight run,im awaiting it's next run with great interest ,this evening

[Mair Snaw]

7 minutes ago, IDO said:

Thanks Captain, hope you are right. Knowing our luck we will all be fist thumping as GFS does a U-Turn and then ECM will flip to a GFS solution!

Weve seen that happen before.... this place was in meltdown then the next ECM came back to the party only for the UKMO to leave the fun... might have been March 2013....

[Methuselah]

From a combination of what the models are currently suggesting (very cold conditions in Scandinavia and eastern Europe), the usual late El Nino signals plus fading memories of previous years, something coming from the east looks like a good bet, to me. So, don't panic, should nothing definitive show-up on today's predictions...It's nae 'game over' - it could be game on!

[Ali1977]

Keep an eye on that front coming in from the NW for Friday, that could produce the goods down south.

[northwestsnow]

GFS not really having anything to do with this mornings UKMO run ..

[IDO]

Short Term: GFS now modelling the track of that Azores spin off low into France, further south than the 06z. So UK uppers not mixed out and backedge snow from the Iceland Low having less marginalty in the Midlands/South early Thursday: