Model Output Discussion 1st Nov.2013

[johnholmes]

I think a touch of realism is required, less mild even colder than the previous weeks yes, but to me I cannot see any major sign of a real change in the upper air wavelength pattern. I keep reading about the large height anomaly off the west coast and how that is going to affect downstream. It does not show any such sign on the anomaly charts with the major polar vortex showing little sign of shifting from what is shown below. Until that is changed, and I have no idea how, then little major change can occur near the UK. The fairly flat westerly at 500mb seems set to continue for 2 weeks at least. Yes there are quite likely to be temporary shifts to bring fairly cold air south but they will be temporary behind fairly active weather systems continuing to run across the Atlantic in the strong upper, largely, westerly flow.

 

I would imagine cold is more likely for the south from anticyclonic type cold, fog and frost if the upper ridge does develop suffieciently for a time, although that is far from a done thing yet.

 

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

furthur data

PNA is predicted to be -ve, NAO just about -ve, AO +ve and the MJO is currently in 1, with reasonable distance from the origin, which equates to 500mb charts, see below, which look not much like either the current 500mb chart nor the predicted anomaly charts 6-15 days.

Its prediction below is, close to the origin, to track via 2, 3, 4, 5, 6, 7 to 8, see below

http://www.americanwx.com/raleighwx/MJO/MJO/NovemberPhase8500mb.gif

 

None of which to me suggests we have teleconnections that support any marked change in upper air pattern for 10-15 days if not longer. Of course the weather may prove this idea wrong but looking with realism at what we can use and to me there is little to support a marked change to deep cold for anything more than a 24-36 hour glimpse here and there in that time.

sorry but that is how I see it and I'm happy to be shot down by others showing charts that dispute what I'm posting.

 

http://www.americanwx.com/raleighwx/MJO/MJO/NovemberPhase1500mb.gif

 

sorry I forgot to show NAEFS at T+240 in the round up of links we tend to use for the 6-15 day time scale, the link will allow you to move forward or back to different time scales.

http://www.meteociel.fr/modeles/naefs_cartes.php?mode=0&code=0&ech=192&map=&runpara=

Edited November 5, 2013 by johnholmes

[johnholmes]

Hints of the NAO going negative as we move into the 2nd half of November

 

 

For those who don't know how it works

 

Positive NAO allows milder wetter westerlies to dominate the UK

 

Negative NAO can trigger northern blocking allowing colder air to sweep across the UK either from the north or East

 

 

Like any predictive tool SS its accuracy decreases the further ahead you look at it. Fine out to 7 possibly 10 days but not very good beyond that.

[phil nw.]

Yes John H as usual sums up things objectively wrt the next 10 days or so.

We can see the NH pattern forecast from the ECM mean charts at days 5 and 10

 

 

A colder westerly setup for sure but with only limited undulations in the jet any deep cold remains bottled up over the Arctic.

Plenty of mid-latitude heights that may build towards the south of the UK in week 2 settling things down for a while.

In all honesty though the outlook remains quite changeable and Atlantic driven which is quite typical of November as the vortex continues to cool over the pole.

 

 

[SMU]

Heres a sausage-

 

http://modeles.meteociel.fr/modeles/cfs/run/cfsnh-0-2250.png?12

 

or another type

 

http://modeles.meteociel.fr/modeles/reana/1978/archivesnh-1978-12-30-0-0.png

 

basically you are looking for a small area ( often sausage shaped) of +VE heights wedged over southern Greenland stretching towards the UK

you wont see the big yellow for deep heights, just the greens of a moderate anomaly-

 

What is does is split the jet with the cold funnelling around the pole SW but allows the atlantic to push to the UK- the Meeting ground is often deep snow for the SW of the uk ( inc midlands etc)

 

This one below- one from the archives- NO this year

http://modeles.meteociel.fr/modeles/reana/2013/archivesnh-2013-3-11-12-0.png

 

not so much a sausage but in exactly the right place to disrupt the flow...

 

S

[Frosty.]

