Winter Model Discussion 18Z 5/2/13 onwards.

[Captain Shortwave]

not sure i agree gfs06z has temps above freezing by wed night as tm air moves in.

The run is a lot better though than the 0z, this run some energy does go south East and a lot less goes North East. Meaning the high stays where it is, just out of reach for us now, but if more energy goes South East then we could get another snow event later next week

Simply put a 6z gfs run is the first run today which suggests this. Frankly the fact it even tried to do this almost made me die of shock

Edited February 7, 2013 by Captain shortwave

[Tim Bland]

Nice jet profile out to the end of next week. could see further undercuting lows?

Edited February 7, 2013 by Tim Bland

[bobbydog]

06 GFS has the low virtually static, centred over SE england for over 48 hours! unlikely?

[snowmadchrisuk]

Well I can see very little in the Models that suggest wide spread Snow next week going by this mornings output's, Sunday Rain to Snow , with the possibility that the Front stalls over the SE and they get a good Snowfall Sunday night , but for the rest of the country the PPN seems to clear quite quickly ...Following this according to the GFS a showery day Tuesday but not really Cold enough for any significant snow amounts especially in the West , and then it has the Atlantic trying to break through from the North West on Wednesday , possibly preceeded by some Snow for some .. But apart from that , I can not see any sustained Cold and Snow in the next 7 days , and it would take a massive turn around for the Cold to back West now ..

[Severe Siberian icy blast]

In the mean time the gfs at t150 looks good , with the Azores high separate to the Russian high and very close to a long fetched easterly with another big slider looking probable to slip in-between the high pressures and dive southeast . Very good looking set up there compared to the 0z

And hear we have the undercut

Happy days your looking at specifics which is far too far away , look the the Synoptics , Azores well to the south , strong Russian high , undercutting energy going under the block , that's a good set up, the main thing is we keep the Azores separate which stops the high sinking and the Atlantic coming over the top.

Massive upgrade in the mid term for prolonged cold

[Methuselah]

Very true. Those anomloy charts have been showing hight pressure over or towards Greenland all winter. They are not worth the paper they are written on until it starts showing in the models (which it never has all winter).

No latitude, they haven't been showing high pressure anywhere: they have been showing expected deviations from the mean...

[Severe Siberian icy blast]

Well I can see very little in the Models that suggest wide spread Snow next week going by this mornings output's, Sunday Rain to Snow , with the possibility that the Front stalls over the SE and they get a good Snowfall Sunday night , but for the rest of the country the PPN seems to clear quite quickly ...Following this according to the GFS a showery day Tuesday but not really Cold enough for any significant snow amounts especially in the West , and then it has the Atlantic trying to break through from the North West on Wednesday , possibly preceeded by some Snow for some .. But apart from that , I can not see any sustained Cold and Snow in the next 7 days , and it would take a massive turn around for the Cold to back West now ..

Sorry but that's a wrong interpretation my friend, the Atlantic is held and the energy split with some going southeast , a big back track from gfs.

[bobbydog]

Well I can see very little in the Models that suggest wide spread Snow next week going by this mornings output's, Sunday Rain to Snow , with the possibility that the Front stalls over the SE and they get a good Snowfall Sunday night , but for the rest of the country the PPN seems to clear quite quickly ...Following this according to the GFS a showery day Tuesday but not really Cold enough for any significant snow amounts especially in the West , and then it has the Atlantic trying to break through from the North West on Wednesday , possibly preceeded by some Snow for some .. But apart from that , I can not see any sustained Cold and Snow in the next 7 days , and it would take a massive turn around for the Cold to back West now ..

have to disagree there mate- the ECM shows plenty of potential for many places-

[TEITS]

So where is the Atlantic?

http://www.wetterzen...s/Rtavn3121.png

Cold spell still going strong into the following week.

Have to say some poor analysis from some today, very poor infact.

Edited February 7, 2013 by THE EYE IN THE SKY

[johnholmes]

below is the brief pdf I promised trying to explain how 500mb charts can and do give guidance to forecasters as to where and when surface features may form.

Comments about the weather next Friday.pdf

[Isolated Frost]

Very true. Those anomloy charts have been showing hight pressure over or towards Greenland all winter. They are not worth the paper they are written on until it starts showing in the models (which it never has all winter).

This winters composite seems good so far. +ve anomaly for most of Greenland, very large +ve anomaly over Svalbard and E Greenland. The notable presence of the -ve anomaly in the mid-north atlantic is what has skewed many perceptions. -ve anomaly straight through Britain as the jet, though southward shifting, has been strong and consistent in it's modelling/composition through the UK, not south of the UK.

Expect this to be diluted over the next few weeks as the Greenland-Scandinavia +ve anomaly strengthens, as signals for retrogression and a resultant s'ward shifting jet and -ve anomalies come into play.

[Isolated Frost]

GFS retrogresses, undercuts and shifts the vortex energy- substantial height building. This at D11 is a superb example of the extended modelling. Plenty to come through beforehand but I do not see any mobile and strengthening jet to disrupt any retrogressive motion set in place. A shift in the hemisphere likely again- more amplified then zonal.

[johnholmes]

Very true. Those anomloy charts have been showing hight pressure over or towards Greenland all winter. They are not worth the paper they are written on until it starts showing in the models (which it never has all winter).

hi latitude

With respect you are wrong. I hope the pdf I am going to post later today explaining in a bit more detail about how to use them and what they show may help you change your view about them. Once more I can say with conviction that used properly they give on about 70% of the instances good even very good guidance on upper air pattern changes. Please read my 12 months of data to show this is true.

Rather than clutter up this thread I am more than happy to discuss anomaly charts with yourself or anyone else on here via pm. Please believe me they do work. I would not be constantly posting about them if I did not believe this.

