Model Outooks: Winter 2008/2009

Snowaddict

Snowbie wrote: »

Threads merged.
There is already two threads for model watching.

In fact 26th (St Stephens day) is miles away. This thread will suffice untill a more reliable time frame occurs for possible snow.
It looks nice but it really is only one run. Lets hope for more after all it is my birthday and be nice to see snow on the 26th.

If an easterly does push through, i would not get over excited as the GFS is overplaying the cold. There is no cold been tapped into at all as the air in eastern Europe/Russia is considerably mild atm. Sure Spain has got more snow than some eastern parts of late.

I agree about Europe not being that cold yet, although it has cooled down quite a bit in recent days, with strong signs of a further cooldown to come.

One important note tonight I think is that both ECMWF and GFS are suggesting very good potential for the post Xmas period. Now of course this is FI, but as I said above, there are several experienced independent forecasters in the UK suggesting that there will be a wintry outbreak post Xmas and into the new year. Many also suggested this a few weeks prior to today.

Its FI, but there has been excellent cross model consistency today regarding synoptics as we head towards the New Year period. Indeed, ECM is very interesting for the entire run tonight. Several GFS perturbations have shown a noticeable dip in recent days. Indeed, significant height rises over Greenland are shown at the end of the ECM run tonight.. It also has an azores low, and the HP does not sink at any time on the run...

This is all fantastic IMO, regardless of whether it comes off or not. If these trends continue to show on the major models over the next few days, then there could be something very interesting ahead. It appears that retrogression of that High or a Scandi high are very possible in the post Xmas and New Year period.

I know that some may dismiss this as being FI and overexcitement at nothing, but both TWO and Netweather have gone into meltdown today. Furthermore, there could be a developing trend given the cross model consistency in the last 24 hours, and ECM's repeated consistency in the last 36 hours.

Caution is always needed of course, as these charts could vanish into thin air... But I do feel that something wintry may be brewing for post Xmas and the New Year, then again I could very well be wrong.

SA.

Snowbie

In FI, the potential looks very good for some cold from the east but how cold?

In reality, there is no cold air pooling around eastern europe, the Atlantic does push through and mixes up the air even over Poland and Russia. When daytime maxima are well below freezing and lower again at night consistently will anything significant cold wise reach our shores in terms of temp. Snow is seperate for the moment.

This is the tapping into i was referring about as really there is no cold to tap into. With a block like that one is showing, it will have to be in place for several days (maybe 4 or 5) just for siberian air to move across EU UK and eventually us.

Although i have not read what they have said on other forum about a Scandi block etc, what happens in the UK can be more severe than what happens in Ireland.
1.They are closer to the source
2.We are more influenced by the Atlantic and air can be modified further crossing over the Irish sea also. ( If we have a full on easterly crossing the country, then the Atalntic is out of the equation but most of the time it can be returning continental maritime air or SSE to SE winds)

Pretty crappy but that is the reality of it all.

Deep Easterly

I agree Snowbie about the depth of coolness needed even within an easterly, and that it might take time. But the small chance of an easterly developing as shown by the models is encouraging in itself I think. Cold pooling will come in time if block stays in right place.

With an easterly, I think the west of Ireland is luckier with regards temps in summer as well as in winter which is why I crave one at anytime of the year. Even without a cold source, the lower dewpoints due to the longer travel across land will favour cooler temps this side of the Isle, and below zero temps can still occur, contingent of course on slackness of airflow. It's our own little continental effect. and God know we are long overdue one*.

*Dryness. God it will be a blessing just to see the roads and paths dry just for once since september.

Snowbie

Snowbie wrote: »

Although i have not read what they have said on other forum about a Scandi block etc, what happens in the UK can be more severe than what happens in Ireland.
1.They are closer to the source
2.We are more influenced by the Atlantic and air can be modified further crossing over the Irish sea also. ( If we have a full on easterly crossing the country, then the Atalntic is out of the equation but most of the time it can be returning continental maritime air or SSE to SE winds)

Pretty crappy but that is the reality of it all.

