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

[ANYWEATHER]

9 minutes ago, TwisterGirl81 said:

Jeeez this would be very destructive 80-90+ mph gusts inland, surely historic if it does verify and keep track and intensity 

Nope, January 2nd 1976.....

[Chesil View]

18 minutes ago, Catacol said:

For those looking further out, JMA monthly published yesterday for February.

UK, as usual on this one, at 10 o clock.

Otherwise the current situation is not what many on here would have hoped for. This GFS for tomorrow screams all kinds of wintry wonders:

but closer examination shows that much of central and southern UK is stuck in a col, neither fed by the strongest and coldest winds from the N and/or NE nor quite in line for the channel runner. There is a day or so to go for surprises to turn up, and as we speak Scotland is getting pasted....but the snow hungry majority in the south are left gasping. Feels like rolling a double 1 and damnably unfortunate.

Then comes week 2. 22-29 Jan approx was always flagged as a week of greatest concern because the impacts of lowering momentum would be greatest and the need to gave got a block cemented in a good place would be highest. But that double 1 effect may be about to land again. (is that like rolling 4 x 1s?!) The strat splits tomorrow

and the zonal mean is much below average, even close to a technical (if very short lived) SSW

- and we could be excused for thinking that there is little better context for ongoing northerly blocking. But look how steep the recovery is, and with little to no model disagreement. Back to average in a flash, and GFS largely puts the vortex back together again by the end of the weekend.

So - what's happening?

Factors leaning towards a cold and blocked outlook have had to work pretty hard to get our blocking pattern in place. Even with a favourable pulse of momentum, a good GWO orbit, and lagged impacts of an amplified MFO through the west pacific we have not quite got the block in place. Meanwhile, as soon as those signals fade into a period when it was well noted that things would get less automatically "good" for winter, we get a collapse of the pattern that is on the crazy side of fast. We go from the good chart at the top of this post to this within 4 days:

No obvious lag here for the flatter MJO phases!! And a reforming vortex has helped support an atlantic pattern in double quick time. It is almost as though the wax wane nature of the atmosphere has been placed on a hill. To get to a blocked phase we have to sprint up the hill on our bike, in first gear, legs pumping and burning once at the top. But then to return to the starting point it is an easy cruise downhill, hands off the handlebars, freewheeling.

Maybe this is CC in action. Or maybe it is just a reflection of some very poor luck for the coming week and the one after. I don't know. I guess in the end, other than to take the learning from it, I don't really care. It has never been easy to get snow to this country and 1988 to 2008 was a 20 year run of misery punctuated by a couple of good moments. Hunting those rare major snowfalls would be no fun at all if they came every year.....but it would be good if the fates could allow us 1 in 5!!

This winter is not done. I read some guff on this thread that I find annoying, folk announcing the default return of a period of westerlies as though there is something wise and significant in doing so. Saying the UK will usually have westerlies and that the best way of approaching UK winter weather forecasting is to say "westerly" each time because you will usually be correct is both lazy and daft. I don't put my money on Ronnie O'Sullivan to win the snooker each time "because he usually does." I do it because I analyse the context and decide it is the most likely outcome....and I might still put £10 on a young outsider with half a chance of making it based on analysis and form, as per Luke Littler in the Darts. If Ronnie is ill the week before Sheffield I probably don't back him at all, despite the past run of success!

And this is where we are right now. January 15, half way through winter. We had a decent start, a disappointing Xmas/NY and now sit in 4 days of frigid air but without widespread snow forecast. Bugger. Westerlies to return for a while. But the analysis doesn't change, and the weighted approach to appropriate forecasting remains. The next momentum cycle is underway, signalled by rising frictional torque as of a couple of days ago. The MJO will be back in the west pacific pretty quickly looking at model forecasts, and while the vortex returns to average it doesnt appear to launch itself into an above average phase. Read Tamara's work rather than mine on this - she expresses the technical aspects of wind flow much better than anyone else on here....but in essence we are set to have more wave action return, a meridional pattern embed and poleward flux that should bring blocking back to the table quite quickly. I haven't seen a seasonal do anything other than go with a negative AO for February and the combination of high momentum and a favourable MJO in a Nino year will bring things back. I had said 3-5 days of atlantic westerlies. That was based on the cold hanging on until Sunday as I had it down as a cold week....but it appears the cold is fading faster than we might reasonably have expected....so it pushes longer. I do think by the end of week 2, that's somewhere around 26/26/28 Jan, we will have a more favourable context back on the table....or at least sitting on the hot plate waiting to be served.

Winter hunting in the UK has never been easy. C'est la vie. But we continue to look, and search, and roll those dice despite the fact that 80-90% of the time they don't give us what we seek.

 

 Thank you Catacol for an honest and informed post about the here and now and also how things can pan out going forward.

In our mainly westerly driven climate regime it is incredibly difficult to get widespread snowy synoptics to affect the UK even when everything appears in our favour. With just tens of miles being the difference between a foot of snow and foot of nothing. Southern England this coming week being a prime example.

We are very lucky to have the likes of yourself. Tamara and others keeping an eye on global background developments seeing as they underpin every broadscale pattern that affects us. 

