Model Output Discussions 12z 01/09/2016

[Mucka]

Not much to add to all the excellent posts prior, things continue to look good for late autumn/early winter blocking at least.

If anything there has been a strengthening of the signal for Atlantic blocking and firming up of a decline in temps for early Nov.

Before then we should see largely pleasant and settled autumnal weather which will peak late October with probably the last real warmth of 2016 - thereafter ensembles show a marked drop away into Nov back to normal or a little below normal.

If the Atlantic blocking signal proves correct then we can expect early November temps to continue to fall away on these graphs through the next few days to somewhat below average or possibly well below average (with the usual caveat that blocking is not necessarily synonymous with cold and that this long predicted pattern is not yet in the bag) 

Likewise, we have not seen the mean 850's really drop below into negative territory as yet, let alone show a "cold" signal but this is largely due to high divergence (which is slowly being ironed out BTW) and if we continue in the same vein next week we might expect the mean to enter negative values into early Nov.

Encouragingly day 8 charts from ECM and GFS show that the evolution toward Atlantic blocking is already well underway now that the trough disruption against declining Scandi high has been resolved through the near to mid term.

But I would temper that with the fact that the models are usually too clean at those ranges, especially in the Atlantic sector where niggling shortwaves only tend to appear inside the 5 day range, especially around SW Greenland.

So that went on much longer than I anticipated (was just going to post ensembles). Put it down to enthusiasm for upcoming prospects.

Have a great weekend all.

 

[Frosty.]

The GEFS 6z mean becomes strongly anticyclonic from the middle of next week, initially across southern uk before extending north to the rest of the uk bringing very pleasant surface conditions for late october with daytime temps becoming unseasonably warm for a time but still with chilly misty nights where skies clear. During early november there are signs of a change to unsettled with the high weakening and drifting away w / sw with lowering heights from the n / ne.

Edited October 22, 2016 by Frosty.

[Frosty.]

There are some interesting GEFS 6z perturbations cropping up for early november which show a possibility of our first cold snap / spell of the season.

Edited October 22, 2016 by Frosty.

[Mucka]

3 pronged attack 

[Zakos]

00z

06z

12z

Clear trend indicating retrogression of the high towards Greenland just in time for November

 

 

[Barry12]

GFS is looking very interesting, backs up the spectacular ECM this morning with the block retrogressing towards Greenland. Ensembles also showing strong support for this also.

 

All this starts at just day 7 too!

Edited October 22, 2016 by Barry95

[SMU]

Yes at T180 we nearly have the first boom chart of the season !

S

[Barry12]

Chance of snow for the 1st November!?

 

 

Edited October 22, 2016 by Barry95

[Frosty.]

This looks good for coldies on the Gfs 12z!

[Frosty.]

Even southwest england gets a bit of snow on the Gfs 12z. It's very good to see wintry charts appearing so early in the season. 

Edited October 22, 2016 by Frosty.

[knocker]

7 minutes ago, ajpoolshark said:

in what respect Knocker?.....It would be helpful if both yourself and the previous poster would clarify your posts, and at the moment they're pretty much one-liner posts that add very little to the discussion...thanks

You are quite right aj my post indeed doesn't add anything to the discussion so have deleted it.

[A.J]

one for the more learned, on the GFS 12z medium res T186 - T240, are we seeing the makings of an omega block in the Atlantic with the Azores Hi linking up with the Greenland hi? (it does disappear in the low-res, but I pay little attention for specifics in low-res)

[A.J]

1 minute ago, knocker said:

You are quite right aj my post indeed doesn't add anything to the discussion so have deleted it.

cheers 

[knocker]

11 minutes ago, ajpoolshark said:

one for the more learned, on the GFS 12z medium res T186 - T240, are we seeing the makings of an omega block in the Atlantic with the Azores Hi linking up with the Greenland hi? (it does disappear in the low-res, but I pay little attention for specifics in low-res)

Well the chart I just deleted would qualify as one. If a bit squiffy

Edited October 22, 2016 by knocker

[Captain Shortwave]

A good effort from the GFS if cold weather is what you are looking for, a cleaner retrograde with heights in the north Atlantic and stretching up to Greenland.

