Model Output Discussion - The Start Of Winter

[knocker]

The NOAA reforecast if it's of any interest.

Chart courtesy weatherbell

 

[nick sussex]

Lack of commentary on tonight's ECM tells us all we need to know really. A pattern change before the New Year looks increasingly fanciful.

I was waiting for the last frame, cross model agreement for an amplified wave to work east across the USA. The troughing in the USA is the trigger for a possible cold Christmas, the uncertainty is really how the models deal with low pressure off the east USA.

 

The ECM is very exciting at T240hrs, as long as we can clear shortwave energy between the high exiting Canada and the Azores high, the amplified wave will then deliver a lovely T264hrs chart.

[SMU]

Evening All-

 

I will hope to add some more details later on this eve, however tonights ECM is now into range on the pattern change depicted by the NOAA AO suite -

 

The GFs has had pattern hints in the last 2-3 days at around 324 which has now landed in the ECm tonight at 240.

 

This is the best ECM 240 chart for a long while & shows the classic atlantic > -EPO link into the pole.

http://www.meteociel.fr/modeles/ecmwf/runs/2014121512/ECH1-240.GIF?15-0

 

The NOAA ensembles on the 00z suite had runs of -4 at day 12-16 so the ECM is no surprise today -

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

 

for my winter forecast I specifically forecast 1 sub -2 AO event in December - so I am certainly pleased with these developments....

 

S

Edited December 15, 2014 by Steve Murr

[wolvesfan]

Evening all,

 

Lots of talk regarding the Azores being a winter spoiler.Could be quite the opposite though as we can see from these three epic charts below,

 

 

 

 WAA from the Azores fuelled the above.We wont get a sustained HLB without it.

[Argyle1980]

Maybe just maybe but ECM now out to Xmas day and could we be seeing a good Northerly flow and maybe a rise in pressure to the southern tip of Greenland !

Come on..... It's christmas.

[snowking]

Lack of commentary on tonight's ECM tells us all we need to know really. A pattern change before the New Year looks increasingly fanciful.

 

Does it really? Or is a more accurate statement that this is a single operational run from a suite of 51 members, 50 of which we are yet to see from the 12z run, that it only runs out to 10 days (preceding the mooted period of change) and shows a lot of promise towards the end of the run on a hemispheric scale regardless, in line with the expected potential?

 

 

SK

Edited December 15, 2014 by snowking

[NorthernRab]

im sorry to say a white christmas does not look likely with the grinch staying put for awhile yet.

 

Christmas is 10 days away - nothing looks likely at 10 days away when predicting the weather!

[nick sussex]

This is my rough projection if the ECM went out to T264hrs:

 

 

I know this is way out into the future so just a bit of fun!

 

 

[ukpaul]

People don't comment when a run is ongoing because they want to see it in toto (and those who don't, often find their earlier comments made to look hasty in retrospect - QED)

 

So, now it's fully out, we can see that it is now showing the suggested pattern change. Having been at the warmest end of its ensembles for the 00z it looks likely that this will change for the 12z.

 

 

Edit: and I should add, thanks NIck Sussex for the links regarding  the bias correction on the GEFS. It looks like it deserves to be paid attention to.

Edited December 15, 2014 by ukpaul

[carinthian]

Does anyone trust in the GFS biased corrected run? If so it looks good for Christmas!

image.jpg

Not beyond the realms of possiblites. Tonights ECM show the possibilities for Christmas, signs of height rises over Newfoundland and up the west coast of Greenland. Colder air mass getting established over Scandinavia with first sign development as appears on latest ECM run @ 240 hours of low pressure system in mid Atlantic that could run across Southern Britain enhanced by a an increasingly stronger baroclinic zone in this latitude which would help to erode the Azores warmer sector flow and heights.

C

[Duane S.]

Lack of commentary on tonight's ECM tells us all we need to know really. A pattern change before the New Year looks increasingly fanciful.

OK, a pattern change before Xmas looks unlikely ( but still still not impossible) but how on earth can you honestly think a pattern change in 15 days time is 'fanciful'?

It seems a case of some people on here needing to control their emotions a bit better and stop the daft posts, based purely it would seem on a few poor op charts. As was asked of another poster earlier, read Tamara's post from earlier, she explains in great detail the background signals and teleconnections that highlight that things are heading the right way. Look through the GEFS members, there have been plenty hinting on a 'pattern change' towards the tail end of the year for the past few days, that is much much less likely to occur when then atmosphere is not conducive to it, i.e. last year. My point being, the opportunity is clearly there for a pattern change.