Well I agree with JH 100 percent, I mentioned polar maritime incursions several times today but I have to say the broadly westerly upper flow pattern with air sourced from the north atlantic and occasionally polar / arctic maritime is a darn sight better than weeks of sw'ly mush from the azores and I think later in the month and through early december we will have an increasing risk of potent cold shots from the nw / n : - )

[shedhead]

I think a touch of realism is required, less mild even colder than the previous weeks yes, but to me I cannot see any major sign of a real change in the upper air wavelength pattern. I keep reading about the large height anomaly off the west coast and how that is going to affect downstream. It does not show any such sign on the anomaly charts with the major polar vortex showing little sign of shifting from what is shown below. Until that is changed, and I have no idea how, then little major change can occur near the UK. The fairly flat westerly at 500mb seems set to continue for 2 weeks at least. Yes there are quite likely to be temporary shifts to bring fairly cold air south but they will be temporary behind fairly active weather systems continuing to run across the Atlantic in the strong upper, largely, westerly flow.

 

I would imagine cold is more likely for the south from anticyclonic type cold, fog and frost if the upper ridge does develop suffieciently for a time, although that is far from a done thing yet.

 

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

furthur data

PNA is predicted to be -ve, NAO just about -ve, AO +ve and the MJO is currently in 1, with reasonable distance from the origin, which equates to 500mb charts, see below, which look not much like either the current 500mb chart nor the predicted anomaly charts 6-15 days.

Its prediction below is, close to the origin, to track via 2, 3, 4, 5, 6, 7 to 8, see below

http://www.americanwx.com/raleighwx/MJO/MJO/NovemberPhase8500mb.gif

 

None of which to me suggests we have teleconnections that support any marked change in upper air pattern for 10-15 days if not longer. Of course the weather may prove this idea wrong but looking with realism at what we can use and to me there is little to support a marked change to deep cold for anything more than a 24-36 hour glimpse here and there in that time.

sorry but that is how I see it and I'm happy to be shot down by others showing charts that dispute what I'm posting.

 

http://www.americanwx.com/raleighwx/MJO/MJO/NovemberPhase1500mb.gif

 

sorry I forgot to show NAEFS at T+240 in the round up of links we tend to use for the 6-15 day time scale, the link will allow you to move forward or back to different time scales.

http://www.meteociel.fr/modeles/naefs_cartes.php?mode=0&code=0&ech=192&map=&runpara=

Excellent post from JH....still nothing in the current model suite to suggest anything in the way of cold weather, well not away from Scottish mountain tops, but at least the big 2 continue to advertise somewhat higher pressure across the south towards the end of the reliable.  FI then shows HP developing across the continent, which looks a fairly natural progression based on current data, so if this has to happen hopefully it will remain close enough to keep things a good deal drier than of late....albeit mild.

Edited November 5, 2013 by shedhead

[tempestwatch]

Excellent post from JH....still nothing in the current model suite to suggest anything in the way of cold weather, well not away from Scottish mountain tops, but at least the big 2 continue to advertise somewhat higher pressure across the south towards the end of the reliable.  FI then shows HP developing across the continent, which looks a fairly natural progression based on current data, so if this has to happen hopefully it will remain close enough to keep things a good deal drier than of late....albeit mild.

I agree, excellent post from JH. Its especially good for learners like myself who ar often confused by conflicting posts. Posts like yous and JH's ais better understanding for me, many thanks

[Summer Sun]

More and more hints from the models now of high pressure building in either late this weekend or early next week

 

 

ECM

 

 

t240 shows the high pushing away

 

 

ECM ensemble however at day 10 (t240) points the the high persisting beyond mid month 

 

 

The GFS ensemble backs ECM's ensemble up as well

 

 

Edited November 5, 2013 by Summer Sun

[Summer Sun]

Latest from Gibby

 

All models continue to show a Westerly flow across the UK between High pressure well to the South and low to the North. A showery airflow covers the North and this will feel rather cold at times. In the South frontal systems continue to move East across these areas at times with more prolonged rainfall, particularly tomorrow. through Thursday and Friday the chillier showery flow over the North will extend to the South too with most showers in the West with a little sunshine in between. By the weekend a new trough looks like traveling East across all areas on Saturday with squally winds and heavy rain for a time before winds veer NW on Sunday with sunshine and showers in colder conditions to end the weekend.

