Model Output Discussion

[Geordiesnow]

Looks like the GFS 18Z run to my eyes, easterly flow(if any) would probably be very weak and we could end up with quite a messy set up.

As i said in previous days, it won't take until at least Wednesday/Thursday to be even sure how shortwaves is going to affect the pattern. Life would be much easier without shortwaves!

[kold weather]

Yep Nick a totally different evolution again from previous runs but overall evolution of the synoptics is the same..but the cold pool that was present just isn't there at all.

Saying that something of an upgrade for the weak easterly on Sunday, so swings and roundabouts.

[Neilsouth]

That cold pool is far far away on this run , shame really might aswell just look to cold and dry weather.

[NorthantsSnow]

Oh boy. A drizzly easterly picking up at T150. Not quite the snowfest we saw on the 06z.

[mountain shadow]

Oh boy. A drizzly easterly picking up at T150. Not quite the snowfest we saw on the 06z.

The reason for that is the cut off high is 500 miles further south than it had been shown. Jet profile shows this well. However I would expect retrogression to repeat after this.

http://209.197.11.134/c9s4a5k3/cds/gfsimages/gfs.20091208/12/144/hgt300.png?dopvhost=charts.netweather.tv&doppl=841a626ccf041cb3cf541ce31e9117a8cf541c06&dopsig=8a17a50c0de9cc9dd63b6e949b14c349

[Geordiesnow]

Whilst shortwaves could still scupper any easterly chances, however i do think an easterly is looking more likely. Will it be a convecitve one or a dull or grey easterly.

The margins for error as we can see from just 6 hours in the GFS runs shows is quite small.

[Tim Bland]

Big downgrade this run. Lets hope its an outlier. Its a short lived topler to my eyes. Not going to bother klooking at the rest of the run but will await the ensembles with interest to see if this has any support (I hope not!)

[SP1986]

The outlook will always chop and change, I think probably most people know that in the back of their mind. It's very unlikely that a model output borne of FI was ever going to stay the same right down to even 120 hours or so. This pattern seems to be one that will still deliver cold even if the original prognosis fails, people will still get frost and fog, it just might not turn out to be an epic - this is what I was trying to say a few days ago (albeit not very well-worded) and was shot down in flames.

That said though, it could return to a similar pattern, afterall it's only one run...

My sneaking suspicions though are the the parallel run will keep a similar vein to what it has for the past week.

[NorthantsSnow]

Why is it not retrogressing properly with the Greenie High? Eurgh, it just sort of stalls over Iceland. Infuriating.

[snowmadchrisuk]

Big downgrade this run. Lets hope its an outlier. Its a short lived topler to my eyes. Not going to bother klooking at the rest of the run but will await the ensembles with interest to see if this has any support (I hope not!)

Maybe , but before people start saying it is just like ECM , it is nothing like ECM , couldnt be more different , just a different possible outcome yet again .

[kold weather]

Tim, its a downgrade for the easyterly BUT the synoptics are practically the same and the evolution is very similar bar the shortwave at 96hrs but still its very similar.

Thus, whilst its not even slightly as cold duen to that shortwave change, its still a COLD pattern which could easily evolve into a good cold shot.

[mountain shadow]

Why is it not retrogressing properly with the Greenie High? Eurgh, it just sort of stalls over Iceland. Infuriating.

???

Retrogressing fine to me.

[Tim Bland]

What do the Meto say about all of this ? i haven`t heard much from them so have they got access to `other charts`? the charts today have confused me ( not hard ) some people saying yes maybe snow orthers saying no snow but cold. just who is right !!

There is no right or wrong just forecasts. All models vary and so do the ensembles. FI starts on Sunday at the moment. I am actualy supprised how bullish the Meto have been today I expected them to sit on the fence a bit longer. 12z has min of 8c in the SE on Tues night on the 06z it had a hard frost! I expect this to be on the warm side of the ensembles and who know what option the 18z will give us!?

[kold weather]

Big battle between the colder air flooding down and the milder air of the big low in the Atlantic looks like its going to happen around 240hrs...just like what GP did believe would happen.

