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martthefart

Model Output Discussion; into 2015

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The three hi res GFS members going along with my hopes for a mid-month change still on the 0z. As the PV spills its guts over the next 10-12 days from the Canadian region to the west, this winter's repeating pattern of a mean disrupted PV allows for some heights:

 

post-14819-0-05474100-1420270244_thumb.ppost-14819-0-48384200-1420270244_thumb.ppost-14819-0-91535200-1420270244_thumb.p

 

How that ridge will develop and whether it will show longevity will take some time to evolve. It's getting the change that is pleasing and we just need this to build in confidence over the next 3-5 days. 50% of the GEFS at D16 now support some sort of heights building in our sector so that is trending.

 

In the next 10 days according to ECM we have short and sharp alternating PM and TM flows, probably averaging out at close to average temp wise. GEM is similar. D6-7 a storm on both passing to the north is worth watching:

 

post-14819-0-16980100-1420271112_thumb.g

 

Followed by a baby ridge in the flow due to helpful phasing, that may flatten or build further in subsequent runs:

 

post-14819-0-23212300-1420270780_thumb.gpost-14819-0-55168100-1420270780_thumb.p

 

Only transient features but may bring snow to the hills of the NW. The London 850's charts continues with its cooling down from around D13:

 

post-14819-0-05133800-1420271515_thumb.p

 

Maybe there is light at the end of the tunnel and we should know more about the MJO and strat warming signals by Monday so things may improve further.

Edited by i'm dreaming of...

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I'm liking the continuation of ridging up the Atlantic -southern tip of Greenland and now looking colder air is flooding South/west of Europe!

Maybe a Icelandic/ScandI ridge developing later on into the 3rd week with lows running to our South?

Again it's FI but it's there for us to watch out for treands

GFS&GFSp.... GFSp has the colder uppers further west too. Happy model watching people!!post-19059-0-38492600-1420272194_thumb.jpost-19059-0-64141200-1420272213_thumb.j

Edited by Argyle1980

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Just seen some tweets and Matt Hugo's update on the strat: https://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/page-56

 

  chionomaniac
@scotlandwx @blancassw @anthonywx just seen. At 10hPa shows Canadian vortex wiped out but instantly superseded by strengthening Russian sect
03/01/2015 07:51

 

Looks like the wait for an SSW will continue with more wave 1 & 2 action needed for a Major SSW. Any guaranteed blocking from an SSW looks likely (assuming it isn't delayed again) for Feb/March. Better than nothing but not really what we wanted.

 

I think we have learned something, that even the Golden Goose can prove as frustrating in the strat as it does in the trop, and that great background signals can be wasted in our location, with the US again getting some potential record breaking cold (again) in the next 7-10 days. 

 

The UK next 8 days temp anomaly from the GFSpost-14819-0-30314000-1420272980_thumb.p

 

Suggests average to just above.

Edited by i'm dreaming of...

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whilst mid month continues to look interesting, I am drawn to the fact that even when the z500 profile looks very promising hemispherically, we still seem unable to view a standing lw pattern. this 'mobility' makes me doubt the chances of a greeny high establishing and we will see either a toppler type as we saw late December or a scandi ridge as the best evolution for cold. (If the euro heights finally allow).

The sinking cold trough across nw Europe as part of a large displacement seems less likely now.

Awaiting the ECM extended to see whether it can end its love affair with the euro high.

The strat tweets don't offer anything we didn't already know. it was already forecast that the strat vortex would establish n Greenland/over the pole. Not convinced that it's headed to Russia. It does look more rounded and not strong which whilst making it less susceptible to splitting (round shape), also allows for height rises to our ne or east. (And over us). Any strong sustained HLB would be a struggle in that set up.

Edited by bluearmy

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.  My point (obviously) was that things can change quickly and did in Nov 10 based on that particular GFS run.  The poster was suggesting little chance of cold in the next 3 weeks...

 

 

No we have the luxury of having over 2/3 rds of it left

 

guys... there is no quick fix here, statistically we might have 2/3 of winter left, but to get a decent deep cold spell the general synoptic pattern has to evolve. the current one is a million miles from a cold evolution, in fact it could hardly be much further away.

cold (or hot in summer) spells dont just pop up out of nowhere, there has to be a pattern in place that would allow it... now there was in november, and december, but now its drifted further away.  we can get a good idea of what lies ahead by looking at the prediction charts for the upper atmosphere, the most reliable are the noaa anomaly charts, and they have consistently projected a flat, stable, westerly flow for the next two weeks at least.

so whilst the synoptic pattern through most of november and december might have given us a quicker route to a cold spell, we are currently further away from that ,  theres no quick fix likely.

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My analogy today looking at the outputs is that the patient has been resuscitated but is still in critical condition and could yet flatline again requiring further CPR!

 

There is a trend now to develop a touch more upstream amplification and even the ECM looks like it might further displace the Azores high at T240hrs.

 

This is mainly due to events in the east Pacific as a more amplified ridge develops building in towards Alaska, and also a possibility that the MJO might be playing a factor.

