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DiagonalRedLine

Model Output Discussion - 31/10/2014 and Beyond

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GFS P goes crazy with developing a -AO

 

attachicon.gifgfsnh-0-168.png

 

The two GFS are not suckling from the same teat at the moment.

 

Just wanted to mention the effect of Typhoon Nuri - some runs are showing explosive cyclogenesis to below a phenomenal 920 mb as an extra-tropical storm by Saturday.

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The two GFS are not suckling from the same teat at the moment.

 

Just wanted to mention the effect of Typhoon Nuri - some runs are showing explosive cyclogenesis to below a phenomenal 920 mb as an extra-tropical storm by Saturday.

 

Indeed the T1534 has it at 918mb and a 500mb hgt. of 4724 gpm. And if you want cold.

 

Charts WeatherBell Analytics (www.weatherbell.com)

post-12275-0-15619800-1415168070_thumb.p

post-12275-0-60604000-1415168600_thumb.p

Edited by knocker

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There is nothing in this mornings GFS run that says anything but wet and windy and that's out to T384.

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Got to agree with knocker this morning very average november wearher showing on the gfs charts very wet in places.

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Not really much to say. It looks clear now that the cold that has headed down to our mid latitude will pass us by, the US in for a 4-6 day very cold shot. The models are now suggesting total disruption of the PV from the mid latitude cyclonic interaction with the jet. This energy will gradually subside and from  FI charts from the GFS it looks like the packets of ex PV low heights will meander around looking for a home:

 

post-14819-0-58635700-1415171700_thumb.p op parallel:  post-14819-0-97061300-1415171724_thumb.p  Control:  post-14819-0-67203000-1415171842_thumb.p

 

The last frame is 21 November and the lower heights are beginning to suggest a more organised split PV. So as others have said the next 2 weeks of November looks like being average for temp and rain for the east, but very wet for the NW/W/SW:

 

Next 8 days: post-14819-0-35550000-1415171981_thumb.g  temps: post-14819-0-30058300-1415172489_thumb.g

 

So its a case of keeping an eye on FI charts to see if and how long it takes for the PV to recover. The ensembles at D16 have members showing a more organised PV to a continued disrupted PV; they are split about 50:50 so looking at the mean for clarity beyond D10 is not going to help at the moment. It will be interesting to see where we go after this amplified pattern flattens.

Edited by i'm dreaming of...

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The model of choice this morning ( which is difficult as overall continuity has been poor ) is the ECM.

 

3 consectutive runs ( maybe 4 ) with retrogression across Scandi. If you want to get cold quickly back into Scandi via troughing then this is the route past day 9/10 & 11-

 

As mentioned these are the interesting days - so if I had to earmark a date for a change it would be the 14th or 15th....

 

GFS- Not really worth commenting on now. As if it wasnt bad enough having one useless operational followed by another 20 equally if not worse ensembles, we now have another arrow in the bag to fire randomly...

 

Stick with the Euros. The same as been the case for the last 14 years.

 

Watch for a chart 'like' this - we want all the negative flow aimed WNW at the SW tip of greenland-

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-20-0-0.png

I take it that the "we" you speak of is the 'Royal We'?? 

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The model of choice this morning ( which is difficult as overall continuity has been poor ) is the ECM.

 

3 consectutive runs ( maybe 4 ) with retrogression across Scandi. If you want to get cold quickly back into Scandi via troughing then this is the route past day 9/10 & 11-

 

As mentioned these are the interesting days - so if I had to earmark a date for a change it would be the 14th or 15th....

 

GFS- Not really worth commenting on now. As if it wasnt bad enough having one useless operational followed by another 20 equally if not worse ensembles, we now have another arrow in the bag to fire randomly...

 

Stick with the Euros. The same as been the case for the last 14 years.

 

Watch for a chart 'like' this - we want all the negative flow aimed WNW at the SW tip of greenland-

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-20-0-0.png

Agree Steve incredible knee jerks this morning gfs has a habit of throwing out runs equal to the euro but then drops the idea only to throw them back into the mix a few runs later.

There's no question in my mind that it will be a slow progression.

Nothing above average showing and in time any warm air will be mixed out patients is the key.

The pv is not likely to regain control like last year.

It's one run let's see what things look like in the next few days because I bet a bottom dollar that the eye candy charts will be back.

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HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY NOVEMBER 5TH 2014.

NEXT UPDATE THURSDAY NOVEMBER 6TH 08:00

THE CURRENT GENERAL SITUATION.
A weak ridge of High pressure will cross East over the UK today followed by a freshening Southerly wind and fronts from the West later tonight and tomorrow.

