Model Outooks: Winter 2008/2009

DOCARCH

Snowaddict wrote: »

we would see significant snow accumulations, particularly in the eastern half of the country, several ice days and widespread transport disruption. In essence, its winter armageddon.....

Sounds very WC...;)

Looks great - why can't FI be now!

Snowaddict

DOCARCH wrote: »

Sounds very WC...;)

Looks great - why can't FI be now!

Oh I know:D... But 06Z was not a complete outlier. Believe it or not, is has support from several other members, particularly towards the end of the run. Its the trends that are all important, and there is a clear trend towards retrogression of the high pressure to Greenland.

As I said above, I think the 06Z introduces the colder thrust too early IMO, as shown on the ensemble graph, but it has to be said, the underlying trends have substantial potential.

The usual caveats apply of course and this is but one run, so caution advised.

Supercell

If it comes off like the charts are saying it will at the moment then winter '09 is going to be talked about for many years, interesting times.

mike65

I'm actually getting worried now.

arctictree

The 06z GFS is the best run I have seen in a long time.

I've saved it here so that it does not change on the next run:



Very cold weather right out to New Years day. Bound to be some snow mixed up in that towards the end of the run. Pity the exciting parts are in FI.

It shouldnt take long in an easterly like that artictree for precip to turn very wintry up your way.

The rest is uncertain.
FI doesnt have the answers.
ECM out to t144 has some of them.

850's aren't as important in an easterly as long as they are below -5 for low ground if you have sub zero dew points..a likely prospect with an easterly eventually and very likely with a northeasterly that became a northeasterly after it was a northerly to the shetland isles.

A very cold surface air feed prolonged beyond a few days is what you want.
I'm not sure the easterly will give us that-it might-thats a wait and watch scenario.
If I remember correctly it was a brief easterly but with very cold surface air and not so inspiring 850's that gave the snow over meath and louth early last january.That surface air was sourced over denmark.
This time even moscow is only -3c currently so,it's not a cold enough feed.

I see a lot of people who should know better on other weather fora showing charts from 6am and midnights with temps of 3 to 4c and saying it's bitter...
Give me a break...they clearly dont know what they are talking about...you'd get that in a southwesterly under clear skies at night:rolleyes:

Also saying 2-5 c by day in Ireland is bitter or a cool spell is misleading.
It's cold alright but if you dont have sub zero dp's you will have rain at those temps..
Also even if it does snow at those temps the first thing you will have when it stops is a very fast thaw.
Useless in my opinion.

So look for maxes of 2c or less if you want to call it cold.


That said,these synoptics and waiting to see what happens and the various twists and turns and above all the very real possibilities is dare I say it nerdfully...exciting!

matt cork

a very interesting read all these posts and even though i have no real idea how to really intepret these charts i have recently started looking at netweathers free long range gfs charts which, for me anyhow, seem quite interest in that they tie in with a number of predicitons here, although the snow risk does seem rather exaggerated

i've only added the uk precipitation and type for 180 and 192 (which i assume are hours from now) but it seems to be a constant onslaught right up to 384





certainly has my kids excited at the moment:D

DOCARCH

matt cork wrote: »

certainly has my kids excited at the moment:D

Jeeeez.......don't be telling the kids anything!.......bad enough with grown up broken hearts!!!........keep the kids out of it:D

Snowaddict

Well GFS 12Z run now coming out, will subsequent runs keep up the retrogression theme. Joe Bastardi has now updated his European blog, the update of which I have posted below. I still am not overly confident, but if Mr Bastardi is correct, then something significant is indeed on its way, and subsequent runs of dreamy wintry charts cannot be ruled out. Its quite a statement from a professional meteorologist and as Supercell said above, if these charts come off winter 09 could be something special. I reamin cautiously optimistic at the moment. Note also when he refers to England, this does include Ireland.

__________________________________________________________

TUESDAY, DEC. 23 2 A.M. UPDATE ON COMING COLD WAVE.

The period we are looking at here has not yet started. The block is forming over Scandinavia, and this will back toward Greenland and as it does, the pattern will reverse so we are looking at much colder weather to end this month and carry well into January. On the table are strong low-level east winds into England with snow there, but the evolution of this is still occurring, and in fact it's warm now. However, the reason for the post is to say the most impressive two- to four-week cold period of any recent winter for the continent on the whole is on the way. Patience, grasshopper, patience.

Judging by email received, I hope now I am clear on this.

