Model Output Discussion 12z 18/10/2012

[phil nw.]

Here`s a brand new thread ready to continue discussion with 12z outputs due soon.

General views about the coming Winter are always welcome on the relevant thread.

http://forum.netweat...pes-and-wishes/

Just model discussion here though please.

[phil nw.]

I`ll start of with a couple of images to show the type of pattern we are looking at going into next week.

A graph showing that the models are expecting a mainly -NAO pattern ie higher pressure to our north and lower pressure further south than normal.

Next to it is a Northern Hemisphere view from the ECM 00z mean output showing how the polar vortex is very much displaced allowing plenty of gaps for some Arctic blocking.

It`s too early to expect a real cold spell yet but if this sort of pattern continues as we enter November then cold lovers could be looking at their first taste of Winter- if we can get on the cold side of the blocking.

Edited October 18, 2012 by phil n.warks.

[Paul]

Latest from Michael Fish - an Indian(ish) summer on the way, but beyond that some question marks...

[Methuselah]

I'm sure that there's a bright red 'Beast From The East' on Michael's charts!

[Met4Cast]

The 06z ensembles showed how real cold flooding Southwards is becoming increasingly unlikely

All eyes on the 12z

[Cheshire Freeze]

I think lower heights over Greenland are going to preclude any retrogression of the HP on this run.....big backtrack since the 00z if so.

[Met4Cast]

I think lower heights over Greenland are going to preclude any retrogression of the HP on this run.....big backtrack since the 00z if so.

Big mark down to the GFS if that turns out to be the case and a big thumbs up to the ECM, it'll be interesting to see how the rest of the run evolves

Edited October 18, 2012 by Daniel AKA WMD

[Met4Cast]

The GFS has made a complete mess of that Greenland high, it looks worse than the FI Spaghetti maps

http://www.wetterzentrale.de/pics/Rtavn1141.png

[SMU]

always the hint of irony thrown in-

An excellent 12z UKMO

http://www.meteociel.fr/ukmo/runs/2012101812/UN144-21.GIF?18-18

However a pretty mediocre GFS

http://modeles.meteociel.fr/modeles/gfs/runs/2012101812/gfsnh-0-174.png?12

UKMO has all the blocking where the GFS has had it on the cold runs-

Interesting 12z as the GFS moves the wrong way the UKMO moves the right way-

never the less some pleasent warmth in the middle

S

[Geordiesnow]

More or less convinced now we will see a warmer spell of weather with some humid(?) air being pumped up, still a question mark over Sunday's rainfall and how heavy and long it sticks around but if/when moves through, regardless if its sunny or not, it will certainly feel on the warm side.

Still question marks over any colder set up though but the models have been consistant on sending colder Arctic southwards via Northerlies, whether this affect us in anyway is still too early to tell.

[phil nw.]

The GFS has made a complete mess of that Greenland high, it looks worse than the FI Spaghetti maps

http://www.wetterzen...s/Rtavn1141.png

Yes much better agreement with recent ECM output and indeed the GFS mean outputs..

Plenty of cold flooding into Scandinavia and Russia next week though.

[Cheshire Freeze]

always the hint of irony thrown in-

An excellent 12z UKMO

http://www.meteociel...44-21.GIF?18-18

However a pretty mediocre GFS

http://modeles.meteo...nh-0-174.png?12

UKMO has all the blocking where the GFS has had it on the cold runs-

Interesting 12z as the GFS moves the wrong way the UKMO moves the right way-

never the less some pleasent warmth in the middle

S

Wow- what a complete turn around. From the 186 chart of the GFS looks as though some form of easterly may result in FI, as unlikely as it may look at first glance at that time.

EDIT: FI offering no northerly or easterly. HP sinking over UK.

Edited October 18, 2012 by CreweCold

[Met4Cast]

Yes much better agreement with recent ECM output and indeed the GFS mean outputs..

Plenty of cold flooding into Scandinavia and Russia next week though.

Yep that's probably more important in the longer term, I'd rather have a good cold pool pushing into Scandi and Russia than a 2 day cold snap over us. Looking closer to the short term some areas could see some pleasant temperatures early next week, I think we have to keep an eye on the potential for some heavy rain on Sunday though, could see further flooding problems

[Methuselah]

Yep that's probably more important in the longer term, I'd rather have a good cold pool pushing into Scandi and Russia than a 2 day cold snap over us. Looking closer to the short term some areas could see some pleasant temperatures early next week, I think we have to keep an eye on the potential for some heavy rain on Sunday though, could see further flooding problems

Aye Daniel...A good snowcover up there would almost guarantee some fun-and-games, in a month or two's time. Synoptics willing of course!