 

GFS then leads us into next week with a warm front crossing NE over the UK on Monday introducing mild and drizzly weather following a spell of rain. A cold front follows with another band of rain but chiefly light in the South as pressure builds to the SW by midweek. this extends across Southern Britain with mist, fog and patchy frost likely for a while. By the end of next week the High slips away SE and pressure falls over the UK again with a return to unsettled weather to end the run in blustery cyclonic winds and temperatures remaining close to average.

 

UKMO closes it's run this morning showing the UK under a SW flow next Monday with a warm front crossing NE with a spell of rain followed by mild and muggy SW airflow with drizzle and mist over Northern and Western coasts and hills while the South and East become largely dry but cloudy and mild once the warm front rain clears late in the day.

 

GEM today is slightly slower to build High pressure up from the SW next week but eventually it does but not before the beginning of the week remains unsettled and breezy with occasional rain with the emphasis of this having shifted towards more Northern parts early in the week. Average temperatures look more than likely for all.

 

NAVGEM shows a Westerly flow maintained early next week with the polar front straddled somewhere close to Southern Britain with occasional rain and drizzle travelling East along it while the north would likely stay broadly showery in a stronger Westerly flow with more organized rainfall returning to all by the middle of next week.

 

ECM too shows a broad and mild SW flow over the UK early next week following a warm front East. Rain, drizzle and hill and coastal fog would affect the North and West while Southern and Eastern parts may have a drier interlude. By midweek a cold front has moved down into Southern Britain bringing some rain while the North turns brighter and colder with sunshine and showers. This front then gets hung up across Southern England with pulses of rain running West to East along it for a time. Late in the week a drier interlude in the South for a day or two with some brighter skies looks possible before pressure falls gently again with an increased risk of a return to mild Westerly winds and rainfall for all as we approach the second weekend.

 

The GFS Ensembles continue to show a trend towards rising pressure to a mean in excess of 1020mbs over the South early next week. This in response to High pressure building up close to the South which sends the Jet stream North and allows mild SW winds to flood the UK around Low pressure well to the NW. As one would expect precipitation values are shown to fall from next week especially over Southern locations while the trend to return slightly lower pressure and increased rainfall is hinted at again towards the end of the run.

 

The Jet Stream forecast remains for it to pump East at high speed across the UK for the rest of this week before a temporary push North of the flow seems likely towards a position just to the NW of Scotland. However, such a push North looks like it may not last very long.

 

In Summary the rest of this week looks set in stone now and this includes the weekend. So all areas can expect rain at times especially across the South in the next 36 hours or so with some copious amounts possible. From Thursday showery weather seems likely with some drier spells in between before a trough at the weekend is followed by a swing of winds to a colder NW point and with fast rising pressure better conditions will be felt in the South. The second week of output is trickier to call as some output brings High pressure up across the UK, especially the South with resultant fine weather along with mist and fog possibilities. Other models show a more muted attempt to push High pressure up instead pushing a warm and moist SW flow across Britain early next week with cloudy skies and hill and coastal fog and rain to the North and West. There is also then a trend hinted to bring more unsettled weather back to all areas late in the output. Yet again this morning there is absolutely no hope of anything remotely very cold or wintry trended or highlighted in any charts I have seen this morning.

 

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

[draztik]

Yes Gav, the ensembles very keen on a pressure rise, and keen on an extended period (though the signal becomes somewhat weaker during the latter stages from GEFS). I'm wondering if we'll see a tweak in the MetO update later.

6-10 day height anomalies ECM Ens 0z

11-15 day height anomalies GFS Ens 0z

[Summer Sun]

Yes Gav, the ensembles very keen on a pressure rise, and keen on an extended period (though the signal becomes somewhat weaker during the latter stages from GEFS). I'm wondering if we'll see a tweak in the MetO update later.

6-10 day height anomalies ECM Ens 0z

11-15 day height anomalies GFS Ens 0z

 

Yeah think we'll see a change in it shortly given UKMO is coming on board now

 

GFS ensemble as you say becomes weaker this is day 16 the high is not too far away so it could go either way from here

 

Edited November 5, 2013 by Summer Sun

[I remember Atlantic 252]

Good, I want high pressure, had enough of low pressure,

[Summer Sun]

I'm wondering if we'll see a tweak in the MetO update later.

 

Little change in the outlook for next week from the met today

 

 

Remaining unsettled and breezy on Saturday with further blustery showers, and sunny spells. These showers will be heaviest and most frequent in the north and west, and locally wintry over the high ground of the north. However a spell of persistent rain and strong winds could also move across the south.

