Model Output Discussion 1st Nov.2013

[SE Blizzards]

A selection of beauty's from the 18Z suit!

 

 

[SMU]

A word of caution to those using the ECM mean past 168 to mediate it against the operational-

 

The ECM suite consists of 50 runs, so for every 1 run that disagrees with the operational the 'overall' picture painted by the mean is blended out to something more normal- in this case a less amplified pattern-

 

There is an alternative way of looking at that though in terms of confidence levels- looking at the ECM op V the ECM mean at 240 its clear there is NOT 100% support for an amplified GH pattern but there is some amplification there so I would say around 60% support for that pattern type on the ECM-

 

not conclusive yet-

 

we would want a stronger 80% signal at 168 to start feeling confident about a particular pattern type...

 

cheers

 

from your regular winter attraction lol

[Snowman.]

Genuinely - can you show me an example since 2009? My own close following of NH weather goes back only that far, but I dont recall a single extended cold period that wasnt linked back to a strat event.

December 62

 

A SSW occurred during January

 

"The spectral energy equations for zonal and eddy kinetic and available potential energies are used to investigate the energetics of the lowest 30 km of the atmosphere during the months of January and February 1963. A major stratospheric warming, manifested in the reversal of the stratospheric meridional temperature gradient and destruction of the polar-night stratospheric vortex, began in mid-January."

 

http://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1965)022%3C0597%3AASOAED%3E2.0.CO%3B2

 

The warming did appear towards the end of December then took till Mid-Jan to take effect.

 

A strat warming is always triggered and never appear out of thin air.

[Biggin]

December 62

 

A SSW occurred during January

 

"The spectral energy equations for zonal and eddy kinetic and available potential energies are used to investigate the energetics of the lowest 30 km of the atmosphere during the months of January and February 1963. A major stratospheric warming, manifested in the reversal of the stratospheric meridional temperature gradient and destruction of the polar-night stratospheric vortex, began in mid-January."

 

http://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1965)022%3C0597%3AASOAED%3E2.0.CO%3B2

 

The warming did appear towards the end of December then took till Mid-Jan to take effect.

 

A strat warming is always triggered and never appear out of thin air.

I could be wrong but last year a threatened SSW warming  was predicted to happen. We waited and waited. While we were waiting for it to happen we had a good cold snowy winter. When it finally came wasnt it a bit of a damp squib ??

[That ECM]

ECM at T216 is going to generate much discussion. Northerly that many have been suggesting? May not last long but would be welcomed by many. Esp those up north.

T240 is going to make many happy. Good to view. Need support from other output but better than seeing output after output showing a flat westerly flow.

Would some one post the chart please as I am on mobile and do not have the technical ability!!?

Edited November 9, 2013 by That ECM

[Jonan92]

Here you are

 

Northerly at 216t

 

 

Very low temperatures at 240t

 

 

[Frosty.]

ECM at T216 is going to generate much discussion. Northerly that many have been suggesting? May not last long but would be welcomed by many. Esp those up north.

T240 is going to make many happy. Good to view. Need support from other output but better than seeing output after output showing a flat westerly flow.

Would some one post the chart please as I am on mobile and do not have the technical ability!!?

There we go, awesome charts from the Ecm 00z op run, stunning    

[bluearmy]

ECM op interests me. The op has consistently hinted at becoming very amplified to our west around the 18th but the ens members which show cold in London have always been a day or two later. It wouldn't be the first time that the op has picked the right kind of solution but been a day or two over progressive. I suspect the 00z op will be an outlier of sorts for London.Now we have the post 20th period well in view on gefs, any heights rise to our nw seems likely to transient and we may well see any ridge sink across us. it's 50/50 whether the vortex then becomes disrupted/split or retains its integrity. If the former, then a mid lat high will be useful for retrogression once the next amplification comes in from the west. my current but feeling is that it may be the latter although perhaps not for too long.

I could be wrong but last year a threatened SSW warming  was predicted to happen. We waited and waited. While we were waiting for it to happen we had a good cold snowy winter. When it finally came wasnt it a bit of a damp squib ??

Your memory playing tricks with you mate. You are wrong. The snow came after the strat warming. Doesn't prove/disprove anything though.

[Frosty.]

Don't see any cold spells but I do see some cooler shots

 

The models have been indicating a cold shot at various times on various output in recent days for the second half or at least the final third of november. These charts here would be the ultimate reward for coldies patience.   make it.....SNOW 

[cold snap]

Net weather mods you want be able to take the day off today.going to be busy in here.