[SomeLikeItHot]

And hear we have the undercut

Happy days your looking at specifics which is far too far away , look the the Synoptics , Azores well to the south , strong Russian high , undercutting energy going under the block , that's a good set up, the main thing is we keep the Azores separate which stops the high sinking and the Atlantic coming over the top.

Massive upgrade in the mid term for prolonged cold

And continues more or less to the end of the 6z run. Shame the air is so warm over East Europe otherwise we would be in the freezer, although it is cooling as it moves across. However I will believe this set up when the ECM shows show agreement.

Edited February 7, 2013 by SomeLikeItHot

[bluearmy]

The ecm op delivers all snow to the home counties on sunday - that will defintely change run to run. couple of things to note. re the weekend, the removal of the warm front getting east of the uk on staurdays fax is a massive plus re sundays potential snow. need to see how that remnant warm front ahead of sunday's active feature is now dealt with on the noon issue. ideally, we need the dp's on the continent to be sub zero so that the surface feed ahead of the system brings those dp's across the uk. that looked like a big ask yesterday evening but with the morning charts, we may have a last chance of it happening when the updated faxes come out later.

secondly, the ecm ens mean is still not pushing the atlantic through in the longer term and a look at the mean anomly shows the uk sitting in the battleground as the atlantic energy sits on a nw/se axis into the continent. knife edge again ? think the 18z gfs last night and adjust it east a bit.

[Severe Siberian icy blast]

Massive upgrade in the mid term for prolonged cold

And continues more or less to the end of the 6z run. Shame the air is so warm over East Europe otherwise we would be in the freezer, although it is cooling as it moves across. However I will believe this set up when the ECM shows show agreement.

Please I beg do not get pulled into this upper air debate , the upper air at this range is not even worth commenting on , look at the bigger picture , good signals now going forward .

[Methuselah]

So where is the Atlantic?

Same place as it always is?

[Frosty.]

The weather looks like exploding into life during saturday night and sunday with potentially large snowfalls across the uk and colder air being sucked into the lows circulation from the east, it's like a cold bomb and it's big and it could bring the heaviest most disruptive and prolonged snowfalls of this winter so far and that is saying something since we have already seen some very snowy weather in certain parts of the uk during the last freeze in January. I think the gfs is modelling the low too far north, it seems even further north than the 00z and the ecm 00z shows it further south but I think most parts of the uk could have at least some snow between sun and tues and the high impact areas could become snowbound before that low fills and clears away southeast, the 6z shows a standoff next week between the scandi high easterly and the atlantic trying to move in.

The azores ridge looks like collapsing rather quicky during saturday and then we are in for an action packed period with snow again dominating the headlines.

Edited February 7, 2013 by Frosty039

[chionomaniac]

Very true. Those anomloy charts have been showing hight pressure over or towards Greenland all winter. They are not worth the paper they are written on until it starts showing in the models (which it never has all winter).

Anomaly charts - not height charts. Again this has been pointed out numerous times that an anomaly is just that.

And the anomaly for the first to months of winter so far at 500 hPa:

It is not the anomaly chart that has the error - moreso your ability to read them correctly.

Edit: note to self read through the thread further to see if anyone else has made the same point!

Thanks IF and JH

Edited February 7, 2013 by chionomaniac

[snowmadchrisuk]

have to disagree there mate- the ECM shows plenty of potential for many places-

Yes I apologize , For some reason wetterzentrale was showing me 00z charts ... I'm at work and stuck on a dongle, and Vodafone in Bristol is at a crawl this morning .... Although r.e just Sunday Monday , if the Low get's stuck over the Country the low 's warm sector will take longer to mix out... I must admit I was heavily influenced by Ian;s post yesterday but nice to see the 6z upgrading .. Ill have a full look at the charts when I finish work ...

[snowking]

I couldn't resist showing you this (may help to put across the other side of the story):

ECMWF snow cover projection by Midday Tuesday (I have left the scale off as I have never found this especially accurate from the source I use)

And the control run:

SK

[johnholmes]

okay folks I give up TRYING to reason with some of you who dismiss my attempts to explain what we can and can not get from close and careful scrutiny of upper air charts, principally the 500mb anomaly charts.

I have better things to do than keep saying the same thing, sorry, I will restrict myself to the more detailed thread where as promised I will post the pdf trying to explain these charts in more detail.

This is not toys out of prams but I have tried long and hard with great detail over about 14 months to show how they can and do give great guidance for major wave length changes 1 to 2 weeks in advance of them occurring. The data is there for anyone who wishes to go through, I think, 30 or 31 case studies from January 2012 to December/January this year.

[Ryan Dutch Weatherman]

Anomaly charts - not height charts. Again this has been pointed out numerous times that an anomaly is just that.

And the anomaly for the first to months of winter so far at 500 hPa:

It is not the anomaly chart that has the error - moreso your ability to read them correctly.

Edit: note to self read through the thread further to see if anyone else has made the same point!

Thanks IF and JH

Thanks , .for your constructive clear message . I hope the people wil learn now finally.

[bluearmy]

Sorry posted garbage due to my lack of computer skills!

the control run has the same starting data as the operational but runs at a lower resolution to T192. thereafter, the op runs at a lower resolution to the control but at more horizontal atmospheric layers. if the control and operational both resemble each other through the post T192 timescale, there can be a bit more confidence in the general pattern shown by the two runs.

[Methuselah]

ECM is sticking to its guns on the 00z run looks like a change maybe on the way later next week as we finally loose the cold air with the Atlantic trying to push in

UKMO, GFS and ECM are not far away at t144

Fairly decent agreement even at this range

But the ECM is always too progressive when it's trying to model the eastward advection of Atlantic air...