Model Output Discussion; into 2015

[Newberryone]

The GEFS 06z mean paints a very unsettled picture once the current anticyclonic spell ends in a day or so, it looks mild, wet and windy but with colder, clearer and showery incursions with snow on hills, especially northern UK and frosty nights during quieter interludes of which there will be some due to the pattern being for ridges to follow depressions continually. This winter is already a cut above the last one because of the current cold spell alone. The mean trends a little colder towards the end.

It's been a nice little cold spell with quite widespread frosts and crisp sunny days for many of us since Christmas so for me the impending change will be disappointing as the high slips away se.

There is no need for me to post any charts to underline the outlook for the next 10-14 days as this has already been well illustrated and explained by many other members today.

I think we all know a prolonged spell of blocking in favour of UK cold is not currently on the agenda so it is more a case of looking for any buckling of the jet which turns the flow more north westerly behind a passing low to the north.

The best we have showing in the reliable appears between T72hrs and T96hrs on the 06z GFS which brings more snow to the north,mainly higher up as the cold front passes through.

Another colder shot again likely a few days later-day 7- after a milder interlude but in all honesty the overall pattern is very strongly +AO/+NAO(low pressure to the north,high pressure to the south) so really it is just a bog standard typical UK changeable westerly set up for now.

It really is a case of gritting our teeth while we wait for some further changes,even if it is only more ridging upstream of the jet to give us a chance of a transient Arctic spell.

Down to each individual's interpretation of model output I can appreciate, but when you have one saying it's going to become very unsettled from early next week, while the other posters overall take on things is for it to become merely changeable, I can see how newbies might be somewhat confused.

Personally, I would right now lean more towards the idea of it being changeable rather than downright unsettled. Besides, heights over Iberia as well as a menacing Azores, look like ensuring the worst of the wind and rain is kept well to the northwest.

[offerman]

Problem is the Azores high is to strong and always riding toward us. If that could drift away westward or further south the the Icelandic low drifts down toward us that would help....

[IDO]

 PV ramped up a notch compared to the 06z at D8 on the GFS op:

 

12z:  06z: 

 

Not pretty.

 

 

[IDO]

It's still possible to get something out of those charts....

For the first one I'm getting a crocodile pushing a pram and for the second one a seal laughing as he throws the UK cold winter in the bin

:-)

 

Yes the PV is mobile as it has been all Winter so there is every chance in time it will move into a different place.

 

Then again at D16 op: 

Edited December 30, 2014 by i'm dreaming of...

[Team Jo]

Couple of posts moved into Ramps,could we keep to Model output discussion.......?

[sorepaw1]

Absolutely and it sort of reinforces my point in that every one of those famous winter cold spells stated, had they happened in the internet era, we would likely have had a fair idea they were coming from all the various background signals / drivers but not

necessarily from preceding trop charts.

As you say though, early days still and I'm sure we'd all take a mild next 3 weeks in order to get a cold spell come the end of

Jan.

As for snowless winters, much more common than not down here! :-)

apparently in 1947 farmers were told to expect a mild winter by weather experts this almost crippled Britain with the loss of dairy animals sheep etc .Just after the war too .These were very hard times. I remember my grandmother saying she was melting snow for cooking and washing as pipes had frozen.she said the weather was wet and windy before.the snow came.

[mountain shadow]

12z GFS old is zonal from start to finish. A few PM shots to keep the Northern hills and mountains covered. Some decent winter storms on the way, so it might be zonal but not boring, although those flooded and storm damaged last year might say different.

Unfortunately on this Op run, no sign of a High Latitude Block to bring any sustained cold spell.

[Mark Bayley]

In terms of sustained cold and snowfall, the 12z GFS is of course horrific with the PV dominating over Greenland. However, some transient snowfalls, especially with distance north, would occur, depending on track of those deep Atlantic lows (and amount of cold air flooding in behind them). Mostly average sums it up. Unfortunately i see no evidence of losing the low heights to our north till at least mid-month despite apparent warmings in the strat. Other factors, such as the MJO, remain unfavourable >

Some may start writing winter off, however, the last third of January onwards is still all to play for, should the strat play ball. 

Edited December 30, 2014 by Mark Bayley

[Jason M]

Yes the PV is mobile as it has been all Winter so there is every chance in time it will move into a different place.