[Geordiesnow]

I think we have to keep an eye on the potential for some heavy rain on Sunday though, could see further flooding problems

The GFS has some heavier than previously projected rainfall on this run and with warm air into the mix, its not really much of a surprise too see this, so as you say, one too keep an eye on.

To be fair, the only trends I have seen from the models was for a warmer spell for the UK, Arctic air to flood southwards and height rises over Canada/Greenland, only the height rises over Greenland has weakened somewhat on this run but apart from that, not an awful lot has changed apart from the details within each run which you have to expect.

As I said, don't get sucked into the charts and it seems some have.

[Cheshire Freeze]

Just for reference, here is the situation we don't want to see gaining a foothold as we enter November....an organising and strengthening PV with HP pushed to mid latitudes.

[Alan Medlock Valley]

Monday looks mild or very mild with a gentle SE breeze. http://www.wetterzentrale.de/pics/Rtavn961.png

GFS shows high pressure over the UK on 28th, a long way off but it wouldn't be warm, frost and fog could be issues with a slack airflow across Northern parts. http://www.wetterzentrale.de/pics/Rtavn2401.png

[AWD]

Surely there is only one way the GEM goes from here;

http://www.meteociel.fr/modeles/geme_cartes.php?ech=144&code=0&carte=0&mode=0&archive=0

The GFS shows the situation I alluded to earlier, with heavy rains fuelled by a steep thermal gradient are possible.

Just for reference, here is the situation we don't want to see gaining a foothold as we enter November....an organising and strengthening PV with HP pushed to mid latitudes.

That's not that bad is it?

Heights edging up towards Greenland and cold air filtering down over northern & Eastern Europe providing decent snow cover there?

Or am I reading from the wrong chapter and we want something like this instead;

http://www.meteociel.fr/modeles/geme_cartes.php?ech=144&code=0&mode=0&carte=1&archive=0

Edited October 18, 2012 by AWD

[Summer Sun]

We might be getting towards the end of October but some warm temperatures are showing for early next week for the south

But its short lived and by the end of the week temperatures return to near normal values

[Cheshire Freeze]

That's not that bad is it?

Heights edging up towards Greenland and cold air filtering down over northern & Eastern Europe providing decent snow cover there?

Or am I reading from the wrong chapter?

It's progression I was alluding to, if you play the frames through to that point you can see the vortex tightening up and becoming more intense. Heights won't make it to Greenland in that scenario as HP is being pushed south around the NH. Low pressure over the pole and a conveyor belt of HP around the mid latitudes.

So we now have the UKMO and GEM going blocked and the GFS crumbling since the 00z. Wonder which way ECM will go.

GEM suceeds with height rises as it keeps the lower heights over Greenland plateau as transient and soon ejects them to phase with the deep LP north of Scandi.

Edited October 18, 2012 by CreweCold

[AWD]

It's progression I was alluding to, if you play the frames through to that point you can see the vortex tightening up and becoming more intense. Heights won't make it to Greenland in that scenario as HP is being pushed south around the NH. Low pressure over the pole and a conveyor belt of HP around the mid latitudes.

So we now have the UKMO and GEM going blocked and the GFS crumbling since the 00z. Wonder which way ECM will go.

Ahh yeah, I see what you mean. Although its probably wise to expect some tightening of the vortex as we go through Autumn as that's "normal".

Edited October 18, 2012 by AWD

[SMU]

People should really stop jumping to immeadiate decisions...-

sure the 12Z GFS was poor-

However remember my comments last week around western greenland- if the lows are getting split & moving north it will work out in the end-

Look at the nice UKMO - note western greenland-

http://www.meteociel...44-21.GIF?18-18

Stunning GEM

http://modeles.meteo...nh-0-126.png?12 note the energy going north over western greenland-

http://modeles.meteo...nh-0-144.png?12 perfect

Nogaps-

http://modeles.meteo...0-138.png?18-18 slightly later than the GEM

http://modeles.meteo...0-180.png?18-18 Similar outcome-

I think the GFS & todays 12z suite ensembles will be wrong- however I will post up the charts later along with the 18z.....

Basically look at the NE states energy around 120- as usual up the left of greenland its game on, underneath is game over..

S

Edited October 18, 2012 by Steve Murr

[Fozfoster]

Just remember the GFS picks up on a theme pretty quick then drops it, only to bring it back nearer the time.

[Methuselah]

As I said before, it's only October. Winter's still six-weeks' hence...

[AWD]

Are these right as they seem odd?

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres

All in agreement!