Model Output Discussion - Spring Has Sprung

[Chesil View]

Looks like a long drawn out process to get to anything cold. Even if the ecm is on the money. We would still be waiting for that UK high to progress to Scandinavia or retrogress to Greenland /Iceland.

Not impossible given the likely ssw but wait and see.

[WYorksWeather]

Tell you what, the GFS ensemble is sticking to its guns on the 00z. Definite tendency now for something colder post 22nd. It has been a while since we've seen any possibility for the mean to get down to -5C or below.

It is of course outside the reliable, and did not have support from ECM at all last night, so still watching and waiting for now. I imagine confidence will increase once the SSW has occurred.

[mulzy]

EPS day 10 mean.  Oh dear - pretty flat.  We are now looking outside the 10 day range for anything cold, potentially 15+ days. Hope the SSW can help us out but as for now looking pretty bleak.

[AO-]

Good Morning,

A quick glance at the charts shows that we can almost write this winter off. Despite all the potential, the delivery failed really. I would like to give credit to the posters that put their heads out in discussing the background drivers. It is really informative even though perhaps not always spot on. Thank you for that. 

 

Here is the EPS of this morning. Not really promising I suppose. Above average, but fortunately not very wet. A serious downgrade since two days ago.

 

Edited February 12 by AO-

[bluearmy]

 Rain All Nightcertainly looks that way 

all the ens suites have a ridge trough profile for the back end of the month. We don’t seem able to get there sooner. That could be strat related too but I’ve lost the will to analyse it.  In general it looks like I posted the other day where the mid levels split properly and the upper levels don’t. The split is readily put back together again which means the Atlantic doesn’t quieten.

the promising week 2 arctic profile on many op runs over the past week has failed to materialise. 

going back to the back end of the month - it’s the end of feb. As far as the prospects of a decent non transitional snowfall is concerned, it would be a struggle - maybe 20% chance that cold enough 850’s involved and then you need to throw a double six! 

 

 

[RJBingham]

Frost free Feb

 

[Mike Poole]

ECM clusters T192-T240:

Cluster 2 and 5 have the ridge in the Atlantic west of the UK, cluster 5 a bit pathetic really as it only has 2 members.  Block’s not up to much on clusters 3 or 4 and cluster 1 it remains mid-latitudes during this timeframe.

T264+:

Clusters 3 and 4 develop a strong block over Greenland, although on cluster 4 it looks to be weakening at day 15.  Both are well orientated.  Cluster 1 and 2 have more of a ridge in the Atlantic, but both pull in air from the north by day 15.  So, again, in this timeframe, there is potential, not sure if it is related to the SSW, but it will need to get its skates on if it is to turn into anything meaningful. 

[ANYWEATHER]

From a purely personal aspect ,I would love the day ten ecm to verify. I don't want any deep cold ,rain ,snow ,gales ,drizzle , dark clouds ,sleet ,freezing rain, wind chill or anything that resembles what this filthy winter has delivered to us for the past three months......! That ecm chart ,would delicious, clear starry frosty nights ,but ,pleasantly warm days in the sunshine. Strong Diurnal temperatures given the time of year. If I think of a Spring chart ,this would be the one......☺

[Purga]

Both GFS & ECM ENS indicating a cool down towards the end of the month. Can & probably will change of course & it always seems to be mañana..

[Gowon]

Winter 23/24 the biggest tease ever?

[TEITS]

 Gowon Even i'm ready to throw in the towel and seek warmth in the model output rather than cold.

The output this morning is just typical of this winter so far. The 12Z ECM last night gave a glimmer of hope which has quickly faded in the following run. Now the only sign of any cold is the last week of Feb but at the moment that looks more like a cool NW,ly than a bitter N/E,ly.

This winter has been very strange. The model output has been inconsistent, poor ensembles, unsuccessful teleconnection predictions, Met O have been predicting cold N/E,lys since mid Jan!, seasonal and longer range models have been useless.

Obviously something else is causing all these failed predictions. Problem is finding the cause can be just as difficult as making successful predictions. You cannot make future successful predictions until you understand the cause.

