Model output discussion - winter proper underway

[SLEETY]

15 minutes ago, tight isobar said:

Theres opt' for colder soulutions..

Although a messy way there!!!!

Some very cold solutions ,maybe it’s not all over,regarding cold weather returning again 

[feb1991blizzard]

1 minute ago, ArHu3 said:

It turned out to be a very early final warming, not a midwinter ssw

But wasn't it Early feb, surely that's still got to be classed as a proper SSW?

[bluearmy]

9 minutes ago, feb1991blizzard said:

But wasn't it Early feb, surely that's still got to be classed as a proper SSW?

Beginning Feb the zonal 10hpa wind touched zero but quickly bounced back to 20 m/s. Touched zero again late in the month. the cool spring likely a result of these strong slow downs with delayed wave downwelling into the trop. I don't think the zonal flow actually reversed at 10hpa and in any event, it wasn't sustained for very long at the beginning Feb. ssw can have an instant downwelling to the trop if strat/trop is well coupled but once you get to Feb you have likely missed the boat for an ssw to have a big effect on winter - it's more likely to give a cold march/April. an event early Jan much more desirable. 

 

Edited December 11, 2017 by bluearmy

[ArHu3]

12 minutes ago, feb1991blizzard said:

But wasn't it Early feb, surely that's still got to be classed as a proper SSW?

 

 

Edited December 11, 2017 by ArHu3

[phil nw.]

Meanwhile back at the ranch no joy in the ext eps days 10/15 looking at the 500 anomalies.

Cross polar +ve hts from Alaska to Siberia.Canadian trough extending across Greenland linking to lower heights towards Scandinavia and the usual Azores high,so a typical westerly pattern.Signs that the Azores high eases west further out into the Atlantic at the end with a more nw angle to the jet. 

[tight isobar]

1 minute ago, ArHu3 said:

 

 

 

The ramifications of a-SSW with lag-and effects in early march...

Are indeed-in stark contrast to the prognosed,1 suspected/expected 'later december'...

Where any effect will be far more noteworthy....

Lets get current diagnosis into context first. There are mid term prospects/decipher' that are knawing away at the bone atm....

But certainly some meat on the bone concerning a warm later this month!

Could be some season this!!!!

[Catacol]

1 hour ago, The Enforcer said:

The key for me is whether the signals are current or whether they are projected. If the former, then, as set out in the NW winter forecast, there can be reasonable confidence in conditions supporting wintry weather emerging at some point.

However, if it is a forecast for favourable background signals then it is just that - a forecast - and as such needs to be weighted accordingly. Hypothetically, a forecast today for a SSW on 1st Jan 2018 is not really any more reliable than GFS charts showing snow on xmas day at T+384. I have lost track of how many times the charts show MJO is expected to move into 'this' phase and a few days later they instead say that it is expected to move into 'that' phase.

 

Key point indeed... and you'll notice today that teleconnective comments are absent because we await exactly what you ask for here - real data rather than forecast data. A few things we do know for sure - the GWO orbit is holding up and the CPC report on the MJO published today (it is updated each week) is quite bullish about the current renewed and observed MJO cycle and observed enhanced convection over the western pacific. The same report also suggests a slow moving MJO cycle from here, at the lower end of the expected rate of transition, so probably holding longer in the 7/8 orbit. We can also see from NH charts that a trough/ridge pattern close to the Himalayas is currently in place and is likely to provide a spike to east asian mountain torque in the next few days... a point made earlier by Masiello on twitter. We know we have an ongoing wave 1 moderate level hit on the vortex keeping it pushed over towards the Asian side with no great coherence to vortex influence currently on tropospheric patterns. We also have a fast climbing temperature over the north pole at 30mb - an old fashioned tool over on JMA that has always seemed to me a handy guide on the state of things over the pole for those (like me) who struggle to visualise the entire complexity of the many layers of stratospheric vortex activity.

We know also that ensemble forecasts from both EC and GFS have swung in the last few days towards a flatter pattern, elimination of the mid atlantic ridge but also an increase in height anomalies to the NE. 

What more would I like to know tonight? I'd like to know exactly where the AAM budget sits... the trend over the last few days... and the actual situation regarding frictional torques. This data has not updated today.

Conclusion? Today's bullish MJO report from CPC and visible east asian torque with associated lag has me firmly fixed to a strong belief in the return of amplification in the medium term. Lack of vortex intensity supports this. Tie into GP's key knowledge on composite data (something I have as a 2018 target to improve on myself....) pointing strongly at a Scandy ridge evolution on the back of the observed GWO orbit and current observed state of the MJO moving slowly through 7/8 and it seems a very good bet that this amplification will produce the aforementioned scandy high. 

