Model Output Discussion

[phil nw.]

To be fair though these low temperatures were recorded with the influenced of snow cover and also with temperature at 850hPa below -5C so it's understandable.

the forecast is for 850hPa temperatures too high for snow/too borderline at 0C to -2C, over the areas suggested.

Not only this but it goes from -2C to -15C in 3 hours, I'm not sure this has ever happened (or ever will).

Although the temperatures have occurred they occurred under conditions far removed from those shown on the 18z - and besides most of the time the GFS has shown these bizarre predictions they generally haven't come off - there was a suggestion of -10C last week at one point over east Wales +48 hours from the actual time, the temperature turned out to be +2C generally.

Dont get me wrong though I dont have a problem with the trends it predicts but if it's predictions run on interconnection then it potentially causes problems with the GFS ability to predict in a stable manner, but whether it does or not I'm not sure... if it doesn't then it doesn't matter much

I think GFS op run was clearly off the scale on those mins,Stephen,

http://charts.netweather.tv/ensimages/ens.20100118/18/t2mShropshire.png

Just a little.

[TEITS]

Excellent trend once again and the most important trend for me has to be the ECM ensembles. I said this morning the colder members have increased and this has followed with the 12Z.

The important question though is have we learn't from this weeks model watching?

Some of the comments this week have ranged from "No sign of anything cold for the next 10-15 days" to "The Atlantic is definitely going to win this battle". What we have seen this week is the models underestimate the blocking to the NE. This is why its important to use your experience/instinct when following certain synoptic patterns. If you rely on the models then you're likely to be misled. At times their are certain synoptic patterns that the models will handle extremely well but this week hasn't been one of those patterns!

I still think Wed is very uncertain. The GFS has pushed the precip further SW with every run and now it only affects SW Wales/SW England. At the rate the models are trending it will be the front on Thurs/Friday that could bring the snow. As for this weekend and the uncertainity continues. The front moving in during Friday is going to struggle to move further E and there is the risk of this becoming stationary over E England. I feel this front over the next few days is worth keeping an eye on, probably more so than the Wed event!

[Blizzardo]

Todays GFS 0z in the short term has snow risk on Wednesday night mainly for North West Scotland.

The Atlantic does push in briefly on Thursday and Friday but the block fights back and by Sunday there is an Easterly influence with a snow risk, especially for the South East by Monday.

Big changes compared to yesterday mornings GFS.

[Great Plum]

Well, I don't often comment on the models, generally because I don't know a lot abouth them! However, Master Plum decided to wake me early this morning sp I've been at a loose end!

Looking at the 00Z GFS run, it does look like the Atlantic is running out of steam - most of the run looks below average but not mind numbingly cold (yet!) There also looks like there will be a lot of high pressure around - perhaps some chance to see the sun which at least around here has been hard to find recently!

One thing I have noted is that the trend does seem to be getting cooler and cooler... I don't understand all (any!) of what is talked about on the technical model output discussion but I take my hat off to those who spend their time looking at the teleconnections. I am hopeful, however, unlike GP (the other and more meterologically talented GP!) of a below average February. However, I can only base this on a hunch rather than anything else... (I did see a number of seagulls inland this weekend though!)

[The PIT]

Wednesday is very uncertain. Morning forecast clearly showing a lack of confidence in the snow and as you say much further west and south than originality predicted. Still a lot of scatter on the models so FI certainly starting for once within T96 boundary, also shown by the uncertainty on Wednesday forecast as well.

[Duane S.]

Just a few differing thoughts from the GEFS ensembles about where we may be, or not, in about a week's time...

[Frosty.]

Nothing thrilling about the 00z runs, a lot of high pressure drifting around but at least temps look slightly below the seasonal average but not much in the way of ppn.

[lorenzo]

The stand off between east and west continues on this morning ECM.

I think the models are stretched at present resolving the issue of where the main energy goes after interaction of the latest atlantic low with the boundary of the seemingly immovable object the SH.

Glimpses of cold, glimpses of Eurohigh - it really makes every run throw up a chart each side of the cold / mild camp wish for or can debate on.

Looking to the 27th is now interesting signs a few days ago on ensembles for another dip in temps, the polar pool of cold air finally moving southeast and setting up somewhere useful for cold. However at that point a euro high is sitting over us and essentially we are the block !

Fully expect later today to change again!

[Strider]

You could well jinx it (or "Murray" it, as I often say as a F1 follower- and yes I mean the motorsport and not the slight modification of FI as in Fantasy Island!). If we see anything like this appearing in future runs:

http://www.wetterzen...00119890116.gif

...then talk of a B******t will be entirely justified. I've also seen it referred to as the "Eurotrash" High, just out of interest.

