Model output discussion - winter proper underway

[bluearmy]

8 hours ago, Bring Back1962-63 said:

Latest MJO and PNA Charts:

Most of the PNA ensemble members are going positive again towards the New Year, having been briefly negative for a few days. I think that this is bang in line with part of what @Tamaraand @Catacol were predicting in their recent posts towards the end of last week.This is what is starting to show up in the model output with fairly low pressure close to the Aleutians and a strong ridge through Alaska and into the Arctic - a classic +PNA signature. Any more on this will be beyond my pay grade!

 

The signal was becoming -PNA rather than +PNA as it retrogressed off the American coast. This negative phase is being truncated and lessened in magnitude by the modelling. Suspect this reflects the fact that the upper ridge will become cut off n of Alaska rather than a mean ridge from the Pacific. We seem to be headed for a holding position where most indicators are fairly neutral and not convinced what surface conditions are most likely for us as week 2 progresses. 

As indicated earlier this morning, the polar ridge looks likely to fail to work in our favour though there are evolutions that aren't off the table quite yet 

Edited December 21, 2017 by bluearmy

[Paul]

Some posts are getting dangerously close to being "winter's over" type ones this morning. Which on 21st Dec can't be model related.

Secondly, GP posted yesterday with an explanation of what's changed.
https://www.netweather.tv/forum/topic/88969-model-output-discussion-winter-proper-underway/?do=findComment&comment=3690236

 

[MR EXTREMES]

Unbelievable active Atlantic onslaught.

With transition between cool in the south to mild,

and cold to cool into Scotland.

Some extremely wet and some pretty potent winter storms with damaging winds.

There's very little wintry weather in the models out even into fi.

reminds me very much of winter 2014 which was Azores wobbling around to our SW in the Atlantic although suppressed.

Although winter 2014 was ok for the north.

It's amazing how quickly the vortex powers up.

I do now believe it will dominate through winter.

A near split vortex,

but not enough to allow ridges to get into favoured locations.

The jet will at times move further south but this to is mostly fired up for direct hit especially in the south.

Of course this might change but I really do see similar set up to 2014 winter.

Although just a month ago I did believe we might be luckier.

Although to see atleast some snowfall down here in the south made a change compared to the last 5 years.

Perhaps cyclone activity maybe confusing model outputs.

Over all very stormy but at least it's not boring.

And flooding is going to be a problem through the rest of this month.

[karyo]

I hear several people in the last couple of days mentioning cyclone activity confusing the MJO signal and the models in general.

I have just had a look at the Pacific satellite image and there are no cyclones to be seen. There was one around the Philippines a few days ago but surely this is still not impacting the models.

[feb1991blizzard]

35 minutes ago, bluearmy said:

The signal was becoming -PNA rather than +PNA as it retrogressed off the American coast. This negative phase is being truncated and lessened in magnitude by the modelling. Suspect this reflects the fact that the upper ridge will become cut off n of Alaska rather than a mean ridge from the Pacific. We seem to be headed for a holding position where most indicators are fairly neutral and not convinced what surface conditions are most likely for us as week 2 progresses. 

As indicated earlier this morning, the polar ridge looks likely to fail to work in our favour though there are evolutions that aren't off the table quite yet 

My guess is zonal for week 2 with snow confined to higher ground in N.England and Scotland but an improvement (albeit the tiniest one) on EPS with very very weak +anomalies over Greenland and Scandinavia suggesting perhaps a bit more potential for around week 3-4

[ANYWEATHER]

20 minutes ago, MR EXTREMES said:

Unbelievable active Atlantic onslaught.

With transition between cool in the south to mild,

and cold to cool into Scotland.

Some extremely wet and some pretty potent winter storms with damaging winds.

There's very little wintry weather in the models out even into fi.

reminds me very much of winter 2014 which was Azores wobbling around to our SW in the Atlantic although suppressed.

Although winter 2014 was ok for the north.

It's amazing how quickly the vortex powers up.