 

Staying largely unsettled and breezy thereafter with showers or longer spells of rain, locally heavy, particularly in the northwest. It will also be windy at times here and feeling cold, with showers again possibly wintry over hills. The best of brighter and drier spells will be in south and east however, where it will remain generally mild by day for November. However when winds ease overnight, it could become quite chilly here leading to frost and fog patches.

 

 

 

No change long term as well into December with a lower risk than normal for frosts, with nothing cold or wintery in sight

[SMU]

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=8&mode=0&carte=0

 

A rogue run from the GFS 06z sets the trend for the second half of November....

 

S

[Frosty.]

WOW..................Perturbation 8..GEFS 06Z = THE HOLY GRAIL...BANK.....     STUNNING CHARTS  

[in the vale]

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=8&mode=0&carte=0 A rogue run from the GFS 06z sets the trend for the second half of November.... S

Quite widespread snow showers from that, albeit rogue as you say. A change has to come at some point!

[Chris K]

WOW..................Perturbation 8..GEFS 06Z = THE HOLY GRAIL...BANK..... STUNNING CHARTS

Haha Frosty - sometimes I love your posts. Even if it's highly unlikely to verify at this stage, you always know when to try inject some extra positivity in this thread

Just having these outputs showing is giving something to clutch a straw factory over if you crave cold weather, even if it does looks like staying generally mild(ish) and changeable for the forseeable...

What I would say is recently there does seem to be some sort of trend for high pressure to cross either over or just South of the UK. This then seems to want to head East into Europe, intially giving us some mild Southerlies for a time. It is at this point that the models seem to be toying with the idea of either having some sort of large high staying over W/Central Europe or transferring it up towards Scandi. Obviously both giving quite marked differences in the surface weather we would likely experience from each.

Edited November 5, 2013 by Chris K

[pip22]

WOW..................Perturbation 8..GEFS 06Z = THE HOLY GRAIL...BANK.....     STUNNING CHARTS  

Thanks frosty, I am really hyped up now.  I so excited!!   If the models do change I be RAGE!

Edited November 5, 2013 by pip22

[A.J]

WOW..................Perturbation 8..GEFS 06Z = THE HOLY GRAIL...BANK.....     STUNNING CHARTS  

lol...

 

Why do I need to write a long reply when a picture or two can paint a thousand words...

 

[Yarmy]

WOW..................Perturbation 8..GEFS 06Z = THE HOLY GRAIL...BANK.....     STUNNING CHARTS  

 

It is a well-known FACT that Perturbation 8 at T336 is the best-verifying chart of all the NWP models.

Edited November 5, 2013 by Yarmy

[Bobby]

Haha, the NASA model wants to give heavy snow to the hills of Wales on Friday/Saturday. I'll eat my hat if that happens.

[Frosty.]

lol...

 

Why do I need to write a long reply when a picture or two can paint a thousand words...

 

index.jpg images.jpg

I blame steve  saying it's the trend for the second half of november..it's about time coldies had some eye candy to gawp at and hopefully those type of charts will make it into the reliable timeframe during the winter, and then more of us will be dressing up like steve

[shedhead]

Just by way of balance.... http://www.meteociel.fr/modeles/gefs_cartes.php?ech=384&code=7&mode=0&carte=0

 

 

 

NOOOOOOOO!!!!.................Perturbation 7..GEFS 06Z = THE HOLY FAIL...*ANK.....   SHOCKING CHARTS    

 

 

  

[legritter]

well im a kind of thinking ,perhaps something is a lurking around the corner ,high pressure seems to be bringing its Top Hat out of the cupboard ,early signs i know but the charts in far outlook dont just pop up gang ,so the possibilty is there .odviousely the next severall days will tell , and mother nature SOMETIMES balances the books , Well i,m taking a big straw out of my winter box ,and theres plenty more to be had with 13 weeks of winter to come .but at present the next week seems very disturbed ,with favoured locations perhaps seeing some wintryness ,

[Summer Sun]

Overnight tonight we'll see a temperature difference of around 20c across the UK in parts of Scotland -5c looks likely whilst in south west England the overnight low will be around 15c