Model Output Discussion 1st Nov.2013

[Snowmadsam]

With any change in the AO "if it does go negative" the ecm would if its correct seem to be just to far westward in its position.The current 850s we have now are actually lower than the 240hrs on the ecm which is a downgrade.Still only one run and the nh charts do still look interesting to say the least!

 

I agree with this, but I'm not that fussed on having a cold spell in the last 10 days of November...lets get everything organised at the pole first...its interesting to see how things are going to be setup...I have always thought the autumn is to lay the foundations of winter e.g get everything in position, the changes that are happening now are very interesting to watch, it also improves our knowledge of how those changes take place.

[Summer Sun]

ECM isn't too keen on anything colder this evening, maybe a wobble maybe not, no doubt the 00z will have something completely different

 

Edited November 10, 2013 by Summer Sun

[Summer Sun]

Latest from Gibby

 

All models show a better week than the one just passed. For many there will be a fair amount of dry weather with some sunshine at times. Equally there will be spells of rain too, these most frequent over the North with weaker bands affecting the South too on occasion, notably Monday night and again early on Thursday. By the weekend High pressure will remain close to SW Britain steering mild Atlantic winds across the UK with a lot of cloud for many but just light rain and drizzle near Northern and Western coasts and hills.

 

GFS then shows more unsettled weather working it's way down from the North and NW as pressure falls and subsequent troughs become more active. Rain or showers would become more active with strong winds to boot and a drop in temperature as colder uppers dig down over the UK. Late in the run the weather is potentially seen to turn stormy with a vigorous Low pressure area to the NE of the UK powering strong winds and frequent showers of rain or hail and sleet and snow over the hills. At the end of the run though pressure builds from the West damping down the showers but maintaining quite cold feeling conditions.

 

UKMO tonight shows next weekend with High pressure to the SW with a broad Westerly flow carrying a lot of dry if fairly cloudy weather with the occasional bright spell too. With winds off the Atlantic temperatures will maintain average levels at worst.

 

GEM holds High pressure further to the SW with troughs affecting all areas as they move SE. Some rain would be experienced by all at times with the heaviest of this in the North. A deep low is then shown to affect all of the UK with rain or showers as winds strengthen from a Westerly point when it will feel rather cold.

 

NAVGEM shows a WNW flow next weekend with scattered showers, heaviest and most numerous towards the NW while SE areas see relatively few while seeing some brighter spells. Temperatures would be close to average.

 

ECM tonight shows a slow decline into more unsettled Atlantic fayre for all as pressure falls and Low pressure pulls down over the UK from the West and NW as the High to the SW declines. The pressure pattern shown tonight at the end of the run doesn't support cold weather of any kind so the chances of frost and fog remain limited as cloud, rain and showers are far less scarce in association with Low pressure to the NW and SW.

 

The GFS Ensembles show a changeable week to come followed by a more definitive cool off, lasting two to three days before the output shows reasonable support for a return to average value temperatures in rain at times for all. Some decent drier spells are shown over the South for a time, especially this week.

 

The Jet Stream is only shown in a reliable time frame of 1 week at the moment when it moves North clear of the UK for a time before filtering back towards and over the UK early next week.

 

In Summary the weather remains very Autumnal. All areas will see some rain at times but with some good dry spells in the South between. Temperatures though never overly cold will feel suppressed at times, especially in the cool and blustery NW flows. In contrast some relatively mild West or SW winds could mean temperatures above average for a time early next week. Frost and wintry precipitation is possible over Northern high ground at times but there looks little likelihood of any meaningful UK cold for the time being from the weather charts on offer tonight.

 

http://www.norton-ra...is(2859336).htm

[That ECM]

A lot of people will be loving the ECM, trouble is most will be Americans. Look how far south the cold air digs in the later frames!!

[Frosty.]

Why is that ? Is it because it gathers more data as it goes from run to run ?

cloud 10 confirmed what a I thought, I didn't know for sure but from all the model watching I do, the 12z, on balance is the best of the bunch.

[Barry12]

If the 00z ECM is also a downgrade then It'll be unlikely we'll see anything worthwhile

[Frosty.]

A lot of people will be loving the ECM, trouble is most will be Americans. Look how far south the cold air digs in the later frames!!

I'm not concerned about tonight's ecm run, we can't expect every run to show us what we want, the 00z will be different again.