Timing? Well - not for the first time of stating.... there's the thing. Lag impacts are uncertain - and I wouldnt want to make a timing prediction at this stage. Our atlantic is not being driven by a rampant vortex this year - indeed I am beginning to wonder if the vortex is going to remain weak for a sustained period now especially with IF tweeting about Metoffice sense of ongoing warming and disruption. A sluggish atlantic makes it difficult to predict how much westerly momentum might gather through next week. Are the models built around a westerly bias that may overcook this signal based upon "normal" climatogical impact of the winter vortex? The models continue (by observation) to underestimate the orbit and direction of the MJO - underestimating first of all the impact of the 5/6 transition but now equally underestimating the move to phase 7... and as such are they failing to pick up an amplification signal for Xmas week?

Laying my cards on the table (admittedly without the data update today...) I think amplification will return more quickly than the ensembles are seeing following a short to shortish period of westerly influence of around a week. 

[tight isobar]

2 minutes ago, Catacol said:

Key point indeed... and you'll notice today that teleconnective comments are absent because we await exactly what you ask for here - real data rather than forecast data. A few things we do know for sure - the GWO orbit is holding up and the CPC report on the MJO published today (it is updated each week) is quite bullish about the current renewed and observed MJO cycle and observed enhanced convection over the western pacific. The same report also suggests a slow moving MJO cycle from here, at the lower end of the expected rate of transition, so probably holding longer in the 7/8 orbit. We can also see from NH charts that a trough/ridge pattern close to the Himalayas is currently in place and is likely to provide a spike to east asian mountain torque in the next few days... a point made earlier by Masiello on twitter. We know we have an ongoing wave 1 moderate level hit on the vortex keeping it pushed over towards the Asian side with no great coherence to vortex influence currently on tropospheric patterns. We also have a fast climbing temperature over the north pole at 30mb - an old fashioned tool over on JMA that has always seemed to me a handy guide on the state of things over the pole for those (like me) who struggle to visualise the entire complexity of the many layers of stratospheric vortex activity.

We know also that ensemble forecasts from both EC and GFS have swung in the last few days towards a flatter pattern, elimination of the mid atlantic ridge but also an increase in height anomalies to the NE. 

What more would I like to know tonight? I'd like to know exactly where the AAM budget sits... the trend over the last few days... and the actual situation regarding frictional torques. This data has not updated today.

Conclusion? Today's bullish MJO report from CPC and visible east asian torque with associated lag has me firmly fixed to a strong belief in the return of amplification in the medium term. Lack of vortex intensity supports this. Tie into GP's key knowledge on composite data (something I have as a 2018 target to improve on myself....) pointing strongly at a Scandy ridge evolution on the back of the observed GWO orbit and current observed state of the MJO moving slowly through 7/8 and it seems a very good bet that this amplification will produce the aforementioned scandy high. 

Timing? Well - not for the first time of stating.... there's the thing. Lag impacts are uncertain - and I wouldnt want to make a timing prediction at this stage. Our atlantic is not being driven by a rampant vortex this year - indeed I am beginning to wonder if the vortex is going to remain weak for a sustained period now especially with IF tweeting about Metoffice sense of ongoing warming and disruption. A sluggish atlantic makes it difficult to predict how much westerly momentum might gather through next week. Are the models built around a westerly bias that may overcook this signal based upon "normal" climatogical impact of the winter vortex? The models continue (by observation) to underestimate the orbit and direction of the MJO - underestimating first of all the impact of the 5/6 transition but now equally underestimating the move to phase 7... and as such are they failing to pick up an amplification signal for Xmas week?

Laying my cards on the table (admittedly without the data update today...) I think amplification will return more quickly than the ensembles are seeing following a short to shortish period of westerly influence of around a week. 

Great post...

And could'nt agree more with all 'noted'.

[damianslaw]

Its been quite an exhausting few days in this thread- with all the talk about yesterday's slider and where might it go.. Alas, I'm going to take a break from model watching for a week, and I expect the models to be showing some interesting developments for the latter part of the month by then, having stuck with a westerly onslaught over the coming days, as some of the background signals for renewed amplification and height rises to our NE begin to emerge - as I believe this is where we will be trending to end the year. Also expecting this thread to be full of woe and dispondency as they fail to show any imminent return to cold - instead I will enjoy what looks like a predominantly cold week with alot of sunshine - plus I'm quite busy.

