ECM Means look broadly in line with this morning's Op. Not quite as cold as yesterday's 12z though

If first of all I am looking in the right place (I may not!), it appears that the ECM is ahead of the game, closely followed by the UKM.  The GFS has been lagging behind but is starting to catch up.  I would prefer someone to concur or correct me before I start posting links.  Sorry, I am no expert and usually look for one of the more regular posters to provide this information.

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Yes indeed. Down here at least I usually look for -10C at 850, but as I mentioned the lower the pressure the closer to the ground that 850 line becomes and thus the higher a temperature you can get away with.

Here's an example (note: NOT based on any particular model).

Say that it needs to be -7C at 4000 feet for snow to make it to the ground. The ground temperature is 2C. I'm using this calculator.

At an SLP of 1025hPa, the 850 line is at 4860 feet (therefore it'd need to be colder than -7 at 850 for snow to fall - probably closer to -10)

At 1005 hPa, it's at 4350 feet (so -8 or so would do)

At 985, it's 3840 feet (so you could get away with -6)

And at 965, it's 3300 feet (so -4 or -5 would do).

Obviously there's a lot more to it than just that (lapse rates, evaporative cooling, boundary layer modification via a warm sea etc), but it gives a rough idea of why the models have been so snowy with relatively modest 850s - this is the polar opposite of a typical "driven by a massive high" cold spell.

Incidentally the ECM showed this beautifully a couple of days ago. 850s under lowish pressure were -5C or so, then as a high built in situ, without pulling in a colder airmass, the 850s fell to -8C over the course of a day - just because the 850 line was getting progressively higher.

We could really do with seeing temperature charts at x height rather than x pressure.

You can detailed temperature lapse rates on Meteociel for places in France where altitude is often key

http://www.meteociel.fr/tendances-neige/27293/aime.htm 

Brian - is this possible for the UK from the data you get?

The ECM looks great until you check the 850s. Cold rain for most!

pattern not details at the moment and that could become heavy snow with small changes

Not for the first time either within the semi-reliable timeframe.

I seem to recall them being at odds within T+240 at times last February prior to the arrival of the Beast, although to be fair ECM was as inconsistent as GFS for a while back then.

I've had chance to investigate.

1) Critical data is par for the course

2) Most non critical data is present but several types are reporting lower counts

So the above would suggest there isn't a specific issue because on any day of the year it is possible for some data counts to be lower than normal.

I've not been able to find out anything about anomalous data. However, I would expect all checks to be fully automatic because there wouldn't be time for manual ones. What probably happens is an alert is triggered when data is missing or anomalous and a case assigned to it for investigation.

Bugger me - quite a change here:

Firstly the PARA has kept things zonal and mild throughout more or less! BUT the ECM?

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Ecm @ 240:

High pressure over Iceland 1030mbs

GFS - Low pressure over Iceland of 945mbs

Its just crazy how different they are!

GFS snow rows on the 0z aren't that different to yesterday's 6z. General pattern is a little better further north, a little worse further south. There should be an overall increase, as we're losing a mild day at the front and adding a colder day at the end, so it's not a straight comparison, but the figures are:

Sorry Iceland actually has a central pressure of 930 - that's 100mb's lower than on the ECM chart at 240: 

ECM also completely different at Days 9-10 compared with yesterday's 12z.  Anything more than a few days ahead is unreliable at the moment. 

Ecm not to be trusted in these situations- its failed miserably in the past with handling northern blocking. It’s the queen of phantom easterlies!!

Pressure is low though, so those 850 temperatures will be at a relatively low altitude... Which may mean snow is more likely.

True but last years easterly - the ECM was the first to upgrade/pick up on this blocking and then followed by the GEM and the last was the GFS Op that picked up on this and all eventually followed the ECM until cross model agreement. etc.

That's what I am beginning to think? I mean we are mid Jan now and models still don't know!?