I'm now beginning to think that for the UK to have cold spells like the good old days we are going to need a significant event to occur. Like the gulf stream suddenly shutting down or a massive volcanic eruption throwing huge amounts of Sulfur dioxide, A nuclear war, asteroid hitting the earth.

Worryingly the nuclear war option is probably the most likely!

[northwestsnow]

ENS showing a cooling down just in time for Spring.

I'm no nostradamus but it's a hallmark of a rubbish winter..

[Penicuikblizzard]

 Gowon had all the drivers and telecommunications supposedly but just goes to show you cannot really rely on them either. The weather will do what it wants Mother Nature!

[northwestsnow]

 TEITS agreed.

I posted on the post mortem thread,a tipping point has been reached for me.

The rare times we do see Northern Blocking take hold  it simply is no match for the Atlantic and gets blown away rapidly.Perhaps we are seeing CC related warm Atlantic ssts taking over ?

I've given up on eps etc,sick to death  of reading eps look amazing at day 15 to see as day 0 counts down we get mild south westerlies,it happens every single Winter.

Fair play to the hard-core coldies sticking it out.

 

Edited February 12 by northwestsnow

[Met4Cast]

41 minutes ago, TEITS said:

The output this morning is just typical of this winter so far. The 12Z ECM last night gave a glimmer of hope which has quickly faded in the following run. Now the only sign of any cold is the last week of Feb but at the moment that looks more like a cool NW,ly than a bitter N/E,ly.

This winter has been very strange. The model output has been inconsistent, poor ensembles, unsuccessful teleconnection predictions, Met O have been predicting cold N/E,lys since mid Jan!, seasonal and longer range models have been useless.

Obviously something else is causing all these failed predictions. Problem is finding the cause can be just as difficult as making successful predictions. You cannot make future successful predictions until you understand the cause.

Indeed, no surprise to me that modelling hasn't continued with the build of heights northwards yesterdays UKMO/ECM signalled. I do think the GFS is being too progressive with the Atlantic still though & suspect we'll end up closer to a UK high, this mornings ECM probably a good fit. 

I think any amplification could come towards the end of the month/into early May but unlikely to see anything of interest re: proper cold/snow before then. It has been a very odd winter, the MetO have done rather poorly with the long-term forecasts. The SSW remains the wildcard & partly the reason there's some hope towards the end of Feb, ensembles certainly show a cooling trend albeit mostly from a Scandi trough again rather than any substantial blocking patterns. 

Very odd year.

[Lukesluckybunch]

Very frustrating once more..last night's half decent ecm again disappears overnight

[Ali1977]

With the GEFS and EPS means looking good later Feb, and the latest op -  think Feb 24th is a good point to aim for anything remotely winter like - hopefully it happens and doesn’t slip Anymore to the right!! 

[Jayces]

 TEITS  Let's hope for a less drastic option than that last one to get some of the white stuff, can't imagine many rushing here to celebrating copious amounts of the 'S' word during a nuclear winter!

On a more serious note, I'm sure there will be lots of post Winter analysis, but one thing I'm personally wondering as our changing climate has been mentioned is do the computer models get regular updates with regard to how they calculate their runs once they've been initialized?

For example, every year we measure the Atlantic SST's, and they change each year but are trending up, is that sort of data adjusted in the computer models annually or do they have a set of historical data they refer to that hasn't been changed for years?

Obviously I've no idea how they work, maybe this is a starting parameter they enter so no need to update them?

[feb1991blizzard]

Make of this what you will. SPV looking stretched  split more at the top now than the bottom!

     

Edited February 12 by feb1991blizzard

[Dennis]

NOAA from 19th

[Cambrian]

Variations on a theme from the last couple of runs from the ECM op between days 6 and 8, yesterday’s 12z on the right, with a welcome high pressure building in the vicinity of the UK and Ireland.  

  

The variation is toward the north of that in how cleanly the linkup with the polar high separates the Canadian and Eurasian lobes of the PV. 

It’s supported by the 0z ECM ensemble mean as a stepping stone between where we are over the next few days and the setup for the end of the month, day 4, 8 and 14. It’s a nice evolution.