I do now believe it will dominate through winter.

A near split vortex,

but not enough to allow ridges to get into favoured locations.

The jet will at times move further south but this to is mostly fired up for direct hit especially in the south.

Of course this might change but I really do see similar set up to 2014 winter.

Although just a month ago I did believe we might be luckier.

Although to see atleast some snowfall down here in the south made a change compared to the last 5 years.

Perhaps cyclone activity maybe confusing model outputs.

Over all very stormy but at least it's not boring.

And flooding is going to be a problem through the rest of this month.

Hi good post but don't think I'm not picking here but using the word cool at this time of year is the wrong terminology. It's either very mild ,mild cold or very cold or freezing .You can have temperatures of ten Celsius in the south of the UK which seems it deams it mild but add the wind factor and it will feel cold not cool. Anyway we look to be entering a stormy spell of weather as you rightly said with spells of milder and colder weather from Christmas to the new year

[swfc]

1 hour ago, Severe Siberian icy blast said:

So if your so certain of a mild and wet January, and now Glacier point also saying a similar theme yesterday, why was in only a week maybe 2 at the most that him and others were posting very good reasoned out posts all pointing to our north east in the new year, very confident forecasts explaining why it looks nearer enough a dead cert???

This happens every year and it seems peeps never learn. 

Signals and teleconnections seem to be as fickle as anything else imho. 

Can you or glacier point explain what's suddenly gone wrong on what seems to be a chatostrophic scale?

Cheers 

Good post esp for new members who tend to get  hooked on these background signals and believe epic cold is a cert.Of course GP and the other guys only speak of back ground signals ete so it isn't a forecast as such.

[mulzy]

We have to be realistic and as been flagged for a while, unsettled weather (wet and windy and often mild) is now clearly signposted.  The 6-10 day 500Mb anomaly charts from both the GEFS and EPS illustrate this perfectly.

AS @Steve Murr has indicated, the strat forecasts are indeed dire.

 

Luckily, we are still early in winter but we can confidently write off the next 10-15 days.  As ever, way too much hope casting happening in here.  All in all, a very poor outlook if snow/cold/wintry weather is what you are after.

Edited December 21, 2017 by mulzy

[mulzy]

8 minutes ago, swfc said:

Good post esp for new members who tend to get  hooked on these background signals and believe epic cold is a cert.Of course GP and the other guys only speak of back ground signals ete so it isn't a forecast as such.

Background signals from teleconnects are flaky at best.  Sorry to say this but am also not a fan of analogues especially when the climate is changing so fast.

Stick to the NWP within 10 days and you will not be disappointed (even then you will be led up the garden path at times).  Rest is just conjecture...

Edited December 21, 2017 by mulzy

[Duane S.]

You miserable bunch this morning. Don't give up hope, nothing is set in stone regards early - mid January. Pret15 keeps the faith ?

 

[stewfox]

1 hour ago, Severe Siberian icy blast said:

So if your so certain of a mild and wet January, and now Glacier point also saying a similar theme yesterday, why was in only a week maybe 2 at the most that him and others were posting very good reasoned out posts all pointing to our north east in the new year, very confident forecasts explaining why it looks nearer enough a dead cert???

This happens every year and it seems peeps never learn. 

Signals and teleconnections seem to be as fickle as anything else imho. 

Can you or glacier point explain what's suddenly gone wrong on what seems to be a chatostrophic scale?

Cheers 

Noooooooo

Fundamental points of model discussion

Not even 1/3rd of the way through winter so all to play for

More runs need

More amplification needed

GFS trending cold will do so again and ECM will come on board. If it doesn't its a crap model

Look to T240 for things of beauty but they never verify of course

Never look out of the window keep your eyes down for GFS12z and GFS 18z

In May a full easterly will come along

[frosty ground]

1 hour ago, Severe Siberian icy blast said:

So if your so certain of a mild and wet January, and now Glacier point also saying a similar theme yesterday, why was in only a week maybe 2 at the most that him and others were posting very good reasoned out posts all pointing to our north east in the new year, very confident forecasts explaining why it looks nearer enough a dead cert???