Low pressure then sinks southwards down the western flank of the trough introducing so Arctic maritime air from the north/north east.

Whilst pointless at this range, the temperatures shown would be a real shock to the system.

Middle single figures for most (5/6C) so showers wintry even at low levels.

On balance the GEM keeps heights over the UK throughout the run.

   

Saying that we could see something colder develop over the following days.

Again it is a case of a retrograding pattern is likely, the question is how far west the pattern can back and as such how cool/cold can it get.

[bryan629]

4 minutes ago, ajpoolshark said:

one for the more learned, on the GFS 12z medium res T186 - T240, are we seeing the makings of an omega block in the Atlantic with the Azores Hi linking up with the Greenland hi? (it does disappear in the low-res, but I pay little attention for specifics in low-res)

I`ll agree with you ther AJ , a clear signal fron the GFS 12z here, solid looking block we have modelled. 

ECM 00z not quite but almost on the same page with positoining...

But overall great agreement synoptically right out to day ten .. so much better than staring at a deep upper trough in the mid atlantic for a change 

 

 

 

 

 

 

[Frosty.]

High pressure retrogression (north westwards) is the theme of today's models and also got a mention from Exeter earlier for the first time so a colder shot from the nw / n / ne could be on the way beyond the upcoming anticyclonic spell.

[knocker]

The GEFS mean anomaly, although hinting at some retrogression, is not anywhere as near amplified as the det. run  It has the HP centred to the south west ridging NE and with through to the east this will veer the upper flow and bring the temps down to around average. This pattern likely to persist, probably becoming flatter with temps below average.

Edited October 22, 2016 by knocker

[bryan629]

10 hours ago, Steve Murr said:

Morning -

October is also on course to beat the record of negativity - beating the hyper winter ( -AO) of 2009-

here are yesterdays ensembles - watch for a move to better clustering on low values on todays updated ones around 4pm-

- All this is in response to the overwhelming model ensemble drop off in the midrange of the 60N zonal wind - which could drop into record breaking negative territory ....

S

Hi Steve 

Heres todays updated AO index... absolutely better clustering .. just a question of how low will it go !! 

[Frosty.]

The GEFS 12z mean looks rock solid anticyclonic from around next wed / thurs until the start of november with just about perfect benign autumn conditions across the uk except perhaps the far nw / n but there are signs of unsettled weather beyond that, especially further north.

Edited October 22, 2016 by Frosty.

[Ali1977]

The GEFS mean is looking good Frosty, nice pleasant weather but won't take much of a shift westwards to becone a fair bit colder. Lets see what the ECM is saying towards the end of the run. 

[phil nw.]

The 12 z GFS mean continues to model those polar +ve height anomalies showing the warm air getting well into the heart of the pv.

A look at day 8-T192hrs just to underline what this does to moving the cold out of the Arctic further south.The second image showing the modeled 2mtr temperatures.

At this stage NW Europe is under the high but we can see the WAA heading north up through Greenland towards the Pole sending the coldest air towards mid-latitudes to our east and north east.Notice surface readings are higher around the Pole than much further south.

Interesting GFS mean charts and according to this run no sign yet of the usual strengthening of the northern jet as we head towards month end.

 

[Frosty.]

As with the 6z,  some of the Gefs 12z perturbations are sniffing arctic air during early november. Hopefully support will strengthen in the days ahead.

[northwestsnow]

Well the models continue to advertise a mainly dry theme- with the clocks going back next weekend, High pressure over or near the UK will start producing some colder nights, im not really thinking all that much about winter i just think it will be nice to see some dry weather in late Oct/early November and the chance to enjoy mother nature without getting soaked to the skin, kind of hoping we get a cold foggy/frosty Bonfire night , far too many seem to have been mild wet and windy in recent times.

http://old.wetterzentrale.de/pics/Recm1681.html

ECM suggesting 'our' high migrating north westwards in the medium term, certainly no sign of the vortex getting its act together soon..

[Ali1977]

And here comes the cold air at the end of the month with the ECM.