[Mucka]

If we do get a pattern change it looks like it will just be the wrong side of Christmas for those who love to see snow falling outside as they tuck into their turkey but still a small chance we can squeeze enough amplification out of the pattern to at least bring in some colder air after a milder interlude in the run up to the big day. Green Christmas (no snow falling) seems likely but not quite a done deal, especially in the North though actual snow on the ground seems a very long shot except on the higher hills and further North still.

 

I certainly won't complain if the ECM 10 day chart is firmed up upon though. 

Not enough support as yet but model watching getting a little more exciting for cold weather fans as we enter the second half of the month.   

Edited December 15, 2014 by Mucka

[igloo]

you never no it could go from that to this in a  day or so it doesnt take long

 

[SMU]

If we do get a pattern change it looks like it will just be the wrong side of Christmas for those who love to see snow falling outside as they tuck into their turkey but still a small chance we can squeeze enough amplification out of the pattern to at least bring in some colder air after a milder interlude in the run up to the big day. Green Christmas (no snow falling) seems likely but not quite a done deal, especially in the North though actual snow on the ground seems a very long shot except on the higher hills and further North still.

 

I certainly won't complain if the ECM 10 day chart is firmed up upon though. 

Not enough support as yet but model watching getting a little more exciting for cold weather fans as we enter the second half of the month.   

 

 

I agree with Mucka 'probability' wise the timing of the pattern change through amplification appears to be homing in ( all be it very disjointed ) on boxing day, however models whilst they are progressive can occasionally be to slow in developing A change & at day 10 there is a margin of error of 24 hours either side-

So we are still in with a shout for something colder from the NW on xmas day.

 

the azores high may well support the ridging towards Greenland as it conjoins with the ridge developing over the east coast...

 

either way it should be an exciting run up towards the big day......

[Cloud 10]

This is my rough projection if the ECM went out to T264hrs:

 

ECH1-240.gif

 

I know this is way out into the future so just a bit of fun!

 

Perhaps something like this Nick?

 

 

 

12z GEFS very keen on an eye-brow raising Northerly outbreak in the last week of December.

 

 

Perhaps we can sneak something in for Christmas day itself.

[Iceni]

If we do get a pattern change it looks like it will just be the wrong side of Christmas for those who love to see snow falling outside as they tuck into their turkey but still a small chance we can squeeze enough amplification out of the pattern to at least bring in some colder air after a milder interlude in the run up to the big day. Green Christmas (no snow falling) seems likely but not quite a done deal, especially in the North though actual snow on the ground seems a very long shot except on the higher hills and further North still.

I certainly won't complain if the ECM 10 day chart is firmed up upon though.

Not enough support as yet but model watching getting a little more exciting for cold weather fans as we enter the second half of the month.

1963 started just the wrong side of Christmas. Boxing Day at 6pm. I remember looking out of the dining room windows and seeing the first snow flakes of that legendary winter fall. Edited December 15, 2014 by Iceni

[knocker]

Not beyond the realms of possiblites. Tonights ECM show the possibilities for Christmas, signs of height rises over Newfoundland and up the west coast of Greenland. Colder air mass getting established over Scandinavia with first sign development as appears on latest ECM run @ 240 hours of low pressure system in mid Atlantic that could run across Southern Britain enhanced by a an increasingly stronger baroclinic zone in this latitude which would help to erode the Azores warmer sector flow and heights.

C

Are we looking at the same chart?

Courtesy weatherbell

[Banbury]

This is my rough projection if the ECM went out to T264hrs:

 

ECH1-240.gif

 

I know this is way out into the future so just a bit of fun!

Think we would all be happy with that

[ANYWEATHER]

If we do get a pattern change it looks like it will just be the wrong side of Christmas for those who love to see snow falling outside as they tuck into their turkey but still a small chance we can squeeze enough amplification out of the pattern to at least bring in some colder air after a milder interlude in the run up to the big day. Green Christmas (no snow falling) seems likely but not quite a done deal, especially in the North though actual snow on the ground seems a very long shot except on the higher hills and further North still.