 

 

[East_England_Stormchaser91]

22 minutes ago, Catacol said:

Key point indeed... and you'll notice today that teleconnective comments are absent because we await exactly what you ask for here - real data rather than forecast data. A few things we do know for sure - the GWO orbit is holding up and the CPC report on the MJO published today (it is updated each week) is quite bullish about the current renewed and observed MJO cycle and observed enhanced convection over the western pacific. The same report also suggests a slow moving MJO cycle from here, at the lower end of the expected rate of transition, so probably holding longer in the 7/8 orbit. We can also see from NH charts that a trough/ridge pattern close to the Himalayas is currently in place and is likely to provide a spike to east asian mountain torque in the next few days... a point made earlier by Masiello on twitter. We know we have an ongoing wave 1 moderate level hit on the vortex keeping it pushed over towards the Asian side with no great coherence to vortex influence currently on tropospheric patterns. We also have a fast climbing temperature over the north pole at 30mb - an old fashioned tool over on JMA that has always seemed to me a handy guide on the state of things over the pole for those (like me) who struggle to visualise the entire complexity of the many layers of stratospheric vortex activity.

We know also that ensemble forecasts from both EC and GFS have swung in the last few days towards a flatter pattern, elimination of the mid atlantic ridge but also an increase in height anomalies to the NE. 

What more would I like to know tonight? I'd like to know exactly where the AAM budget sits... the trend over the last few days... and the actual situation regarding frictional torques. This data has not updated today.

Conclusion? Today's bullish MJO report from CPC and visible east asian torque with associated lag has me firmly fixed to a strong belief in the return of amplification in the medium term. Lack of vortex intensity supports this. Tie into GP's key knowledge on composite data (something I have as a 2018 target to improve on myself....) pointing strongly at a Scandy ridge evolution on the back of the observed GWO orbit and current observed state of the MJO moving slowly through 7/8 and it seems a very good bet that this amplification will produce the aforementioned scandy high. 

Timing? Well - not for the first time of stating.... there's the thing. Lag impacts are uncertain - and I wouldnt want to make a timing prediction at this stage. Our atlantic is not being driven by a rampant vortex this year - indeed I am beginning to wonder if the vortex is going to remain weak for a sustained period now especially with IF tweeting about Metoffice sense of ongoing warming and disruption. A sluggish atlantic makes it difficult to predict how much westerly momentum might gather through next week. Are the models built around a westerly bias that may overcook this signal based upon "normal" climatogical impact of the winter vortex? The models continue (by observation) to underestimate the orbit and direction of the MJO - underestimating first of all the impact of the 5/6 transition but now equally underestimating the move to phase 7... and as such are they failing to pick up an amplification signal for Xmas week?

Laying my cards on the table (admittedly without the data update today...) I think amplification will return more quickly than the ensembles are seeing following a short to shortish period of westerly influence of around a week. 

Terrific post. Gav partridge seems to be going for a colder than average winter this year by the way. Taking into account a whole range of dynamics (E QBO, decline of solar activity, La Niña which was unexpected!, warmer than normal water towards Svalbard.) 

 

[Derecho]

Looks like the pub run may follow the ECM and UKMO in sinking the high to our west and failing to link it to Scandi.

We may have to endure westerlies for a while, if they persist past christmas we may end up with our 7th mild christmas in a row (although 2014 saw some chillier weather).

Hopefully they won't last that long...

EDIT: Actually the 18z manages to hold off the milder air.... that told me!

Edited December 11, 2017 by Quicksilver1989

[West is Best]

I don't mean to sound too much like a broken record, but there continues to be massive scatter in the GFS ensembles. There's a staggering 25C difference for Christmas Eve and near enough 15C difference just a week away. Those are pretty colossal scatters. It means there are a number of possible and perhaps plausible perturbations in the forecasting models. Perhaps worth bearing in mind, alongside the various upstream signals.

[feb1991blizzard]

1 minute ago, West is Best said:

I don't mean to sound too much like a broken record, but there continues to be massive scatter in the GFS ensembles. There's a staggering 25C difference for Christmas Eve and near enough 15C difference just a week away. Those are pretty colossal scatters. It means there are a number of possible and perhaps plausible perturbations in the forecasting models. Perhaps worth bearing in mind, alongside the various upstream signals.

The problem is though the scatter is mostly between just below average and severely mild as opposed to cold - very cold.

