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Model output discussion - summer rolls on


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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
4 minutes ago, Mike Poole said:

Some odd comments in here today, almost as if some people are subject to cold bias!   Even if it isn't winter.

Cut right to the chase ECM at T240:

image.thumb.jpg.d719d5eaf76f1a7abbd494ed6bee2091.jpg

On the money as per warm, possibly very warm and settled start to September. 

850s are generally between 4C and 6C though... classic conundrum chart for the time of year, slightly more SE input and its a very warm set up, but if an easterly element gets in, the sun is no longer strong enough to warm us up alone and we stay slightly chilly (as I suspect happens here) . 

Would not want to call this one yet - settled yes, warm don't know. 

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
6 minutes ago, Man With Beard said:

850s are generally between 4C and 6C though... classic conundrum chart for the time of year, slightly more SE input and its a very warm set up, but if an easterly element gets in, the sun is no longer strong enough to warm us up alone and we stay slightly chilly (as I suspect happens here) . 

Would not want to call this one yet - settled yes, warm don't know. 

As we say in winter, get the cold air in place first and then look at snow potential..in the case of the Ecm 12z..get the high in first..worry about the uppers later.

192_mslp500.png

216_mslp500.png

240_mslp500.png

Edited by Frosty.
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
22 minutes ago, Man With Beard said:

850s are generally between 4C and 6C though... classic conundrum chart for the time of year, slightly more SE input and its a very warm set up, but if an easterly element gets in, the sun is no longer strong enough to warm us up alone and we stay slightly chilly (as I suspect happens here) . 

Would not want to call this one yet - settled yes, warm don't know. 

Yes, agreed, but we're not even into Autumn yet, ECM ensemble means from 12z suite, still looking very promising for a warm up, here T192,T240

image.thumb.jpg.dd07470a1054e9c4ded49943a124cc01.jpg

image.thumb.jpg.1fc31aa0ee212a99487caa0efbe28b14.jpg

Difficult to to tell much from the mean plot, but I can't see any reason the warm up is not the form horse based on today's output.

Edited by Mike Poole
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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
11 minutes ago, Mike Poole said:

Yes, agreed, but we're not even into Autumn yet, ECM ensemble means from 12z suite, still looking very promising for a warm up, here T192,T240

image.thumb.jpg.dd07470a1054e9c4ded49943a124cc01.jpg

image.thumb.jpg.1fc31aa0ee212a99487caa0efbe28b14.jpg

Difficult to to tell much from the mean plot, but I can't see any reason the warm up is not the form horse based on today's output.

Yes, agreed it probably is - the mean looks perfect - the cold path is lurking though

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
1 hour ago, Man With Beard said:

Yes, agreed it probably is - the mean looks perfect 

I wouldn't say the mean looks perfect, it's more like a north / south split with scotland, especially further NW missing out and staying changeable and cooler but becoming largely fine and pleasantly warm further south / southeast, at least for a time.

Edited by Frosty.
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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

I must say that the Euro's backs the cpc 500mb outlook with a link up from the Azure's height's to Scandinavia where as the gfs doesn't

here are the 6-10 and 8-14 day anomoly's from cpc and an animation of the ecm showing the link up of height's from the azures to Scandinavia

610day_03.thumb.gif.7dcc79ff93e321e675d85f194d402bb1.gif814day_03.thumb.gif.4df0f53551f8cbb5e77ac4e3f857e24c.giftempresult_uuj8.thumb.gif.cbf595ae725e0af423236fed9a748476.gif

now the gfs and ecm at day 10,a stark difference there

gfsnh-0-240.thumb.png.13f319860f2678d540cf24b04e11f649.pngECH1-240.GIF.thumb.png.8e75f1e35cb488fceb42319dd2cd99c8.png

and the ecm ens,the op was a cold outlier too

graphe_ens3_php.thumb.png.d3df73569135e853eb53a7a4d97fcb73.png

i  am going away to St Ives on the 3rd of Sept and i am hoping the anomoly charts are correct.