[ANYWEATHER]

I think we have to pinch ourselves, We are in the first third of November, Models agree that we will have a "normal" Novembers week ahead, and  then we are teased with some Wintry synoptics  later in the month... I think this is certainly possible  but November 2010 was an extreme event, anything near to that will be amazing! No charts to prove my post but ecm and gfs  show something similar, if you view the models ,you know what I mean!!  

[bluearmy]

people - look at the big picture. at 8 to 10 days away, the 12z op will pretty well be an 00z ensemble member plucked at random.  at a range more than a week away, it pays to look hemispherically rather than just the atlantic.  the flow will be amplified as we head into the last third of the month. we have no idea whether it will be moreso upstream, downstream or in our vicinity. we have a ticket for the raffle. a week ago there was no raffle. the top prize is unlikely to be as rewarding as it would be in a few weeks time but its still worth a go.  lower your expectations and you will cope better with the pendulum swings. a shame there are a few pointless posts this evening but you know which are best ignored. as far as the 12z ecm is concerned, i rather like it as the NH profile looks like it would bear fruit at some point in the next few weeks. 

[SMU]

^^ Yes the ECM 240 has a split vortex for the first time in the season-

 

It may not be perfect for us but things are building up nicely...

 

S

[bluearmy]

A lot of people will be loving the ECM, trouble is most will be Americans. Look how far south the cold air digs in the later frames!!

 

 

excellent - that would drive some WAA ahead of it - its certainly looks sharp enough

[Frosty.]

There is plenty to interest coldies on tonight's GEFS 12z perturbations and mean, not as much as the 6z but it's swings and roundabouts. The timeframes of interest are still deep in FI and there are lots more changes to come, in any case, even if the charts looked perfect, mogreps would probably be less good which was the case throughout last winter when we had all those stonking ecm charts at T+240 hours and non of them verified, otherwise last winter would have been a rerun of 1963. I think a cold spell will evolve beyond the week ahead but it's still in the 10 day range which is very murky territory in meteorological terms.

[legritter]

Modells are very interesting to watch as  SNOWMADSAM says and good learning at the moment with plenty of options open .we just need to remember this in 10 days time when or if a cold shot comes off .but pressure out to our west does seem to want to rise substantially but its positioning will be critical for us in good old uk .theres plenty of time for the pole to get some good cold in and besides it does not take long for deep cold to set up if we get the right positioning of pressure and besides if you have a look around the northern hemisphere theres some impressive low temp in one or two places .some meaty highs also setting up all looks good in my opinion but remember good things take time 39/40 46/47 and remember juicy charts sometimes disappear but reappear ,all very complex but thats the modells for you ,never ending trillions of trillions of info from all over the globe which for a split second in time is stopped in its tracks for a forecast ,so thats why its good sometimes to look at it over a period of days and compare ,and of course to discuss it here on a very lively and dedicated forum ,Lamps at the ready 

[Summer Sun]

NAO starting to firm up a bit more now on going negative somewhere around the 18th ish

 

[tight isobar]

Regrets) ..position playing with regard run to run is not model reading.ecm caliber, not playing ball for cold synopsis is most certainly not writing on the wall! Sit back and inhale...with develops,, with overall recent output, it could be a significant scenario were on the cusp of.

Playing ball!!!

[swfc]

NAO starting to firm up a bit more now on going negative somewhere around the 18th ish

 

Indeed and is picked up on mo .Will it be to far west or over us only time will tell but as sm and bluearmy have said the nh charts are on the change and the pv is coming under quite a lot of pressure in the longer term.Very interesting to watch and a good learning curve for the less exp myself included!!

[PolarWarsaw]

There might not be any direct or potent cold weather to affect our shores in tonight's charts, but I think overall things are looking very positive for something colder towards the end of the month. The vortex splitting in the later frames of this evenings 12z ECM, the NH pattern and news of a -NAO perhaps taking shape. All in all, the building blocks to winter are just through the foundations stage....on to the bottom floor next!

Edited November 10, 2013 by PolarWarsaw

[Purga]

Yes looking essentially mild still throughout the whole of the ECM 12z and ending with the usual Low pressure to the North and High pressure to the South

Could be the odd frost around and fog in the south of the UK with precip threat mostly in the north and some wintry stuff over the higher ground.