MODELS-2 WEEK HEADLINE  Generally unsettled and rather windy at times with rain or showers. Temperatures look like staying generally quite close to average though it will feel rather chilly at times. Perhaps becoming drier from the North later.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast indicates an undulating Jet flow but generally at a position to the South of the UK over the coming week to 10 days before edging slowly north to be crossing West to East over the UK by two weeks time.

GFS OPERATIONAL Today's operational run shows a sustained period of Atlantic Low pressure steaming in off the Atlantic to become slow moving across the UK over the coming week This means spells of rain and showers in temperatures generally close to average with strong winds too at times. Later in the run little changes with Low pressure areas just a little further North by then and therefore delivering the wettest and windiest conditions to the North and West with little change in temperature

THE GFS PARALLEL RUN The GFS Parallel run suggests little difference from the operational in maintaining a large Low pressure complex being strung out across and around the British Isles for the majority of the two week period and delivering sustained periods of rain and showers at times to all in temperatures generally close to average though with some day to day variations.

THE GFS ENSEMBLES.  The GFS Ensembles also complimentary to their other runs in respect to the favoured option being Low pressure coming in from the west frequently and becoming slow moving over or just to the west of the UK with much rain and showers in strong and blustery winds as a result. The Ensembles also shows a tendency to rise pressure slightly over Southern Britain late in the period though insufficiently enough to prevent rain at times still with temperatures close to average overall.

UKMO. UKMO today shows an unstable Westerly flow following the depression being over the UK this weekend. This means the rain and showers over the weekend will continue next week though with Low pressure holding further to the NW than other models troughs alone will provide the rain and showers then with some drier intervals in between and close to average temperatures.

THE FAX CHARTS  The Fax Charts shows a series of fronts and depressions moving gently East across the UK over the next 5 days with rain and showers at times in sometimes strong and blustery winds from between South and West.

GEM  GEM looks very disturbed this morning with a procession of Low pressure and fronts crossing the UK repeatedly over the next 10 days with showers and longer spells of rain in close to average temperatures. strong wnds too would be a feature of some of these depressions and fronts at times.

NAVGEM NAVGEM too holds Low pressure in total control of the UK weather streaming in from the West and becoming slow moving near our shores. There would be spells of windy and wet weather alternating with brighter and more showery spells in average temperatures.

JMA JMA continues the themes of the others feeding repeated Low pressure into the vicinity of the UK with rain and showers for all areas as a result in strong winds from a generally SW or cyclonic flow.  

ECM. ECM still favours slow moving depressions slowly filling in situ over the UK this wekend with rain and showers as a result before a preference towards sliding Low pressure down to the SW of the UK late in the run as pressure builds to the NE. This then brings the wettest weather to Southern and Western areas whereas the North and East would be drier and perhaps brighter and a little chillier.


THE ECM ENSEMBLES  The ECM Ensembles show strong support at Day 10 for a Low pressure belt to stretch from Greenland to the UK with pressure High to the North and NE. This closely mimics it's operational flow in as much as it indicates rising pressure to the North of the UK but maintained very unsettled weather for many parts of the UK.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS There seems strong agreement between the models that shows a lot of Low pressure close to the UK over the next few weeks with rain never far away from any one location for any great length of time.

MY THOUGHTS  The charts this morning illustrate a very unsettled and at times windy couple of weeks to come as Low pressure areas stream into the UK from the West and become slow moving while filling over our shores. There are of course many small differences in subtle details between the models day to day but they all illustrate a generally somilar pattern. So we are left to try and pick out small differences and one such one is from UKMO this morning in as much that at Day 6 it holds Low pressure well to the NW while the UK lies in an unstable Westerly flow under less Low pressure and while this means little differences in conditions at the surface as it stands it may be that if the Low holds further North than other models suggest it might not be as wet overall as some predict early next week. ECM also differs a little in bringing Low pressure right down to lie to the SW of the UK by Day 10 with SE winds as a result. Rain at times would continue towards the South and West whereas with pressure higher to the Northeast other areas could become drier and chilly feeling. However, on the grand scheme of things this is nit picking and the general message is for spells of rain and showers in average temperatures for the next couple of weeks with no widespread frost and fog issues likely under such cyclonic conditions. Then as we look beyond the term of the output this morning there is somewhat less desire to rise pressure to the North than has been hinted at recently with only ECM flying the flag of higher pressure in the Greenland areas in 10 days time and while this offers no immediate passage into the chance of anything wintry so early in the season it is what is needed to make the Azores High less influential and to stem the flow of deep Low pressure areas bulldozing their way over the Atlantic and to the North of the UK.

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Back to "Model Output Discussion" please Gentlemen.

 

Many Thanks, PM.