Edited by Allseasons-si
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On 15/08/2018 at 13:57, Tamara said:

.....rather than heading through low angular momentum La Nina Phases 1  into 2, (as suggested at face value by those operational outputs a week out) which models a sharper Atlantic ridge and hence greater cool air advection from the NW than has been the reality  The reasoning as so often discussed in these posts being the degree of upstream amplification in the Pacific which serves to retrogress the high that is downstream from this in the Atlantic - and with the polar jet pulling troughs around the top of the high c/o of a more NW/SE axis. If the model overcooks the upstream amplification, then it overcooks the polar flow and looped jet axis

Looking at the Pacific we see an increase in trade winds (covered in last post) following the passage of westerly winds c/o tropical activity which is now in end/re-start cycle - simply a natural pause in the tropical cycle and coinciding with CCKW towards the Western Hemisphere. Its this that modelling is jumping on and gunning for as pattern evolution to Atlantic ridge.

1432391455_2018-08-15(1).thumb.png.d854ea9419067167253232376473e6bf.png

 

This actually mirrors the sequence during the first half of July - the difference being that the trade wind increase is set to be weaker this time (albeit seasonal wavelength changes since then mean that the polar Jetstream is rather naturally adjusted further south according to this latest global wind-flow position than earlier summer). Notwithstanding that, the significance of the trade wind increase being weaker compared to back then is that in related terms, global atmospheric angular momentum is significantly higher than it was in early-mid July -

188379646_2018-08-15(2).thumb.png.308b84e226b841ca9c870c76c26f8ac3.png

 

- so extrapolating an establishing mid Atlantic ridge ahead on this basis needs some care and caution and none of the usual MOD discussion premature declarations in terms of an early autumn (beyond a possible transitory cooler interlude)

This isn't 'teleconnections' saying "No" to an Atlantic ridge either - its an attempted diagnosis as to how likely a wind-flow pattern is to assist it developing and lasting for any meaningful time.

Compare current AAM establishing closer to parity to the  more -ve longer term establishing pattern of August/September last year c/o the persistent easterly trades and La Nina standing wave. N.B Its seasonal wavelength changes that are the essential importance here which heighten the Atlantic ridge synoptic response to -ve AAM conditions from mid summer increasingly into autumn

Funnily enough, the closest 30-day AAM analogue up to and including 15/08/18 (same time of year +/-15 days) was 08/08/06 - indeed this period is still the closest with 15/08/06 being the best match to the latest figures from 22//08/18 -

880606354_AAMAug06-Aug18.thumb.png.b9920bd0dd8ec121c98930dc3b47b716.png

And that part of Aug 2006 saw copious Atlantic ridging -

692848228_RidgingAug06.thumb.gif.8f0755ec05c801091f2dfb15c40bb344.gif

 

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
9 hours ago, Allseasons-si said:

I must say that the Euro's backs the cpc 500mb outlook with a link up from the Azure's height's to Scandinavia where as the gfs doesn't

here are the 6-10 and 8-14 day anomoly's from cpc and an animation of the ecm showing the link up of height's from the azures to Scandinavia

610day_03.thumb.gif.7dcc79ff93e321e675d85f194d402bb1.gif814day_03.thumb.gif.4df0f53551f8cbb5e77ac4e3f857e24c.giftempresult_uuj8.thumb.gif.cbf595ae725e0af423236fed9a748476.gif

now the gfs and ecm at day 10,a stark difference there

gfsnh-0-240.thumb.png.13f319860f2678d540cf24b04e11f649.pngECH1-240.GIF.thumb.png.8e75f1e35cb488fceb42319dd2cd99c8.png

and the ecm ens,the op was a cold outlier too

graphe_ens3_php.thumb.png.d3df73569135e853eb53a7a4d97fcb73.png

i  am going away to St Ives on the 3rd of Sept and i am hoping the anomoly charts are correct.

None of the op runs are particularly enticing this morning - all pretty flat, with the promised build of high pressure not showing up at all.

Hopefully the NOAA anomalies - which show strong height rises in our neck of the woods in the 8-14 day period - are on the money.

