Model Output Discussion 29th December - Into mid-Winter.

[Ali1977]

Pretty sure this will change but this is v v cold and starting to drag in cold from the NE - this would be awesome if true. 

[Purga]

Icelandic High anyone??

[Ice Day]

At 222 we are developing our own cold pool with a comatose Atlantic.  Strange looking chart but I like it!

[Purga]

1 minute ago, Ice Day said:

At 222 we are developing our own cold pool with a comatose Atlantic.  Strange looking chart but I like it!

We could well get some ice days Ice Day,,,,,

[nick sussex]

Just now, Ice Day said:

At 222 we are developing our own cold pool with a comatose Atlantic.  Strange looking chart but I like it!

Lol! yes its all very slow moving but I'd rather have this trend than a hideous west negative NAO. We want any pressure rise to the north boxed in and not allowed to be pulled nw.

[bluearmy]

liking this solution in respect of what the background wants to do through week 2 - get a good wedge of heights to our north and the Atlantic will have to head far enough south to keep the uk in the cold side. 

[Kentish Snowman in Yorks]

2 minutes ago, Purga said:

Icelandic High anyone??

A UK Coldpool and an Icelandic Sausage!  What's not to like?!

Seriously this is developing into a very cold run for the UK.  

[Dennis]

5 minutes ago, Purga said:

Icelandic High anyone??

yes look at this too 

[blizzard81]

What worries me most is the complete lack of interest in the models to build a true Greenland high. I suspect it is due to a lack of WAA. It all looks rather sluggish and just seems to be waiting until the atlantic wakes up again. Another wasted opportunity in the offing!

[nick sussex]

1 minute ago, bluearmy said:

liking this solution in respect of what the background wants to do through week 2 - get a good wedge of heights to our north and the Atlantic will have to head far enough south to keep the uk in the cold side.

Yes definitely if we can box that wedge into the north then it will remain cold. I'm not interested in any blocking to the nw if its going to be too west based and push the Euro high ne ahead of the dig in the jet in the Atlantic.

[Ice Day]

Just look at the cold building to the north east waiting for a trigger.  Will it come on this run though?

[Purga]

Very nice snowy chart for many of us

FI well and truly but nice to go to sleep on..

 

Edited January 12, 2017 by Purga

[nick sussex]

We're in a bit of a catch 22 situation here.

At the moment the overall trend is to develop a west based negative NAO which is very risky, whilst that ECM op might have looked interesting we would need a correction se'wards with the main block further east otherwise we run the risk of being stuck on the wrong side of the jet, this could force a lobe of high pressure ne'wards ahead of the dig in the Atlantic and end up with a Euro slug over southern Europe.

It really depends how west based the negative NAO might set up, theres westish chance of trough disruption over France and low pressure trying to edge ne'wards into the UK with of course snow chances but you can't normally sustain a west based neg NAO and keep cold.

If its too far west its game over for cold and snow.

The GFS 18hrs run has a different take on things with that lobe of high pressure to the north and it will likely stay cold well into week 2. With that though its less clear cut re snow chances.

If we had a strong signal for a more central/central eastish negative NAO I'd be cheering that on so its a difficult one. I absolutely hate with a passion too far west based neg NAO's, they drive me nuts as you see the cold piling south well to the west of Europe into the mid Atlantic.

Anyway regardless of what I like or don't like we have to accept whatever verifies!

PS I think the plan should be! we give the ECM and GFS ops a few more runs to see if overall they and the ensembles trend east/se with any blocking. If they don't we bail out and look for the wedge of high pressure to the north!

Edited January 12, 2017 by nick sussex

[Froze were the Days]

Yes a good 18z run, but don't really have much confidence in the GFS currently - I think after about 200z it just tinkers around with slack heights to our north without much of a clue and typically ejects the high pressure to the south east at the end of the run (who would have thought that). Saying that the rough trend is the key and that's no Atlantic for 10 days maybe, IF only we could tap into some decent uppers.

[Singularity]

If the jet lacks oomph, under a west based NAO it can just get trapped with a ridge WNW from over or just N of the UK.