 

[February1978]

2 minutes ago, kold weather said:

Man that front is close to the south coast, or even on the south coast on Wednesday on the 12z runs.

Honestly its well within the margin of error still. I recall a similar rain event which progged to only brush the south coast but ended up producing a pretty signifncant rain event back in December. 

Thats not to say I think its the likely outcome, I think its not. But its still close enough call that it will need very close watching right through to Wednesday, we are talking literally 10-20 miles making the difference between basically nothing and 3-5cms into southern coastal counties. 

I agree with this, 50 miles is not far in NWP, would make a massive difference to us. I've seen rain extend quite a bit further north than forecast in this type of set-up before.

That said, there is pretty good consensus between the models for it to stay at coast or south.

[pinball wizard]

10 minutes ago, TwisterGirl81 said:

Jeeez this would be very destructive 80-90+ mph gusts inland, surely historic if it does verify and keep track and intensity 

It'll probably end up over the Pyrenees by the weekend...

[ANYWEATHER]

9 minutes ago, pinball wizard said:

It'll probably end up over the Pyrenees by the weekend...

Nope......

[Battleground Snow]

On the end of the gfs run we are still being plagued by euro heights, but pressure is increasing to the north east, while starting to weaken to our south.

Will be keeping an eye on the ecm eps over the coming runs to see if this solution can gain any traction.

 

[Mcconnor8]

Are perturbations 6, 11 or 27 really too much to ask for? 

[Troubleatmill]

4 minutes ago, Mcconnor8 said:

Are perturbations 6, 11 or 27 really too much to ask for? 

Not sure what you are looking at buddy, the UK looks mostly dry on those three ens members?

[saintkip]

1 minute ago, Troubleatmill said:

Not sure what you are looking at buddy, the UK looks mostly dry on those three ens members?

Look at his location and look where the snow is, pretty obvious my friend 

[Eagle Eye]

When I can be bothered (I have a great work ethic), I'll do my own update long-term but for now. The Pacific trough and Alaskan ridge switch over and in the context of the situation, that's just mild down the line for us because essentially it's just which one is stronger is on the day not which one we've got. Once the Pacific trough goes properly, then we can start to get interested again. Looking like early February is our best chance of it going for a whole and the Alaskan ridge taking over. 

Edited January 15 by Eagle Eye

[The Enforcer]

1 hour ago, kold weather said:

Man that front is close to the south coast, or even on the south coast on Wednesday on the 12z runs.

Honestly its well within the margin of error still. I recall a similar rain event which progged to only brush the south coast but ended up producing a pretty signifncant rain event back in December. 

Thats not to say I think its the likely outcome, I think its not. But its still close enough call that it will need very close watching right through to Wednesday, we are talking literally 10-20 miles making the difference between basically nothing and 3-5cms into southern coastal counties. 

I remember that one, forecast at T+06z: dry; actual: hours of heavy rain.

There has been more than one instance where rain was not supposed to reach my location in the most recent forecast, but ended up as far north as Manchester. There was one where an upper front popped up at T+0. Not sure why models couldn't detect it before then? I recall another band of rain that was supposed to skim South Wales and instead covered the entirety of Wales in heavy rain, all change at T+0. I am sure these examples only stick in the mind, because they are so unbelievably wrong at such short range and when there is zero or negligible departure short range it is 'no news', so that probably remains the majority. However, suffice to say that there is sufficient evidence to merit a 'watching brief' up to T+0.

Edited January 15 by The Enforcer

[KTtom]

1 hour ago, EML Network said:

Why isn't anyone talking about this >> ??









If it comes to pass as modelled, this country will be on it's knee's !

Sods law, when you want a low to track further south into France, it'll stay put! Shows 90 + for my location

[Ali1977]

This will stir things up - a cracking Feb on the way hopefully - and March. As per the long range METO really ️

[kold weather]

5 minutes ago, The Enforcer said:

I remember that one, forecast at T+06z: dry; actual: hours of heavy rain.

There has been more than one instance where rain was not supposed to reach my location in the most recent forecast, but ended up as far north as Manchester. There was one where an upper front popped up at T+0. Not sure why models couldn't detect it before then? I recall another band of rain that was supposed to skim South Wales and instead covered the whole of the Wales in heavy rain, all change at T+0. I am sure these examples only stick in the mind, because they are so unbelievably wrong at such short range and when there is zero or negligible departure short range it is 'no news', so that probably remains the majority. However, suffice to say that there is sufficient evidence to merit a 'watching brief' up to T+0.

I think the other thing that warrants it is there are ensemble members and the occasional operational model still making it into at least parts of the south. Interestingly the ARPEGE ensembles have swung northwards considerably in its most recent run.

Its a classic low chance but high impact scenario, and I'm willing to bet the met office already have a yellow/amber warning ready made should things seem to be north of where currently expectations are.

Lets just say I wouldn't be surprised if there is a small line of 5-10cms on the ground by the end of Wednesday. I also wouldn't be surprised if the front never leaves the French coastline. Both and everything inbetween is still on the table.

