ukpaul

People seem to be vastly underestimating how an easterly affects up here; there’s a whole lot of high ground and, as the ECM vedur.is chart shows, it is a prime position to be in. Warm North Sea + cold uppers + elevation = thumbs up. The UKMO is the only model moving that potentially away at the moment by pumping across dryer less unstable air but that maybe just from Scotland. Having lived ‘down south’, a north easterly is a better prospect than a northerly, same as here but that looks less likely as the ‘second wave’ event at the moment.

Depends where you look and where you live. GEM, GFS control and GEFs good for all, GFS op better for the midlands northwards, UKMO not very convincing for anyone, ICON potentially poor for all.

GEFS is excellent at 192, only a few being tempted by a supposed southwards movement. Ship steadying?

The GFS appears to be leading the dance here, wherever it goes then other models toy with it 12/24 hours later. Yesteday’s high issues, for example, now showing more widely whilst GFS embeds cold then pushes through all sorts of opportunities. Where does the dance end up? I think most models will look GFS like by tomorrow and just hope that the GFS op doesn’t waltz off in yet another direction!

Is that the same feature as the 120h fax is showing or is that a separate one?

You can get them via the GFS 0.25 here, -13 or so appears to be the lowest. I would say that those on ECM would be lower than that, given the colder upper air. http://www.meteociel.fr/modeles/gfs/royaume-uni/point-de-rosee/3h.htm

Those charts are useless, way overestimated any snow from the westerly snow showers we've had, yet missed the one time when it did give us laying snow for more than a few hours!

And for the 2m temps, which shows the effect more starkly.

Isolated the op alongside the mean, so that people can check against it for future reference (n.b. for central UK)

Ensemble mean is much better than the op (n.b. that means for everyone!)

This is correct, which is why it is strange that people seem to be okay in the south with the coldest uppers being cut off. They are needed for the convection that is not being shown on these charts. The high is modelled further south and it can be that sort of precipitation that dwindles. The further north the high, the better chances exist for south of the M4 (I lived there for over twenty years, I speak from experience!),

The high pressure to the north is inflating and pushes down on the system over us in succeeding frames. This keeps thinks okay for snow for a while but the coldest uppers are then cut off and by Wednesday the spell is cold but mostly dry.

The difference between the two can make a big difference as regards convection. Snow can fall, yes,but that isn't the reason we would benefit from the colder uppers we were getting before this run. Let's look at the ensembles and see where it lies though..

The high was an issue on the 06z GFS and UKMO as well but seems to have been glossed over. ECM had a very different solution so maybe that is going to steady the ship later but GFS and the way it increases blocking from t144 down to t0 is a direction we don't want to see this time. Hopefully a temporary blip.

The PPN is okay for the north at that point but it's the way that GFS goes that is the danger, the high is now squeezing out the cold flow from Europe, now -9/10 as opposed to reaching -15. EDIT: This is what was warned about earlier, people should be looking at the way that goes before suggesting this is as good a run. Lower uppers being squeezed back to continental Europe equals shorter for everyone.

Some concern still on the high inflating to push PPN too far south for most of the country. Would be happier with a northwards correction quickly after this at 144 from the UKMO.

My only concern is the system being squeezed by the high to the north. Any more of that and we get into cold but drier air. ECM toyed with that for a few runs and dropped it but it needs an eye being kept out for that.

Back edge snow for five minutes or so, bit of a wintry mix though. Now for the stratospheric warming and, hopefully, more fun and games!

How can something be a fail when it wasn't supposed to happen anyway? The forecasts were very clear that this was a rain event with maybe a little bit of back edge snow.

The dew points are marginal and remaining above freezing for a lot of the time and that’s the most likely reason for any lack of concern from the forecasts. If they play ball, even then, If you look closely there are embedded features in the flow with higher uppers making it very hit and miss, even in heavy precipitation. Could all change last minute with a slightly different setup emerging, keep an eye on the dew points (they have to be below zero for any snow to fall). Had some epic horizontal blizzard conditions here yesterday, by the way, although it only started settling after sundown.

In the sweet spot today, with heavy snow all morning so far. Fields white all around and only the temperature creeping above freezing spoiling the fun! Note to those wrist slitters from the south in the mod thread - do what I did and move north, the property's cheaper and the weather snowier!

Last time I came across 'Recretos', he was posting about volcanic activity on a volcano forum (volcanos being another interest of mine). Looks like he's diversifying!

Must be very high up, there was snow visible until this morning but it had gone by the end of the day up on the tops. Nothng lying down here in the valley, of course. So the chart looks fairly accurate for this area in the far west of West Yorkshire.

A centimetre or two maybe for these parts on Tuesday, although EURO4 sees no lying snow, even in a lot of upland Pennine areas. The curse of the internet and echo chambers, soon we’ll have two forums in one, one hyping things that end up not being delivered by 0h and the other saying ‘nothing to see’ and then being surprised when there is!

Take it back, the slight delay and just enough of a squeeze allows the front to hit at more favourable times and without compromising dewpoints, although it's pretty knife edge for a while.