swilliam

Looks like the ECM is siding with the GFS for the midweek low.

You can tell it is a BH coming up - a finger of green pointing unerringly at the UK Longer term it looks a bit warmer but still decidedly wet. Even into FI Could be interesting meteorologically speaking though

The low res part has blown up that low to the West of us so probably best to ignore the rest of this run.

The result is that the jet stream is less strong and more amplified. This measns that the the LP is more likley to go SE and the Azores high dissappear off as seen in the later frames.

PV much further W on this run 06 12

You can see actually that it is at the top (mildest) on all the runs - the 18Z being the worst though as it is a long way from the mean.

Yes I pointed out the ensemble cluster from 20-23 Jan this morning with the op out of kilter - nice to see it is following its ensemble!

No-one is having the rug pulled from under their feet. I do not understand why you say that there has not been a pattern change (which means a change on the overall pattern - not just in our locality). This is where we were at the end of Dec - no blocking just a large deep intact vortex and a flat pattern round the whole of the NH . We are now here with extensive NH blocking - unfortunately for us though is is mostly on the other side of the globe but you can see our current block and the large one that has developed over NW Russia. Forecast a week ahead and still large amounts of blocking in the NH - again not very favourable for us. Remember a pattern change does not necessarily mean lots of cold and snow - just better chances for this which what we currently have.

Hi Kold Sorry I I was not really picking on your post I was just a bit fed up of reading a lot of posts which started of similarly beginning which one is right/wrong, talk of climb downs, kick on teeth for the ECM etc. and would just like to concentrate on what is being shown. This of course includes discussing the differences between the outputs and why they might occur and what is significant. Looking at the longer term ensembles there does seem to be a general trend for slightly milder weather after next weekend. this is probably to do with where that low near Iceland goes. Some nice runs in far FI as the PV generally becomes more fragmented.

Looks like the OP is still a bit out of kilter with the ensemble judging the short term ensembles - note the clustering at about -5

Why does it matter which one has moved which way and by how much - the interpretation is entirely subjective depending on whether you are considering will it snow and how long will be cold where I am to how flat/amplified the flow is or to the bigger picture (including NA and then to the whole NH). It appears to me that the difference between the models was due to small differences in the way and timing of ejecting the low from the Conus. Depending on this gives larges changes in the weather we can expect in our neck of the woods. This 'discussion' only leads to argueing as can be seen by the subsequent posts. If you want to compare the models use the official verification stats which paint quite a clear picture I think. Much better is to concentrate on what the models are showing, how this is changing, what level of agreement is there (not stating which one is right or wrong - nobody knows) what are the prospects for the weather in the UK based on interpretation of the models. As far as I can see it is all very unclear beyond the short NW outbreak next weekend and even the intensity of that is still not known. So I am expecting a lot of changes in the medium term output over the next few days.

Yes and that is because the upper low over the NE pacific is much deeper and greater in extent (especially s) on the ECM compared to the GFS

Why do you say that when it consistently is lower in the verification stats (and worse than the UKMO)

The 18z was uncannily similar to the 12 Z despite the PV being further West. We had to wait till the end to get the easterly again. For those unhappy about the output you just need to be patient - mxxxxxx about the charts will not changeanything.

The PV is not so far East on this run 12z 18Z

Short ECM ensembles out and op is near the mean. Interesting change in the ECM mean profiles between 192 and 216 hrs. You can see the PV East of Greenland disappear at 216 and a commensurate several degree drop in the mean 850 temp over the UK. I guess it proves NS is right to keep going on and on and on and on and on and on about this!

No - I just think any major cold has probably now been put back to beyond the 19th Jan whereas we had a chance of getting this earlier. There still could be shift in the medium term as well but this seems unlikley - I am just saying what is showing on the last run and how it has changed compared to previous runs.

I think they are (poor) in comparison to earlier runs. Any significantly colder weather has been pushed back to the 19th Jan (over a week away and in FI) and there is good agreement for this. Nearly all of the very cold runs have disappeared. So maybe not raging mild zonality but a major shift.

Yes this is true - people often say the models are more accurate when the weather is zonal but that is only because they are not scrutinised so much - I made this point a while back. A good example is when we have a big storm in a zonal setup - the strength and position of this then varies run to run and has a major impact on our weather.

It has to be said the ensembles do not look great either with most of them supporting the OP at 192 hrs.

You can disagree with them writing off the whole of January - the models currently only go out to the 27th (and the GFS is showing and Easterly at that point)

It does have another go in the far reaches of FI and looks like being successful - does not mean anything though apart from it is possible.

Yes it is very similar to the GFS at that time.

You can see the result on the later output with the block tending to sink and we end up with Westerlies - might get something in FI but that is just guesswork beyond about 192hrs.

Which would mean that we are unlikely to get an undercutting low at the 1st attempt - we will need either a 2nd or 3rd attempt for this (obviously then at a later time) or multiple bouts of the Azores high building with WAA to our west to drag the ridge west (like pertubation 7 as a I pointed out earlier).