Model Output Discussions 06z 04/11/16

[phil nw.]

Certainly a cold few days to come in this early bout of Arctic air and we don't look like changing over to something milder until towards the end of the coming week.

A look at the latest London temp graph

shows a an upward trend into week 2 before easing back down towards a mean average but of course as expected a wide range of options around the mean line by that time..

A look at the gefs 00z stamps for Friday coming and pretty good agreement by then that the Atlantic eventually wins through

Some differences in timing in clearing the trough from the east but taken along with the operational charts a more westerly pattern establishing by next weekend..

Looking further on and and some form of further Atlantic ridging is hinted at-quite strongly in the ECM op-but even the watered down mean charts at day 10 show something

so in week 2 a changeable outlook with some mix of air masses as the mean jet runs across the UK- perhaps something colder if future Atlantic ridging shows up strongly which would bring in a more northerly flow.

[North East Blizzard]

The Ecm may be slightly over doing things but with all the background signals I wouldn't rule out charts like that coming off in the not to distant.

Lowest sea ice on record since 1981, high snow cover across Siberia and Scandinavia, still a negative ao, zonal winds at the lower end of the scale, warm Canada etc.

One consistent theme that I can see is that the PV isn't really recovering, even in the later stages of most models. Also the trend to set up a chunk over Greenland seems to be weakening with every run too.

 

[Mucka]

I posted yesterday on the ECM V GFS debate and added to that by highlighting likely issues with yesterdays GFS 12z run along with an explanation of likely corrections.

For those who think GFS handles these situations well then please compare this afternoons 12z (when it comes out) with yesterdays.

The further in the output we get the more the models will compound any inherent bias. ECM over amplification, GFS too flat and fast as a general rule in these situations so usually a blended solution is required.

The GFS only begins to see the potential to split energy in the nearer time-frames where any bias is not compounded and the resolution high enough - the ECM sees the potential but usually over-eggs the pudding.

We have also heard a lot about not taking Op runs in isolation which is obviously good advice, especially where we have quickly evolving patterns as now.

That said, when an operational run breaks away from previous runs with a potential pattern change it is absolutely worth highlighting and paying attention to, just don't take it as gospel and assume it is the way forward.

If we take this mornings output as a whole it is clear the models are toying with the idea of more resilient high pressure/ridge to our NE and better trough disruption SE, that is fairly significant but too early to call it a trend.

Upstream is even more uncertain - over the last 24h we have seen everything from a fairly flat jet modeled to a strong Atlantic ridge.

On that basis I would pay more attention to earlier developments and see how far West the pattern backs (how strong the high pressure to our NE is and how much trough disruption we get through the mid term)

[nick sussex]

Some news re whether the ECM has gone off into fantasyland or whether theres any mileage in its medium term view. The big issue at present is how amplified the pattern might be over the eastern USA, US forecasters haven't ruled out the more amplified solutions but theres a large spread of solutions.

You'll note that the GFS 06hrs run increased the amplification compared to its earlier 00hrs run. So we'll have to see whether that trend continues this evening.

[bluearmy]

Para ecm finally out and doesn't support the amplified pattern of the 00z op in its latter stages 

[Frosty.]

34 minutes ago, bluearmy said:

Para ecm finally out and doesn't support the amplified pattern of the 00z op in its latter stages 

We can still dream can't we

Edited November 5, 2016 by Frosty.

[Ali1977]

So now some are saying GFS is the daddy, it would be nice if this run throws something good up around day 10!! Looks quite similar to the last run although slightly better around Greenland and NE cabada with regards heights!!

I spoke too soon, nothing happening on this run!!

Edited November 5, 2016 by Ali1977

[Derecho]

Quite a lot of changes from the GFS in the past 24 hours...

At this rate we may end up getting a second attempt at an undercut.

The Scandi high is much further west but will the ECM and UKMO back it up?

I think anything after T144 should be taken with a huge pinch of salt!

Edited November 5, 2016 by Quicksilver1989

[blizzard81]

Certainly a correction westwards on the models throughout the course of today. It started with the GFS 06z op and now the 12z GFS & UKMO.

[Ravelin]

21 minutes ago, Ali1977 said:

So now some are saying GFS is the daddy, it would be nice if this run throws something good up around day 10!! Looks quite similar to the last run although slightly better around Greenland and NE cabada with regards heights!!

I spoke too soon, nothing happening on this run!!

Oh I don't know....

Every run is different at the moment though, especially day 9 onwards. Uppers nothing special either.

Edited November 5, 2016 by Ravelin

[weirpig]

Another run another outcome on the gfs this run sees us initially in north westerly flow then into a easterly with increasingly colder uppers  making there way over the uk . Model watching this season certainly isn't boring 

[booferking]

Middle of Nov looking interesting if these charts keep popping up

Edited November 5, 2016 by booferking

[Barry12]

ECM 00z, GFS 12z, and many of the GEFS perturbations are showing another attempt at ridging towards Greenland around day 10. GLOSEA5 is also showing support for blocking mid/late Nov so there is certainly a bit of support for the ECM. I wouldn't be surprised if this is a growing trend.

