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Model Output Discussion - 31/10/2014 and Beyond


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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Talk about chalk and cheese!

 

 

 

This, from the same starting conditions, can develop to such disparity at only 336 hours - those fretting about winter LRFs  take note: if the regular NWP has such difficulties resolving the atmosphere, how the blazes can we even contemplate monthly and beyond as being in any way accurate.

 

Yes it does make one wonder just how such a huge difference can be created and from the same stable so to speak.

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Ian Fergusson posted this in the Wales/SW regional thread if anyone missed it.

 

With MOGREPS and EC EPS in good agreement on re-assertion of cyclonic SW'rly into 10-15d trend period (and no sign of any easterly cold advection at least on current signals), we are into a rinse-repeat cycle for W Country that will seem all too familiar in broad sense from last year...


It does look like a slacker, calmer period for a while before a renewed surge from the Atlantic, fuelled by the PV NE Canada way.

 

This would seem to fit the GFS P take

 

gfs-0-312_rru4.png

Edited by Bobby
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

This, from the same starting conditions, can develop to such disparity at only 336 hours - those fretting about winter LRFs  take note: if the regular NWP has such difficulties resolving the atmosphere, how the blazes can we even contemplate monthly and beyond as being in any way accurate.

 

But well reasoned winter LRFs generally don't go into any accuracy, rather they will describe general trends that may happen with weather patterns each winter month. Yes NWP will often have difficulties nailing down positions of ridges and troughs, but winter LRFs will look at the bigger picture, i.e how the state of QBO, ENSO and snow cover, for example, at the begining of the cold season has an impact on the stratosphere which can then give forecasters an indication of the likely state of the AO and NAO - which can then infer whether we are more likely (or not) to see cold and snow spells over the UK at some point this winter.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

After my usual close morning look at the EC-GFS anomaly charts I wrote this

tue 11novtue 11tue 11nov

Ec-gfs

Certainly changes on both with the uk shown more under ridge than trough conditions, from the original n Russia/n Europe/Scandinavia area, not sure of the way each treat the uk area trough, rather differently. One thing in common is the deep low over ne America; not too different from noaa 6-10 here, and the area close to uk, not that similar really, but all 3 suggest a fairly slack flow for the uk area. The deep cold off ne America and the strength of the flow across the atlantic coupled with the decrease in flow strength just w of the uk suggests to me some pretty deep lows coming close to the uk in the 6-10 day time scale. Have to wait and see if this does happen?

60dm difference at 500mb from n florida to the far n of the gt lakes!

 

There is no sign yet on any of the models or Met Fax at 120h of any of this but it does look like something to watch out for. Essentially a diffluent trough is just about showing on these charts close by the uk(w of), an area where fairly rapid deepening of lows does occur. Of course the old fella could be talking rubbish again. A week ahead should start to show how right or wrong this idea is.

sorry missed adding the links

EC-GFS

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

NOAA

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

also interesting to see the statistics at day 6 for the models, EC as is often the case in the lead, but over the last few days watch the newcomer?

http://www.emc.ncep.noaa.gov/gmb/STATS/html/new_acz6.html

Edited by johnholmes
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Posted
  • Location: Exile from Argyll
  • Location: Exile from Argyll

But well reasoned winter LRFs generally don't go into any accuracy, rather they will describe general trends that may happen with weather patterns each winter month. Yes NWP will often have difficulties nailing down positions of ridges and troughs, but winter LRFs will look at the bigger picture, i.e how the state of QBO, ENSO and snow cover, for example, at the begining of the cold season has an impact on the stratosphere which can then give forecasters an indication of the likely state of the AO and NAO - which can then infer whether we are more likely (or not) to see cold and snow spells over the UK at some point this winter.

 

Thanks, Nick. I understand fully what you say but the teleconnections that you mention are being discussed on here as being in opposition to what the winter forecasts indicate. Some of the models have updated with the October SAI now known but, if anything, the picture has warmed for both sides of the Atlantic. Very knowledgeable people are describing conflict in the indicators - what are us less informed individuals to make of it all?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Very knowledgeable people are describing conflict in the indicators - what are us less informed individuals to make of it all?

sit back and watch and wait, it is for sure a very interesting situation. 

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

Thanks, Nick. I understand fully what you say but the teleconnections that you mention are being discussed on here as being in opposition to what the winter forecasts indicate. Some of the models have updated with the October SAI now known but, if anything, the picture has warmed for both sides of the Atlantic. Very knowledgeable people are describing conflict in the indicators - what are us less informed individuals to make of it all?

