Can someone explain Shannon Entropy?

I thought she was an actress on Beverly Hills 90210 back in the 90s!

GFS control run is stunning!

http://modeles.meteociel.fr/modeles/gens/run/gens-0-1-132.png?6

Very High levels of uncertainty...

a majority of GEFS members now have an easterly on Monday, albeit a transient one in most cases

I don't know if there's an actual SSW occuring now unless it is happening at very high levels I (we?) don't have access to through the models, but I think it's fair to say the strat has generally warmed up since December and the strat vortex as been displaced and diminished.

We had an SSW event in late Dec/ early Jan that bordered on major, although it produced displacement, not mini-vortices.

The warming which looks increasingly likely from about t+240 should be more significant as it will be hitting an already weakened and diminished strat vortex.

In December there was about 2 weeks with scarcely a cold ensemble run and the actual weather was beyond zonal - days on end with rain and winds gusting to 60 or 70mph.

The warming that occurred post Christmas + general stratospheric warm up since is probably the reason things have slowed somewhat and we can see some cold in the models.

And it looks like there's more to come.

If mainland Europe was cold it would be stunning........

A sign of a shift to more Anticyclonic circulation (50%) out  at the end of FI.Could this be the SSW effect .

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=360&code=11&mode=0&carte=0

Be interesting if that could be proved

Meanwhile, the 6z shows a messy picture. The UK under trough based slackness which eventually allows an easterly in FI

Much as the MetoFaxes indicate, a low looks set to slide under the Scandibloc but the uppers aren't that great

Plenty more rain for some in the next few days

A fairly reasonable improvement in the 06z ensembles from what I can see.  This is for somewhere in the region of Manchester!

http://modeles.meteociel.fr/modeles/gens/runs/2014011606/graphe3_1000_233_37___.gif

Just had a look at the GEFS 06Z ens for Eastern England - I fully expected the Control to be a cold outlier but it had a lot of support! Very interesting, particularly given the news relating to MOGREPs. Watch this space. (The last 2 weeks have, if nothing else, been a much more worthwhile period of model watching as they all continue to chop and change after months of continual Atlantic dominance).

I would advise people to watch the runs on the 500mb/SLP paramater at the moment as opposed to the SLP/850hpa. The former gives you much more useful information about where blocking is happening; and also upper level features have a higher verification anyway. I would note in particular the slight amplification of the midatlantic high, and modest height rise in Greenland. Meanwhile in the arctic we have, yes I know...., another bering high nudging into the arctic! Before you laugh it is worth noting that there is a surface high developing in the arctic on the siberian side, combined with height rises on the pacific side this could become a notable feature down the line. Now take this all together we have the potential for blocking to form somewhere else other than scandanavia, the main limiting factor being the cyclogenesis still occuring from cold air over canada. OK so my point is, the cold air will come once we have the blocking; "we're not aiming for the truck" , the rewards down the line could be far greater, scandi highs with no northerly component rarely deliver significant snow anyway.   

 wonder if we'll see any of this in the coming weeks?

Well, correlation is never total proof of cause, just a probabilistic balance.

I've been watching the strat for several winters now, on a purely subjective observational level.

It is my perception that even small changes in strat temperature produce tropospheric results, sometimes subtle or short lived.

An example would be a slight shift in stratosphere temp from below to substantially above average in late November/ early Dec 2012. It really was a blink and you'll miss it kind of event, however....

This preceded a great deal of excitement on these forums and a week or so later we had transient, localised ice days and some lying snow.

As the warming was relatively minor and transient, however, I did not expect the cold to last and sure enough it was not until a much bigger warming the following January that we got a lasting snow event which was followed by incursions all the way into Spring 2013.

On the flip side the major SSW of late January 2012 delivered sustained deep February cold to continental Europe, but the same plunge merely kissed our East Coast, so it is far from exact.

There are people with far more knowledge than me and better brains who could probably make more of this.

For interested model watching coldies who are condsidering a jump off the Humber Bridge in an endless zonal winter, however, I would say the strat is always, always worth a look before you go! You can go all the way out to t+384 on GFS at both 10 and 30 hPa and it's accurate out to about t+192, and still better than tropospheric modelling at t+240.

The only bad thing is that it is difficult for those without a great deal of time to access ensemble data. You can get raw data from NCEP or pay to see it on a specialist site.

I would say if the tropospheric ensembles and the control runs don't deliver but the strat has been warm, then have your snow shovels and sledges ready and expect a flip..... that's how strong I think the correlation is from having followed it for a while.

Hi all,

Here's today's video update;

Colder For A Few Day's Next Week?

http://www.gavsweathervids.com

Look's like winds could pull into the east, briefly, before the westerlies probably return. It remains a complicated pattern though.

Cheers Gavin.

Well explained as usual.

I think us coldies will have to travel North for the moment.

Getting there slowly but surely.....http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=262&y=37

http://www.meteociel.fr/modeles/gfse_cartes.php?jour=16&mois=1&annee=2014&heure=6&archive=1&mode=0&ech=6&carte=0

http://www.meteociel.fr/modeles/gfse_cartes.php?jour=16&mois=1&annee=2013&heure=6&archive=1&mode=0&ech=6&carte=0

A year ago the Scandi HP formed.

A year on the same day the same  has happened although the comparison shows significant differnces.

My memory is that the easterly flow did not get in properly until the 19/20th.

Not the best of runs so far. Less of a push from the east .

Less of a Slider low at 138hrs.

More of a flattening of the flow from the atlantic. ie - Mid atlantic HP remaining strong rather than backing away west and allowing LP over iberia.

Although saying that - the HP to our east seems to look all that much more healthier.  less features spoiling the southern flank.

Oh dear. Goes up in smoke but at least we have pressure rising over the pole

http://www.meteociel.fr/ukmo/runs/2014011612/UN144-21.GIF?16-17

but it

Previously, the models had been flip flopping for some time and we were having similar 'will it, won't it' conversations on here.  That's not to say it will be the same this year but it does show that it can happen and we had a lot of snowy days right up to April last year.

perhaps events high up are playing havoc with the models. Could do with a belter from ECM just to calm the nerves

I actually think this is a good run.  At least we can put this "fake easterly" to bed and get on with the action that should build after it.