Ben Sainsbury

I actually think that area circled on the accumulation chart will receive a red warning, seems best location.

Have to agree, but yeah GFS 12z looking a little better.

Ah that helps, cheers!

4th Place? Do you mean within the verification stats of the high res models, excluding GFS, ECM etc. A little confused?

To add the ICON and NetwX NMM look to go hand in hand. GFS, ECMWF, ARPEGE, HIRLAM all point towards heavier, more widespread snow.

Not hugely but still a somewhat small west shift, Bristol throughout looks to be the far far edge. However I can't even trust high-res models, all of the showers the Bristol area witnessed yesterday, not one high-res model forecasted that. I always wonder whether the batch of snow will still correct eastwards as that is the general theme with these events.

And obviously as it stands we have an Amber warning out, we sit under the Highest Impact and 3rd Likeliness of happening. All it takes is for the Met Office to be 90% confident or so (few hours before the event) an in theory should be a red.

The only website I’ve seen possible snow accumulations mentioned was one of the Met Office graphics on Twitter was that 20cm was possible Thursday, and 0-15cm on Friday. Personally not worried about precipitation intensity, I think it’ll produce the goods we are looking for.

Agreed, merely eye candy as all precipitation is accounted for in its accumulation. As inaccurate as these snow depth charts normally are, my intention was just a case of showing how well the ECM has delivered (snow depth wise) compared to other models/previous runs.

For what I see the ECM 12z will have produced some of the largest snow totals of all the runs so far. Exceptional chart, the hardest hit being the Dublin area receiving almost 65cm of snow between Thursday and Saturday. Whilst most other places looking in excess of 20-25cm.

As the large potential snow event has now come into range on the NetwX MR model, I was intrigued to have a look. Can safely say I'm in shock and as unlikely and unpredictable it is to forecast as far ahead as Thursday. We're looking in excess of 18 hours of snow and as the rain to snow ratio is approximately 1:6, we're looking at 15cm+, likely much more. Just for fun tho and taking with a massive pinch of salt but interesting nevertheless given no marginality.

Small 850hpa temperatures changes up to T96 on the GFS and ECM, ECM maybe 6 hours behind in bringing in the cold, but a deeper cold pool over Russia.

I completely agree with you, without the ECM I have little confidence that the other big models are likely to get the pattern nailed on. At the beginning of the SSW event, many of the models were playing with the idea of high moving NE across the UK, but as a whole the models generally flipped between cold & mild setup. I only feel once the ECM caught onto the pattern, that many of the other models were beginning to firm up on the pattern we are looking at. Given its such a complex setup we are looking at, the verification statistics and the exceptional vertical resolution of the ECM that it would be stupid to ignore personally. The ECM has the largest capability of correctly modelling this pattern. But as many of you have said, almost all the other big models have consistency forecast a very cold pattern for several days now with good cross agreement, so who knows.

This is where I disagree, for the deep cold we are most certainly looking a week away. But for the general pattern we are looking at 72-96 hours at most; we are very close to nailing this upcoming spell. (Although the GFS seems to bring the cold in 12 hours earlier compared to the ECM)

How can I identify where a trough exists on the charts?

Crazy stuff in Bristol, was just sat at my desk and all of a sudden the chair I was sat in started shaking was crazy, truly indescribable feeling.

Only have a basic understanding too, but the ECM which have double the vertical levels of GFS has a better grasp at predicting the track and development of weather systems than the GFS. I think?

Interesting, done a little research... For comparison with JMA's 100 levels of vertical resolution. The ECM uses 137 vertical levels, whereas the GFS uses 64 levels. Whether there are any relation to how the JMA & ECM have a similar pattern at the moment unsure. EDIT: ARPEGE runs with 105 vertical levels. Therefore the 3 models all of which following a blocked pattern all have the largest amount of vertical levels compared to the UKMO and GFS which have less.

Correct! If I'm right its upgrade took place just over a year ago.

I have been thinking and reading about each of the models especially the GFS and ECM. I have seen many mention on here that the ECM has been particularly poor this winter, whether this be the case or not, this has no impact on the current projections from the ECM. If I'm going to be quite honestly I think this is merely a case of all the models performing exceptionally poor given the SSW. Given a record breaking SSW how can any of us expect the models to handle this well when this is data they haven't received before? (If you know what I mean) For the cold scenario that we all hope for the ICON has been excellent with consistency but I have a lack of knowledge to comment on it's general consistency, however now the ECM is in line with the ICON (and should take the lead in regards to the upcoming pattern) I next expect the GFS to move in line. After some research it seems that the GFS whilst using the ECM initialisation data performed much better than using its own "initialisation" data, you may wonder why this is relevant? Well I expect as I mentioned already for the GFS to be the next model to now move in line with the ECM as it begins to latch on to the trends that the ECM have picked up on. Whether this is relevant or not, it's my own personal opinion (& very much an amateur), we'll see what happens! For the time being lets enjoy some very controversial model outputs!

I completely understand where you are coming from, but I still struggle to believe that the pattern will completely flip being just 96 hours out. We can of course see small changes but I just don't see its latest run being wrong given its current consistency.

Really is almost impossible to tell. From what I see the low coming out the south coast of Greenland is a little stronger, high pressure over UK a little more SE, all in all minuscule differences which shouldn't have much of an impact to the general pattern that is evolving.

Am I not the only one excited about these showers in the NW!?

It's interesting with this upcoming event Thursday night into Friday. The current GFS shows rain turning to snow readily across the SE as the colder 850hpa temps move in from behind. There has been an increasing tendency over the last few days for our weather pattern to correct east. Not only that but from my own experience I don't expect the front to move so quicker into the block of cold air sat over us, have a strange feeling the front is likely to slow down or to be pushed further as it moves eastwards hopefully allowing the cold air to undercut the front. Obviously the NetWx SR currently shows just a band of rain for Friday but if the front doesn't move through so swiftly, who knows what will happen.

Was going to add for Friday looks impressive for some heavy back edge snow as the cold 850hpa temps move in. Temperatures hovering around the 2'c mark, arriving early morning, marginal but could pay off.