Model output discussion - 16th Nov onwards

[mountain shadow]

If we can get to the 10th December with an Arctic high as good as this and a fragmented tropospheric vortex then all options would still be on the table for mid to late December, too early to write the whole month off................yet

 

http://max.nwstatic.co.uk/gfsimages/gfs.20151124/06/384/npsh500.png

[Neilsouth]

 unfortunately, for us though, with a vortex still sat over Greenland.

 

 

Why does this keep happening or dumping itself over NE states? It's been a real nail in the winter coffin these last what, 4 years?

[mountain shadow]

Why does this keep happening or dumping itself over NE states? It's been a real nail in the winter coffin these last what, 4 years?

I asked Chiono this once. The main areas of troposheric polar vortex tend to sit over the continents because they get colder quicker than the oceans/sea ice and remain colder for longer as well. So during Winter the PV tends to sit over with NE Canada/Greenland and Siberia. 

[Ravelin]

OK so the trend recently hasn't been good, but then again who was realistically expecting anything but zonal in Dec, with maybe the odd cooler spell?

 

As for writing off Dec, well I'm not going to yet. Here's the current output from the recent model runs for the major models at day 10 (as near to the same time as I can). Doesn't look like they are all pointing to the same result to me, so beyond that the options are far from set in stone.

 

 

 

 

 

 

 

Edited November 24, 2015 by Ravelin

[knocker]

Not without interest a quote this morning from Michael Ventrice

 

ECMWF EPS 11-15d fcst remains locked into one of the strongest El Nino type pattern's I've ever observed as a fcster

 

[Ali1977]

Not without interest a quote this morning from Michael Ventrice

 

ECMWF EPS 11-15d fcst remains locked into one of the strongest El Nino type pattern's I've ever observed as a fcster

Didn't he say not without interest from mid till late December? 

I'm not one to write chances off chances of cold, but the next 2 weeks are definately not looking good :-(.....then again, it's not often late Nov and Early Nov ever look good.

[johnholmes]

To be quite frank if anything there is a strengthening threat between all of the output of a very mild SE/NW split in the weather coming up again from next week and because of the nature of these setups they can be an absolute stubborn animal to break out of once established which on past proof has given the UK weeks and weeks of mild weather in Winters past without a hint of cold. I am not of course saying that this is going to happen this time round but it does look like the chance of anything wintry is put back to well into December at least unless the models start to diverge from their current output soon. Sorry folks just saying it as I see it.

 

not totally supported by NOAA or EC-GFS anomaly charts Gibby, nor really from Met 6-15 day outlooks, link below to that

http://www.metoffice.gov.uk/public/weather/forecast

links to the anomaly charts are in my earlier post if anyone wishes to check this=post 687

Edited November 24, 2015 by johnholmes

[Mucka]

Much talk of Westerly dominance through Dec today which is certainly the strongest signal

BUT

Today's output actually offers a little hope has Nick and Revelin pointed out earlier for day 9+ in that there is a signal for more upstream amplification - trough into Atlantic possible helping build heights to our NE and perhaps a ridge being built behind the Atlantic. Admittedly that is at the "very optimistic" end of any forecast but both ECM and GFS 06z hint at the possibility though GFS is much faster an d flatter

 

 

We also know ECM tends to overdo amplification in FI whereas GFS tends to under do it.

ECM ensembles show how slim the chances are of getting blocking but at least there are some (read 1 or 2 ) dissenting members against the mobile westerly regime.

 

 

Definitely nothing to pin your hopes on but something to watch for this evening.

Edited November 24, 2015 by Mucka

[weirpig]

There seems to be a little dispondancy on the thread the past few days  regarding a more westerly dominated period for our little part of the world, But having looked at many lrfs for the upcoming winter the first part ie december through to mid january was also likely to delever this.  El ninos quite often favour cold latter parts of the winter   so surely anything  colder this side of the new year is a bonus 

[Ali1977]

Well well well, GFS has much more going for it in FI.