Not that this may be relevant anyway if the models are indeed being too progressive with the MJO forcing feedback - the 18z GFS happening to be a good case for this.

Edit: To me the EC monthly looks way too fast with the MJO impacts! Margin for error probably allows for that scenario though, knowing our luck. 

Edited January 12, 2017 by Singularity

[Man With Beard]

EC monthly goes down the west based NAO for D11-D18 

Eventually gets back to its usual northern heights anomaly by D25

 

 

 

 

[Trom]

51 minutes ago, Purga said:

Icelandic High anyone??

Would anyone happen to have a chart of the jet stream for roughly the same time.  Sorry I don't have access right now.

[booferking]

2 minutes ago, Trom said:

Would anyone happen to have a chart of the jet stream for roughly the same time.  Sorry I don't have access right now.

There you go.

[Trom]

Thank you - you don't see that very often in these Isles.  I guessed it had to look a bit like this from the charts but wow that really is a dead Atlantic stream.  Like someone flipped a switch.  Not really any energy heading North or South from the US let alone West.

[Seasonality]

1 hour ago, blizzard81 said:

Typical 18z. If that run comes off I will eat my slippers!

Say what you like about the GFS in general, the old chestnut about the 06z and 18z somehow being fantastically crap compared to their midday and midnight brothers just isn't true. I can't find the research on this at the moment. Maybe someone else could oblige.

[Gibby]

Surprised (unless I've missed it) there hasn't been more disappointment in this chart tonight. I know it's at 10 days but it has shown a marked increase in the sinking of the High to Northern France in comparison to recent runs with the dreaded Westerlies setting up across the UK. This could be what IF is referring too in his earlier tweet for the end of the month from ECM.

[london-snow]

46 minutes ago, Gibby said:

Surprised (unless I've missed it) there hasn't been more disappointment in this chart tonight. I know it's at 10 days but it has shown a marked increase in the sinking of the High to Northern France in comparison to recent runs with the dreaded Westerlies setting up across the UK. This could be what IF is referring too in his earlier tweet for the end of the month from ECM.

Gibby two days ago the meto was forcasting a return to mild as early as next week with no mention of cold either side of a brief milder blip or no blip at all. So how can a day 10 chart onwards be correct?

 

I'd say going on today's output and agree that the easterly prospect is somewhat diminishing with either a cold high or cold SE feed however it won't take much to budge into a more favourable situation (cold and snow wise). 

 

We are literally not talking about mass changes here so next 24-48 hours will be very interesting for the mid range pattern going forward.

 

On to the mornings runs we go with settling snow...

 

 

[radiohead]

1 hour ago, Seasonality said:

Say what you like about the GFS in general, the old chestnut about the 06z and 18z somehow being fantastically crap compared to their midday and midnight brothers just isn't true. I can't find the research on this at the moment. Maybe someone else could oblige.

There isn't a huge difference between the 4 runs and at times the 06Z or 18Z will score better than the midday and midnight runs. So it's very silly to dismiss the 06Z and 18Z.

However. I have learned that while there is no difference in the southern hemisphere, NCEP have (previously at least) noticed that the 06Z and 18Z tend to score a little worse in the Northern Hemisphere. There is a PowerPoint presentation about it, I can't remember exactly where I found it or what year it is from though.

[SomeLikeItHot]

56 minutes ago, radiohead said:

However. I have learned that while there is no difference in the southern hemisphere, NCEP have (previously at least) noticed that the 06Z and 18Z tend to score a little worse in the Northern Hemisphere. There is a PowerPoint presentation about it, I can't remember exactly where I found it or what year it is from though.

My memory was that say 72hrs forward 6z and 18z are worse than 12z and 0z, but at the same time, eg 6pm next sunday then 6z is better than  0z and 18z is better than 12z, as the accuracy degrades as you go forward and the accuracy differnce is between the runs is than the accuracy degrades over 6 hrs.

[Cheshire Freeze]

Opportunities endless from here at 168 hours