But for now, no sign of any of those- at most a Euro High sat very close to Britain, but more likely a bit further north than that, and no pronounced jet to the N and NW.

Out of interest, how warm was it in that winter?

The GFS esembles are just scatter gun after this week tbh...

[Jarrow Posh]

GEM looks like an absolute peach in FI to my untrained eye.Thoughts anybody!

[NorthNorfolkWeather]

Looking to the 27th is now interesting signs a few days ago on ensembles for another dip in temps, the polar pool of cold air finally moving southeast and setting up somewhere useful for cold. However at that point a euro high is sitting over us and essentially we are the block !

Fully expect later today to change again!

A really good post stating what SHOULD be obvious, for a block to happen, someone sits under the block.

Like you Lorenzo, I expect to see some evolution of this, we could get some more cold, we could get mild, but it's been fascinating watching how FI has moved from T184 to T36, the models still don't know what will happen tomorrow, with even the media (sorry mods, wrong thread I know) not sure whether Birmingham or London will see any snow

[SussexmarkyMark]

Excellent trend once again and the most important trend for me has to be the ECM ensembles. I said this morning the colder members have increased and this has followed with the 12Z.

The important question though is have we learn't from this weeks model watching?

Some of the comments this week have ranged from "No sign of anything cold for the next 10-15 days" to "The Atlantic is definitely going to win this battle". What we have seen this week is the models underestimate the blocking to the NE. This is why its important to use your experience/instinct when following certain synoptic patterns. If you rely on the models then you're likely to be misled. At times their are certain synoptic patterns that the models will handle extremely well but this week hasn't been one of those patterns!

I don't think that is a 'range', as both comments you have written mean pretty much the same thing. The range was from "No sign of anything cold for the next 10-15 days" to "The Easterly is definitely going to win this battle". To be fair though, the vast majority of posters went for something in between - fairly benign early on, briefly colder mid-week and then mild and wet towards the end of the week, which is pretty much the way it has been going - although those sort of comments are usually ignored and forgotten as they are not 'exciting' enough for the hope-casters.

As for the charts this morning, certainly more of them hinting at a more easterly flow over the weekend and into next week, particularly for more eastern parts of the UK. Still nothing too severe, but certainly hints of a more continental influence than Atlantic influence, but the trends are not there yet to be definite.

Edited January 19, 2010 by SussexmarkyMark

[BLAST FROM THE PAST]

What is clearing through the mist is that medium term we must be looking NW for the end of Jan into FEb pattern. Height rises up there to start a synoptically similar period to New Year and early Jan. Jet will kick south as retrograde occurs, its messy but that is where we are heading. This is where I mainly differ from GP as ther next cold shot is unlikely to be brief because the block will drift slowly ese as we go through Feb. But what Nick S says I agree, absolutely no B coming for sure.

BFTP

[Frosty.]

What is clearing through the mist is that medium term we must be looking NW for the end of Jan into FEb pattern. Height rises up there to start a synoptically similar period to New Year and early Jan. Jet will kick south as retrograde occurs, its messy but that is where we are heading. This is where I mainly differ from GP as ther next cold shot is unlikely to be brief because the block will drift slowly ese as we go through Feb. But what Nick S says I agree, absolutely no B coming for sure.

BFTP

The gfs & ecm 00z look similar at T+240 with high pressure pulling further west with a chance of an outbreak of arctic air but still too far out and high pressure generally in control until then but at least we get some decent frosts. The ukmo 00z looks disappointing at T+144 compared to the 12z yesterday.

[yamkin]

Very interesting comments from the 'TWO Forum' courtesy of warrenb

I think we are in for one cold month of February. slight strat warming, a dying El Nino and a jet that is allergic to Iceland all point to a PV all over the place and the cold just getting stronger. The models will start to come round to a Atlantic ridge going north and joining with our Siberian friend over the next week or so.

[TEITS]

although those sort of comments are usually ignored and forgotten as they are not 'exciting' enough for the hope-casters.

I certainly haven't forgotten them as I actually saved a few posts!

The point im making is the change in the model output these past 48hrs isn't actually that surprising because we see the models regularly blast any blocking away. However some failed to see this because they were relying on the models instead of using experience/instinct. Im not having a pop at anyone im just saying at times we need to use forecasing instinct when viewing certain pattterns on the models. What you call hopecasting I call instinct!!

Back to the models and there is no doubt the GEM is the pick of the bunch. However I still feel +144 is very uncertain at the moment as this mornings 0Zs prove. However an E,ly is looking increasingly likely but its what happens beyond that is more uncertain.