  

Something like this happening is clearly on the cards, to get from here at day 4 on the 0z GEFS to where we are at day 12 (a couple of days quicker than ECM).

The extent and nature of the split of the tPV is clearly still to be pinned down, but strong indications that its machinations will switch the Northern Hemisphere profile from lateral to longitudinal. 

Reversal of the Barents / Kara ridge to a trough, ridging up through Greenland all the way up through the pole so that the Arctic cold is split, cold air sweeping south over both North America and northwest Europe…

  

…plenty of interesting variations on this theme likely to become available as the season has finally managed a 3 lobe PV pattern with a favourable 2-way split of the cold air, with the strong Greenland ridge, and the East Asian and North American lobes showing signs of linking up.

The interest for me is not all about hanging on in there for at least some prospect of seeing some wintry weather to round off the winter.

The end of February, beginning of March is often cold, even in years with a strongly coupled PV, so I’m really interested in how the troposphere plays out the final throes of this season characterised by a phenomenally weak stratospheric PV. 

[Penrith Snow]

When considering the possibility of cold weather in late February have a look at the MetO 120 hour fax chart.

The 528dam line (often referred to as the low level snow line) stretches from Newfoundland up to Southern Greenland, through Central Iceland across to Northern Norway, down through Finland then south through Poland towards the Black Sea.

Everywhere south and west of this line is not going to see any low level snow, that represents 85% of the Atlantic/European sector!

Such an expanse of mild air and northwards location of the 528dam line is normally found after late March at the earliest, normally you would see the line across mid or low latitudes in at least one area of Europe or the Atlantic.

Even by modern standards the extent of mild air in the European/Atlantic area of the globe is as remarkable as it is depressing.

Andy

[Downburst]

 Jayces It' a great point. My immediate thought is that the data collected is just that data, so a number from an observation lets say of temperature is a given, despite the fact that it's lets say 1.5 C high compared to climate. So I don't believe the medium range models are struggling with background changes. However the models are not perfect and there are many built in difficulties https://confluence.ecmwf.int/display/FCST/Known+IFS+forecasting+issues and perhaps for instance underestimating urban heat etc as one example will be exasperated. 

[Rain All Night]

15 hours ago, Rain All Night said:

12z deterministic runs, Mon 12th to Sun 18th (day 7)

I really don't fancy the ARPEGE's version of our little late-week low; ECM's take on it is not hugely dissimilar.

Miserly old GFS has recently been grooming its callow sidekick ICON to join it in showing the most miserable possible outcomes, and here they broadly agree that heights shall not pass to our north. For now, the other models ignore their dissent.

GEM, JMA and CMA (perhaps not exactly the holy trinity of models) have all gone back to the idea of a Scandi high of sorts.

12z ensemble means, Mon 12th to Mon 26th (day 15)

Hooray, the full ECM ensemble is coming out at a reasonable speed again.

ECM seems willing to give us a fair few Atlantic-free days from 17th Feb onwards, the other two models preferring just three or four days max by the looks of it.

The tease of cold troughing to our northeast is still making an appearance, from around 24th Feb. But if this does transpire, then it may be that high pressure to our southwest will be waiting in the wings to keep any cold air flows away from us...

Bonus

2024's second brief and shallow dip below zero for the zonal mean zonal winds at 10hPa looks likely for around 19th February.

0z/6z deterministic runs, Mon 12th to Mon 19th (day 7)

Looks as though the GFS had it right again about those 'green' heights to our north.

0z/6z ensemble means, Mon 12th to Tue 27th (day 15)

The Scandi trough signal is still alive and kicking this morning.

Edited February 12 by Rain All Night

[damianslaw]

 Penrith Snow Its an observation others have made this winter, the extent of heights to our south positioned at more northerly lattitudes than usual it seems.. the 'iberian high'... the extensive warmth from last summer/autumn a possible reason, but it has thwarted the colder air advecting south.

Looking at the week ahead the models yet again show heights to our south being the key force.

We may see a change post any SSW should that verify..