Model Output Discussions 12z 01/09/2016

[weirpig]

1 minute ago, Frosty. said:

Plenty of cold GEFS 6z perturbations, and there were others

Yep  Karl  Much better than this time last year chart wise that is.  Most have frequent Northerly North Westerly incursions  with quite low uppers filtering down the country  a couple even have a cold easterly late on in the  run.   All in All a nice set of ensembles.   It could well be a chilly Bonfire night this year.  Maybe.

[Barry12]

I've got to admit I'm a bit underwhelmed with the output this morning, ECM would have average to above average temperatures throughout. And while the Northern hemisphere is still looking blocked - which is far better than last year. It's still nowhere near as good as it was just 48-72 hours ago.

 

The GFS chart on the left is the forecast for the 31st October 48 hours ago, the right is the current forecast

Lets hope the 'good' charts staying in the 7-10 day range isn't a theme this year!

Edited October 25, 2016 by Barry95

[Met4Cast]

6 minutes ago, Barry95 said:

I've got to admit I'm a bit underwhelmed with the output this morning, ECM would have average to above average temperatures throughout. And while the Northern hemisphere is still looking blocked - which is far better than last year. It's still nowhere near as good as it was just 48-72 hours ago.

 

On the left is the forecast for the 31st October 48 hours ago, the right is the current forecast

Lets hope the 'good' charts staying in the 7-10 day range isn't a theme this year!

 

Classic example of the ECM over amplifying things in the long range only to correct to less amplified in the mid-term. I think we need to be very cautious of any amplification shown by the ECM beyond T144, seems to have had this problem for a couple of winters now. 

Good to see continued support for a disorganised vortex though, that's the trend we want continuing into early November. 

[weirpig]

8 minutes ago, Barry95 said:

I've got to admit I'm a bit underwhelmed with the output this morning, ECM would have average to above average temperatures throughout. And while the Northern hemisphere is still looking blocked - which is far better than last year. It's still nowhere near as good as it was just 48-72 hours ago.

 

On the left is the forecast for the 31st October 48 hours ago, the right is the current forecast

Lets hope the 'good' charts staying in the 7-10 day range isn't a theme this year!

You are right Barry  the charts you have posted  does show that over the last 48 hours  the  overall pattern isnt quite as good.  However the mean on the Gfs  isnt bad at all  i think most would snatch your hand off  for these charts compared to last year

[Barry12]

2 minutes ago, Daniel Smith said:

 

Classic example of the ECM over amplifying things in the long range only to correct to less amplified in the mid-term. I think we need to be very cautious of any amplification shown by the ECM beyond T144, seems to have had this problem for a couple of winters now. 

Good to see continued support for a disorganised vortex though, that's the trend we want continuing into early November. 

The charts I posted are actually from the GFS, but yes I agree with that.

[Mucka]

Just one run but agree with above posts that 06z are most blocked and coolest for a few runs.

Lots of chopping and changing on upstream predictions and uncertainty in longer term signals at the moment though.

We are back to waiting for the ensembles and mean anomaly charts to firm up on mid to longer range signals but always fun to analyse Op charts and what may transpire in the areas there is uncertainty and given this is the model output thread we may as well pointlessly but joyously over analyse current output 

One such area genuinely worthy of watching developments will be how the low over Iceland in the chart below disrupts/undercuts/or rides over the ridge built over the UK as it pushes East.

GFS 00z had this low disrupting and splitting energy SE/NE whereas ECM goes for it undercutting

GFS 06 z has even less disruption SE (undercut)

 

Undercut, what's it good for? (why could it matter?)

If we look through GFS 06z ensembles then we see the Op is not well supported with the majority of runs undercutting or at least with much better disruption (further West, more energy forced SE then NE) and this leads to the better blocking we see and ultimately better prospects for cold down the line.

The more undercut we can get from this low and importantly the further West we can have that happen then the more blocking we will likely have to work with through early November with the obvious caveat that we cannot know whether upstream vagaries will work with us or against us.

 

 

 

Edited October 25, 2016 by Mucka

[Ali1977]

There has been some downplaying of NH blocking over the last few days but things still look good.  

