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Model output discussion-mid Autumn and beyond


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EC clusters D8/D9: Slightly favouring the ECM op idea of a very mild southerly influence, but not without the possibility of a much chillier UK high (away from NW)?

ec-ens_nat_z500scenarios_2018110700_204.

But by D12, the clusters are back to sniffing out height rises to the E or NE

ec-ens_nat_z500scenarios_2018110700_300.

Very interesting cluster 1 on the D15 chart. Though plenty of westerly ensembles in there too, clearly.

ec-ens_nat_z500scenarios_2018110700_360.

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Thanks knocker. Useful to come over to this thread for a dose of reality rather than seeing P14 of the 18z GFS run which shows cold weather at 300 hours, when we all know that it's standard wet, windy

Hi Malcolm, I just saw your post after doing mine above. Yes this thread seems under used which is a shame.The idea of this one as you probably know is for any members to post what hopefully

Finally getting time to check how the 500 mb anomaly charts have been over the past week. They have not consistently but generally gone from suggesting trough domination to one that now has ridging as

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The gfs still looking to drop a lobe of the vortex into the north west Atlantic creating a very strong thermal gradient between it and the subtropical high, a 180k jet swinging east.

gfs_z500a_nh_32.thumb.png.e1ae9b35f8ccf7dcea7774dc932b0e3a.png

This energy hitting the block does cause the trough in the eastern Atlantic to deconstruct but the strength is such it overcomes the re surging high pressure leading once more to a NW/SE split, On this run anyway

gfs_z500_vort_natl_34.thumb.png.921c6fde131b1e521353a6a06191f61f.pnggfs_z500_vort_natl_38.thumb.png.4275cbff82386b9105df83014153d213.png

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Towards the end of the run the ecm also drops the vortex lobe into the North west Atlantic which initiates the downstream amplification. The 300mb chart illustrates well the impressive resilience of the resurging ridge in the east under the massive pressure which deconstructs the trough

ecmwf_z500a_nhem_9.thumb.png.a18fc06e8b7f1eee914c98186b29cd37.pngjet.thumb.png.c7899e1753a53565370dc93ac145cf1f.png

And by the end of the run it's honours even with some WAA wafting over north west Europe

t240v.thumb.png.91606463d15b73a8cc53d6f8fdbce042.pngindex.thumb.png.0e4765ee7a47cee4fe11807f3c0e4f7c.png

 

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Consistency in the models continues in the reliable, and beyond.. a stuck pattern until next week, when we revert back to where we have been past few days, and see warm air advection move through the UK into the Pole as a more amplified flow takes shape - both ECM and GFS are showing significant WAA, and the trough having a real struggle to break through as it is forced westwards again - end result, heights would have an easy time of migrating north through scandi and cause the trough to split and an undercut scenario as shown by GFS output today - a very plausible evolution as we move through latter part of the month - a cold evolution after a very mild interlude. Southerlies can quickly be replaced by northerlies. Not sure what is causing the current high pressure to remain so stubborn, in an average year the westerlies and jet would sweep it aside easily at this time of year, but 2018 has been far from normal - the jet has been so sluggish.

We are not in a normal default zonal pattern at the moment, and haven't been in the main since March.. I remember back to Nov 2009 when we had a similiar case, with the trough having trouble breaking through just sitting to our west with low pressure and fronts circling around themselves, it produced a very mild and very wet month, with lots of southerly/sw airstreams - thankfully it looks like we are going to be spared the same degree of wetness this time around, but then events changed markedly second week December..

 

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There is a fair bit of unanimity between this evening's NOAA, GEFS and EPS medium term anomalies, all with fair amount of amplification. The significant features being the twin vortex lobes Franz Joseph and northern Canada with associated troughs, eastern North America/ mid Atlantic with the latter stretching south to North Africa. Coupled with ridging over eastern North America and resurgent ridging into Scandinavian.

Resulting in a very strong westerly upper flow exiting the eastern seaboard across the Atlantic which tends to split, and thus weaken, on reaching the eastern Atlantic, courtesy of the trough/ridge axis  All of this results in a weak south westerly flow over the UK which portends a NW/SE split with systems either tracking NE or diverging south and avoiding the UK. Temps are above average with this scenario. Of course all of this is very knife edgy as the precise orientation of the trough/ridge axis is paramount

gefs_z500a_5d_nh_53.thumb.png.89e4e1b9af6f7617aa7bdc13422df76e.pngindex.thumb.png.fc6de064062396c60eae893a04819b47.png814day_03.thumb.gif.5e2c0208d30245c63e031e5b5414b272.gif

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Following on from the SR post the trough to the west quickly disrupts under pressure but the whole process in then repeated so that by Thursday we have this situation with a lot of WAA being pumped north over the UK.

gfs_z500_vort_natl_29.thumb.png.be606539cc0e9b963682d0f84cbb7ce8.png

The question is, will the block to the east hold under this pressure?

 

 

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The ecm is not dissimilar at the end of next week and between them the intense vortex lobe and the block destroy the Atlantic trough  From there the battle rages with the block refusing to give an inch and hence WAA wafting north over the UK

ecmwf_z500a_nhem_9.thumb.png.0fa5a09660f1fda75ec7c89ada941362.pngindex.thumb.png.4f8ac99ff8e9022ad882f842e3d7bdab.pngt228v.thumb.png.7744c2c4d180b75b50788f7fec5dc9d4.png

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58 minutes ago, Man With Beard said:

...lots of interesting ECM ensembles for around 15th/16th November giving maximums between 16C and 18C, which would be very mild for the time of year.