 

Yes if it wasn't for the possibility of an SSW it would be doom and gloom on here as both EC and UKMO Long Range have been very consistent for a milder and wetter DJF than average. Both have updated in the last few days and maintain this strong signal. JMA have also been firmly in this camp for D/J (Feb not out yet):

 

post-14819-0-59001300-1415709851_thumb.p  post-14819-0-64660000-1415709862_thumb.p

 

Current December from CFS: post-14819-0-62882400-1415710284_thumb.p post-14819-0-31937800-1415710293_thumb.p

 

My take on it FWIW, is that background signals suggest that we are in for a poor winter with respect to cold but the unknown knock on effects from the current warming(s) may give us a backdoor to something wintry. Whether after the possible warming we revert to the background signal again is anybodies guess.

Edited by i'm dreaming of...
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Once again the ECM goes from Champ to Chump!

 

Generally the models have moved away from the stronger blocking shown a few days ago and we've seen a long drawn out drama with the trough disruption near the UK, the shortwave near southern Greenland has scuppered the ridge backing west, we've today also seen less amplification upstream as the ridge in the western USA is now wanting to be broken down by the operationals.

 

The timing of this is important and also if the models will indeed break this down, comments from NCEP do suggest uncertainty continues and as that amplified ridge has a large knock on effect downstream then perhaps we should wait for this evening to see if the models have over reacted or perhaps a bit too quick on this front:

 

This is the most pertinent part of that discussion

 

...OVERVIEW...

PERSISTENT UPPER PATTERN WILL FEATURE A RELOADING TROUGH IN THE
CENTRAL AND EASTERN STATES WHILE THE WESTERN RIDGING MAY SHOW
SIGNS OF BREAKING DOWN BY NEXT WEEK. CORE OF THE NEGATIVE HEIGHT
ANOMALIES /AROUND -3 OR SO STANDARD DEVIATIONS/ WILL SHIFT INTO
THE GREAT LAKES REGION EARLY NEXT WEEK AS A COLD UPPER LOW SWINGS
THROUGH SOUTHERN CANADA. BIGGER QUESTIONS REMAIN IN THE WEST AS
THE ENSEMBLES SHOW A WIDE ARRAY OF SOLUTIONS PERTAINING TO HOW THE
RIDGE MAY START TO BREAK DOWN -- OR NOT -- BY MON/TUE NEXT WEEK.

 

FOR EARLY NEXT WEEK IN THE WEST... THE MODELS/ENSEMBLES SHOW JUST
ABOUT EVERY POSSIBILITY FROM MAINTAINING THE RIDGE AS-IS TO
SNEAKING ENERGY THROUGH IT INTO N CALIFORNIA TO ESSENTIALLY
DESTROYING IT. HAVE NO FAITH IN ONE OR ANOTHER DETERMINISTIC RUNS
AS THEY WILL KEEP CHANGING FOR SEVERAL MORE CYCLES. FEELING RIGHT
NOW IS TO LEAN TOWARD MORE RATHER THAN LESS RIDGING BUT ALLOWING
AT LEAST SOME ENERGY TO APPROACH THE COAST

 

The full discussion can be found here:

 

http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html
 

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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

N America going into the freezer again this season

Rnamavn969.png

Hopefully we will follow them this time rather than what happened last year. :wallbash:

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

N America going into the freezer again this season

Rnamavn969.png

Hopefully we will follow them this time rather than what happened last year. :wallbash:

 

That's dew point I think, not temperature (might be wrong, I'm not fluent in German!). Although the US is being plunged into a cold spell.

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

That's dew point I think, not temperature (might be wrong, I'm not fluent in German!). Although the US is being plunged into a cold spell.

 

Yes its the dew point

 

These are the 850's for the same time

 

gfsna-1-96.png?6

 

New York could be struggling to get above 5c on Saturday which is well below normal

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Posted
  • Location: Northern Ireland
  • Location: Northern Ireland

GFS, GEM and Euro all singing from the same sheet by day 10 with a build of pressure closer to the UK. 

 

Not the freezing beasterly we wanted but could be sunny and chilly..

 

Rtavn2407.gif

It doesn't look too cold to me with double figure maximums. Thats mild.

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Posted
  • Location: Emsworth, Hampshire
  • Location: Emsworth, Hampshire

I still can't get over why people are starting to write off winter? 

 

GFS +102hrs

 

post-9530-0-66516900-1415715259_thumb.pn

 

Polar vortex still pretty much struggling. Yes the US has a rather deep trough for the time of the year, but I wouldn't be worried. No one can say if this will be another wet and mild winter, but the set ups are like night versus day compared to last year. And it's only November after all!

 

Anyway, expect more of the same wet weather towards the Mid to End of November as the trough is staying put right out to the end in the US...

 

GFS +192hr

 

post-9530-0-30307800-1415715551_thumb.pn

 

Note the 970mb Low to the South of Alaska, that area seems to be a area where Low's are stalling and just spinning around, sending warmth North (ridge) into the Polar region. I posted about that last week with Extra-tropical storm Nuri. When you get a Low entering that area, you tend to get a trough set up around N America within 7 to 10 days. And that's exactly what we have now. Shift those Low's and you stand a better chance of shifting that trough. 