[bluearmy]

The latest ec 46 Icelandic charts out to 30 days show the pattern of week 2 continuing with low height anomoly extending across the Atlantic from the Canadian vortex with pos NAO and high height anomoly to our east and north but not looking close enough at this time to assist the coldies. the global view will reveal more detail. Obviously clusters will help dictate if any change in Exeter's 30 dayer

Edited December 11, 2017 by bluearmy

[feb1991blizzard]

5 minutes ago, bluearmy said:

The latest ec 46 Icelandic charts out to 30 days show the pattern or week 2 continuing with low height anomoly extending across the Atlantic from the Canadian vortex with pos NAO and high height anomoly to our east and north but not looking close enough at this time to assist the coldies. the global view will reveal more detail. Obviously clusters will help dictate if any change in Exeter's 30 dayer

What about week 3 and 4 please?

[tight isobar]

6-of 1-half a dozen of the other!..

Although we lose uppers of a colder factor..

18z @180 hrs offers better aligning heights..of a wrap towards scandi!!!..

Knife edge is an understatement.

.....@compare 12z-18z snaps.

Edited December 11, 2017 by tight isobar

[bluearmy]

4 minutes ago, feb1991blizzard said:

What about week 3 and 4 please?

Post edited - I was referring to weeks 3 and 4 !

[Man With Beard]

1 hour ago, phil nw. said:

Meanwhile back at the ranch no joy in the ext eps days 10/15 looking at the 500 anomalies.

Cross polar +ve hts from Alaska to Siberia.Canadian trough extending across Greenland linking to lower heights towards Scandinavia and the usual Azores high,so a typical westerly pattern.Signs that the Azores high eases west further out into the Atlantic at the end with a more nw angle to the jet. 

Phil this definitely seems the favoured route to cold on the ECM ensembles - many individual members gradually retreating the Azores High back towards Canada between D11 and D14, and while no great appetite for a Greenland High, many members send a flow from its direction. That to me seems the most likely path to Christmas cold based upon the latest ECM output (if there is a path), not the easterly route - and this is quite consistent with the morning's ensembles

[Methuselah]

I wonder if that 1020 hpa isobar goes round the entire planet?

[tight isobar]

If nothing else some decent surface cold/frost/fog=seasonal.

Russian waa again catching the attention, and the pacific ridge/waa would aid muchly with decent advection with squeeze on the forming canadian-lobe...

Access to developing/possible scandi making heights!!!..

More modeling required for sure!!!!!

[feb1991blizzard]

Might as well throw this in there as well then, pity we cant see a breakdown of months.

Edited December 11, 2017 by feb1991blizzard

[feb1991blizzard]

Ha Ha.

[bluearmy]

8 minutes ago, feb1991blizzard said:

Might as well throw this in there as well then, pity we cant see a breakdown of months.

There’s that same theme of flattened Azores ridge with the Canadian vortex throwing out low heights at nw europe

the ec46 is more troughy than I thought in week 3 - basically the low heights sink slowly across us though with no amplified pattern out west we would be relying on runners into the base of the trough to provide any snowfall away from the usual places in cold zonality.

post day 30 isn’t really worth commenting on but it doesn’t revert to climatology and what is noticeable through the entire run is no appetite other to have low or neutral slp anomolies over France 

it’s notoriously unreliable but it’s interesting nevertheless 

 

[Man With Beard]

6 minutes ago, feb1991blizzard said:

Ha Ha.

Never seen that on the mean chart before! Not a sausage on models like ARGEPE and next to no snow on the ECM for that day - think I know which one I'm going to trust for now!!

Further on, EC clusters not completely without Scandi High potential at D10 - Cluster 3 - bit of a long shot though.

Surprised not to see more amplified Atlantic ridges between D12 and D15 - clusters look a bit flattish - but I saw enough individual ensembles with northwards ridging in the Atlantic to justify a cluster, surely?

 

 

[feb1991blizzard]

1 minute ago, Man With Beard said:

Never seen that on the mean chart before! Not a sausage on models like ARGEPE and next to no snow on the ECM for that day - think I know which one I'm going to trust for now!!

Further on, EC clusters not completely without Scandi High potential at D10 - Cluster 3 - bit of a long shot though.

Surprised not to see more amplified Atlantic ridges between D12 and D15 - clusters look a bit flattish - but I saw enough individual ensembles with northwards ridging in the Atlantic to justify a cluster, surely?

 

 

Looks like even cluster 3 wouldn't deliver any time soon afterwards anyway to me - this isn't looking good for the next month from where I am standing, decent strat charts on the 18z again, that's what I'm going to be following from now on.