To be honest, the ECM clusters last night were less then emphatic too compared with a day or two back.

ec-ens_nat_z500scenarios_2018082212_240. ec-ens_nat_z500scenarios_2018082212_300.

No strong height rises anywhere over the UK there, mainly all ridge and westerly based.

Edited by mb018538
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Mixed signals also from the anomaly charts, differences between ec;gfs with noaa, noaa showing more definite indications of ridging than ec/gfs does this morning. Overall a signal for ridging rather than troughing being the main upper air pattern. But temperature wise not sure what it indicates, not major heat as far as I can see from the charts below.

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

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

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
7 minutes ago, johnholmes said:

Mixed signals also from the anomaly charts, differences between ec;gfs with noaa, noaa showing more definite indications of ridging than ec/gfs does this morning. Overall a signal for ridging rather than troughing being the main upper air pattern. But temperature wise not sure what it indicates, not major heat as far as I can see from the charts below.

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

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

Those NOAA anomalies were only generated from the 6z GFS ensembles yesterday, with no input from the ECM etc. Perhaps we have been led down the path again? Low pressure may be stronger than first anticipated and we just remain with a flat pattern, and no heat as you say.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
13 minutes ago, johnholmes said:

Mixed signals also from the anomaly charts, differences between ec;gfs with noaa, noaa showing more definite indications of ridging than ec/gfs does this morning. Overall a signal for ridging rather than troughing being the main upper air pattern. But temperature wise not sure what it indicates, not major heat as far as I can see from the charts below.

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

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

Sounds par for the course at this time of year, at least there's some pleasant weather indicated further s / e beyond this cooler fresher changeable spell.☺

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

This morning's ECM clusters follow on fairly well from the assessment of last night's by @mb018538 and though periods of height rises still look in the offing, the ECM is moving away from a sustained settled spell of settled weather.

First T144 - well the eastern height rises that were hinted at a week ago are indeed there, but the trough to the west is too close to the UK to allow a strong southerly:

ec-ens_nat_z500scenarios_2018082300_144.

Another short settled spell around the turn of the month (31st August)

ec-ens_nat_z500scenarios_2018082300_204.

And still a pretty good situation by 2nd September, with the 582 line well into England and the 564 line clear of Scotland on most clusters, suggesting the jet will be to our NW for the weekend after next (**change in colours are due to change in anomaly against monthly mean - September has climatically lower heights than August)

ec-ens_nat_z500scenarios_2018082300_240.

But into the first full week of September, the low to the NW starts to bite back. Tricky forecast, and I have a little wager this period will be tricky for many days. Will the low stall slightly west allowing a plume? Will the low push a front through introducing cooler, showery conditions once more? Or, like clusters 3 and 5, has the low been overstated meaning heights prevail more strongly? I tentatively suggest the period 3rd-5th September will be a very interesting period to watch in the coming days, as various possibilities will exist.

ec-ens_nat_z500scenarios_2018082300_300.

 

 

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Well after the weeks of Summer warmth we are seeing a change to cooler fresher Atlantic air and it does now look less likely that we see a rerun of those recent high temperatures after this Polar Maritime incursion.

I think the influence from the Icelandic trough will be enough,after the initial breakdown,to just limit the Azores ridging and keep us in more typical gentle westerly flow heading into September.

Days 5 and 10 ECM mean 500hPa charts and last night's Noaa anomalies

EDE1-120.GIF?23-12EDE1-240.GIF?23-12610day.03.gif

A look at the London ens graph for temp/rainfall

ensemble-tt6-london.gifensemble-rrrcum-london.gif

shows temperatures closer to normal in the coming 10 days with maximums around 21C more likely than the recent 25C+ although after the more unsettled blip in the next few days a return to quite dry weather looks likely especially further south and east.In this pattern as ever the far North west will be prone to more interruptions to settled conditions.

Certainly not a bad outlook as we start Autumn.

 

 

Edited by phil nw.
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Posted
  • Location: North Wales Riviera
  • Location: North Wales Riviera
On ‎22‎/‎08‎/‎2018 at 07:06, mother nature rocks said:

For ‘more balance’ as temps are normally undercooked by 1-3 degrees that would take many more places above 30*c. 