Ciao for now. ***
__________________________________________________________

If anything, Joe Bastardi has upped the possible severity of the cold spell.

The next few weeks are going to be really really interesting.

SA.

nacho libre

Has this Joe Bastardi fellow being right more times than he has been wrong in the past? anyway, if this does turn out as he predicts i'm might take a trip to the garden county early in the new year.

Snowaddict

nacho libre wrote: »

Has this Joe Bastardi fellow being right more times than he has been wrong in the past? anyway, if this does turn out as he predicts i'm might take a trip to the garden county early in the new year.

Not too sure about his levels of accuracy to be honest, but I do know that he is one of the chief forecasters with Accu Weather in America.

Regarding the 12Z GFS run. Earlier on, the first bite of the cherry so to speak was at about T+180, where cold air flooded down over the country. Things are further east on this run because retrogression takes longer, and it is not until the 5th that a really cold easterly / northeasterly flow reaches the country.

I believe that GFS is going to have difficulty in modelling this type of rare setup, however I think its pretty accurate with the arrival of the very cold air and real wintry setup. If things keep trending the way they are at the moment, it will probably be around the 3-5th of January before substantial cold reaches us, from what I can ascertain at the moment and IMO based on the most recent GFS and ECMWF outputs.

GFS shows an interesting setup in deep FI of southerly tracking lows and very cold air over Ireland. This type of setup is often quite favourable for snow events.



The chart that follows on from this shows another severe plunge coming down from the north, with substantial height rises over Greenland.



Thats 2 GFS operational runs showing very similar trends of height rises over Greenland, allowing a wintry blast over Ireland.

Its still too early to make a call on this, but ECMWF will be crucial this evening, to see if continues to show clear retrogression. It will be also most interesting to see where this GFS operational run stands in terms of the ensembles.

At the moment, I would still put 40% on the risk of a potentially severe wintry outbreak into the new year.

Most encouraging to see these continued trends.

Scubadevils

Thanks SA for all of these reports... in my four years watching boards, NW and TWO, I still haven't got around to learning more about the models but it's good to read analysis here for a more local take on things. Speaking of which, where is Weathercheck these days?! - Amazed he is not here given the potential on offer.

Snowaddict

Felixdhc wrote: »

Thanks SA for all of these reports... in my four years watching boards, NW and TWO, I still haven't got around to learning more about the models but it's good to read analysis here for a more local take on things. Speaking of which, where is Weathercheck these days?! - Amazed he is not here given the potential on offer.

No problem at all. I'm not sure to be honest. Yeah, given these spectacular outputs I wonder where he has go to? TWO and Net Weather went into meltdown this morning, hundreds of members online after the 06Z run, so its nice to post here. ECMWF will be coming out in about 50 mins and thats what I will be really pinning a lot on. It has been almost flawlessly consistent over the past 5 or 6 days, so its output tonight is crucial to see if it continues the trend. The 12Z ensembles are going to be very interesting also. I will do a quick analysis of them as soon as they are fully out.

Regards,
SA.

opr

Seriously how have i got sucked into reading this thread almost everyday :P

Come on the COLD !!

Opr

DOCARCH

Felixdhc wrote: »

Thanks SA for all of these reports....

I just want to second that - thanks SA, keep up the reports.

I have stopped looking at model discussions on NW as it moves to fast (too many stupid, opinionated and critical posts to keep up with!).

Snowaddict

DOCARCH wrote: »

I just want to second that - thanks SA, keep up the reports.

I have stopped looking at model discussions on NW as it moves to fast (too many stupid, opinionated and critical posts to keep up with!).

No prob at all, thanks again.
Well the 12Z ensembles are out and its very good to excellent news from what I can see.

Here is the upper 850hPA chart for 12Z GFS:


There are a significant number of members dropping towards the -10 line at various stages of the run. Indeed GFS operational is not too much of a cold outlier for the 12Z run at all, with strong support from several other members. Many members even trend below GFS operational, with two members breaking the -10 line. I have gone through the mean pressure charts also, and there is a clear trend towards retrogression of the high to Greenland / for height rises over Greenland.

Now there are still a number of nasty milder members on that run, but a clear cooling trend is visible. So much so that the ensemble mean drops to -5 or almost -5 from the 4th of January onwards.