 

We need all the help we can get here so we  have to hope the MJO can make it into phase 7 and have sufficient amplitude, further to BA's post we shouldn't however expect some super Greenland block to appear, a toppler looks perhaps more likely, perhaps a re-run of the Christmas set up, the question this time is could we sustain that for a bit longer with the topple towards Scandi?

 

Overall at least a little interest but we need to see this trend continue and theres a long way to go.

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My analogy today looking at the outputs is that the patient has been resuscitated but is still in critical condition and could yet flatline again requiring further CPR!

 

There is a trend now to develop a touch more upstream amplification and even the ECM looks like it might further displace the Azores high at T240hrs.

 

This is mainly due to events in the east Pacific as a more amplified ridge develops building in towards Alaska, and also a possibility that the MJO might be playing a factor.

 

We need all the help we can get here so we  have to hope the MJO can make it into phase 7 and have sufficient amplitude, further to BA's post we shouldn't however expect some super Greenland block to appear, a toppler looks perhaps more likely, perhaps a re-run of the Christmas set up, the question this time is could we sustain that for a bit longer with the topple towards Scandi?

 

Overall at least a little interest but we need to see this trend continue and theres a long way to go.

 

 The orientation of the Atlantic trough is in line with the evolution on the EPS extended from yesterday.

post-12275-0-18132800-1420275879_thumb.p

Edited by knocker

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Sorry I'm not following that. The orientation of the Atlantic trough is in line with the evolution on the EPS extended.

Why are you using the mean, its obvious that some members don't develop that bit more amplification so you mute out any signal. The GFS and GFS P build the ridge in and you can see the ECM operational starting to do that but not quite as amplified.

 

As the ridge builds in the effect is to stretch the PV and low heights to the north, follow the GFS from T192hrs. If there is a signal for renewed amplification then IMO its the operationals that would generally see this first. The mean IMO is used too much in here and is useless if the pattern is undergoing a change.

 

I'm not suggesting some super cold or long term change, as you can see from my earlier post, the best possibly is a toppler but at this point its a whole lot better than the tripe currently being dished up by the NWP.

Edited by nick sussex

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Going to have to respectfully disagree here mushy. I believe that weather is ultimately chaotic, and most good cold spells I can remember suddenly appeared on charts at about T180, so whilst I accept that the next week will not produce any cold weather as such, I won't yet write off anything outside days 8/9.

 

This is not to deride in any way long range forecasts, anomaly charts or other drivers, because I think they are valuable tools in helping us understand the weather. However, many fine forecasters have been proved wrong at surprisingly short timeframes in the past by sudden changes in atmospheric conditions, and with 2/3rds of winter left, that is why many of us feel that epitaphs to either the winter or a particular month are being written too quickly.

 

Already the models are picking up on colder signals mid-month and it would not surprise me to see them brought forward in future runs.

 

Someone will no doubt light a fire in Southern Greenland later today and start off a whole new chain of events :D

 

no probs.... maybe i shouldnt have sounded so catagoric, you are right of course the weather is chaotic, it isnt set in stone that the next two weeks wont produce a deep cold evolution, but it is unlikely.

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the extended ecm ens now retrogressing those iberian heights to the west and allowing for a broad weakish nw euro trough centred s scandi. at the moment, that is at two weeks so unable to see how mobile the pattern will stay/lessen. all in all, that indicates a wintry period (wrt what we've seen thus far) but it could be a fairly fleeting visit.

 

i noted that yesterday's cpc 8 and 11 day mean gefs analogs were only registering around 0.77.  that's  quite low and perhaps reflects that the mean isnt likely to verify (hemispheric lw pattern). i doubt we are going to see a set up that didnt exist before!  maybe there are more marked changes afoot ?

Edited by bluearmy

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well from what im seeing from the models all of them out until fi is a very strong azores with very little movement.

ECM1-216.GIF?03-12

gem-0-216.png?00

navgem-0-180.png?03-05

gfs-0-192.png?0gens-0-1-180.png

not any of these charts look realistically likely to lead to anything remotely interesting for mid month.

and purple and orange in these locations = jan wipeout.

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There are VERY slight signs on the anomaly charts, much like the signal quoted by Fergie re the Met O clusters, suggesting some slight veer of the upper flow. IF this occurred 10-15 days time then the incidence of colder outbreaks behind surface weather systems would increase. However to me there is as yet no real sign of heights building sufficiently to really veer the flow to originate from the Greenland/Iceland or further north as yet. Stormy or very windy interludes for more northern and western areas especially at times, slightly milder air ahead of these systems and colder air for a time behind them. Even some snow down into parts of England is a possibility but more likely over high ground in these systems. But overall still no major signal of longer deeper cold yet from whatever direction NW, N NE or E.

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Morning all,

IMHO we can never rule out a cold outbreak regardless of what the NWP show,many a cold spell has cropped up at short notice take this one for instance a seemingly dire chart below,

archivesnh-1986-1-20-0-0.png?

Fast forward ten days to this,

archivesnh-1986-1-30-12-0.png?

