Model Output Discussion - Colder but how cold and for how long?

[Rob 79812010]

To me, everything seems pretty much on track. Last week of Jan was always looking like a warm up. It's what comes after that..... 

[AltonMatthew]

23 minutes ago, Lord Grogon said:

So my non-technical take on what will happen. Based on nothing more than my direct experiences, plus reading this site.

1) It will get much colder over the weekend. There will be much talk in the media of "stiff northerlys" and "arctic blasts"

2) A few places in the north will get snow showers. But on the whole most places will remain dry. Some will grumble at this, but others will maintain that we should keep the faith.

3) There will be much talk of a big midweek snow event. But ultimately it will trend southwards and miss the UK.

4) There will be louder grumbles,  but others will say "at least it is still cold".

5) A much bigger low will approach from the west. There will be talk of "battleground scenarios" and "midlands north event"

6) The low will pile through. There will be snow on the leading edge that will produce dramatic pictures on the news. But overall it will soon become a rainy/slushy mess. It will mark the end of the cold spell and people will be sad.

7) Others will say "Doesn't matter. Background signals are supporting an even better cold spell opportunity next month." There is much rejoicing and the chase is resumed" 

This is 100% how it will go. Well done Lord Grogon! 

1 minute ago, Rob 79812010 said:

To me, everything seems pretty much on track. Last week of Jan was always looking like a warm up. It's what comes after that..... 

But lets be honest. Its always "What comes after that". Typical FI chasing that produces nothing notable.

[Tamara]

References, as ever, crop up to x+y= responses to MJO phases in isolation. Again, to keep reiterating, tropical AND extra tropical wind-flow has to be assessed in respect of synoptic responses. There is no linear single interaction/response between the tropics and extra tropics without looking at directional flux of propagation of wind-flow as well, at this time of year, considering the interactions between the troposphere as a whole and the polar field.

Eastward moving tropical convection waves (MJO) at high amplitude and set against very high +ve inertia within the aggregate global wind-flow budget is going to retain greater amplification tendency than a situation where angular momentum and angular momentum tendency are both suppressed. In this sense, and taking the present scenario where the MJO is moving through the so called "La Nina response phases" of the Maritime continent, it is not as simple as equating this to increased polar jet+ Atlantic westerly forcing = mobile +NAO pattern and breakdown of blocking patterns.

The more extended period is fraught with so many pitfalls for NWP that I would genuinely stop trying to second guess the outlook for the last third of January. It makes sense that the Canadian lobe of the polar vortex will send energy towards the Atlantic but based on both the modelling within the polar field, which is highly unstable, and so much latent +AAM inertia within the aggregate wind-flow budget and then in addition to all that  - another very sizeable push of inertia and momentum between the tropics and extra tropics during the period under consideration;  there are so many hurdles for NWP to handle that extended ensemble data is next to rudderless at this time.

This assessment is intended to be neutral in respect of the overall diagnostic - but it happens to be one that continues to keep cold blocked patterns in the ascendancy for N/NW Europe and tendency for the white water rafting within the sub tropical jet stream to be adjusted upwards within modelling suites day on dy. That doesn't inextricably mean another 1947 redux, but probabilities do suggest that attempted Atlantic breakdowns will be attritional and prone to be shorter lived, if they occur, rather than any wholesale mobile pattern change.

Increased westerly mobility has higher probability for more southern parts of Europe - overall.

[MATTWOLVES 3]

I wished I wouldn't have said anything about the met insider information now

Let's be honest here if it's solid there may be a little alteration too the 1st part of the update.. but I very much doubt the 2nd part would be altered at all! Not unless the likes of Glosea have had a massive climbdown overnight.

And keep in mind how often have we had people in the past say they've got a friend at Dominoes who knows a council figure for the gritting service, and they've been told to stock up big time on grit this year

And mogreps does look cold out till next weekend and let's be honest so much is subject to change at this range as we've seen with the models over the last several days!

But I tell you what if this bloke is lying he's being unfollowed

@Tamara brilliant as ever and many thanks..I just don't know what I'd do without you

Edited January 11 by MATTWOLVES 3

[tight isobar]

54 minutes ago, Jackski4 said:

So we’re really all now freaking out because some random dude said to @MATTWOLVES 3 on Twitter that the met office are going to downgrade a forecast for over a weeks time? Oh okay then 

Nuts isn’t it!!!

[Rain All Night]

9 minutes ago, Tamara said:

References, as ever, crop up to x+y= responses to MJO phases in isolation. Again, to keep reiterating, tropical AND extra tropical wind-flow has to be assessed in respect of synoptic responses. There is no linear single interaction/response between the tropics and extra tropics without looking at directional flux of propagation of wind-flow as well, at this time of year, considering the interactions between the troposphere as a whole and the polar field.