In recent days the ensemble mean 850hPA temps have been approaching -5 from about the 4th / 5th of Jan onwards. This is definately one to watch. A general rule of thumb is that we need upper 850hPA temps of at least -5 in order to allow for snowfall. From an easterly type setup, -7 to -8 at least to ensure snowfall to all levels.

Overall, an excellent set of ensembles. This reinforces confidence for a possible wintry outbreak from around the 3rd to the 5th of January. Although, of course this is FI and is subject to change.

All eyes down for the ECMWF to see what it brings.

Regards, SA.

Pangea

Very nice comments since last nite, so is the early indication that the cold/snow will chiefly be on the east coast? strange the cold coming from the eastern direction
, Im in Donegal

Scubadevils

I can't help but read NW too but do find it confusing with conflicting reports on the same models - especially when they seem to be from people with a good understanding.

This really seems interesting though. In my four years of reading these forums, I have never witnessed such a consensus for something big potentially upon us. My fear though would be that something special does occur, but with us a tad too far west to benefit.

Anyway, exciting times, especially given the time of year... I can see me sneaking off during family visits over Christmas for quick model updates! My wife hates winter :pac:

arctictree

Just had a look at the 12z GFS. Looks like cold and dry for the reliable timeframe. After that the current run goes for a prolonged snowy breakdown.

Spectacular charts to be honest but completely FI. In fact, it is showing two days of heavy snow starting on the evening of Monday 5th to Wednesday 7th.

Looking forward to seeing what the ECM brings...

Snowaddict

Pangea wrote: »

Very nice comments since last nite, so is the early indication that the cold/snow will chiefly be on the east coast? strange the cold coming from the eastern direction
, Im in Donegal

As Artictree says, these charts are still in FI, so nothing still certain. However, there is a slight trend for the colder evolution to be from a direction north of east at first at least. That doesn't rule out snow in any part really due to possible troughs crossing the country etc and if we get low pressure systems coming up against this very cold air, then there is the possibility for widespread and possibly heavy snow events. But still too far out yet.

If we can shore up the trend of retrogression in the next few days, and if there are clearly continued signs of this colder outbreak, then I wouldn't rule out possible snowfall anywhere. Hang in there another few days, its all to play for yet.

In the shorter timeframe, we will have an easterly flow by the end of this week, however it won't be cold enough to be conductive to snowfall from what I can see at this point. There might be the outside chance of some snow grains in places, but unlikely at this point.

Quick addition, tonight's T+144 chart from the UK Met Office is excellent from what I can see.
At this point, that high appears to be very likely to be heading for Greenland. The artic front is even showing on this run. This could possibly suggest that GFS 06Z was not too progressive with the run. However, this is one run, so yet again caution advised. Thats 2 out of 3 models looking highly favourbale this evening. Will ECM continue the trend and become the 3rd? We will find out within the next 30 minutes or so..

Snowaddict

ECMWF run is completed and although its not fantastic news, things are still looking very very good.

Retrogression of the high pressure to Greenland / height rises over Greenland again are shown, however the evolution is markedly slower to previous runs in comparison.

The fact that the significant height rises are still being shown is quite positive, but I would have preferred a slightly firmer retrogression pattern to be shown, in order to sustain confidence in the evolution of the colder outbreak.

In conclusion, not by any means a bad run, no raging atlantic kicking in, but the evolution of the colder spell has been delayed somewhat if this run were to verify. Therefore, I think its sufficient to say tonight that 2.75 out of 3 models are on board regarding the outlook. Although if the ECM went out further, it would show an easterly / northeasterly, so not terribly out of tandom with the latest GFS outputs.

Encouraging once again, the delay of the onset of the possibly more potent cold is a bit bothering, but not too concerning at this point.

The chart for T+192 hours from now: (1035mb high over Greenland)




T+240 Chart: (1040 mb high over Greenland and southerly tracking lows)



For comparison, the 12Z GFS operational chart at T+240:



At present, I would put 60% in favour of retrogression of the high to Greenland and currently 40% in favour of a wintry outbreak into the new year.
18Z GFS will be interesting tonight.

SA.

Felixdhc

Felixdhc wrote: »

I can't help but read NW too but do find it confusing with conflicting reports on the same models - especially when they seem to be from people with a good understanding.

People on NW who post things like 1-4c at night is a severe cold spell do not have a good understanding of much so ignore them.
People on NW who think this Easterly is the holy grail are talking nonsense because it doesnt feed in freezing surface air or sub -5c 850 air according to the models-so ignore them.They are going on with a whole heap of nonsense with the exception of those of course who are genuinely discussing the theory of it all as opposed to getting carried away saying xy and z is fairly certain.