I'm just hoping the next EC seasonal model back up the last run showing a blocked winter as a whole, however going off what Ian F said earlier about the issues forecasting even a monthly run from the EC I'm wondering if this was actually way way off the mark.

[Frosty.]

Confidence in the outlook from next tuesday is low but the expert view is still for a change to colder NWly / Nly winds with an increasing frost risk as well as breezy / showery conditions, especially in the n / ne and eventually cold enough for hill snow in the north which ties in with those Gefs 6z mean / perturbation charts I posted above and previous page. It appears as though once established, it could remain on the cold side or at least below average with winds predominantly between NW / N for a while which would suggest a reloading pattern with a nw / se aligned jet.

Edited October 25, 2016 by Frosty.

[beng]

49 minutes ago, Daniel Smith said:

 

Classic example of the ECM over amplifying things in the long range only to correct to less amplified in the mid-term. I think we need to be very cautious of any amplification shown by the ECM beyond T144, seems to have had this problem for a couple of winters now. 

Good to see continued support for a disorganised vortex though, that's the trend we want continuing into early November. 

Just to be pedantic, those screenshots are from the GFS model output.

Edited October 25, 2016 by beng

[Man With Beard]

Rather busy recently and have been following the models in spurts only, but it does feel like a sense of "groundhog day" with this Greenland High. There must have been 100 medium-term modelling attempts at a proper 500mb Greenie High since early 2013. Virtually all have failed, and even the ones that succeeded didn't last long. A few days ago, the black-hole anomalies were being wheeled out again. It really isn't a surprise to see them failing again. To go three and a half years without one of any notable length, well that's ridiculous - it wasn't long ago that we had such highs lasting two or three months at a time (summer 2012 comes to mind). I do wonder if something has happened atmospherically to hinder its development.

This morning's charts, op and mean

  

  

Close but not a home run. A temporary N/NWly on the back of a Scandi trough but that's the lot.

Except of course for the ECM op, which continues to embarrass itself when it comes to heights in the Greenland area. When viewing the ECM op from now until April 2017, I'd strongly recommend putting some sort of censorship over the Greenland area in its T144-T240 charts. Maybe just write on your mobile/tablet/PC screen in black permanent marker pen in the spot where Greenland comes up? You may miss a few texts and emails, and it might make the Iplayer or gaming a bit tricky, but it'll save many of you a lot of anxiety pills and you might even enjoy Christmas for once.

[Faronstream]

1 hour ago, Ali1977 said:

There has been some downplaying of NH blocking over the last few days but things still look good.  

I'm just hoping the next EC seasonal model back up the last run showing a blocked winter as a whole, however going off what Ian F said earlier about the issues forecasting even a monthly run from the EC I'm wondering if this was actually way way off the mark.

From my perspective you seem to know alot about the upper air temperature (850hpa), might i ask what air pressure enterprises we need if we want a winter  with both cold and humid conditions? Normally it is either dry/cold or humid/mild  but i know easterly and northwest winds can bring us the combination but where must we have the pressures positioned then?

[legritter]

Afternoon all ,just a quick reply to Faronstream question above ,If we have high pressure cells positioned favourably to our North  far n /west or Scandy etc and they are persistant [staying in place for a good time that will bring us the cold temperatures ] .Areas of low pressure then tracking across say northern france  will quite often bring us snowy conditions For some ,If an active low is positioned to our west weather fronts will push warmer air into the cold mix ,depending on Many synoptic situations it can be humid mild at certain heights in the atmosphere .Another way of looking at your question would be December 1962 Boxing day [mid evening in my kneck of the woods ] A large area of relatively mild air and steady moderate rain across southern britain was gradually being replaced by very cold air which undercut ,SNow turned very heavy with massive flakes [so some very mild conditions aloft ,eventually temperatures mixed more, so snow then became moderate in size ,the cold air came as a result of a ridge of high pressure moving west to our north ,i wont get to technical as you can read this all up easily on the Internet .

Indeed most heavy falls of snow is a result of moist air battling colder dryer air ,also as a general rule winters with above average pressure to our north and lower than normal to our south [but many combinations ]

Ps  after this event it did turn briefly mild till 29/30 dec ,but thats another story and not Model output ralated ,catch you all up later ,hoping for some good charts tonight after this morning slight back track ,cheers .