[sunnijim]

5 minutes ago, KTtom said:

Sods law, when you want a low to track further south into France, it'll stay put! Shows 90 + for my location

I think we started like this in October before the Storm corrected South on future runs and effected Channel Isles and Northern France.

Depends on any belt of high pressure over the continent as to Sothward shifts.

GEM and ECM not interested so still an outlier solution anyway.

 

[Troubleatmill]

The graph ensembles for the 12z GEFS don't paint a pretty picture, however the postage stamps are starting to show the next blocking ideas

[Troubleatmill]

31 minutes ago, saintkip said:

Look at his location and look where the snow is, pretty obvious my friend 

I know mate, it was tongue in cheek #regional discussion buddy

[February1978]

1 minute ago, kold weather said:

I think the other thing that warrants it is there are ensemble members and the occasional operational model still making it into at least parts of the south. Interestingly the ARPEGE ensembles have swung northwards considerably in its most recent run.

Its a classic low chance but high impact scenario, and I'm willing to bet the met office already have a yellow/amber warning ready made should things seem to be north of where currently expectations are.

Lets just say I wouldn't be surprised if there is a small line of 5-10cms on the ground by the end of Wednesday. I also wouldn't be surprised if the front never leaves the French coastline. Both and everything inbetween is still on the table.

ECM keeps it away from the south coast on 12z (except Cornwall) on this one. 

But watching brief until it happens as you and saintkip say........

[Duane S.]

I'm going to go very simplistic here...

I've been wondering these past few days, how much weighting there is in the models with regards to the MJO and Enso state.

As in, MJO P6 + El Nino = (essentially) zonal.

If they have much less weighting on the transportation / direction of heat flux (very favourable from what I can see) , then I wonder if we could expect a very abrupt flip in the mid - long range output in the coming days

[Battleground Snow]

17 minutes ago, Duane S. said:

I'm going to go very simplistic here...

I've been wondering these past few days, how much weighting there is in the models with regards to the MJO and Enso state.

As in, MJO P6 + El Nino = (essentially) zonal.

If they have much less weighting on the transportation / direction of heat flux (very favourable from what I can see) , then I wonder if we could expect a very abrupt flip in the mid - long range output in the coming days

I'm just starting to see some signs of life in the extended,

Would be nice to accelerate towards that solution, ecm does get to phase 7 faster.... So extended EPS may offer some further hope tonight.

Control, attached, alongside a couple of the best gefs members, also attached is the mean anamoly.

Let the next chase commence!

Edited January 15 by Battleground Snow

[Scott Ingham]

14 minutes ago, Battleground Snow said:

I'm just starting to see some signs of life in the extended,

Would be nice to accelerate towards that solution, ecm does get to phase 7 faster.... So extended EPS may offer some further hope tonight.

Control, attached, alongside couple of the best gefs members, also attached is the mean anamoly.

Let the next chase commence!

Look at that date mate 29th for the change! Surely not 2 in a row! Fits in perfectly with retrogression into the back end of the first week of Feb! 

[Fozfoster]

6 minutes ago, Scott Ingham said:

Look at that date mate 29th for the change! Surely not 2 in a row! Fits in perfectly with retrogression into the back end of the first week of Feb! 

Yeah, I agree, there’s nothing happening till the end of the month earliest(cold persuasion)

Edited January 15 by Fozfoster

[Marting]

18 minutes ago, Battleground Snow said:

I'm just starting to see some signs of life in the extended,

Would be nice to accelerate towards that solution, ecm does get to phase 7 faster.... So extended EPS may offer some further hope tonight.

Control, attached, alongside a couple of the best gefs members, also attached is the mean anamoly.

Let the next chase commence!

Yes, agree the signs building for the scandi ish high pressure in 2 weeks time. A trend to watch in the Gefs

[Battleground Snow]

6 minutes ago, Scott Ingham said:

Look at that date mate 29th for the change! Surely not 2 in a row! Fits in perfectly with retrogression into the back end of the first week of Feb! 

I'm interested to see how the retrogression is going to try to shift the tpv away from Greenland as it looks like a beast ATM,

Perhaps some assistance via Atlantic wave breaks?

I'm flying out of the country late on the 28th so the 29th fits well for the next spell of cold weather

[Scott Ingham]

4 minutes ago, Fozfoster said:

Yeah, I agree, there’s nothing happening till the end of the month earliest(cold persuasion)

Yeah 100% this is sign posted by events in the Strat, a move into MJO phases supportive of mild Atlantic weather and ensembles rock solid from the 20th. It’s the following week that will be fun to watch as we see a much better Strat profile, an impending +EAMT event and the tropics quickly moving thunder storm activity into the west pacific. Do we go North East the retrogress or straight North West to Greenland. For me it’s North East then retrogression. Time for chase number 3 this year!

2 minutes ago, Battleground Snow said:

I'm interested to see how the retrogression is going to try to shift the tpv away from Greenland as it looks like a beast ATM,

Perhaps some assistance via Atlantic wave breaks?

I'm flying out of the country late on the 28th so the 29th fits well for the next spell of cold weather

A better start profile and movement into phase 7/8 of the MJO will take care of that quicker than you’d expect looking at the models (even though as you say it looks like a beast over Greenland)