Thats about 75% of the posters on NW you have to ignore I'm afraid.

Snowaddict wrote:

ECMWF run is completed and although its not fantastic news

]Thats a bit of an understatement.That ecm chart you show is bland.
It's an extension of hp blocking in and around our shores with beggar all of an Easterly and that beggar all is not off a cold enough continent.
A south westerly on a clear night would be colder and thats useless with all due respect.

I think it's a lot of straw clutching to be honest when one keeps saying oh...it's there but now it's a week later and then when the week is up...to say again oh it's there but a week later etc etc etc

Maybe maybe,whatever cold shots are going to come [and they should if we do actually get a northern block..BUT remember we dont have one in place yet and AHEM people here and on other Weather Fora seem to keep this ,oh it'll be here in another week thing going :rolleyes:] maybe they will come eventually.
I simply dont know and the models dont either apparently.

Gonzo

wud love is all this turned out to be true, we've been deprived of a proper easterly snowy winter since 1991! thats before many boards.ie posters were born.

Deep Easterly

ECMWF 12z 240hrs 850's:



Yes it's FI, Yes it may well never happen blah blah blah yawn yawn yawn, but who cares, its a great looking chart and I hope to God above that something like this comes into play, as I think we all deserve something special with the weather after such a crap 8 years of winter filth. :)

Snowaddict

Deep Easterly wrote: »

ECMWF 12z 240hrs 850's:

Yes it's FI, Yes it may well never happen blah blah blah yawn yawn yawn, but who cares, its a great looking chart and I hope to God above that something like this comes into play, as I think we all deserve something special with the weather after such a crap 8 years of winter filth. :)

Well said DE. I completely agree. If you can't be optimistic at these FI charts, then there might not much to be optimistic about in terms of weather, given the recent winter trends.

However, I remain very optimisitc about this one and the period into the new year.

Snowaddict

Deleted User wrote: »

Maybe maybe,whatever cold shots are going to come [and they should if we do actually get a northern block..BUT remember we dont have one in place yet and AHEM people here and on other Weather Fora seem to keep this ,oh it'll be here in another week thing going :rolleyes:] maybe they will come eventually.
I simply dont know and the models dont either apparently.

This is the model output thread Black Briar yeah? Therefore I think we can discuss all charts from the model output, even the one's in FI . Also which ECM chart are you referring to, because the one at T+240 is not that bad at all, very cold air approaching from the east.:)

Also, to be fair, even recent NOAA discussions suggest clear trends towards the retrogression of this high pressure. Furthermore, this chart below - The 500mb anomaly chart issued by NOAA on the 22nd also indicates that retrogression / height rises are favoured over the next 8-14 day period in or around the Greenland area.

I would also like to quote the Met Eireann forecaster on the Six One News this evening who referred to the high pressure system now coming up over the country as 'a blocking High'. Of course this has not retrogressed yet, and may not, but the signs are there for it. Of course it could all go wrong, but the suggested pattern at the moment is not for the high to sink, it is for it to retrogress with height rises favoured over Greenland.



This second chart from today's GFS 12Z is at T+180, the back end of the more reliable timeframe, but still just about there. It shows a clear splitting of the polar vortex, which has in recent winters so stubbornly set up shop over Greenland for such sustained periods, depriving us of any real wintry potential. Again, I'm not saying any of this will materialse exactly as shown now, but there is great potential there, and retrogression did appear in the more reliable timeframe on today's 06Z GFS operational run.



Latest NOAA Discussions this evening at 21:00 approx state:

''EWD VERY STRONG
POSITIVE HT ANOMALIES OVER THE BRITISH ISLES WORK WWD TO EAST OF
CAPE FAREWELL SUPRESSING THE PERSISTENT WEST ATLC/SERN SEABOARD
RIDGING'' - Basically they are expecting the high to retrogress also..

Snowaddict

Snowaddict wrote: »

This is the model output thread Black Briar yeah? Therefore I think we can discuss all charts from the model output, even the one's in FI .

With several pinches of salt.I am flabbergasted at the attitude in some fora especially NW,the naivety is breath taking.