[SMU]

Afternoon

people being to harsh on the ECM when the GFS landed in the same boat-

The full greenland blocking was never past  168 on either model- taking the 144 charts from 2 days ago & transpose them to todays 96 - they are very accurate & the polar blocking hasnt been downgraded, if anything the GFS through 108 has a good solid 2 wave pattern, far stronger than the 06z-

Theres no point having huge expectations for the period of 25 Oct -5th November, its very much the transition period for continental cooling- however if anything did turn up alls well & good-

The blocked theme runs out to day 16 & possibly beyond when the UK starts to enter the fray as the days get shorter-

Its all good people- Not to long to wait....

S

[shaky]

2 minutes ago, Steve Murr said:

Afternoon

people being to harsh on the ECM when the GFS landed in the same boat-

The full greenland blocking was never past  168 on either model- taking the 144 charts from 2 days ago & transpose them to todays 96 - they are very accurate & the polar blocking hasnt been downgraded, if anything the GFS through 108 has a good solid 2 wave pattern, far stronger than the 06z-

Theres no point having huge expectations for the period of 25 Oct -5th November, its very much the transition period for continental cooling- however if anything did turn up alls well & good-

The blocked theme runs out to day 16 & possibly beyond when the UK starts to enter the fray as the days get shorter-

Its all good people- Not to long to wait....

S

Have you noticed steve the last 3 runs from gfs have amplified things a lot more in the north atlantic and greenland between 120 and 144 hours!!by tomorrow we could have a full blown greenland high!!lol!!

[SMU]

Could be a GEM easterly coming on 12z GFS

GEM was the only model to get the non greenland high correct

[SMU]

11 minutes ago, shaky said:

Have you noticed steve the last 3 runs from gfs have amplified things a lot more in the north atlantic and greenland between 120 and 144 hours!!by tomorrow we could have a full blown greenland high!!lol!!

Yes 

 

watch the scandi ridge though not greenland !

[feb1991blizzard]

1 minute ago, Steve Murr said:

Could be a GEM easterly coming on 12z GFS

GEM was the only model to get the non greenland high correct

This mornings run is showing a respectable Greenland high, lets hope it gets a Greenland high correct this time!

[SMU]

HUGE UMKO 120 - !!!

 

 

[Captain Shortwave]

A fine weekend on the cards with high pressure firmly in charge

   

So settled with some sunny spells though morning fog and low cloud could suppress sunshine amounts in places, especially towards the south east underneath the centre of the high.

It is worth noting that the UK offers something different for Sunday.

How the low heights in the Atlantic are handled differs greatly with the GFS sharpening the trough and creating a cut off low, the UKMO nowhere near this and in fact deepens this low as a stronger upstream jet interacts with this. Still lots of amplification and polar blocking, just not it the right place yet for a cold UK solution.

[feb1991blizzard]

1 minute ago, Steve Murr said:

HUGE UMKO 120 - !!!

 

 

Cripes!!!,   Just wondering what the OPI would end on this year if we could see it, record breaking???

[I remember Atlantic 252]

much better, the Halloween rain nowhere near us, decent dry day on this run

[Mucka]

17 minutes ago, Steve Murr said:

Could be a GEM easterly coming on 12z GFS

GEM was the only model to get the non greenland high correct

JMA didn't go for it either Steve, even less so than GEM.

This afternoons runs seem to want to undercut the low I highlighted as a key player in the mid term earlier - UKMO is an extreme example but it has probably been most accurate out around 120 for our neck of the woods over the last few days.

Plenty of model wobbles, would of been an exciting (excruciating) watch in mid winter. 

 

Edit.

For noobies, just to compare Northern Hemisphere GFS 12z with undercut to 06z with little/no undercut to illustrate what I meant about increased prospects for sustaining MLB/HLB blocking through early Nov. 

Edited October 25, 2016 by Mucka

[Frosty.]

5 minutes ago, I remember Atlantic 252 said:

much better, the Halloween rain nowhere near us, decent dry day on this run

Yes it looks very pleasant / benign..perfick

[Barry12]

UKMO brings the Greenland block back!

Edited October 25, 2016 by Barry95

[Ali1977]

this is only the 1st Nov and look at the difference between the 6 and 12z. Crazy, much better 12 though.