This is the crux of it.
In the january '87 at the height of it,there was a day long snowstorm in Dublin that actually spread down from scandi in a northeasterly.It was so strong that it gave a dump of snow even way down at valentia as it exited the country into the atlantic.
Dublin of course had wellington deep snow at sea level..certainly at ucd anyhow.

The temp at it's worst in that airmass daytime in Dublin was -2c.
In Cardiff and Manchester it was -4c and lower still in eastern Britain iirc at as low as -8c.

So basically if the air temp is going to be 1 to 4 c in Britain all you'll get here in Ireland at best is a rainy sleety sometimes slushy mess as it modifies even further on route here.
You need -10c 850 air for dry snow here.
Anything warmer than that is too marginal and even if it does fall , will go the minute the sun goes out.

Those are the facts.

Snow addict take note that many of the so called experienced posters [who I believe have no experience of the proper 80's style snow synoptics of the type that they are now getting excited about because well most of them weren't even born then and ergo have never seen an experience like it] are just wishcasting.

Snowbie

Deep Easterly wrote: »

Cold pooling will come in time if block stays in right place.

Thats the key DE, if it just stays put. We have had 8 or 9 day dry Scandi blocks in the past.
It will also pave the way for more cold pooling for the future.

The best setup here would be this block to hold for a few days, retro into GL, an Arctic high to sink down into Scandi and start the whole process over but the cold be in place already and we be talking Ice days most certainly midlands and West. Snow is never certain in an easterly though, flurries at best. Unlike a N'ly, we need a Med LP, some frontogenesis from the Atlantic or a convergence to form out in Irish sea with E'lys

some of the best snow I saw in Dublin in the 80's came from shallow lows formed in the easterly feed.
Ah nostalgia...

Snowaddict

Deleted User wrote: »

This is the crux of it.
In the january '87 at the height of it,there was a day long snowstorm in Dublin that actually spread down from scandi in a northeasterly.It was so strong that it gave a dump of snow even way down at valentia as it exited the country into the atlantic.
Dublin of course had wellington deep snow at sea level..certainly at ucd anyhow.

The temp at it's worst in that airmass daytime in Dublin was -2c.
In Cardiff and Manchester it was -4c and lower still in eastern Britain iirc at as low as -8c.

So basically if the air temp is going to be 1 to 4 c in Britain all you'll get here in Ireland at best is a rainy sleety sometimes slushy mess as it modifies even further on route here.
You need -10c 850 air for dry snow here.
Anything warmer than that is too marginal and even if it does fall , will go the minute the sun goes out.

Those are the facts.

Snow addict take note that many of the so called experienced posters [who I believe have no experience of the proper 80's style snow synoptics of the type that they are now getting excited about because well most of them weren't even born then and ergo have never seen an experience like it] are just wishcasting.

Hey Black Briar. The main forecaster who I am following is quite experienced IMO... John Holmes of Netweather.. He has seen many a cold winter and has been very succesful so far this winter... forecasting the below average period of temps for the first part of December etc.

Anyway, time will tell, although at the moment, there is a potential for a wintry type setup... But thats all it is, potential. Nothing firm and too far out in the unreliable timeframe. Lets just see what subsequent runs bring over the next few days.

Regards,
SA.

Deep Easterly

Snowaddict wrote: »

Hey Black Briar. The main forecaster who I am following is quite experienced IMO... John Holmes of Netweather.. He has seen many a cold winter and has been very succesful so far this winter... forecasting the below average period of temps for the first part of December etc.

Anyway, time will tell, although at the moment, there is a potential for a wintry type setup... But thats all it is, potential. Nothing firm and too far out in the unreliable timeframe. Lets just see what subsequent runs bring over the next few days.

Regards,
SA.

Yep, I agree SA that things are looking exciting on the model front. OK, they may never materialise, but not harm either getting excited about them. As it is such a rare site to see, and who knows, maybe our turn will come. While I am with BB that another jan 87 would be a lot to achieve, there is no harm in wishing for something half as good as this in the near future. Keep up the excellent analysis SA. Always an interesting read in these dark drizzlely drab days.

nacho libre

i hope your optimistic nature is rewarded Snowaddict. although, we won't get any snow out of it, a de would be much more preferable to the mild and dreary muck we presently are getting.