Also which ECM chart are you referring to, because the one at T+240 is not that bad at all, very cold air approaching from the east.:)

ECM 240 is 10 days away.
A week ago if it existed,it's projection would have been 17 days away.It is irrelevant as to how nice it looks.
T144 and less is what we can draw reasonable conclusions from but beyond that you may aswell take out text books and discuss dreamt up scenarios because they would have as much bearing on reality.

The problem I have with your posts are that you intermix reality with far FI non reality and thats a mind mangle.
Idealy I think near time model output and FI should be in separate threads Everywhere.

Also, to be fair, even recent NOAA discussions suggest clear trends towards the retrogression of this high pressure. Furthermore, this chart below ( The 500mb anomaly chart issued by NOAA on the 22nd) also indicates that retrogression / height rises are favoured over the next 8-14 day period.

We'll see.It may or may not happen.

I would also like to quote the Met Eireann forecaster on the Six One News this evening who referred to the high pressure system now coming up over the country as 'a blocking High'. Of course this has not retrogressed yet, and may not, but the signs are there for it. Of course it could all go wrong, but the suggested pattern at the moment is not for the high to sink, it is for it to retrogress with height rises favoured over Greenland.

1. yes a high blocks out the atlantic thats what ME were probably referring to.
They were not going that step further to say it was going to freeze us in Easterlies or North easterlies or Northerlies from a polar origin.
They simply mean dry when they say that.
I've heard them use the term many many times.


By the way I don't disagree that all the wildest of scenarios hoped for across NW and Two are possible.They are and a lot more so than any other time in recent history if we get the block in place.
We have to get there first.

Snowaddict

Deleted User wrote: »

With several pinches of salt.I am flabbergasted at the attitude in some fora especially NW,the naivety is breath taking.

ECM 240 is 10 days away.
A week ago if it existed,it's projection would have been 17 days away.It is irrelevant as to how nice it looks.
T144 and less is what we can draw reasonable conclusions from but beyond that you may aswell take out text books and discuss dreamt up scenarios because they would have as much bearing on reality.

The problem I have with your posts are that you intermix reality with far FI non reality and thats a mind mangle.
Idealy I think near time model output and FI should be in separate threads Everywhere.

Agree with a fair bit of that there but I do always state the caveats associated with deep FI and FI. But it is certainly going to be quite a tedious process to get that block in place. At the moment it looks like it will retrogress, but who knows as of yet...

Back to the model output anyway, I wonder what the GFS 18Z operational will bring.. :rolleyes:

LEIN

I have found my self glued to this thread over the past week. I know it can all fall apart at the last hurdle and we could end up with mild muck but its still exciting to speculate. Its enjoyable to see the blue shades approaching Ireland especially with the boredom of the damp greyness we have had over the past couple of the days.

I believe there is something coming and its a fooking long time coming too!

Keep up the interesting posts SA.

Bring on the big freeze.

Snowaddict

18Z GFS Operational Run:

In the more reliable timeframe, at T+114, the high pressure is centred slightly north of Ireland, with height rises beginning to show over Greenland - 1032 mb. An easterly flow will still be in place at this time frame, but one that is not conductive to snowfall.

Max temps for 12 noon on Sunday 28th suggested 3 - 5 degrees C widely. So feeling quite cold anyway.

A very important point to note is that Retrogression of the High towards Greenland is clearly underway at T+129 on this run, within the reliable timeframe. Heights of 1040mb also over Greenland at this point.

T+129



At T+144, the high is clearly retrogressing, with a northerly pole sourced plunge developing north of Iceland.

http://212.100.247.145/gfsimages/gfs.20081223/18/144/h850t850eu.png

At T+159, the high is now centred south of Greenland, moving further north with each frame. It is approximately 200 miles too far east to allow for a direct northerly over Ireland at this point, however this could change later on the run.

http://212.100.247.145/gfsimages/gfs.20081223/18/159/h850t850eu.png

Ireland misses out on the first very cold incursion by about 150 - 200 straight line miles on the first part of this run, however by T+288 (which is of course FI territory) the high is further north west and there is a northeasterly flow over Ireland with upper temps 850hPA temps of -7 to -8 approx.



Out further into FI, we have a low over the Med, and look what happens over Ireland.... T+360 timeframe now.. A very very potent easterly develops with upper 850hPA temps of between -10 and -12.





Well as you can see from the charts above, this run yet again delivers a top classic wintry outbreak, with a very very near miss around T+180 also. Encouraging? Yes, to say the least.

Ensembles should be interesting again.

Regards,
SA.