Edited November 10, 2013 by Purga

[garbagebags]

Yes looking essentially mild still throughout the whole of the ECM 12z 

 

I dispute your wording slightly if I may. I would say "mild" at this stage would be 10-15 degrees. Althought the ECM isn't as cold as the GFS. It's certainly Average to slightly below average. I really wouldnt call it "mild"

[bobbydog]

such terrible model runs lately. all they keep showing us is autumnal weather in the short to medium term. anyone would think it was autumn!

its so disappointing the way, at longer range, they consistently keep showing us high pressure blocking, in the form of a massive aleutian high and a mid atlantic ridge in the run up to winter, keeping the PV from gaining strength.

who would want that??

next thing you know, they will be showing us wintry weather..... in winter!!!...... unbelievable!!

 

if we dont get heavy snowfall in november (autumn...) then winter is over!

 

(unless of course, you are fully aware that winter starts in december and the charts (and all the other signs, like eurasian snow cover for example, are showing potential for a winter of epic proportions....)

[Snowman.]

When I saw the 12z ECM 'normal' didn't spring to mind.

 

 

 

Completely normal... 

 

On serious note there is not point chasing for Heavy snow on the 20th of November best we can hope for is the PV to be disrupted which will open a whole lot of options for us in December. Currently the only thing I don't want is a raging PV covering Greenland in 50 shades of purple.

Edited November 10, 2013 by SN0WM4N

[nick sussex]

There are some good signs across the output that at least give a chance of something colder, theres good support now for the high to be displaced to the west and more amplification upstream in the USA.

 

The ECM seems to have disappointed people this evening but its operationals past 168hrs for the last week have been woeful in terms of accuracy, the ensemble mean has never backed a single one of its colder scenarios.

 

So I'm not sure why people think its all of a sudden got the detail right in FI, the key thing overall is we might finally see a good drop in pressure over central Europe and its really where the chips fall after that, you always take a chance with a more meridional pattern to end up on the cold side of any troughing, but at least theres a chance and also the PV might finally take a hike or at least split.

[Frosty.]

The Ecm 12z ensemble mean looks a lot better than the op run in my opinion, the jet is shaped much better with a robust looking nw-se alignment with polar maritime air being drawn down across the uk, I can imagine that arctic air could be mixed in with wintry ppn not just confined to hills and with the colder air, frosty nights would become more frequent. The bottom line is, the op run was a bit of a mess, this paints a better picture if you want cold weather to arrive between 8-10 days from now.

[Tom Jarvis]

all eyes now on the pub run wonder if has been downing a few pints!!!!

[SMU]

Evening All-

 

Watching the models over the last 3-4 days has felt like walking the wrong way along the travelators at Gatwick airport-

We seem to be moving along in time but not actually getting anywhere- even the cold is stuck at 192 & beyond-

 

I think we have be spoilt in recent years with some cracking charts-  who'd have though this was a recent November chart after so many winters of pain-

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-29-0-0.png

 

The problem with being spoilt is that it raises expectation - & that's bad on here as the expectation in November is always that the next 1963 is just around the corner.....

 

So far in the early season dogfight of cold & mild we haven't had much cold to cheer about, a few fleeting glimpses of PM air-  finally our first ground frost here at 2c the other night-

 

Things 'feel' as there on the turn though,but its slow - why>? because once that global wheel of zonality is spinning its a tough nut to crack-

The overall NH picture looks pretty flat as it stands with just the pacific ridge interrupting the zonal express, we are going to need see some vorticity moving NORTH into the pole, as that's usually accompanied by high pressure reaching out to the pole-

 

The ECM 240 shows some interesting developments-

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013111012/ECH1-240.GIF?10-0

 

* A split in the vortex across Russia, with some 532 heights towards the pole -

* An amplifying + PNA pattern - although not VERY strong just yet

* Atlantic Ridge, however the jet riding over the top-

 

I think the suggestion will be that we will see a PM airflow continue for a while yet- oscillating with a SW flow -

Eventually I think the jet eddies enough that we get a breakaway low to cross the UK introducing a fully amplified pattern-

 

I feel a toned down version of the November 2005 end seems on the cards-

 

In summary keep your eyes on 20/21 November- watch for a low /trough digging SE over the UK & fingers crossed for enough weakness in the zonal wind to allow heights to build towards Scandi afterwards....

 

Chow.

S