 

SM

Edited by SnowMania
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Posted
  • Location: Newton in Bowland
  • Location: Newton in Bowland

And there we have it. We're looking at a circa 4 week timescale for the next period of interest as a couple of us pointed out yesterday. SB I think it was clear that this first attempt was to fail, so no need to apologise for that! A sense of realism is always required!

As touted by Chion and one or two others including the 16-30 day MetO updates. Still plenty on interest in the models though with a trough to our West and a block to our East going nowhere fast, unfortunately for us that spells a rather wet outlook for the next few weeks at least. Edited by Hocus Pocus
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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

The output was a bit of a muddle this morning, I expect ECM to be more in line with UKMO this evening after an unusually progressive Op this morning.

 

It is hard to see how we could get the required blocking from current output to drag some unseasonably cold air over the UK before November is out so I won't try to make a case for that based on actual output but things change and there is still plenty of interest in the output one way or another.

 

If you enjoy a good straw clutch though;

A slither of hope exists around day 7/8 if the models are too fast and flat with the jet off the eastern seaboard, if so we could still see some WAA toward Greenland, a sort of cavalry charge to head the Atlantic off at the pass so to speak. Unfortunately there is little evidence for this at the moment but UKMO would probably go on from day 7 to make a better fist of it than GFS though not likely nearly amplified enough to save the day. ECM isn't worth assessing in this regard but hopefully it will be a bit more useful this evening.

 

Still, hard to see a Greenland high forming at all as the Atlantic ramps up though a "weakish" Icelandic high may be a reasonable possibility day 10+ if there is enough amplification to get good trough disruption west of the UK around day 8. All of that is quite far ahead and quite possible pie in the sky but if you enjoy seeking out possible cold even while the trend is against you that is the sort of timeframe and areas I would be looking at for any surprise developments.

 

Otherwise it is sit back and wait and see how things develop and remind ourselves it is early November, winter hasn't even started yet. :good:

Edited by Mucka
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

As touted by Chion and one or two others including the 16-30 day MetO updates. Still plenty on interest in the models though with a trough to our West and a block to our East going nowhere fast, unfortunately for us that spells a rather wet outlook for the next few weeks at least.

Indeed. Though the hysterics in the model banter thread are rather amusing. Someone hit the nail on the head yesterday regarding the NWP when they said it's like a movie. The plot is in place and we're just witnessing the plethora of twists along the way.

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Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

 

 

Not the freezing beasterly we wanted but could be sunny and chilly..

 

 

 

No, that will have already arrived, prior to the 21st November chart you've posted. :good:  Some four days of Easterlies and then the above would be a perfect setup for colder weather still, come December, if not before and maybe even some white stuff getting mentioned in deepest FI.  :clapping: Although having read some of the other analysis in here, it might be a case of how long any HP influence hangs around if indeed it even develops as shown. One thing is for sure the Easterly remains on the cards and t+240 onwards is yet unable to be determined. Will we see a rampant NH Jetstream being modelled across the NWP outputs IS the most pertinent question by then I suspect.

 

GFS 12z and UKMO 12z are about to roll.   :gathering:

 

Here is our starting point, just where will things lead from here?

 

post-7183-0-20431200-1415720258_thumb.pn

 

I would suggest the locations to focus on are North Pacific region (ex-Nuri evident at this stage?), Eastern seaboard of USA and the Greenland, Iceland North Pole region. All IMHO and I'll let others add "more meat to the bones" as things progress.

Edited by gottolovethisweather
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Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

It doesn't look too cold to me with double figure maximums. Thats mild.

 

Initially yes, but I hope and think the fog and associated frost would peg back temperatures to well below at the surface when compared to the expected t850s, especially at a local level.

Edited by gottolovethisweather
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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk

dont want to be a killjoy and although very early days but the gfs 138 does look a little worrying with the other segment of polar vortex its seems to be heading towards greenland and possibly linking up with its other half....

 

gfsnh-0-138.png?12

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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

Meantime back in the real world the ENS paint the usual picture of above average 850hPa temps and lots of rain although things could be drying out somewhat in time - AND - there are a few colder runs appearing in FI land, the mean is still above average.

MT8_London_ens.png

 

We will need to see more of the colder runs appearing and also coming more into the reliable timeframe - for the time being though it's 'business as usual'. :wink:

Edited by Purga
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Posted
  • Location: Burton-on-Trent (90m), Larnaka most Augusts
  • Location: Burton-on-Trent (90m), Larnaka most Augusts

GFS 12z shows a much more southerly tracking low in the North Atlantic than the 06z before, leaving a bit of space for high pressure near the Greenland/East Canada area.. Not really expecting anything to come from it though as all the pros seem to think mild and unsettled will win in the end.

 

http://www.wetterzentrale.de/pics/Rtavn1381.gif

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