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Model output discussion-mid Autumn and beyond


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At T84 the ecm has a positively tilted upper trough digging way downto  the south west in mid Atlantic

T84v.thumb.png.449f34394f875d8681f4c82ff3abc631.png

As it deconstructs, courtesy of the the energy exiting the south east seaboard and high pressure ridging to the east, a surface low that has evolved in the base tracks north east and deepens and brings rain and strong winds to the UK at T132.with a possibility of snow on the frontal edge in the north on high ground

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This clears away quite quickly before the next major trough arrives courtesy of the aforementioned energy

jet.thumb.png.0e806be967b74b8820ec6d6f519eb6d9.png

 

Edited by knocker
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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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Although there are still some upstream issues vis amplification and the vortex with tonight's medium term mean anomalies they are still very much on the same page regarding the NW Atlantic trough/Greenland ridge alignment. Thus still a very strong westerly upper flow exiting the eastern seaboard south of the trough which diverges to some extent in mid Atlantic courtesy of the aforementioned alignment and so is weaker as it reaches the UK. But this still portends a continuation of changeable weather with temps varying around the average, which the det runs will sort,

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The ecm swings the low to the south west mentioned at the end of the short range post north east across the UK on Wednesday and this could produce snow on the high ground north of the frontal boundary. This low quickly scoots away to be followed immediately by the next depression bringing some wet and windy weather on Thursday

T120a.thumb.png.724974c8b0076667c6964e248e8a258c.pngT132a.thumb.png.3e4fef3f87a338c9a602812636c73920.pngT162v.thumb.png.43cca7ea9fb9b620a54e70a8d3ed61e5.png

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Still room for it to change, but does look like models, such as the 06Z GFS and 00Z ECMWF, don’t track that small Low from the South-West early next week as far South as it did previously. Nor does that little cyclone seem to track as far East through the U.K (more towards the Western side of the island), resulting in milder 850 hPa temperatures getting dragged further North through the U.K from the South. The chance for something wintry for the Midlands next Wednesday looking less likely (though again, some adjustments could still happen). 

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1 hour ago, DiagonalRedLine said:

Still room for it to change, but does look like models, such as the 06Z GFS and 00Z ECMWF, don’t track that small Low from the South-West early next week as far South as it did previously. Nor does that little cyclone seem to track as far East through the U.K (more towards the Western side of the island), resulting in milder 850 hPa temperatures getting dragged further North through the U.K from the South. The chance for something wintry for the Midlands next Wednesday looking less likely (though again, some adjustments could still happen). 

Not sure I'm following your point vis the 00 ecm RDL It does track the low across the UK into Denmark and en route the front straddles the UK so I would have thought snow along the northern boundary on the higher ground a possibility as I stated earlier. Having said that it is days away so minor adjustments will make a huge difference so no point in worrying about it at the moment.

T120t.thumb.png.9cd49a6ad39d035c7326bada3c345ab8.png

EDIT

I don't normally look at the 0600 gfs but I see your point there. More mixing of the air and a less sharp delineation for starters.

Edited by knocker
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5 hours ago, knocker said:

Not sure I'm following your point vis the 00 ecm RDL It does track the low across the UK into Denmark and en route the front straddles the UK so I would have thought snow along the northern boundary on the higher ground a possibility as I stated earlier. Having said that it is days away so minor adjustments will make a huge difference so no point in worrying about it at the moment.

T120t.thumb.png.9cd49a6ad39d035c7326bada3c345ab8.png

EDIT

I don't normally look at the 0600 gfs but I see your point there. More mixing of the air and a less sharp delineation for starters.

Indeed, knocker. Maybe worth taking more notice of when that time frame gets closer, but as you say, still too far out to bother about much. 

Yeah, my observation regarding that 00Z ECMWF and its track of that Low was probably off the mark to be honest and I probably could have explained it better. Just had a quick look at the run before having headed out earlier. ? 

Edited by DiagonalRedLine
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Well well well 
The GEM and GFS appear to have tasted something interesting...a much more amplified pattern, starting at the onset of low res and resulting in a scandi HLB. Eyes down to see where that sits within the ensembles and whether ECMWF latches onto a similar pattern. 

 

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The ecm has the front across the north Midlands on Wednesday but the dew points north of it are a tad high so any snow would be on the high ground.

t114a.thumb.png.309c50513c6a78a9127ecfbb6103542a.png

This low quickly clears east before more wet and windy weather arrives

t144v.thumb.png.ccc6a94d7c37f5560f77871aafed6252.pngt180v.thumb.png.73acf6de0013c6e296370621e69d14c1.png

 

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Michael Ventrice

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Just a massive ball of blue out over the North Pacific. this represents a strong vortex to spin down across the North Pacific in the coming weeks, driving an extension of the North Pacific Jet. Aligns well with the poleward surge of westerly momentum.

