Model Output Discussion 01/09/17

[Snowy L]

1 hour ago, comet said:

by the looks of things the strong northern blocking being shown by the models in the mid to long range is completely trop led, with a total disconnect between trop and strat. 

I have always been of the belief that such blocking would have to be coupled to the strat at least up to 30mb level or higher so I for one am very surprised to see such blocking in the charts. Mind you it has not verified yet

 

I remember Chiono explaining to me about what happened in 2010 as there was nothing in the stratosphere happening that could have indicated the tropospheric vortex being completely destroyed twice in November and December of that year.

 

Basically it was wave breaking in the troposphere, so a troposphere-led split of the tropospheric vortex.

 

BTW I am not suggesting we will get 2010-like conditions, just thought this is a useful example of how we can still get brilliant tropospheric synoptics without the help of the stratosphere.

Edited November 6, 2017 by Snowy L

[SMU]

Updated 18z shows the formation of a trough in the Northerly fow - worth keeping an eye on certainly not out of the question -

[Methuselah]

1 minute ago, Steve Murr said:

Updated 18z shows the formation of a trough in the Northerly fow - worth keeping an eye on certainly not out of the question -

I'll believe it when I see it, Steve!

[Guest]

6 minutes ago, Steve Murr said:

Updated 18z shows the formation of a trough in the Northerly fow - worth keeping an eye on certainly not out of the question -

Would that have NE Scotlands name written on it?? could be some fun and games..

[knocker]

Some impressive weather in southern Europe and the Med as the cold trough sinks a long way south.

[Allseasons-Si]

14 minutes ago, Ed Stone said:

I'll believe it when I see it, Steve!

It's in a reliable timeframe though pete(138hrs),so a chilly northerly flow with wintry showers affecting the north,maybe some wintryness further south in the form of sleet,hail showers on coasts(wishbone affect)

The latest from the 18z is much flatter than the 12z,but it is one run,i stress that there is always chopping and changing in the NWP,so move on 18z you are sober tonight

 

Edited November 6, 2017 by Allseasons-si

[Jonan92]

Flat 18z GFS solution at 198h

[knocker]

In a nutshell the 18 very similar to the 12 certainly out to about T204. Time for Horlicks.

[bluearmy]

A rather different Arctic solution to the 18z will lead where, I wonder, in deep fi. .........

[Allseasons-Si]

1 minute ago, bluearmy said:

A rather different Arctic solution to the 18z will lead where, I wonder, in deep fi. .........

Destination....pete tong

no heights in the polar regions what so ever on this run.hopefully not a trend,do we discount it?

[MattTarrant]

2 minutes ago, Allseasons-si said:

Destination....pete tong

no heights in the polar regions what so ever on this run.hopefully not a trend,do we discount it?

No, but the pub run rarely fails to bring a surprise (Normally disappointing).

[bluearmy]

Initial look at the ec46 out to day 28 has no real surprises with high height anomalies  to the north and low to the south with high slp anomoly centred around Iceland/Greenland for the 20/28 day period 

steady as she goes ......

[Allseasons-Si]

8 minutes ago, knocker said:

In a nutshell the 18 very similar to the 12 certainly out to about T204. Time for Horlicks.

Is it!

the gfs 12z 210hrs and the gfs 18z 204hrs

i spot a big difference

i think you need that Horlicks

and no harm intended buddy

[tight isobar]

Blocking certainly less prominent via 18z gfs.

And thats 'one ugly' compact pv.

But its 1-run..

And thers a whole lot of unraveling in coming days!!!

Hold one to ya hats!

[Allseasons-Si]

18z,one for the rubbish bin and hopefully not pulled out again by Ian brown,

night chaps.

[Jonan92]

We will have to wait and see in the morning if this run has picked a new signal or it's an outlier

[ITSY]

Poor run, yes. But yet this is still the final frame...suggests to me that something is still on the cards. Besides, most forecasts and models are only still in the block/piece building stage. Nothing to lose at this stage...

 

 

[Sperrin]

Poor enough run on the 18z but still ends up pretty decent. The trends appear to be gathering momentum. Hopefully this continues.

Dr Cohen's blog this evening makes for good reading, though. 

http://www.aer.com/science-research/climate-weather/arctic-oscillation

[Man With Beard]

EC clusters again mainly blocked to our north, especially the control run, but still a "spoiler" cluster in there.