Eastward moving tropical convection waves (MJO) at high amplitude and set against very high +ve inertia within the aggregate global wind-flow budget is going to retain greater amplification tendency than a situation where angular momentum and angular momentum tendency are both suppressed. In this sense, and taking the present scenario where the MJO is moving through the so called "La Nina response phases" of the Maritime continent, it is not as simple as equating this to increased polar jet+ Atlantic westerly forcing = mobile +NAO pattern and breakdown of blocking patterns.

The more extended period is fraught with so many pitfalls for NWP that I would genuinely stop trying to second guess the outlook for the last third of January. It makes sense that the Canadian lobe of the polar vortex will send energy towards the Atlantic but based on both the modelling within the polar field, which is highly unstable, and so much latent +AAM inertia within the aggregate wind-flow budget and then in addition to all that  - another very sizeable push of inertia and momentum between the tropics and extra tropics during the period under consideration;  there are so many hurdles for NWP to handle that extended ensemble data is next to rudderless at this time.

This assessment is intended to be neutral in respect of the overall diagnostic - but it happens to be one that continues to keep cold blocked patterns in the ascendancy for N/NW Europe and tendency for the white water rafting within the sub tropical jet stream to be adjusted upwards within modelling suites day on dy. That doesn't inextricably mean another 1947 redux, but probabilities do suggest that attempted Atlantic breakdowns will be attritional and prone to be shorter lived, if they occur, rather than any wholesale mobile pattern change.

Increased westerly mobility has higher probability for more southern parts of Europe - overall.

It sounds as though you don't think we need to be worried about these ensemble means. I'd be thrilled if you were right!

Edited January 11 by RainAllNight

[Chasbrown]

3 minutes ago, MATTWOLVES 3 said:

I wished I wouldn't have said anything about the met insider information now

Let's be honest here if it's solid there may be a little alteration too the 1st part of the update.. but I very much doubt the 2nd part would be altered at all! Not unless the likes of Glosea have had a massive climbdown overnight.

And keep in mind how often have we had people in the past say they've got a friend at Dominoes who knows a council figure for the gritting service, and they've been told to stock up big time on grit this year

And mogreps does look cold out till next weekend and let's be honest so much is subject to change at this range as we've seen with the models over the last several days!

But I tell you what if this bloke is lying he's being unfollowed

Never give up, Matt!

[Battleground Snow]

That really is a decent shift in the right direction on mogreps if you compare it with the 00z set.

Suggests the low doesn't get very close though 

Edited January 11 by Battleground Snow

[winterof79]

7 minutes ago, MATTWOLVES 3 said:

I wished I wouldn't have said anything about the met insider information now

Let's be honest here if it's solid there may be a little alteration too the 1st part of the update.. but I very much doubt the 2nd part would be altered at all! Not unless the likes of Glosea have had a massive climbdown overnight.

And keep in mind how often have we had people in the past say they've got a friend at Dominoes who knows a council figure for the gritting service, and they've been told to stock up big time on grit this year

And mogreps does look cold out till next weekend and let's be honest so much is subject to change at this range as we've seen with the models over the last several days!

But I tell you what if this bloke is lying he's being unfollowed

I'll follow him but not on twitter.

Edited January 11 by winterof79

[Met4Cast]

12 minutes ago, Tamara said:

References, as ever, crop up to x+y= responses to MJO phases in isolation. Again, to keep reiterating, tropical AND extra tropical wind-flow has to be assessed in respect of synoptic responses. There is no linear single interaction/response between the tropics and extra tropics without looking at directional flux of propagation of wind-flow as well, at this time of year, considering the interactions between the troposphere as a whole and the polar field.

Eastward moving tropical convection waves (MJO) at high amplitude and set against very high +ve inertia within the aggregate global wind-flow budget is going to retain greater amplification tendency than a situation where angular momentum and angular momentum tendency are both suppressed. In this sense, and taking the present scenario where the MJO is moving through the so called "La Nina response phases" of the Maritime continent, it is not as simple as equating this to increased polar jet+ Atlantic westerly forcing = mobile +NAO pattern and breakdown of blocking patterns.

The more extended period is fraught with so many pitfalls for NWP that I would genuinely stop trying to second guess the outlook for the last third of January. It makes sense that the Canadian lobe of the polar vortex will send energy towards the Atlantic but based on both the modelling within the polar field, which is highly unstable, and so much latent +AAM inertia within the aggregate wind-flow budget and then in addition to all that  - another very sizeable push of inertia and momentum between the tropics and extra tropics during the period under consideration;  there are so many hurdles for NWP to handle that extended ensemble data is next to rudderless at this time.

