FI Charts ( T120+ onwards) Winter 2022/2023 **READ MOD NOTE IN FIRST POST**

GFS has a Scandinavian High forming in the latter half of the run, it's been flagged a few times in the last few days. If it verifies then hopefully it gets angled right, it could be the difference between cold from the PV in Siberia or hot air from North Africa.

A really excellent UKMO video demonstrating the model divergence and discussing the marginality.

Just for purely selfish reasons, as a Corkie, I do not like the UKMO haha

How cold are the temps really out east this year yet? Really a north or better still N East would give a beter opportunity for the sneacta. Id even take a north and hope some kind of disturbance shows its hand.

GFS ensembles show cold out to the 16th now.

I remember March 2013 well. It was bitter cold queuing to get into a concert in the Olympia. A few days later in Belfast, equally as cold but snow everywhere and in lambing season too. It was horrific with many lambs perishing.

Most of northern England was the same too.

I think the latest op run of the GFS is way off the mark in comparison to what the remaining 29 perturbations are showing. The OP run showing the low introducing much milder air is almost certainly a massive outlier regarding next Tuesday/Wednesday and the Atlantic low. The majority of the perturbations show cold hanging on and the low either stalling further out to our west or sliding to our south. As far as I can see, the breakdown is as follows:

Slider Low with snow risk in southern half of Ireland and further north in some cases (cold): 20

Low holding and spinning off to our west or southwest (cold or a little less cold than this weekend): 6

Low tracking over Ireland (less cold to mild): 4

5.50pm edit add on:

GFS run with little support for mild intrusion.

That alone wouldn't do much, especially given we already have a very blocked troposphere. However, such events occasionally can transform into major sudden stratospheric warming events. These increase the risk of blocking patterns provided downwelling from the stratosphere to the troposphere occurs. Blocking patterns come with an increased risk of cold weather to Europe. Where the blocking sits is always key after the downwelling occurs. The interesting bit though is, what would a major stratospheric warming do with an already blocked troposphere? Even if we do see a weakening of the block in the high latitudes next week, there's the expectation for a "reload" later in December and into January and that's without the influence of any stratospheric warming.

ECM has potential for some decent snow in the Southwest next week. This will obviously change but very interesting to follow over the next few days.

ECM, GEM, UKMO and ICON all showing the low sliding under Ireland, they can't all be wrong and the GFS right can they?

Whatever about the possibility of frontal snow with the low, it could still introduce mildness to the south for a day or two, they look well primed to keep the cold flowing from the East for another few days which is nice. Especially after those 100 straight days of southwesterlys which I'm still annoyed about 🙂

The inversion that one of the GFS runs was showing for the 17th was attention grabbing- quite warm uppers yet still very cold at the surface. As regards the low it could be the models are now getting a handle on the tropical low and what happens after its interaction with cooler waters. Of course the better heights around Greenland are a factor too on most models

I see the UK Met Office have a percentage ratio where they think the chances of the low Sliding is 70 per cent against 30 per cent for it to come further north. I'm absolutely loving taking walks in this weather. Of course i would love a snowfall as much anyone here, but i'll take the cold and dry option over wet Atlantic driven if this is what we are set for.

Hi all, thanks for your updates and for passing on all the knowledge. I’ve been trying to use the thread to follow the ‘journey’ of this particular weather setup with the class I teach in primary school. One question today was about the low pressure that could slide through off the south coast, and I wasn’t sure how to answer it. What makes the difference between that low producing frontal snow in Wexford / Waterford / Cork when it hits the cold air versus the low producing our usual winter wet, cold windy day? Does it depend on how far south the Easterly/North Easterly wind maintains its influence?

Im teaching 10 year olds so it’s useful instead of just showing them weather in the book, following a weather event like this and bringing in the required vocabulary from the curriculum as we go. Thanks again for your help!

Hi. You have it pretty much spot on already. Putting it simply, the airmass in place over Ireland must be sufficiently cold enough when it interacts with an encroaching area of low pressure. When this system clashes with the cold air it produces snow on its leading edge. The slider element refers to the low pushing up against the cold air before slipping away south and east.

The image below (Beast from the East language not mine...) is a good example of such a system

ECM ensemble mean at day 7 is a sight.