Scandy high anyone?

[Ravelin]

It's just one run, in the depths of FI, and certainly not guaranteed to happen, but it shows that nothing is 'locked in' and the output is highly variable at the moment...

 

 

 

[Gael_Force]

Isn't it always the way... just as Doctors Doom pronounce the imminent demise of the patient!

[Captain Shortwave]

The pattern looks very westerly based at the moment with agreement on the Azores high moving back into Europe from around day 5/6.

 

UKMO

 

GFS

 

A classic north/south split looks likely and going by the recent model output any change will probably come from the Euro high becoming more influential for the UK in some form or another.

 

The GFS goes for a Euro/Scandi block whilst the GEM creates a classic Eurotrash high.

GFS

 

GEM

 

The GFS is pretty chilly but not cold whilst the GEM would give temperatures in the mid to high teens.

 

No real surprise given these types of set ups are quite common given the background signals.

[Ravelin]

The GFS is pretty chilly but not cold whilst the GEM would give temperatures in the mid to high teens.

 

 

Your GFS chart is 3 days after the GEM chart, the GFS chart for the same time as the GEM isn't too dissimilar...

 

 

Which then of course goes on to develop into the "Euro/Scandi block", so the GEM scenario could go the same direction given time.

[Captain Shortwave]

Your GFS chart is 3 days after the GEM chart, the GFS chart for the same time as the GEM isn't too dissimilar...

 

 

Which then of course goes on to develop into the "Euro/Scandi block", so the GEM scenario could go the same direction given time.

Actually there is one key difference between the GEM and the GFS, the GFS develops a weak Atlantic ridge which cuts off low heights west of Iberia around day 10

 

Whilst the GEM shows a broad Atlantic trough

 

The GFS the hops the ridge over onto the Euro high allowing the jet to dig south east in the Atlantic and undercut the ridge, whilst the GEM would keep a SW/NE jet axis across the UK and hence the mild conditions.

 

At this point there doesn't seem to be much wintry on offer to me, again mixed with a chance of something more anticyclonic developing as we head towards the second week of December perhaps.

Edited November 24, 2015 by Captain shortwave

[mulzy]

Just for fun - GEFS ensemble number 1 - an extreme case of cherry picking!

 

[Liam J]

Just had a scan over the GEFS, some horror show charts in there this evening! A number of them with the Euro high positioned allowing air to be sourced from North Africa.... All in FI though which can be very erratic and hard to place any faith in. 

 

A few mean charts showing a similar theme from the last few days.

 

 

 

Edited November 24, 2015 by *Sub*Zero*

[knocker]

The GEFS 6-10 anomaly tonight keeps the familiar emphasis upstream bu it does shift it a bit downstream with a trough SE over Scandinavia and ridging to our SE thus bringing the UK more under the influence of HP.

 

The 11-15 moves the trough east, along with the Russian HP and pushed the European HP further north thus increasing the influence of the surface HP on the UK.

 

Winds generally from the SW/W and temps a little above average. Need to see what the ecm makes of this. Rather supports the position of the ops

 

 

[nick sussex]

The ECM and GFS broadly similar in terms of the overall NH pattern upto T192hrs. However if you compare the ECM 00hrs with tonights you'll see the dismal run to run continuity.

 

There is some uncertainty from T168hrs onwards upstream and the amplification of low pressure and how it interacts with the PV over Greenland.

 

The New York state forecast from NCEP.