This happens every year and it seems peeps never learn. 

Signals and teleconnections seem to be as fickle as anything else imho. 

Can you or glacier point explain what's suddenly gone wrong on what seems to be a chatostrophic scale?

Cheers 

Things change and they can change back or there could be another set of signals that show something in a few weeks time. Just another winter on NETW

[Timmytour]

2 hours ago, Broadmayne blizzard said:

 

For newbies another rule to take on board. nine out of ten of these 'promising' scenarios will fail to deliver widespread cold and snow.

 

Ain't that the truth.  Getting the cold and snow in for the UK is a bit like the chances of throwing three sixes with three dice.

The hope that some FI charts offer, or some teleconnections offer for the future, is no more than advising that one of the dice is certain to fall above average...ie 4,5 or 6.

It's a long way from here to assume it will come in as a 6 and the other two dice will duly oblige!

[Ali1977]

20 minutes ago, mulzy said:

We have to be realistic and as been flagged for a while, unsettled weather (wet and windy and often mild) is now clearly signposted.  The 6-10 day 500Mb anomaly charts from both the GEFS and EPS illustrate this perfectly.

AS @Steve Murr has indicated, the strat forecasts are indeed dire.

 

Luckily, we are still early in winter but we can confidently write off the next 10-15 days.  As ever, way too much hope casting happening in here.  All in all, a very poor outlook if snow/cold/wintry weather is what you are after.

This was posted earlier , does this not suggest a quick return to a strat slow down ?

Edited December 21, 2017 by Ali1977

[frosty ground]

18 minutes ago, mulzy said:

We have to be realistic and as been flagged for a while, unsettled weather (wet and windy and often mild) is now clearly signposted.  The 6-10 day 500Mb anomaly charts from both the GEFS and EPS illustrate this perfectly.

 

Luckily, we are still early in winter but we can confidently write off the next 10-15 days.  As ever, way too much hope casting happening in here.  All in all, a very poor outlook if snow/cold/wintry weather is what you are after.

That chart is from the GFS right? is it just the Operation run or is it the Full Ensemble Mean?

[feb1991blizzard]

The wave height charts on the ECM don't look too bad tbh.

[Chesil View]

Just now, s4lancia said:

You miserable bunch this morning. Don't give up hope, nothing is set in stone regards early - mid January. Pret15 keeps the faith ?

 

Nice one S4L I knew we could rely on you to find the new trendsetter. lol

[Singularity]

Those 10 hPa zonal mean charts are very sensitive to the movement of the vortex at the moment - the big rise occurs as it drifts across the pole having been displaced for some time; there's little or no strengthening of the circulation itself being indicated.

Only longer-range hints from GFS of further stratospheric warming of any note to come though. How much and how soon varies with reach run depending on how the Arctic blocking aligns itself and to what extent it connects with mid-high latitude features. Seemingly a bit of a jackpot situation there.

Somehow posted this early when pressing 'enter'? That's not normal!

 

Here we can see the observed atmospheric state still edging toward the transitory state that could lead onto a renewed rise,  but also clearly evident is the point at which GEFS decays out the Pacific MJO activity and the atmospheric state snaps back into a La Nina-like state. Shows just how close we've come; it would not have taken a lot more MJO amplification or duration to achieve the upward kick scenario with downstream amplification in useful places for us. It has been tense to watch us come closer and closer, only now reaching a point where a shortfall looks the more likely outcome.

The subsequent IO emergence of convective activity is probably being overdone by GEFS though, hence the GLAAM drop as well, so beyond a week's range I'm inclined to treat it's output with even more suspicion that usual.

Best chance we have later next week and a bit beyond is if the stratospheric forcing can tone down the westerlies sufficiently for the jet to dig further S into Europe, but the modelling currently favours this to happen in the middle of the N. Atlantic, which has the opposite effect on temperatures to what is desired by most on here.