 

I certainly won't complain if the ECM 10 day chart is firmed up upon though. 

Not enough support as yet but model watching getting a little more exciting for cold weather fans as we enter the second half of the month.   

Theres no pattern change on the way, well not this side of Christmas! So the weather in the run up to Christmas and perhaps beyond , will be similar to what December has already provided. There will be some wintry weather away from some milder conditions at times with frost ,wind chill, sleet,snow . Models are still hinting at a rather cold Christmas day, so if youre a betting person where do you think the snow is likely to fall??? I think if youre in the North and West with some elevation then perhaps, if models are correct a white Christmas is possible, anyway if nothing else a fascinating  period of model watching!    

[inghams85]

What is striking about the 47 and 62 charts is the -EPO ridge (similar to the ingredients building for the pattern change at the end of December)

Evening all,

 

Lots of talk regarding the Azores being a winter spoiler.Could be quite the opposite though as we can see from these three epic charts below,

 

 

 

 WAA from the Azores fuelled the above.We wont get a sustained HLB without it.

[ukpaul]

Are we looking at the same chart?

Courtesy weatherbell

 

Well, maybe, maybe not....

 

 

Edited December 15, 2014 by ukpaul

[Mucka]

1963 started just the wrong side of Christmas. Boxing Day at 6pm. I remember looking out of the dining room windows and seeing the first snow flakes of that legendary winter fall.

 

Ah lovely and of course you could have no idea of what was about to follow...

It must have been an incredible winter to experience but at least younger folk got a taste of extreme winter weather in recent winters.

I was actually alive back then, just not particularly aware of the fact

 

I seem to remember back in the 70's and 80's we would often have a milder period toward and even into Christmas but get a cold blast and snow as we headed toward or into the New year but the memory is notoriously unreliable as a guide to past events and weather memories seem even more susceptible to errors. Not sure how it stacks up on actual historical charts.

 

I guess we should keep our feet on the ground for now though as one ECM 10 day chart does not a winter make.

JMA is not that far off though it is less amplified and any Atlantic ridging would be weaker than on ECM one expects.

 

 

It may be that we need more than one bite at the cherry and we don't get a true pattern change until into the New Year (dangerously assuming it will happen)

But until tomorrows output I am going to dust off that crusty old phrase favoured by pragmatists and state that I am cautiously optimistic cold is on its way.

Here is to another 63 (except in an alternate universe where everyone is kept safe and warm)

 

Me? warm and fuzzy? Bah humbug!

Edited December 15, 2014 by Mucka

[knocker]

Well what?

Edited December 15, 2014 by knocker

[ukpaul]

Well what?

 

Full comment had been cut off, now restored.

[OldMetMan]

which happens to be a year thats been chosen on a lrf on an american weather site.

 

the problem is the azores heights is also well and truely at home to our south and could be there for weeks to come judging by the model outputs and could possibly move futher east setting up a bartlet type block.

 

theres lots of talk on the american sites of a winter storm dated around the 19th to the 21st of this month over the pond in the states.

and also talk of the vortex setting up like last year over there in the states,

so dare i say a return to a rerun of last winter ?

 

although id be very intrigued to how much effect this could have here,

 

i suspect a return to a more typical zonal that we are getting now,

but less intense than last winter as the vortex is not as strong as last year.

how weak is the vortex currently is there a chance of a strengthening vortex.

 

http://theweathercentre.blogspot.co.uk/2014/10/official-2014-2015-winter-forecast.html

I wish I knew the answers!

Looking at this time last year, things were very different indeed:

Never say never, but I would have expected to see something in place over Canada already if we were in for some sort of re-run. As it is, the pattern over most of continental N America has been strangely benign. That in itself makes me a bit suspicious, because I am wondering how the pattern will change. It just seems most unlike a typical mid-December situation there and I can't get a handle on what exactly will happen - yet

I cannot point to any specific "drivers" and say those are my reasons for expecting a major change. I rely solely on my "weather instinct" for want of a better term!

I wouldn't worry overmuch over the Azores HP. Sometimes it can work in our favour when it comes to coldness.

I follow the US WV satellite imagery a lot because it highlights the changing long wave pattern very well. Hurricane forecasters make use of these a lot because of this.

I'm keeping an eye on the jet strength and path, watching for any noticeable change. When I can get a clearer idea of what is changing and how, I shall post about it to be sure!