Snowbie

GFS 18Z has no hint of an easterly from a Scandi block but instead places a HP cell over us for the same peroid above. A bad run for the optimist.:(

Snowbie

A whole lot different than the last but similar to before

850mb temp




Precip

Snowaddict

Snowaddict wrote: »

Hey Black Briar. The main forecaster who I am following is quite experienced IMO... John Holmes of Netweather.. He has seen many a cold winter and has been very succesful so far this winter... forecasting the below average period of temps for the first part of December etc.

Anyway, time will tell, although at the moment, there is a potential for a wintry type setup... But thats all it is, potential. Nothing firm and too far out in the unreliable timeframe. Lets just see what subsequent runs bring over the next few days.

Regards,
SA.

The vast majority of posters on TWO and NW have a fair to very good grasp of weather theory but most of them lack experience ie they have never seen the type of weather extremes visit these islands that they are wishing for.
Ergo they tend to get carried away to the point of being unrealistic.

Don't get me wrong,theres no lack of merit in discussing hopecasts

Snowaddict

Snowbie wrote: »

GFS 18Z has no hint of an easterly from a Scandi block but instead places a HP cell over us for the same peroid above. A bad run for the optimist.:(

Hey Snowbie. Yeah its not such a fantastic run when you compare it to the previous one. However, I'm very encouraged because of the amount of blocking on this run. The 18Z operational is very similar to some of the perturbations from the 12Z in terms of the positioning of the high.

IMO, the fact that we are seeing consistent blocking is the key, and that the high has held up moving into the higher resolution part of the run. A nice Scandi high of 1044mb is shown for Xmas day. Lets just see where subsequent runs go, but 11/20 or 55 % of the perturbations went for some form a colder outbreak ranging from cold to very cold and wintry on this run.

We should have a better idea by the weekend and after subsequent runs.

If you want some nice easterly FI eye candy, then perturbation number 2 is the chart of the evening.

Regards,
SA.

SA-I only count 2 runs in the dublin ensemble above that dip below -10 850 air.
Thats 2 and in far FI.
The bulk of the rest are -5 or above which is practically useless.
Theres no pont in looking at pertubations with brief flirtations with our shores it's not good enough.
Snowbie was speaking from experience above when he said we needed at least 5 days of a flow for some goods to be delivered.

De bilt ecm ensembles wont be able to tell you the story either as debilt is far better positioned by a long shot thn we are to get cold from an easterly being actually on the continent.

Snowbie

Yea P2 looks good, what it shows is a euro block which becomes Scandi, then to been plonked back over us which moves north and links with a GL HP to form a northern block.(a drunken block:D ) Trust me that is easier to explain in text than to post charts.

But there is little cold to begin with on that run SA, then looks interesting nearer the end. Northern blocks are much better IMO as most of the time they deliver more wintryness and have the guaranteed cold source from them with little modification.(Takes a short time for it to cool down) Thats just going on comparisons of past blocks and snow. (Past being 30yrs or so)

2 runs in a row now from GFS that demonstrate the futility of looking at FI in them.

Trends how are ya :rolleyes: Anything past 5 days in model watching has always been fools gold.
As I've said many many times,it's interesting to discuss charts for what they say but beyond that in FI they are meaningless.

Hope you are not too disappointed SA as I doubt you'll be coming on here with a t384 chart from tonight and saying how good it is! You might find a few pertubations but all they are are experiments with the data-they actually have no basis other than that and certainly arent forecasts.

The ECM's are usually more reliable but on weather fora we have silly people yes silly people looking at de bilt ensemble data and making huge leaps that arent there.
For instance see'ing ice days when closer looks shows the ice days are ice nights...shur we have them here in an atlantic flow :rolleyes:
Then theres the complete folly of thinking that de bilt means something .
It takes a lot to get an Easterly to debilt but it takes a near miracle to get it to Ireland.