Aythings possible.

 

The strats warming as we speak,

30mb9065.gif

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Morning all,

IMHO we can never rule out a cold outbreak regardless of what the NWP show,many a cold spell has cropped up at short notice take this one for instance a seemingly dire chart below,

archivesnh-1986-1-20-0-0.png?

Fast forward ten days to this,

archivesnh-1986-1-30-12-0.png?

Aythings possible.

 

The strats warming as we speak,

30mb9065.gif

Interesting that you post that example as I remember it clearly, however, I also remember that in his 1985/86 winter review Philip Eden remarked on how unusual the switch from strong zonal to stable easterly was at the end of January.

Also the zonal flow of January 1986 was colder than is the case now with a much less prominent Azores High.

Andy

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Morning all,

IMHO we can never rule out a cold outbreak regardless of what the NWP show,many a cold spell has cropped up at short notice take this one for instance a seemingly dire chart below,

archivesnh-1986-1-20-0-0.png?

Fast forward ten days to this,

archivesnh-1986-1-30-12-0.png?

Aythings possible.

 

The strats warming as we speak,

 

 

Just producing charts like that is very unscientific and really of no use. 1986 had very different background signals, one being we were in a low sun spot cycle:

 

post-14819-0-92245800-1420279680_thumb.p

 

For that type of comparison you have to have similar variables so a composite reflects the possibilities. Solar activity the last two months have been on the rise and this may be one of the factors that has drowned out the other positive signals. Remember Nov-Dec 10 was also similar to 1986 in that it was also at the lowest point of a sun cycle. During solar minimum these type of cold snowy events are far more likely than our current cycle. 

 

So IMHO we won't see a flip like you highlighted above. It is going to be very hard to get a trop led cold block and an SSW is probably our best shot; bearing in mind the current Winter's performance it is hard to argue against that.

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Thankfully I have more time to post now. A couple of points I wish to highlight.

 

Take a look at the N hemisphere chart as from today.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015010306/gfsnh-0-6.png?6

 

Now fast forward to +168 to +240.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015010300/ECH1-168.GIF?03-12

 

Now it is during this period as the core of the PV is to our NW that very strong winds could occur and even possible cold NW,lys.

 

Fast forwarding again to distant F.I and yet again the trend towards the PV weakening and splitting continues.

 

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-324.png?0

 

At this stage any blocking and following cold N,lys is more likely due to HP to our W ridging NW. How we continue from this stage is uncertain. We may eventually see blocking become established over Greenland rather than the Atlantic but this depends on the PV and whether it will reform or not.

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Why are you using the mean, its obvious that some members don't develop that bit more amplification so you mute out any signal. The GFS and GFS P build the ridge in and you can see the ECM operational starting to do that but not quite as amplified.

 

As the ridge builds in the effect is to stretch the PV and low heights to the north, follow the GFS from T192hrs. If there is a signal for renewed amplification then IMO its the operationals that would generally see this first. The mean IMO is used too much in here and is useless if the pattern is undergoing a change.

 

I'm not suggesting some super cold or long term change, as you can see from my earlier post, the best possibly is a toppler but at this point its a whole lot better than the tripe currently being dished up by the NWP.

 

I had altered my original post but I take it you are saying it's inappropriate to use the mean anomalies  such as NOAA, GEFS and the ECM for indicators of longwave pattern changes, albeit not in isolation?

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GFS 06z op still threatening a very mild Saturday (10th): post-14819-0-09975900-1420281013_thumb.p

 

Though the P is less inclined. Another test on the P's performance I think.

 

Sun-Mon (11th-12th) potential for a storm: post-14819-0-31865900-1420281180_thumb.p post-14819-0-72541000-1420281365_thumb.p

 

Very wet and windy if that verified but the pattern is too flat and the storm too strong for much snow. Still looks fluid as to the PM/TM trade off as each run throws slightly different variations on that zonal feed.

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GFS op continues the theme from the last couple of days with FI potential:  post-14819-0-36168700-1420281760_thumb.p

 

At that range details are not a concern. The pattern change continuing is the main upbeat theme.

Edited by i'm dreaming of...

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well from what im seeing from the models all of them out until fi is a very strong azores with very little movement.

ECM1-216.GIF?03-12

gem-0-216.png?00

navgem-0-180.png?03-05

gfs-0-192.png?0gens-0-1-180.png

not any of these charts look realistically likely to lead to anything remotely interesting for mid month.

and purple and orange in these locations = jan wipeout.

I find this post a little misleading, may be better if you could put up the northern hemisphere view so we could take in the hole picture. Also having just viewed GFS , GFSp and GEFS they all lead to a colder solution mid month ? Confused by your post.

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12z clusters are offering glimpses of a different story after mid-month with markedly more meridional pattern(s), but of course it's just not worth detailing all that stuff showing out post-15 Jan until we see a fair few more output cycles for signs of continuity.

Can i ask 2 questions,

 

What exactly is a more MERIDIONAL pattern as apposed to a zonal pattern and secondly,why would such pattern be poor for cold in the south?

Cheers.

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