This assessment is intended to be neutral in respect of the overall diagnostic - but it happens to be one that continues to keep cold blocked patterns in the ascendancy for N/NW Europe and tendency for the white water rafting within the sub tropical jet stream to be adjusted upwards within modelling suites day on dy. That doesn't inextricably mean another 1947 redux, but probabilities do suggest that attempted Atlantic breakdowns will be attritional and prone to be shorter lived, if they occur, rather than any wholesale mobile pattern change.

Increased westerly mobility has higher probability for more southern parts of Europe - overall.

Mentioning 1947 is going to cause a riot.. 

[IanT]

This “event”, this thread.

Surely the longest/worst/best chase in the history of NW…!

 

 

[Ali1977]

5 minutes ago, Battleground Snow said:

That really is a decent shift in the right direction on mogreps if you compare it with the 00z set.

Suggests the low doesn't get very close though 

That’s an awesome update nearly full on support to stay cold - I expect stronger blocking in the 12z then - and still a good METO long range. If the block stays strong the low could still hit the U.K. then be moved away as the ridge opens back up behind it - hopecast but possible. 

[syed2878]

44 minutes ago, Johnp said:

Who is Mark Vogen?

Mark Vogen is the brother of James Madden

[syed2878]

Just before I started typing this, I know models not yet have handle on things where we go next week. Just out of interest. Just had the Met Office email new release and they are still talking of disruptive snow for next week. No mention yet of any breakdowns

[Tamara]

6 minutes ago, RainAllNight said:

It sounds as though you don't think we need to be worried about these ensemble means. I'd be thrilled if you were right!

No. In a nutshell. There is such a wide envelope within those means, and, as outlined the overwhelming suspicion that the jet stream will keep tending to align to send too much polar jet energy on a flat eastward path, that the best that can be said is that assessment of these means should sensibly be incremental day on day. This, much rather than the folly of instant face value extrapolations. Extended means are especially volatile, over smoothed, and subject to considerable further much more detailed evolution than they are within much more traditional zonal winter patterns.

[snowking]

37 minutes ago, Metwatch said:

Cotswolds did very well as well, approaching a foot in some localised spots.

Thread here:

 

The highlight to me were the incredible snowfall rates below. I remember the M6 between B'ham and Telford seeing some issues as well, although missing out here, millions still saw snow which is impressive given it was more of a disturbance rather than a proper frontal low snowmaker.

 

Just to back this up further, in my tiny part of Hertfordshire we had pushing on for 4 inches of snow from this event too - again just a further emphasis on ignoring precipitation forecasts at such range

[winterof79]

To be fair Mogreps i see are only out to Friday latest.Gefs don't uptick until after Friday

Edited January 11 by winterof79

[Kreftysoton]

6 minutes ago, syed2878 said:

Just before I started typing this, I know models not yet have handle on things where we go next week. Just out of interest. Just had the Met Office email new release and they are still talking of disruptive snow for next week. No mention yet of any breakdowns

The only thing they mention at the very end of the update is milder conditions returning at the weekend.  But we knew that i guess.

[AdrianHull]

21 minutes ago, MATTWOLVES 3 said:

I wished I wouldn't have said anything about the met insider information now

Let's be honest here if it's solid there may be a little alteration too the 1st part of the update.. but I very much doubt the 2nd part would be altered at all! Not unless the likes of Glosea have had a massive climbdown overnight.

And keep in mind how often have we had people in the past say they've got a friend at Dominoes who knows a council figure for the gritting service, and they've been told to stock up big time on grit this year

And mogreps does look cold out till next weekend and let's be honest so much is subject to change at this range as we've seen with the models over the last several days!

But I tell you what if this bloke is lying he's being unfollowed

@Tamara brilliant as ever and many thanks..I just don't know what I'd do without you

And what's the worst that can happen? Met office announce a barrlet starting on the 22nd... But on the positive side your name will be up in lights as as we would declare this day..... Matt Wolves Day!!!!! 

In all seriousness mate keep being you. You're an absolute breath of fresh air on here

[Rocheydub]

Tamara is the Nigella Lawson of Netweather…

[phil nw.]

Forgive me for the number of images in this post but i thought i would try to give my views on the coming 10 days or so.It's just an overall picture so no micro details just how it looks like the pattern might change-- with supporting data.

To begin i think we can say with some certainty the cold will deepen from Sunday as the Arctic air arrives from the north.We will have to keep an eye on the small low development around Iceland shown around day 4 and how that interacts with the general cold flow across us by then.But after all said and done modeling shows the cold gets to the south coast by Monday.