 

Then again at D16 op: gfsnh-0-384 (2).png

How about this little beauty from day 10 of the GFSP.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=code&mode=0&mode3h=0&runpara=1&carte=1&runpara=1

Somebody def needs to tell that vortex it's in trouble!

I suppose if it does go bang in a few weeks though it might be rather dramatic and pretty good fun.

[IDO]

GEM makes more of the baby ridge next week and gives us some very mild uppers before returning to zonal:

 

cc

 

Not exactly what the Doctor ordered but a welcome relief; though unlikely to verify.

Edited December 30, 2014 by i'm dreaming of...

[dragan]

Looking at the models, yet again, i can see westerly winds prevailing, although there is a hint that things could get much milder indeed. No hint of cold unfortunately.

I can feel a mild January coming up with perhaps a colder late February/March. 

[bobbydog]

12z GFS old is zonal from start to finish. A few PM shots to keep the Northern hills and mountains covered. Some decent winter storms on the way, so it might be zonal but not boring, although those flooded and storm damaged last year might say different.Unfortunately on this Op run, no sign of a High Latitude Block to bring any sustained cold spell.

to be fair, there is a high latitude block. just that its on the wrong side of the pole. i'll take a couple of decent storms as a consolation!

thing is, we need to accept that the next couple of weeks will most likely be zonal - and get over it! what we need to concentrate on is looking for signs beyond this for changes to a colder scenario. obviously no guarantees but from a simplistic view, this 'lop-sided' hemispheric pattern doesn't look sustainable (to me anyway) for more than a couple of weeks. i do think this winter will deliver, just a bit later than we all thought

[karyo]

Decent warming where we want it on PGFS 30HPA.

http://max.nwstatic.co.uk/gfsimagesnew/gfs.20141230/12/222/npst30.png

Will it work its way down to 500H though?

Yes, that's an upgrade compared to previous runs. 

[jmatt81]

You can see how the stratosphere at 10hPa has shown a recent rise in temperature.

 

 

As for further down at 30 hPa not so much

 

[John Badrick]

Looking at the models, yet again, i can see westerly winds prevailing, although there is a hint that things could get much milder indeed. No hint of cold unfortunately.

I can feel a mild January coming up with perhaps a colder late February/March.

There is a hint things could lead to blocking (see strat thread for models)

This is a model thread, so do you have any models to back up your theory???

[dragan]

There is a hint things could lead to blocking (see strat thread for models)

This is a model thread, so do you have any models to back up your theory???

Yes there is the GFS and ECM models that back up my theory. There is more to blocking than just the strat, but like you said, thats for a different thread.

[TEITS]

Yes there is the GFS and ECM models that back up my theory. There is more to blocking than just the strat, but like you said, thats for a different thread.

+384 only takes us to the 15th Jan.

[Captain Shortwave]

There is a hint things could lead to blocking (see strat thread for models)

This is a model thread, so do you have any models to back up your theory???

Pretty much most of the output over the past 3 or 4 days. Yes there is warming going on in the stratosphere but as of yet it is not correlating to a favourable pattern change over our side of the pole.

Output at day 6

UKMO

GEM

GFS

Parallel

Blocking over Alaska but a westerly driven pattern over us with varying degrees of amplification.

 

Beyond this at day 8

GEM

GFS

Parallel

 

If anything by week 2 the Greenland/Canadian lobe intensifies and brings a zonal spell of weather to the UK

GFS mean

At this present time the output looks very zonal in nature with a strengthening jet across the Atlantic with winds generally from the west.

GFS ens further on favour the dominant lobe of the polar vortex to remain over Greenland.

Edited December 30, 2014 by Captain shortwave

[John Badrick]

Yes there is the GFS and ECM models that back up my theory. There is more to blocking than just the strat, but like you said, thats for a different thread.

So what about your cold late Feb/March prediction?? Can you explain why you think it won't be cold for the next 7/8 weeks and what models back this theory???

[johnholmes]

apparently in 1947 farmers were told to expect a mild winter by weather experts this almost crippled Britain with the loss of dairy animals sheep etc .Just after the war too .These were very hard times. I remember my grandmother saying she was melting snow for cooking and washing as pipes had frozen.she said the weather was wet and windy before.the snow came.

 

not sure where the predictions came from as Met only went 24 hours ahead, no such thing as a weather computer model in those days.