Edited November 5, 2016 by Barry95

[Ravelin]

You know how outrageous this mornings ECM looked at D10...

Well, GFS 12....

OK, so the ECM is still outrageous but maybe not looking quite so outrageous now.

[Man With Beard]

My oh my ... Did that UKMO rum just happen? It's very nearly back to those boom charts from the ECM earlier in the week!! T72 - disruption about to happen but much nearer the uk. T96 - resultant surface trough straight through the UK. T120 - trough clears to a renewed easterly. T144 - fresh disruption in the Atlantic again, no westerlies get in!!

Edited November 5, 2016 by Man With Beard

[Banbury]

7 minutes ago, booferking said:

Middle of Nov looking interesting if these charts keep popping up

Yes GFS isn't Atlantic dominated is it

[mcweather]

GFS 12Z has England and Wales bathed in minus 6 uppers at the end, picking up on that trend for the final third of the month perhaps.

[bobbydog]

1 minute ago, Ravelin said:

You know how outrageous this mornings ECM looked at D10...

Well, GFS 12....

OK, so the ECM is still outrageous but maybe not looking quite so outrageous now.

Watching how that run evolves, it doesn't look anything special, however, knock a degree off the uppers and a slight westward adjustment and you have an a snowy easterly! Plus that's without a Greenland high.

[nick sussex]

The output is a dogs dinner. All over the place with the limpet PV having looked like it wanted to re-new its love affair with Greenland being told the divorce papers are in the mail.

The ECM 00hrs run which seemed to determine to inflict more pain on the sensibilities of cold lovers may at least have a little mileage especially as the GFS and UKMO have picked up the amplification baton and thankfully not dropped it so far like the 4X 100 mens relay squad often do.

US forecasters to be honest are as uncertain as the outputs and say the range of solutions for the eastern USA seem limitless, issues surrounding shortwaves tracking into the mid-west and how amplified the pattern might end up being.

So my advice for the timebeing is enjoy the rollercoaster ride and make sure to keep the motion sickness tablets on hand!

[Singularity]

 

Uh... what happened to that low over central Scandinavia?

Okay - I can answer my own question; days 4-5 see a plume of warm air headed for western Asia, along the western edge of which a lowering of pressure is predicted to occur, but whereas previous runs have consolidated a single, quite vigorous low pressure system from this, the 12z divides the potential between a couple of weaker disturbances. 

That storm has been an important factor in cracking the blocking  high's defensive walls prior to the Atlantic approach. Without it, the game changes - and GFS has to rely on a well (or should I say poorly) placed and timed shortwave low to erode the defences and prevent the Atlantic trough from disrupting.

Blocking highs over Scandinavia have a habit of messing with any 'Atlantic goes here in a nice orderly fashiion' assertions on multiple occasions in a row. Even so - I wasn't expecting to see it finding a potential way  back this side of mid-month!

[Mucka]

Interestingly a few GFS ensemble members  going for a linking of Atlantic and Scandi ridges in the mid term. Quite different to what was on offer yesterday even among the more favourable perturbations.

 

 

If the models keep trending this way then things should develop quite quickly as far as any blocking and potential cold signal goes for our little island.

Could all disappear of course but a very interesting ECM and weekend output coming up either way.

Edited November 5, 2016 by Mucka

[Singularity]

The improved HLB picture is also beneficial longer-term as wave-breaking pushes the stratospheric vortex more toward Siberia as opposed to it loitering near the N. Atlantic.

No guarantees with this sort of thing, but worth smiling at for the sake of it really 

[nick sussex]

The UKMO could have been a lot more interesting at T144hrs if this shortwave energy didn't stop the high over Scandi from exerting more pressure on the troughing near Greenland. It could still get there if the upstream pattern can amplify more which would help the energy head more se. You can see the annoying shortwave here:

 

 

[Weather Observer]

Good feeling about the coming winter. I think the models will be more "on topic" and we won't have to post all those golden oldies. I sense the models are toying with a Scandinavian high. GFS keeps pressure relatively high there throughout its run. It could nudge back in or we could have a full on incursion. Pre Christmas easterlies have been a rarity and can be wasted because of the warm North Sea. But no harm in hoping.

We are due one and I don't buy the fifty heads argument. The next one is always going to be tails for me. Btw did you notice the rosy glow in the cumulus tops at sunset. There's ice in them clouds.

 

[BLAST FROM THE PAST]

1 hour ago, Ravelin said:

You know how outrageous this mornings ECM looked at D10...

Well, GFS 12....

OK, so the ECM is still outrageous but maybe not looking quite so outrageous now.

Not outrageous but too soon imo.   Quite a month ahead.  Nice to see the Scandinavia HP having some say in this, not quite controlling but quite involved.  UKMO is a corker

 

BFTP