ECM ensembles just come out and these are amazing compared to 36hrs ago. The Sunday 12Z run had hardly any cold members and now we see a massive cluster of these with very few mild members!

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Amazingly the Seagulls could yet prove more reliable than the models and some forecasters!

[swilliam]

GEM looks like an absolute peach in FI to my untrained eye.Thoughts anybody!

yes - an outstanding run - 1060mb block in S.Norway and 1040 in Greenland -

then the high retrogresses to Greenland - this would be the absolute best we could hope for out of the current set up.

Seems fairly unlikely but not impossible.

[yamkin]

I certainly haven't forgotten them as I actually saved a few posts!

The point im making is the change in the model output these past 48hrs isn't actually that surprising because we see the models regularly blast any blocking away. However some failed to see this because they were relying on the models instead of using experience/instinct. Im not having a pop at anyone im just saying at times we need to use forecasing instinct when viewing certain pattterns on the models. What you call hopecasting I call instinct!!

Back to the models and there is no doubt the GEM is the pick of the bunch. However I still feel +144 is very uncertain at the moment as this mornings 0Zs prove. However an E,ly is looking increasingly likely but its what happens beyond that is more uncertain.

ECM ensembles just come out and these are amazing compared to 36hrs ago. The Sunday 12Z run had hardly any cold members and now we see a massive cluster of these with very few mild members!

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Amazingly the Seagulls could yet prove more reliable than the models and some forecasters!

Good post TEITS. Have you seen the London set of ensembles? They are very interesting. http://www.wzkarten3.de/pics/MT8_London_ens.png (MOD's, just using London as an example)

[SussexmarkyMark]

I certainly haven't forgotten them as I actually saved a few posts!

The point im making is the change in the model output these past 48hrs isn't actually that surprising because we see the models regularly blast any blocking away. However some failed to see this because they were relying on the models instead of using experience/instinct. Im not having a pop at anyone im just saying at times we need to use forecasing instinct when viewing certain pattterns on the models. What you call hopecasting I call instinct!!

Well at least we can agree with something, as I 100% agree with interpreting the models with experience and instinct as that is exactly what I go for, that's why I had no expectation of a full-blown eaterly this week .

What is clearing through the mist is that medium term we must be looking NW for the end of Jan into FEb pattern. Height rises up there to start a synoptically similar period to New Year and early Jan. Jet will kick south as retrograde occurs, its messy but that is where we are heading. This is where I mainly differ from GP as ther next cold shot is unlikely to be brief because the block will drift slowly ese as we go through Feb. But what Nick S says I agree, absolutely no B coming for sure.

BFTP

Not sure why my previous post was deleted. I was just asking what a 'B' was, as I have no idea what he was referring to.

[I remember Atlantic 252]

Well at least we can agree with something, as I 100% agree with interpreting the models with experience and instinct as that is exactly what I go for, that's why I had no expectation of a full-blown eaterly this week .

Not sure why my previous post was deleted. I was just asking what a 'B' was, as I have no idea what he was referring to.

this is a B 4th feb 2004, nothing like that due thankfully

[Tom D]

GEM looks like an absolute peach in FI to my untrained eye.Thoughts anybody!

I remember the ECM showed the block moving west trying to get over Greenland a couple of days ago, but it completely backed away from that idea and looks a bit messy now.

I think that one is something of a perfect scenario, and perfect scenarios at that range don't always happen (although this winter you never know!)

[SussexmarkyMark]

this is a B 4th feb 2004, nothing like that due thankfully

Thanks. Although I have to say that chart looks quite nice to me as a change from the horrible grey, chilly nothingness of the last couple of days.

[TEITS]

Looks like the front stalls across the E on Friday.

http://www.wetterzentrale.de/pics/Rtavn904.png

Outside chance of this turning to snow later on.

A chilly saturday according to the 06Z.

http://www.wetterzentrale.de/pics/Rtavn10217.png

Edited January 19, 2010 by THE EYE IN THE SKY

[nick sussex]

Well if you believe the gfs snow pushes westwards at 96hrs! Hard to have too much faith in the output at this point so we'll have to wait till this evening when hopefully agreement can be reached between the models.

[TEITS]

Well if you believe the gfs snow pushes westwards at 96hrs! Hard to have too much faith in the output at this point so we'll have to wait till this evening when hopefully agreement can be reached between the models.

We even have an ice day on Sunday for some regions!

Have to say at the moment im seriously mistrusting the models even though the 06Z is showing what I want to see. However in a strange way im finding this more entertaining than if a cold spell was locked in with all models agreeing.