A big shame the 12z doesn't take the shortwave down, but we will have to wait for the other models to see if its a trend.

[Thundery wintry showers]

A somewhat odd run- something of a stalemate around T+120 and then the evolution kicks off after all around T+168 (I'm sure we will get a very potent east-north-easterly out in FI now). Will have to see how ECMWF and UKMO handle this as the GFS looks unlike any other evolution so far.

[nick sussex]

The gfs does overdo the cold but i've never seen those upper air temps over eastern europe before ,as for the gfs to me it looks a complete mess but in a good way!

[weather eater]

Maybe , but before people start saying it is just like ECM , it is nothing like ECM , couldnt be more different , just a different possible outcome yet again .

No Chris it’s not, and what does this tell us, FI is closer than we think and the models are unsure. No doubt that won’t stop some seizing on the idea that this is how it will all pan out, at least till the ECM comes out, and that gets seized on as the genuine article.

[Frosty.]

The GFS is now getting the wobbles as the timeframe for change gets nearer, now I suppose it's time for the ecm to step up and bring the beasterly roaring back.

[Harsh Climate]

In the more reliable time frame 0 - 120h the run is fine, it only goes pearshaped as we head into FI which to be fair is only one of many outcomes.

Even with this outcome: http://www.wetterzentrale.de/pics/Rtavn2161.png

Hardly a downgrade of epic proportions!... Im very interested to see what the ECMWF has on offer later, if its much different to earlyer that will clealry state the massive uncertainty in the models post 96h. Many more runs needed!

[Anti-Mild]

A somewhat odd run- something of a stalemate around T+120 and then the evolution kicks off after all around T+168 (I'm sure we will get a very potent east-north-easterly out in FI now). Will have to see how ECMWF and UKMO handle this as the GFS looks unlike any other evolution so far.

I was going to say the exact same thing! A very strange run that is totally at odds with any other tun in the last few days. I'm sure the op will be a mild outlier in the short/medium term.

[patneve]

I'm still confident of an easterly - the building blocks are there - I wouldn't look after 100 hrs, they have changed, are changing, and will change

[mountain shadow]

If anyone wants to know what a large -NAO looks like, this is it.

http://209.197.11.128/c9s4a5k3/cds/gfsimages/gfs.20091208/12/240/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf04e3eacf54e3ba1e91e8f1cf54e359&dopsig=4e0503e28f52af39d72c4ed98c5bdd40

I can't but keep repeating myself but we are entering a much much colder period next week. Whether it snows or not initially is irrelevant. Lets get the cold first.

A hugely negative AO to be followed by a hugely negastive NAO means only one thing. The former throws the cold air off the pole and the latter delivers it to us.

[snowmadchrisuk]

A somewhat odd run- something of a stalemate around T+120 and then the evolution kicks off after all around T+168 (I'm sure we will get a very potent east-north-easterly out in FI now). Will have to see how ECMWF and UKMO handle this as the GFS looks unlike any other evolution so far.

Well the MJO looks like it will have entered phase 8 today , I wonder if this is having an effect on the models.

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

[doublebarrel]

There is no right or wrong just forecasts. All models vary and so do the ensembles. FI starts on Sunday at the moment. I am actualy supprised how bullish the Meto have been today I expected them to sit on the fence a bit longer. 12z has min of 8c in the SE on Tues night on the 06z it had a hard frost! I expect this to be on the warm side of the ensembles and who know what option the 18z will give us!?

Thanks for the reply Tim before this gets deleted i`ll be quick. exactly it is so confusing !

even TWS is saying the same so what chance have i got the main cold looks too far over for my eyes ( but they`re dodgy ) !

[Lewis]

Not a very nice 12z, messy and tbh, all what we want to see is once again back in FI and nothing near to the reliable time frame.

Back to the drawing board for the ECM me thinks, if the ECM shows what it showed this morning, i think a lot of people will be disappointed i for one will not be, as i just want to get out of this mild zonality and SW'esterlies.