Edited by Polar Maritime

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Looking at the GEFs and ECM anomaly this morning at D10 they are almost identical. The only difference is the former makes bit more of the mid Atlantic ridge. The surface analysis are also identical and no sign of retrogression on either.

Charts WeatherBell Analytics www.weatherbell.com

post-12275-0-96496700-1415178793_thumb.p

post-12275-0-91745900-1415178800_thumb.p

Edited by knocker

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Still we look for a longer term way to engage colder weather. Its still Autumn and the atmosphere is a state of flux as the season slowly changes. Longer term, the ECM recent consistent runs will put us in the building blocks for a colder outlook. Todays GFS has done a reverse regarding a colder outlook again to a milder scenario and UKMO continues to show a unsettled westerly regime which confirms its forecast for most of the remainder of this month. What ever happens after mid-month, looks like a lot of rainfall next week, particularly Southern Britain. Lets hope ECM continues to show the slide southwards and a colder block will arrive eventually. Just hope to god, you guys do not fall into a soggy spin cycle like last winter season. At least some will see the coldest night tonight for maybe over a year !

C

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surely the retrogression mr murr mention (above) re the ecm is only one option. and so far theres nothing in the ecm runs that would suggest anything cold , within the reliable it could get pretty mild with a southerly scourced southeasterly. yes, IF the scandi-high retrogresses it might lead to an early cold spell. but thats currently not being shown on the runs, and im still waiting for the retrogression of the high promised last may to happen!

ignoring the gfs is foolish imho. it is a perfectly sound data resource and whilst statistically it might not be as accurate as the ecm, its still not that far behind and often gets it right when the ecm doesnt. however, im not sold on the current gfs atlantic westerly outlook. the anomaly charts support the ecm's biscay/azores low option.

 

I think the best practice is to take a look at what all the major models show. This is the same type of methodology behind ensemble forecasting rather than focusing on just one model, especially when dealing with long range events. I certainly wouldn't ignore the GFS(P) at the moment since it has the highest resolution of any global model out there now, but neither would I look at it in isolation.

 

Exciting times ahead as the winter approaches. The model threads are going to be a lot of fun and there has already been some interesting stuff popping up out in FI. But as always, it's good to remember that we have to be objective looking at FI output, it's easy to embrace the charts we want to see and dismiss the ones we don't.

Edited by radiohead

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The GFS this morning continues to show a cool/wet N/W flow with-in the reliable time frame, Before a cut off low sits over the UK and then it all gets a bit messy, But the flow does return from the N/W again.. With the Models persisting to struggle with back-ground signals in the N/Hemisphere i would again take anything +144hr with a large pinch of Salt. As with the past few days the interest continues, And a few on here are certainly making interesting discussion out of it as to where/if it takes us.

 

gfsnh-0-60.png?0gfsnh-0-108.png?0gfsnh-0-336.png?0

Edited by Polar Maritime

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GFS P and GFS very different at day 6. GFS P sending WAA into Greenland

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GFS P and GFS very different at day 6. GFS P sending WAA into Greenland

 

GFS P could provide some proper excitement in FI.

 

 

 

A well written post from Snowking there,however i remember the key word last winter was "patience" which didn't bear much fruit,so i think "jam today" should be the slogan this time. :)

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Looking very unsettled next week as well as very mild uppers into Europe and the UK from ECM - last chart FI but not untypical.

Recm2402.gif

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Euro and parallel both take a step forward at day 8 with the undercut, unfortunately it weakens at day 9 and 10 (the stronger the secondary low to the east undercutting, the better)..

 

Recm1921.gif

 

Rpgfs1923.gif

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GFS P and GFS very different at day 6. GFS P sending WAA into Greenland

2 questions for the experienced model watchers please.

 

1. What is it that results in 2 models showing such differences in the Greenland area in what is sometimes termed the "semi-reliable" period (t144)?

2. The GFS(p) leads on to a damp south easterly (especially in my backyard) rather than a damp south westerly.  How quickly do warm temperatures in the euro high switch to cold on the surface?  My memory from living in Germany suggests it can happen almost overnight.

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Interesting to see where we were last year

http://www.meteociel.fr/modeles/ecmwf/archives/2013110800/ECH1-72.GIF?00

 

and where we are projected to be next week by ECM

 

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014110500/ECH1-144.GIF?05-12

 

Superb post by SK.

Fascinating to model watch as things slowly evolve over the Arctic regions.

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Thanks Snowking, that's one of the best posts of the season so far - I'm afraid, if anything, you've made me even more optimistic about cold getting here eventually!

 

I was thinking the same thing about the PV though - it's still not game, set and match, here's an instance where a shocking PV in early Nov became a formidable one by late Nov:

 

archivesnh-2000-11-10-0-0.png?

archivesnh-2000-11-30-0-0.png?

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