[John Badrick]

Pretty much most of the output over the past 3 or 4 days. Yes there is warming going on in the stratosphere but as of yet it is not correlating to a favourable pattern change over our side of the pole.

Output at day 6

UKMO

GEM

GFS

Parallel

Blocking over Alaska but a westerly driven pattern over us with varying degrees of amplification.

 

Beyond this at day 8

GEM

GFS

Parallel

 

If anything by week 2 the Greenland/Canadian lobe intensifies and brings a zonal spell of weather to the UK

GFS mean

At this present time the output looks very zonal in nature with a strengthening jet across the Atlantic with winds generally from the west.

GFS ens further on favour the dominant lobe of the polar vortex to remain over Greenland.

But they only take us to mid Jan!! (Which are almost pointless after 10 days at a push anyway) If you read his original thoughts he talks about cold end of Feb/March

[Captain Shortwave]

But they only take us to mid Jan!! (Which are almost pointless after 10 days at a push anyway) If you read his original thoughts he talks about cold end of Feb/March

There are a lot of factors which are currently unfavourable to cold weather developing on our shores, one of these is the MJO which refuses to move to a phase favourable for blocking to develop in the Atlantic. Add to that whilst there is warming in the Stratosphere, there is no guarantee off a favourable split which could aid blocking on the Atlantic side of the pole.

Other factors which have muted the OPI/SAI signals have come from persistent low heights over north west Asia which prevents the Siberian high developing and extending its influence both north into the pole (wavebreaking) and west towards Europe.

So at this point we only have a potential split in the strat which could aid developing cold weather at this time. As we are looking at over a week away before we may see a split caused by warming over Greenland, there is no guarantee on this occurring yet and of course seeing the split maintain. The ECM looks best for this at the moment. I would say the first half of January at least is looking like being dominated by westerly winds and little chance of significant cold arriving. Beyond then we may see something if any stratospheric event leads to a quick response down in the troposphere, but again no guarantees on when this will arrive and of course the blocking could end up in the wrong place. 

So week 1 looks like turning changeable with temperatures near or a little above normal. Week 2 looks likely to follow the same route albeit we could see something occur. Beyond this at the moment we can only go by the metoffice outlook, which suggests the only feasible route to cold at the moment is having high pressure set up near the UK to bring dry and frosty weather.

[John Badrick]

There are a lot of factors which are currently unfavourable to cold weather developing on our shores, one of these is the MJO which refuses to move to a phase favourable for blocking to develop in the Atlantic. Add to that whilst there is warming in the Stratosphere, there is no guarantee off a favourable split which could aid blocking on the Atlantic side of the pole.

Other factors which have muted the OPI/SAI signals have come from persistent low heights over north west Asia which prevents the Siberian high developing and extending its influence both north into the pole (wavebreaking) and west towards Europe.

So at this point we only have a potential split in the strat which could aid developing cold weather at this time. As we are looking at over a week away before we may see a split caused by warming over Greenland, there is no guarantee on this occurring yet and of course seeing the split maintain. The ECM looks best for this at the moment. I would say the first half of January at least is looking like being dominated by westerly winds and little chance of significant cold arriving. Beyond then we may see something if any stratospheric event leads to a quick response down in the troposphere, but again no guarantees on when this will arrive and of course the blocking could end up in the wrong place. 

So week 1 looks like turning changeable with temperatures near or a little above normal. Week 2 looks likely to follow the same route albeit we could see something occur. Beyond this at the moment we can only go by the metoffice outlook, which suggests the only feasible route to cold at the moment is having high pressure set up near the UK to bring dry and frosty weather.

So week 3,4,5,6,7,8+ could be cold, not a bad position to be in really

[Polar Maritime]

Some very potent Pm shot's showing towards the end of the run, On a strong Meridional Jet. There would be Blizzards for the UK with these synoptic's, Certainly a very stormy/wet period coming up, All to play for after next week with much uncertainty..

 

Edited December 30, 2014 by Polar Maritime

[Bullseye]

Why with current output is the worry about the vortex over Greenland/NE Canada? Can we not get heights building in Scandinavia while vortex is positioned over GL/NE Canada? Or can we get heights into GL even though PV is located over NE Canada like what the current output is showing? Maybe PV strength has been underestimated this winter. Lastly some relief with the updated Cohen blog based on Strat and Ecm/Gfs comparison. My bad if barking up wrong tree. Cheers.

Edited December 30, 2014 by Bullseye