Cold Winter Night

Give me GFSp instead of EC tonight! Far better, with heights over Iceland instead of them sailing out Into the West.

ECM similar to this morning. From a cold&snow POV good for the North, bad for the South and the continent. The GH & deep trough are too far to the Northwest for many unfortunately, and we are not talking about details here. I can only hope there will be some more heights to the Southeast of Greenland, but these are not the stellar runs I was hoping to see. 850hPa Temperatures are impressive over Europe, 2m Temps: not so much. All that beautiful cold air is wasted over warm Gulfstream waters, the continent is not cold at the surface, covered with clouds. High DP's I think. True cold still far to the East in Russia. EC 2m temps at 240

The Stronger-Scandi-High-As-It-Gets-Closer scenario is a serious one to keep an eye on. An outsider for sure, that plays out 72h-144h from now. It's a big IF, but IF the SH gets even stronger than on GEM now, with lower heights over Europe, we could reach a tipping point, where the High does not dissolve as it did on previous runs, but survives. That would take us into classic territory. Scandi High - Retrogressing towards Greenland - Supported by amplification in Atlantic. Cold moving West in lower latitudes, over South Scandinavia/Baltic/Poland instead of North Scandi/Norwegian sea.

UKMO 144 yesterday and 120 today. This timeframe is far from resolved yet. Scandi heights more pronounced, getting pinched more, lower heights in Eastern Europe. The Azores/Iberian High more West than yesterday.

Another interesting round of 12Z's coming up soon. This morning I went through this: 1. Quickly going through the runs: Wow! Charts look great, massive upgrade! 2. Looking more closely: Yikes, they are not that good at all. Heights way too far Northwest. 3. Ensembles, esp. EPS + plume De Bilt confirm: downgrade. The De Bilt plume was actually a bit of a cold bucket of water in the face. It is good for you folks who live in Scotland, the North of England, Northern Ireland perhaps, but not for those in the South or for me in Holland. Whether it is formally called a West based -NAO or not does not matter much, but we really need heights between Greenland and Norway for deeper and lasting cold. I was hoping for a stronger Scandi high to develop in the 72-120 timeframe. This is still getting modelled stronger every run and has my interest these 12Z's. If it gets strong enough, it will sustain itself through CAA and WAA. It would force an undercut, allowing depressions to enter from the West and cold to come in from Siberia. That would be my preferred scenario, some GEFS-members do this to an extent. It would assist in a Greenland High that extends in the GIN area. Retrogressing Scandi Highs are the foundation of much better Greenland Highs. Based on EC-72 this morning it would look like this:

Between 144 and 168 that round shaped low over Labrador just doesn't get the WAA going, and as a result the Atlantic/Greenland High fails to amplify and misses the connection to the Arctic High.

Stunning differences 24 hours apart. EC 192h yesterday and 168 today. Atlantic, Arctic, Europe: all different. Illustrates what @Kasim Awan said earlier. So many changes at a timeframe where EC-Op usually excels.

At +144h I wondered how the rounder shaped Arctic High would change the outcome. Here it gets stretched in the right direction I'd say. It is not far from GFS. Those lingering heights over France are a pain though. Let's see what happens there +192h.

Exactly. It would be nice if there was a bit of an extension of the Greenland High towards Scandinavia, forcing the core of the low pressure to move towards Central Europe. I expected the Scandi High to develop more today, but I guess I was wrong.

GEM and UKMO at +144h not entirely unlike, especially near Labrador, where the new ridging takes off. GEM at the later timeframes might therefore give some clues about the direction UKMO would have taken.

GFS speeding up quite a bit. At +168h already solidly ridging into Greenland.

Ah yes, well I was responding to you, and also a bit to some who were quick to conclude that the new GFS (GFSp) would be worse than the current GFS, just based on this past month's 500hPa height verification being a little lower. I know 500 hPa heights give a good indication, but they're just one parameter in a huge and complex model that covers NH and SH, Trop and Strat. Plus, these verification stats came up in response to the likelihood of the very cold GFSp verifying, but we won't know the verification of that output until after it happened. This run might become one of those dips, end up in the middle of the pack, or it might become GFSp's heyday. We simply don't know in advance. For all we know, this specific run might verify brilliantly, just not in our area, so we end up in mild SWlies, OR it has terrible verification, but we still end up in deep cold. Both are possible, because those stats apply to the entire Northern Hemisphere outside of the tropics.

The verification process of these models is a little bit more sophisticated than simply eyeballing a one month line graph of just one variable (500hPa heights). Tomorrow things might look different again. Based on these data alone, the only thing you could say is that they are all extremely close. Add to that the fact that we are currently in a situation with rare events and combinations of background signals and this might become a good test for the verification of all models in a complicated setup that includes both Troposhere and Stratosphere.

Let's be honest, we have seen several great runs, not just on GFSp runs, but all of the models have shown similar developments, operational runs, ensembles and ensemble members. And it is counting down as well, a couple of days ago we were looking at the +300-384h charts with excitement, now it's much closer already. The Operational runs that do not look that great do so in the later stages. There are massive changes in the output, and huge disagreement between models, at timeframes as near as +72h and that gives enough reason for at least 'synoptical excitement'. We cannot look at details yet, certainly not +144h and later. I am particularly interested in the developments surrounding the Scandi High and the Arctic High at +72-144h. In the past, models have underestimated those features, and I see them more developed on the output as it comes closer in time.

UKMO +144h looks very chaotic, but it starts to build heights in the Atlantic, heights are still developing in the GIN-corridor (Greenland-Iceland-Scandinavia) and in the Arctic. All good for the longer term. I think a UKMO +240h could look very good, but we will never know.

ECM is more like GFS than UKMO or it's own 0Z run. Subtle changes in the shape of the Southern Russia High and the Arctic High move the low on the Northern Russia coast closer to Scandinavia tonight, so the medium term is much different. But indeed it ends with 'potential' at day 10. All is well that ends well?

Yes, the good trends have been in all models for days now, despite all the wobbles. And so much more interesting than what we have seen the past few years! More interesting than the post-192h FI charts by GFS (P) will be the ensembles 96-168 and what ECM/EPS presents tonight. Will they join the rest showing medium term height rises popping up NW and NE?

Greenland High or Scandi High? GFS can't choose and goes for both.

GFS obviously not as good as ICON, but we do see the formation of a Scandi High.

Yes, more than 6Z, although not as much as UKMO at that same timeframe.

If a North Pole high moves, it will always go South I suppose you mean towards Svalbard/Scandinavia.

My take from the runs this morning: Still a growing Arctic High. Still multiple spv lobes. Still a tendency to increasing heights in Atlantic and GIN area. Still lowering heights to our East. The exact placement and strength of these features can make up to a 15-20C difference in our surface temperatures in a fortnight, with similar large consequences for precipitation type and amount. No reason for being downbeat, no reason for being overly excited. A great opportunity for everyone to practice their fence-sitting skills!

It's a pity we cannot see the strat data right away. But the theory that quick changes in the output would appear after the technical SSW happened, seems to get confirmation again.

Don't forget the GFSP. If reality ends up looking like this, GFSP has been the most consistent in modelling this.

Some mild Siberian air coming at us.