[ITSY]

Preliminary look at GEFS members support flatter 18Z op run. Not ideal but plenty more runs to be had...

edit: last post before bed - actually, if you look through the pack, most defer the onset of serious blocking but wind up in a similar place. It's actually quite stark just how disrupted the NH profile is by the end of most runs. At the risk of sounding like a lame duck prime minister, nothing major has changed. Hopefully I'm more right than she was. 

Edited November 6, 2017 by ITSY

[Daniel*]

Well I was divided whether to post it he or alternatively the tweet thread but it is model related so...very impressive indeed and not regarding Eastern half of CONUS. 

All frangible stuff by this time next week if the ‘momentum’ carries forward this forum will ‘explode’ - I think it’s time to buckle in and see where it takes us an early ride.  

 

Edited November 7, 2017 by Daniel*

[Cheshire Freeze]

This is why I warned people not to get too excited...

The pretty hemispheric patterns are quickly fading on the GFS...that's two runs in a row now. Compare that to the 12z ECM of yesterday for same timeframe-

We're now back at day 10 before we start to see manifestations of interest once again

History shows we've been here many many times before and history also shows us that any promise is likely to be held in FI before being snuffed out altogether once this trend starts.

P.S @bluearmy The EC46 proved itself to be about as useful as the morning after pill in a nunnery last winter!

[swfc]

After yesterday the bar was set so high "be it 10-14 days away" anything regarding a change was going to be slightly watered down regarding the polar blocking ete.nothing unusual there given the fluidity of the nhp and pv.for sure the current output is not without interest but hasn't actually started yet!! Id suggest the chances of blocking are still there but as always it will wax and wain over the next week or so.the usual Atlantic onslaught hasnt reared its head atm and all to play for going threw November. Relax folks!!

[northwestsnow]

1 hour ago, CreweCold said:

This is why I warned people not to get too excited...

The pretty hemispheric patterns are quickly fading on the GFS...that's two runs in a row now. Compare that to the 12z ECM of yesterday for same timeframe-

We're now back at day 10 before we start to see manifestations of interest once again

History shows we've been here many many times before and history also shows us that any promise is likely to be held in FI before being snuffed out altogether once this trend starts.

P.S @bluearmy The EC46 proved itself to be about as useful as the morning after pill in a nunnery last winter!

But then again GFS is hardly the most reliable model -

[knocker]

Not surprisingly I've nothing to add, or correct, vis last night's anomalies post so straight on to the here and now.

Currently an active cold front lies Scotland, west Wales to Cornwall. This will bring rain, heavy in places, accompanied by squally winds gusting 40-50 mph as to all as it moves east during the day finally clearing the south east in the early hours. Thus the relatively speaking milder air in front will give way to cooler behind which are already into N. Ireland.

So tomorrow a fresher, sunnier day for most but the next batch of fronts quickly approach N. Ireland and western Scotland bringing more rain and strengthening winds,

So to this morning's gfs, The aforementioned fronts are associated with a deep depression tracking east and is 965mb east of Iceland by 00Thursday. At the same time the front's are orientated across Scotland and down the western side of Wales and England. This tracks east and dissipates bringing some light patchy rain as it goes clearing by the afternoon giving another brief clearance before a frontal wave wings around the high cell to the south west and arrives over Ireland Friday evening. This moves quickly south east across England and is Germany by 12 on Saturday.

But now the expected amplification takes place, the next wave nips SE west of Cornwall, and by 12 on Sunday the major low 983mb is over Sweden with the high Pressure ridging north just to the west of the UK. Thus a very fresh NW/N wind over the UK bringing wintry showers, snow on the high ground to the north with temps dipping below average through Saturday night and Sunday.

The ridge again quickly move east on Monday giving a more benign day but the rest of the week is essentially back to the battle between the Azores HP to the south west and the energy flowing around it and despite some brief efforts of the HP to ridge NE it is quickly put straight back in it;s box. So essentially a few days of sunny spells, interspersed with periods of rain, quite windy at times and it goes without saying tending to a N/S split. It also goes without saying that next week remains subject to revision.

All of this fits very well with this morning's GEFS which also continues in the same vein as lasts night vis the pattern change in the later period.

 

Edited November 7, 2017 by knocker