 

LOOKING FURTHER AHEAD...SIGNIFICANT UNCERTAINTY CREEPS INTO THE
EXTENDED RANGE AS A BROAD UPPER LEVEL OVER THE WESTERN U.S. IS
TRANSPORTED EAST ACROSS THE NATION`S MID-SECTION ON THE CUSP OF A
RESURGENT SOUTHERN BRANCH OF THE JET STREAM. THE CONSENSUS IS THAT
THIS WILL RESULT IN THE DEVELOPMENT OF A STORM SYSTEM EAST OF THE
MISSISSIPPI...HOWEVER ANY DETAILS REGARDING THIS LOW ARE SUSPECT AS
POSSIBLE LOCATIONS FOR THE LOW BY TUESDAY RANGE FROM THE LOWER GREAT
LAKES TO THE DELMARVA. HOPEFULLY WE WILL SEE MORE CLARITY AS WE MOVE
THROUGH THE WEEK AND THE MODELS GAIN A BETTER HANDLE ON THE PACIFIC
ENERGY MOVING EAST.

 

We might see a stronger ridge thrown ne ahead of this low depending on the amplification upstream at that time.

[Cloud 10]

Very messy ensembles from the 12z GEFS after day 5,with pretty much everything still on the table.

 

 

 

 

^^^^lol,Nick.

Edited November 24, 2015 by Cloud 10

[Singularity]

Interesting from the GFS det. this evening, as it effectively changes the angle of attack on the vortex by using a powerful Scandi Block that emerges from the Euro High in about 10 days time.

 

Meanwhile the ECM det. has reverted to an amplifying Siberian trough - but not nearly as pronounced as it was on it's previous 12z det. run. There's also the threat of the trough over Greenland merging with the one over Siberia, which would be rather unhelpful.

 

To be honest we now have little consensus to base outlooks beyond a week ahead on, so we're left looking out for anything interesting with in the next 7 days. As it is, I can see the threat of copious rainfall amounts and very strong winds for the far north Sun/Mon but with a lot of uncertainty there as well... there really isn't much on offer that can be discussed without heavy use of caveats! Just some spells of rain and fluctuating temperatures, all within the usual range for late Nov and early Dec.

 

Never mind though, we can save our energy for when it does kick off - assuming it does.

[gottolovethisweather]

Oh well I did suggest a newer clearer  trend might emerge via the various NWP outputs by midweek (at least that's what I meant by my post, sorry for any confusion there). It's just NOT the one I hoped for or expected to see, Euro High and potential for W/SW flows over the UK, yuk! See below.

 

https://forum.netweather.tv/topic/84434-model-output-discussion-16th-nov-onwards/?p=3289848

 

I've replicated below the most relevant section in reply to Nick F's original post who in my opinion has forecast the forthcoming set up very accurately.

 

• "Overall, the bigger picture NH wise and those stratospheric signals remain of interest though, according to those in the know, so let's see how things unfold as head deeper still into month end. I reckon after these usual weekend wobbles within the various NWP outputs, they might yet pick up on an entirely different evolving trend again as we head into the midweek period."

Moving into our prospects post November then.

 

Two things to watch in the run up to the start of Winter proper (after all, it is only 24th November even now) are whether the PV waxes or wanes and of course where it positions itself consistently within those latter FI stages in the outputs. Another aspect of note I feel is the NH Jet situation over the Pacific and just how it might affect the NH Jet position leaving the US as it heads for our shores. It was precisely this last aspect that was well modelled in the GFS operationals some ten days back or so and led me to think a complete change was in the offing and so it did, unfortunately for those looking deep cold for now.

Edited November 24, 2015 by gottolovethisweather

[Eskimo]

I know things can change, and they can definitely change very quickly. I know we are only in late November, and perhaps 2010 has skewed my expectations a little. It's just that, every time I check the models, it seems that the blowtorch westerly/SW regime is getting stronger and not subduing like some are saying. 

I mean look at the state of this from the GEM & GFS....yuck!!

Edited November 24, 2015 by PerfectStorm

[cold snap]

Please update or start a new thread .

Everytime I see the cold snap incoming ,I'm getting

Edited November 24, 2015 by cold snap

[dragan]

A few of us (mainly knocker) kept getting slated for suggesting a west to south west dominant period, even although the evidence was there to back it up.

No matter how much 'potential' a set up may appear to have for a cold period, on our little island 90% of the time it doesn't happen