A incredible ECM considering the recent suggested output.

The trend has to keep coming over further runs.this has been hinted out,and the signal has been geting stronger by the day.

[radiohead]

It's interesting to imagine which direction the ECM would go beyond T240 there. A Scandi high perhaps?

[Frosty.]

The most pleasing thing to me this morning is how the ecm 0z has followed through with that cliffhanger T+240 hours ecm 12z chart last night, this run shows us what we almost saw last night..Bring it on.

[Frosty.]

The GEFS 00z perturbations show some support for the Ecm 00z op run, there are a lot more which also have potential but these are my pick. even the GEFS 00z mean shows a colder trend locking in as time goes on, so I would say there is a good chance of a much colder shot from between northwest and northeast during the final third of nov with a risk of snow

Edited November 9, 2013 by Frosty.

[lorenzo]

I dont know enough about Canadian warmings yet... but it is a small straw I still have a finger in contact with. I have asked Chio about it over on the Strat thread but he seems to have gone very quiet. That isnt a great thing in itself because when he senses a warming, or reads one coming, he tends to post quite frequently. His silence to me is deafening.

 

CH, Canadian warming events are very rare, whilst one is overdue they are a bit of an anomaly in themselves and cannot be really categorised until after the fact with re-analysis. Last one 13 yrs ago ! Evn without the CW there is plenty of other interest.

 

Here are a few of the latest TC's for PNA / AO / NAO, the positive regimes of the AO and NAO heading toward a more neutral > negative position.

 

With the PNA being an upstream pattern that is not often referred to on here, this image neatly shows how the hemispheric pattern is set up. The ECM earlier this week very bullish about the cold plunge but has backed off a little.

 

Onto the ECM which is pretty amazing looking and let's hope it maintains the theme.. 144 is a point of interest as this is where that MA ridge really cranks up.

 

Then some fantastic cold looking charts thereafter.

 

Great to see, will we have a game of ECM picks up a trend, drops it, GFS picks up the trend, drops it, then both verify and annoy the hell out of everyone with GFS getting the blame..

[bluearmy]

the pacific ridge seems uncertain as to where it might push into the arctic. the past few runs have trended towards an amplified kamkatchkan ridge leaving the aleutians/eastern alaska more uncertain.

the ecm op 850's iare outside the spread of the ens mean at day 10 for the south of the uk. that means its extremely unlikely to verify at that timescale. not a shock really, given that it showed snow and freezing surface temps at its conclusion.

Edited November 9, 2013 by bluearmy

[shedhead]

An interesting and cold looking chart from ECM, but let's not forget it's still 9 days away and as such very unlikely to verify as shown.

 

GFS offers this for the same timeframe, but whilst it's encouraging to see a similar pattern being touted we are still talking FI, so until we see synoptics like this inside T+120hrs caution is still strongly advised.

 

 

IF it comes off, Mr Madden will have been spot on of course....

[stewfox]

We don't need the strat, we have already been through this recently and we don't need it again.The strat doesn't control NH weather patterns and in fact troposphere usually starts a warning in the first place.We have had plenty of cold periods of weather with out the help from the strat, people tend to rely on it so much.

In need, we all know a low going 50 miles off its original course can make the difference between blizzards and rain for this tiny Island. I dislike how some strat folk are writing off chunks of UK weather and model forecasting. Words like we wont see any locked in pattern now till year end is hopecasting rather then model watching.We have seen time and time again how major changes first picked up with a signal can shift the mood within this thread within T72.Also I'll take a short live northly for 2/3 days currently showing in F1 rather then this show of constant disppointment of no sustained blocking.The models are showing general average November weather. Rain sleet snow fog frost mist , I'll take that rather then having Mr Barlett to dinner. Edited November 9, 2013 by stewfox

[Summer Sun]

Whilst the ECM operational might want to deliver something cold from the north, the anomaly and ensemble remain uninterested like last night and instead they keep high pressure over the UK

 

Anomaly

 

 

Ensemble

 

Edited November 9, 2013 by Summer Sun

[Chess01]

Whilst the ECM operational might want to deliver something cold from the north, the anomaly and ensemble remain uninterested like last night and instead they keep high pressure over the UK

 

Anomaly

 

 

Ensemble

 

Clutching straws here summer sun

[Summer Sun]

Latest from Gibby

 

All models continue to support a well documented pattern for the next week. In short a changeable Westerly or NW flow will affect the UK through the period around an intensifying High pressure area close to the SW next week. The High will never be quite close enough to prevent troughs and some spells of rain moving East or SE from time to time, notably tomorrow night and Monday and again on Wednesday. In between rather colder and brighter conditions will interrupt these milder interludes with some sunny spells but a cold wind from the NW.