We'll have one as usual in April mind you :rolleyes:


The above is a commentary on people running away with themselves as regards models - it's not to say that a bitter cold spell cant happen-it's just GFS FI is definitely not the place to look - The place to look is the ECM and UKMO to be honest within 5 to 6 days and maybe out to T168 at a stretch

kerry1960

A High Pressure in the neighbourhood might not be such a bad thing for Christmas ,

at best some sunny days and frosty nights ,

at least it will be dry :P,

at worst we may end up with 24hr cloud cover ..yuk .

j1979p

Well I think everyone knows how unreliable long term forecasts (or whatever you want to call the product of these models) are and how they can change so rapidly.

I, for one, still think it's fun to post the GFS graphics and/or your interpretation of them. It can always give you a little bit of hope and is a fun way of exercising your meteorological skills.

Pangea

I dunno, some times it can just snow out of the blue , too many charts lol
Its happened before in the past. :pac: :eek:

Snowaddict

Deleted User wrote: »

2 runs in a row now from GFS that demonstrate the futility of looking at FI in them.

Trends how are ya :rolleyes: Anything past 5 days in model watching has always been fools gold.
As I've said many many times,it's interesting to discuss charts for what they say but beyond that in FI they are meaningless.

Hope you are not too disappointed SA as I doubt you'll be coming on here with a t384 chart from tonight and saying how good it is! You might find a few pertubations but all they are are experiments with the data-they actually have no basis other than that and certainly arent forecasts.

The ECM's are usually more reliable but on weather fora we have silly people yes silly people looking at de bilt ensemble data and making huge leaps that arent there.
For instance see'ing ice days when closer looks shows the ice days are ice nights...shur we have them here in an atlantic flow :rolleyes:
Then theres the complete folly of thinking that de bilt means something .
It takes a lot to get an Easterly to debilt but it takes a near miracle to get it to Ireland.

We'll have one as usual in April mind you :rolleyes:


The above is a commentary on people running away with themselves as regards models - it's not to say that a bitter cold spell cant happen-it's just GFS FI is definitely not the place to look - The place to look is the ECM and UKMO to be honest within 5 to 6 days and maybe out to T168 at a stretch

Good evening BB. I thought that was you on Net Weather alright:D. I still think there is no harm in posting FI charts, once you mention the clause that they are 99.9% likely to change on the next run and not likely to ever materialise and are open to substantial change etc. (I usually do state this). The pattern still remains pretty blocked, even on the 12Z GFS, which was a low outlier in terms of pressure later on in the run.

Just to add some more optimism, I may not post GFS operational at T+384 tonight, but if anyone wants to see some bitter wintry eye candy then may I refer you to perturbation number 16 (GFS 12z) - from T+180 onwards. Some stunning synoptics. However, this is a huge outlier in terms of cold, practically impossible that it would materialise to be honest.

Either way, its equally part of the model output IMO, and nice to see. Also, it will be interesting to see if ECM keeps or ditches the recent trend this evening.

SA.

Snowaddict

Another very consistent run from the ECMWF model this evening.

Persistent signs of a high pressure dominated outlook up to T+144.

At T+168, this high then becomes a Scandi high of sorts (albeit rather elongated).

Now after this, the output is unreliable, however I would note that between T+168 and T+240 there are signs for the high pressure to retrogress towards Greenland... T+240 shows the start of what this could lead to.

However, too far out to even rely on. At the moment its quite solid to say that from about 70 - 80 hours from now the weather will become dominated by High Pressure located directly over the British Isles. Later on there is the potential for this High to move to Scandianvia, or for retrogression to Greenland. The key again on this output is that the high does not sink, bucking the trend of recent winters. However, these later outputs are at least 192 hours out yet and too far to be any way certain about.

What I will conclude is that the ECMWF has been very consistent on recent runs. Also worth noting that the UKMO chart at T+144 is very promising on tonight's run (However this chart at this timeframe has not performed very well recently).