So we might get up to 25-27 degrees IF we're lucky. Why do people seem to think that the max temp is the forecast temp for that period?

ukmaxtemp.png

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Posted
  • Location: Droitwich
  • Weather Preferences: Cold cold cold!!
  • Location: Droitwich
24 minutes ago, Danielvn said:

So we might get up to 25-27 degrees IF we're lucky. Why do people seem to think that the max temp is the forecast temp for that period?

ukmaxtemp.png

Because that’s what that run at that given time was showing. As we all know a couple of days down the line things can and will change for the better or the worse. 

Typically it doesn’t matter which chart you look at, you can normally add on 1-3*c.

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK

Some adjustment on the latest fax chart for Sunday 12z with a delay in the advance of frontal progression from the Atlantic. A weak ridge may give a fairly nice day for most. Also the central pressure of the Low pressure system associated with the fronts not as deep.

 C

fax96s.gif

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

After this coming weekend the Gfs 12z operational shows a good deal of fine weather across all parts of the uk with strong ridging / high pressure at times and it's occasionally pleasantly warm but there are some cooler spells too with chilly nights..there is some rain from time to time but the emphasis is on dry and fine conditions with sunny spells..nothing very warm / hot but not bad overall.☺

 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

Really good run from the GFS 12z for settled and warm, here at T192, T240 and at the end T384:

image.thumb.jpg.1a1b65587462eba5a0ef3d59fb6276c9.jpg

image.thumb.jpg.823fb896c5f0079f5239936c7d8646d5.jpg

image.thumb.jpg.409da186d7e528c683c57240b471dbc6.jpg

GEM less good, high pressure in the south for a while, but no real longevity. 

UKMO T144, maybe hinting at GFS evolution:

image.thumb.jpg.1b86669dc31388b913bf909340c428d0.jpg

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The GEFS 12z mean indicates plenty of pleasantly warm fine weather thanks to increasing ridge / high pressure influence developing during  next week and beyond across southern uk once this cooler changeable spell is over. Northern uk continues generally more changeable and cooler than further south but even the north has some pleasant spells too.  

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

Well at T192 we have chalk and cheese from the ECM and FV3, so there is a awful lot still to be resolved re where we're headed post bank holiday, here's the charts ECM first:

image.thumb.jpg.1a1d64f340a5782add6279b9b0fc9ace.jpg

image.thumb.jpg.dfed43f12ba4606ffe7c1644b73dc85e.jpg

The FV3 is the one that agrees with the background signals, long rangers and Met Office update, that's where my money is, and it is consistent with GFS earlier.

Edit: ECM gets there in the end T240, not quite sure how. Here goes:

image.thumb.jpg.41eab657c826359e884edf85eb9fc478.jpg

Edited by Mike Poole
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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

These op runs are gradually getting worse from the last two or three days, where it looked for all money we’d see a nice build of high pressure around the turn of the month. Now it’s looking a bit dicey, and we may not see much of a settled spell at all.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The Ecm 12z is certainly a mixed bag but at least it ends well!

240_mslp500.png

240_thickuk.png

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Posted
  • Location: Hertfordshire
  • Weather Preferences: SNOW AND FREEZING TEMPS
  • Location: Hertfordshire
5 minutes ago, Frosty. said:

The Ecm 12z is certainly a mixed bag but at least it ends well!

240_mslp500.png

240_thickuk.png

It's been ending well for the last 6 or 7 days but doesn't get any closer lol . I think MWB posted about this a little while back saying that it may be one of these times when the models keep trying to build high pressure close to us or over us but as we get closer it gets watered down ? Hope I've got that right , sorry MWB if I haven't . And as you say frosty real mixed bag on the ECM tonight . A low to the SW and a low to the NE at day 8 

IMG_2506.PNG

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

Exactly right. The only good ecm charts have been stuck at 240 for the last 3 days now, if it was following up then we’d be seeing these charts down at 168-192 by now....instead we have more messy low pressure intervention. Nothing desperately unsettled, just enough of a pain to keep things fairly nondescript.

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