 

GFS then shows the end of next week with Southern areas becoming settled for a time as the High moves over with mist and fog and rather chilly conditions developing while the North stays more changeable with rain at times. At the start of the second week winds swing Northerly briefly with a cold shot for all with some wintry showers in the North and East and night frost with the end of the run seeing a rinse and repeat of this scenario before a High pressure elongates across the north with Low pressure further South bringing some rain and sleet and a cold East breeze here while all areas become cold and frosty later.

 

UKMO shows High pressure close to the SW late next week with a cold north wind over England and Wales though away from the odd shower in the East t would likely be dry. With a ridge over Scotland here lies the greatest risk of frost overnight in lighter winds.

 

GEM maintains a changeable theme right out to Day 10 with some troughs crossing East at times especially over the North with rain now and again alternating with rather brighter and chillier interludes.

 

NAVGEM builds High pressure across England and Wales next week with Scotland staying mild and breezy with some rain. Fog and perhaps frost could well become an overnight and morning issue for Southern Britain under light winds.

 

ECM potentially shows the first wintry blast of the season next weekend as a Low moves South down the North Sea with an Atlantic High toppling over the top of it to the North of the UK setting up a spell of rain followed by North then NE winds with wintry showers or rain and sleet at times all the way down to Southern Britain into the start of the new week.

 

The GFS Ensembles are trending colder slowly with the mean gradually falling just the colder side of average rather than above. There are no huge amounts of rain shown anywhere but there is some highlighting the proximity of troughs of Low pressure at times.

 

The Jet Stream continues to show a migration North next week as a High builds to the SW before it's trend becomes more undecided and broken beyond that.

 

In Summary today there does appear the risk of something rather colder on the horizon breaking us out of the Atlantic train. There are various ways that this is shown ranging from High pressure building across the UK from the Atlantic bringing a spell of quiet settled weather with mist and fog or the ECM route of sinking Low pressure South over the North Sea with an Atlantic High ridging East over the top and bringing a spell of much colder north or NE winds and no doubt some snow to the higher ground and possibly not just in the North. The problem is it is still a little too far away to give much confidence of this happening as shown but I do believe there are rumblings in the atmosphere which could produce something more exciting for the wintry contingent among us before long.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[Frosty.]

I agree with summer sun, at least the mid range between T+168 & T+240 looks anticyclonic for most of the uk. The GEFS 00z mean shows this clearly, most of the gefs 00z perturbations are very settled during that timeframe, it's what comes after that which interests me.

[Summer Sun]

Before we get to anything cold the short term shows some welcome dry settled weather developing especially but not exclusively in the south

 

 

Thursday looks a blip

 

 

Before pressure builds in strongly again

 

 

I think we can say with some confidence now the Atlantic train of low pressure systems is running out of steam

 

Edited November 9, 2013 by Summer Sun

[SomeLikeItHot]

Whilst the ECM operational might want to deliver something cold from the north, the anomaly and ensemble remain uninterested like last night and instead they keep high pressure over the UK

 

Anomaly

 

 

Ensemble

 

Its not a particularly strong signal for high pressure over us, but rather the result of a wide range of ensemble outcomes from north to south of us as there is no strong centre. You've got to remember if the split of ensemble paths was 50% to the north and 50% to the south and nothing centred on the UK, we can still get an ensemble mean that is centred over the UK. Certainly there is no consensus on the 240 hour outcome, but is there ever? But I would be surprised if the ECM Op was an outlier. Its probably biased to being more ensemble members over or to the south, but the low near Iceland would be much lower than 1000 if there wasn't a group of ensembles putting high pressure there.

[joggs]

Anybody heard from Dave aka Teits yet?.Its about this time of the year he re-surfaced on this thread lol.Hopd he's ok.

[legritter]

Certainly looking good if your after a possible cold shot .we have gone from the last frame of ECM showing cold to last couple now hinting the same .every run is interesting but tonights could be especially so .certainly something of a change in my opinion is possible in about a week or so .lets sit back gang and enjoy the ride yet again .