The other main point is the probable Atlantic approach later next week modeled on the UK T144hrs model.

Just to show that this is very much still on the table but as already been said nothing is certain at that range but to give an idea. of what is likely to come.

Now looking at the combined 850hPa ensemble graph

Cold this coming week but no denying there appears to be a trend upwards beyond .

This, shall i say less cold period, has been spoken about as the mjo enters a warmer phase before forecasted to move into a more favourable area for a return to blocking later.

Looking above at the Stratosphere the spv is currently expected to split into 2 centres up to mid-level in the coming few days before reforming in week 2.We can see these 2 centres over Siberia and Canada ,which enables the current Greenland area ridging of heights

These from gfs latest and yesterdays ecm both showing the same trend.

 

 

As can be seen the gfs images are a top to bottom profile and show what Amy Butler called the pair of trousers on the split image.The Ecm image is for 100hPa level,.Both sets do show the vortex reforming which seem to imprint down to our level.This would support the upwards trend in temperatures with a probably return of the westerlies at least for a short while.

The change towards showing on the day 10 ensemble 500hPa mean anomalies.

The pattern moving north as heights over the pole start to drain away.

So the hope is that in the next week or so we will see some snow either from minor disturbances or a battleground event from the south west which may become the main feature as it fights it's way up the country as a mild pattern tries to take over.The uncertainty is how far north this will establish and of course for how long.

Plenty of interest going forward i reckon. 

 

 

[Battleground Snow]

ECM 06z mean has trended the low slightly north.

This is going to be a long 6 days watching this

[winterof79]

Potential for more persistent snow through Tuesday in the northwest.

Widespread frosts continue by night with wintry showers from the northwest between further potential pulses of snow as weather fronts move in from the west

 

Not sleet or rain 

Edited January 11 by winterof79

[Cold Winter Night]

13 minutes ago, Tamara said:

References, as ever, crop up to x+y= responses to MJO phases in isolation. Again, to keep reiterating, tropical AND extra tropical wind-flow has to be assessed in respect of synoptic responses. There is no linear single interaction/response between the tropics and extra tropics without looking at directional flux of propagation of wind-flow as well, at this time of year, considering the interactions between the troposphere as a whole and the polar field.

Eastward moving tropical convection waves (MJO) at high amplitude and set against very high +ve inertia within the aggregate global wind-flow budget is going to retain greater amplification tendency than a situation where angular momentum and angular momentum tendency are both suppressed. In this sense, and taking the present scenario where the MJO is moving through the so called "La Nina response phases" of the Maritime continent, it is not as simple as equating this to increased polar jet+ Atlantic westerly forcing = mobile +NAO pattern and breakdown of blocking patterns.

The more extended period is fraught with so many pitfalls for NWP that I would genuinely stop trying to second guess the outlook for the last third of January. It makes sense that the Canadian lobe of the polar vortex will send energy towards the Atlantic but based on both the modelling within the polar field, which is highly unstable, and so much latent +AAM inertia within the aggregate wind-flow budget and then in addition to all that  - another very sizeable push of inertia and momentum between the tropics and extra tropics during the period under consideration;  there are so many hurdles for NWP to handle that extended ensemble data is next to rudderless at this time.

This assessment is intended to be neutral in respect of the overall diagnostic - but it happens to be one that continues to keep cold blocked patterns in the ascendancy for N/NW Europe and tendency for the white water rafting within the sub tropical jet stream to be adjusted upwards within modelling suites day on dy. That doesn't inextricably mean another 1947 redux, but probabilities do suggest that attempted Atlantic breakdowns will be attritional and prone to be shorter lived, if they occur, rather than any wholesale mobile pattern change.

Increased westerly mobility has higher probability for more southern parts of Europe - overall.

Thank you for your very insightful posts as always.
I can imagine it must be refreshing for you for once not to be forced by the diagnostic to go against the cold preference in here...

What I do wonder about is why apparently the NWP in the extended is so rudderless, as it seems to generally ignore that retention and renewed push of +AAM. With your explanation of the wind flow budget in mind I would expect a very large spread later on, but this morning's EPS had only a handful of members that retain heights in more Northerly latitudes, the ensemble even seems to converge on that +NAO outcome that is the polar opposite (quite literally) of a +AAM response. EPS even more so than GEFS, I must say.

Considering all this, it seems like we might have to brace ourselves for some model output surprises over the coming week. A highly interesting battle between GSDM and NWP.

[MJB]

Just now, winterof79 said:

Potential for more persistent snow through Tuesday in the northwest.

Widespread frosts continue by night with wintry showers from the northwest between further potential pulses of snow as weather fronts move in from the west

And potentially through the week until it warms up next week, looking at the charts