Ladyofthestorm

Yes GFS is forecasting a Euroslug.

That's a massive area of high pressure over the UK . (1044mb) Now if we get zonal winds reversal, that blocking high pressure sits in the Atlantic, bringing us very cold air. Plausible surely?

GFS long way off Fl , zonality cut off and Easterly ensues. One to define watch.

I am not so sure the High will hang on like a limpet. The ensembles are telling a very different story. Trend is the friend. High pressure eroded away allowing the cold in. The 850s suggest a gradual decrease in temps as the process continues. It is a waiting game. A significant SSW has taken place, zonal winds expect to reverse. I would imagine it will be a Nly first then Easterly or NE

Also Jan 2001, 2002 and 2003..

I can cope with that!!!

Ive seen the GFS do this so many times before the Effects the a SsW takes place, goes back to manufacturing reset state in FL. Fear not.

Most likely scenario.. Nly before the Easterly!!!

Classic omega block developing on that run. The models are sniffing at something.

Subtle changes in the 18z. Event time 138hrs.. The models are beginning to make the adjustments. That high looks less of a blocking feature. Could slip SW and let the North flood gates wide open .

3.6C for me please

If there is one image that paints the picture of uncertainty in the models created by this SSW, It would be this one. Note the GFS Operational and the GEFS control are outliers running warmer than the mean. We really cannot make any reasoned judgements past Christmas day! Expect big upgrades (cold) in the next 5days or so.

Get a feeling the models have yet to take into account the effects of the SSW. January looks very very cold.

That was my photo took over Old Deer in Aberdeenshire in Dec 2012. All I can say. It was weird!!!

Get that feeling that the 18z is sniffing at a substantial Nly Outbreak post Christmas t175 . The run gives too much emphasis on the Jetstream flattening out, find that hard Ends believe The end of the run a load of cobble. Typical 18z. I really don't think the models have a grip on the impact of this SSW event... Yet

Good morning! ECM now also toying with the idea of a Nly breakout of the polar vortex. Most likely affect of this SSW. I am of the personal opinion that this event will disrupt not split the vortex. That comes later I think with an additional warming post January. Christmas snow looking very unlikely for most but that wasn't in doubt since the flip in the GFS chart last weekend. Now chart watching for post Christmas period. Let's see where this goes.

Not unheard of though, Dec 1993, Jan 2001, Jan 2003, We do get them. Usually a blocking area of High Pressure though.

I agree BFTP, this SSW event is looking special. It wouldn't surprise me to see a very cold January. Snow, I am less sure of but cold I am confident with. Is it just me or does the Altantic patterns look like they are weakening on the GFS run to run? Xmas I am pretty confident won't be mild and wet for us.

Mind you the GFS ops runs yesterday were all cold outliers on the resembles graph. I think we are going to have to wait and see. It feels like both the GFS and ECM are heading to a compromise.

I agree. The GFS is going along with a very wavy Jetstream. A theme of last winter if I remember rightly.

I know.. Lol.. right stronger Jetstream at T192, but still very kinked. What's coming out of the USA is not as potent.

I am concerned about the GFS operational run being a cold outlier. However, It does look like the GEFS is trending colder too Do I let my heart rule my head and say GFS or do I go for the ECM???

That's more like it from the GFS 0z instead of these crazy lows from the Atlantic.

The ensembles for the air pressure are all over the place. With just 4days agreement before they go their very seperate ways. What I have mentally noted was that 4days ago the GFS has overplayed the Atlantic. That huge area of low pressure is far less potent now than it was forecast a few days ago. The Scandi High pushed much further west than predicted by the models 5days ago. I get that feeling the teleconnections are building up to something special and the models can't quite grasp the idea yet and factor it into the runs .

Unusual synoptics in the offing so we can't really find similar analogue years. I get that feeling the SSW event or two, will eventually split the PV and then weaken it. The Jetstream will buckle allowing initially a very cold Nly blast to a Scandi High bringing in an Easterly. The Atlantic once buckled will struggle to ramp up again