Temperature-wise, those maximums of 16 to 18*C could almost be passed off as a (very) cool Summer’s day. Pretty incredible if some of those ensembles came off. 

(I admit though I’m looking forward to a colder end to the month (should it happen)), but some mild or very mild weather before-hand would be fine, too).

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Latest UKMO/GFS outputs shows the next few days are looking unsettled with rain or showers quite widely under the influence of the deep Atlantic low now arriving out west.

Day 3 on the fax shows it just to the west of Ireland continuing to push frontal systems across the UK.

fax72s.gif

Further on day 5 charts shows a broad westerly flow well established across N.Europe

viewimage.pbx?type=gfs;date=20181108;timviewimage.pbx?type=gfs;date=20181108;tim

quite a strong flow at 300hPa exiting the eastern seaboard heading across the Atlantic.Some splitting near the UK but enough of the jetflow pushing across Scandinavia to at least temporarily weaken the Euro  block but  wait, a further inflation of said block is on the cards next week according to the gfs mean.

gensnh-21-1-162.pnggensnh-21-0-180.png

so another burst of mild southerlies looks likely.

 

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Things taking shape quite nicely now for fairly secure predictions beyond the usual 5-7 time -frame.

There is likely to be a nice mild few days around mid month as ScEuro ridge builds in far enough West to drag a Southerly flow across the UK.

ECH1-192.GIFgfsnh-0-192.png?12

Thereafter we are likely to see a cooling trend as high pressure begins to dominate and the flow slowly becomes more continental.

graphe6_1000_259_57___.gif

That should take us to the last week of November where the big question is whether the mid latitude blocking will be able to get into more Northern latitudes and orient in such a way to bring in cold arctic air either off the continent or from the North.

If you are a cold fan then the first prospect of an early Christmas present could come end of Nov/Early Dec but as always with deep FI all to play for.

 

Edited by Mucka
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The ecm drops the very intense vortex lobe into the north west Atlantic and the polar and subtropical jets merge in the subsequent very tight thermal gradient between it and the subtropical high pressure.

t162.thumb.png.53ef077f159ac79949b198349e316da7.pngjet.thumb.png.1dce07754f66aedb6cad835758cea3a2.png

Which hits the block and amplifies the downstream trough/ridge axis and wafts a fair whack of waa into north west Europe

t216v.thumb.png.a187d1c041a95a6eec7ba5eb909aad5e.pngtemp.thumb.png.9f475525309dc2df7a2c0909dcb904b5.png

Edited by knocker
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Moving forward to Thursday of next week and the first trough hits the buffers of the block and shoots south as the aforementioned American trough enters the fray in the western Atlantic, with a very strong jet of 130hts at the 500mb level knocking on the doors of the Atlantic ridge

gfs_z500_vort_natl_27.thumb.png.21ebfa510a5537c08924d0ceb76abf73.png

Which is quickly broken down but our old friend in the east is more resilient and by midday Saturday the situation is thus

gfs_z500_vort_natl_35.thumb.png.7405dd3d42a067fc7249a5735c2eec79.pnggfs_t850a_natl_35.thumb.png.d4247a1798d17cc1a17c2476638ab15b.png

 

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Little to add vis the ecm. which is also going for amplification of the trough/ridge axis at the end of next week thus longitudinal lmovement curtailed  and WAA instigated

index.thumb.png.a9dc5944b6694676a042f10c2c0dd448.png

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Calm start then turning stormy later I personally think this should be named based on wind strengths although not unusual will effect a large area at a busy time plus combined effects of heavy persistent rain making for some bad driving conditions a couple charts to show the weather this evening..

A0C02BF5-FCDC-4C2C-BB29-E341D3047796.thumb.png.568a90de431c3cde3b5482d50ef0ac5b.png

31C62994-DF32-4FC1-8C50-6DEF21DAE1F8.thumb.png.814e911d9a2076febf60191fedd453e5.png

Wind gusts are shown to exceed 60mph through the English Channel just coming a bit inland into the south of uk with gusts widely 50 to 55mph some locations inland will no doubt exceed 60mph briefly before the rain clears, all in all a stormy evening in store not to mention more flooding likely for Northern Ireland.

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The gfs is more aggressive with the Atlantic trough next week and pushes it through by the weekend The WAA into Scandinavia is verging on the ridiculous

gfs_z500_vort_natl_29.thumb.png.6329df26c2bd8340fafcb5d8588d0bdf.pnggfs_z500_vort_natl_33.thumb.png.a923bbb3f4a72f143335beed6eaa52e7.png

Edited by knocker
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The weather becomes more settled from Wednesday, apart from Scotland where a front still lingers  as the high pressure flexes it's muscles and the Atlantic trough starts to disrupt

t120v.thumb.png.d4139a9869a636fb8e2798bf879b7be3.png

by Friday the disruption is accomplished with a new cut off upper low NW of Morocco whilst to the west the lobe of the vortex and the Arctic air enters the north west Atlantic, From this point the intense upper low dominates the Atlantic as it nudges east against the block but some ridging from the Azores helps out and diverts the trough a tad north. All of which initiates quite intense WAA over northern Scandinavia as the eastern ridge distorts under pressure and colder air slips down the eastern flank into eastern Europe by the end of the run whilst fronts and some rain do actually make it to western regions

index.thumb.png.511a76dc905f8ed4cf182a224f403cf7.pngt210.thumb.png.f08316a52a453ced5113d0b18fff9ce1.png

Edited by knocker
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