After that, we're back to trying to modify the pattern toward allowing a well-placed Scandi high, as GP has been alluding to as the best bet for good results next month. Unless, that is, a major stratospheric warming comes about after all.

Edited December 21, 2017 by Singularity

[nick sussex]

Barring a few GEFS which survive the zonal onslaught the SS Save Christmas has now sent out an SOS!

The surface temps though dont look that mild , looking at De Bilt and given the set up which would mean northern parts of the UK would be colder there still could be some snow during Christmas week.

There are still differences in the medium term between the big 3 with how low pressure exits the ne USA and the speed of that .

So not great this morning but the jet still remains on a more southerly track upto T240 hrs and there’s always a chance of a surprise with that.

 

[NO LONGER POSTING]

Well the GFS 00z is a horror show for cold, the Atlantic express gets going and it will be hard to shut it down.. 

Its also a pretty common thing that this happens, well on recent winters anyway, but we shouldn't act all surprised by it, technically speaking winters in the UK are not cold given our latitude, you can thank the Atlantic for that. 

I'm not surprised in the slightest that we are entering a stormy period of weather, would winter in the UK even be winter if we didn't?

GFS is struggling though on anything storm wise and positions etc as per the norm, EMC also but not as stormy. 

GFS does tend to blow up low pressure systems then back track though, boxing day storm being one that was on the cards and now moved back. 

Watch this space but I think we need to see the cold diminish somewhat on the Eastern coast of the USA before we see anything of an improvement, that's one hell of a temperature gradient 

 

Even in the darkest of FI on the GFS it somehow manages a "winter plume" of likes in summer it would be a scorcher 

[mulzy]

9 minutes ago, frosty ground said:

That chart is from the GFS right? is it just the Operation run or is it the Full Ensemble Mean?

Just the operational.  The ensembles show a spike up too before returning to more normal values.

[Tim Bland]

35 minutes ago, mulzy said:

We have to be realistic and as been flagged for a while, unsettled weather (wet and windy and often mild) is now clearly signposted.  The 6-10 day 500Mb anomaly charts from both the GEFS and EPS illustrate this perfectly. Luckily, we are still early in winter but we can confidently write off the next 10-15 days.  As ever, way too much hope casting happening in here.  All in all, a very poor outlook if snow/cold/wintry weather is what you are after.

Lots of negativity this morning. It’s not a poor outlook it’s just average IMO. Not sure how anyone can say it’s a poor for the next 10-15 days if you like wintry weather. Large parts of the UK will see snow next week, perhaps some are being very IMBY ?

 

Edited December 21, 2017 by Tim Bland

[frosty ground]

6 minutes ago, mulzy said:

Just the operational.  The ensembles show a spike up too before returning to more normal values.

As the saying goes probably not the best idea taking one operation run at its word

Edited December 21, 2017 by frosty ground

[frosty ground]

8 minutes ago, nick sussex said:

Barring a few GEFS which survive the zonal onslaught the SS Save Christmas has now sent out an SOS!

The surface temps though dont look that mild , looking at De Bilt and given the set up which would mean northern parts of the UK would be colder there still could be some snow during Christmas week.

There are still differences in the medium term between the big 3 with how low pressure exits the ne USA and the speed of that .

So not great this morning but the jet still remains on a more southerly track upto T240 hrs and there’s always a chance of a surprise with that.

 

Yes the possibility of snow up here is real....

[mulzy]

2 minutes ago, Tim Bland said:

Lots of negativity this morning. It’s not a port outlook it’s just average IMO. Not sure how anyone can say it’s a poor outlook for the next 10-15 days if you like wintry weather. Large parts of the UK will see snow next week, perhaps some are being very IMBY ?

 

Northern hilly areas will see some snow - I would not call that "large parts of the UK".  

Those ECM snow depth charts are very misleading.  Treat with huge truckload of salt.