Either way, there are many areas of potential shown on the model outputs tonight and as I continue to say, the pattern looks very blocked and is a far cry from the recent winters of endless low pressure systems crossing the country bringing mild southwesterlies. However, the outlook is open to change.

Regards,
SA.

You don't want an elogated SH.
That doesnt open the door to the East as pressures too high and the stretch stops any flow inwards

Snowaddict

Deleted User wrote: »

You don't want an elogated SH.
That doesnt open the door to the East as pressures too high and the stretch stops any flow inwards

Yep agreed very much there BB. Indeed, thats exactly what happens on this run. The potential easterly is scuppered. What do you make of the latest ECM run?

I wouldnt like to give much stead on it past 168 and even that is stretching it.

I guess by this time forthnight if northern blocking hasnt happened and we dont have a scandi High-we'll see how much we were hopecasting.

Neither are impossible.

http://www.wzkarten.de/pics/Recm2401.gif

That would do nothing for us weatherwise.
It also tells us nothing unless it went further north and brought in the real cold from the North East jan '87 style.
No scandi high that time and the river avoca froze

Snowaddict

Deleted User wrote: »

I wouldnt like to give much stead on it past 168 and even that is stretching it.

I guess by this time forthnight if northern blocking hasnt happened and we dont have a scandi High-we'll see how much we were hopecasting.

Neither are impossible.

http://www.wzkarten.de/pics/Recm2401.gif

That would do nothing for us weatherwise.
It also tells us nothing unless it went further north and brought in the real cold from the North East jan '87 style.
No scandi high that time and the river avoca froze

Indeed, there is always the danger that the high could be blown away, but the pattern looks quite stubborn to me from what I can see. If the ECM went out further than T+240 tonight, the charts could be mouthwatering following on from the 240 chart. It would probably be the early new year before we would see the onset of anything very cold though.

However, things do look very positive, but as you point out very correctly the usual caveats apply and there is always the danger that these charts could vanish nearer to the time...

SA.

j1979p

I think it might be a good idea for somebody to put this caveat in a sticky or something so that you don't have to mention this in every post SA

Seriously though, I think we can all safely agree that forecasts after about 5-7 days are hopecasts in most situations. We should be able to describe weather conditions while simply mentioning it is based on GFS or whatever.

Snowbie

Well said SA, always err on the side of caution judging charts even into the relatively near future. Although some runs look mouth watering the odd spanner is thrown in. At +96hrs out or in the reliable timeframe we be in the more definite setup and nowcast less than +24hrs out, this is the golden rule i follow but with a block that is 1045mb+ and consistent on consecutive runs you could almost go as far as +120hrs out to be close to certain. As rare but has happened in the past when block patterns have come off even in FI.

I am a little doubtful due to a N or Scandi block would hold atm as the N arm of the Jet has some energy over the N latitudes and never breaks south of us too much. This is off last runs i noticed and have not checked it since. If this relaxes, were in business.

The only pattern that I see is northern blocking of various sorts and that has to develop yet.

Northern blocking is useless without pressure patterns in our neck of the woods playing ball and no model up to and beyond T144 shows that happening [yet]

Honestly some of the posts on the model threads on NW and TWO are like reading chapters of mills and Boon.
It's all the same except in those [so I'm told ] theres always a happily ever after.
You could take any of the threads of the last few winters and you will read the exact same things being said without the happily ever after though.

Deep Easterly

Are you saying BB, that even speculating about charts in FI is wrong? as I thought this was the purpose of this particular thread? I think we all know that more often than not hoped for set ups often are modified severely or even done away with altogether once they reach within 12/24rh timeframe.

While I understand you reason for caution, too much caution kills the idea of the thread and wears down the enthusiasm of those who like to analyse models at a far out range. It is only a model outlook thread and I see no harm in anyone wishing to give a run down of FI charts; In fact, it is quite educational to listen to if this, then that discussions.

We are all weather nuts here, please please let us enjoy our little escapism

No I'm not saying it's wrong.
Nothing wrong with speculation on various scenario's.

Theres nothing wrong with being realistic either though.