1937372684_DtRx7AQUUAAu8Ws.jpglarge.thumb.jpg.95fd12ac4a1eef064521d20b66896500.jpg

meanwhile back on the farm after Wednesdays low the next system rushes in on Thursday which quickly passes through leaving the next bout of general amplification in it;s wake

t132.thumb.png.d87dc162b701d5a57cfa7edd3cb3f01e.pngt180.thumb.png.44a714665fa5236ed369b9f2366f1848.png

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The Siberian vortex lobe has drifted over the Aleutians and weakened but the Canadian trough >  in the NW Atlantic is still gong strong with a strong upper flow exiting south of it,  This backs initially around the Azores high pressure which is ridging in the eastern Atlantic but veers NW in the vicinity of the UK, courtesy of the European trough. This would perhaps suggest unsettled with a N/S split with temps varying but a tad below average. All rather depending on the precise orientation of the ridge/trough axis

8-13.thumb.png.d22e850a73801a560da12b0300fc2391.png

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BY 1200 Monday the upper trough is about to deconstruct to the west as surface fronts trail across the south of the UK. Thus some patchy rain here and very mild, but much cooler to the north under a very transient northerly

T48v.thumb.png.36d4d8a5f2a94aa99127b72a2a5d7853.pngPPVI89.thumb.gif.04c29c3917ec3f8ed163ab87a9d0a668.gif

But one low that has formed at the base of the deconstructing trough tracks quite quickly north east to bring some heavy rain and strong winds to most places on Wednesday. Any snow on the northern boundary of the front will be at high levels, albeit a very marked N/S temp contrast

t90v.thumb.png.c0e7720baae1518dfe45b2dc4259cffe.png

The low quickly east over the southern North Sea leaving a very transient ridge, although time for a widespread frost on Thursday morning, before fronts and rain from the next system arrive Thursday morning.This heralds the arrival of the next major trough which brings some very wet and very windy, possible severe gales in places. weather over Thursday/Friday/Saturday

T150v.thumb.png.35994f619330b29e0d505ebc929095a9.png

The low moves into the North Sea by Monday leaving the UK in a northerly airstream as the subtropical high amplifies to the west but there is still a lot of energy in them there hills,

jet.thumb.png.be66448db7fdeae73c47c82d89b706dd.png

 

 

Edited by knocker
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One thing that would seem apparent is should the amplification of High Pressure around the Atlantic area come off (which looking at both the operational models and those mean charts, is possible), then could at least see more in the way of settled conditions over the U.K. Great for places, particularly Western parts, that have had flooding troubles. 

Off course, though, will depend exactly where the possible Atlantic ridge ends up. But is likely it could end up being close enough to the U.K (or maybe directly over it) to dry things down a bit. 

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This morning's updated fax charts have the warm front sliding across central England as the low tracks into the North Sea. So some heavy rain in Wales and England, perhaps some snow high up.

PPVK89.thumb.gif.fefb2a76ab86cb4ab859512d2bf8ed8b.gifPPVL89.thumb.gif.492fa9c58618c873c29fb3de21a381f8.gif

Subsequent to this, after some very brief ridging, the ecm has the next fronts arriving through Thursday accompanied by heavy rain and strengthening winds, mainly north of the Midlands.

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But as these fronts clear east a nasty little low forms in the upper trough and tracks north east to be just west of the Hebrides by 1200 Friday. This, and the associated fronts will bring heavy rain and gales to all on Friday, but particularly in the north where the gales could be severe.

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The low eventually clears to the east and thereafter it's a return of the battle between the subtropical high amplifying and the twin energy flows leaving the eastern seaboard. All of which could result in gentle zephyrs in Sidney land. And this scenario is not a million miles away from last evening's mean anomalies.

t204.thumb.png.bbebb9bb117fe2675c961f1934a55516.png

 

 

Edited by knocker
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The good news is that the EPS medium term anomaly this morning is still looking relatively benign

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I also notice this morning, en passant, that another nail has been plunged into the irony coffin with the other thread talking about borefests

 

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It looks like another unsettled week to come with lows and frontal systems crossing the UK.The temperature difference between north and south still apparent for much of the week.A  brief northerly brings the polar air down south so Tuesday looking the coldest widely.

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Any signs of a break in the Atlantic conveyor is reserved for week 2 where there are signs of  Azores ridging developing north towards W.Europe.

Day 10 means

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At this stage the jet is still running over the top so a mid-latitude location looks likely for any high cell.That Greenland vortex still promising to contain any northward development of any blocking.Depending on the location of the high though it could bring some frosts and fog and temperatures by day a little lower.

 

Edited by phil nw.
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At T84 (Thursday 00) the next batch of frontal rain is approaching N. Ireland and western Scotland (it does soon after sweep through) but it's worth pausing here to look west because east of Newfoundland and along the south east coast of the US to lows are forming in the baroclinic zone

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The first one deepens and tracks rather erratically north east and lands over th Hebrides by 12 Friday bringing rain. snow on the mountains, and severe gales. This low moves away into southern Sweden over saturday before the next chap arrives on Sunday.

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After that amplification occurs with another very intense trough swinging NNE from the zone and the subtropical high ridging north to the west of the UK

gfs_z500a_nh_32.thumb.png.2f8f8dd3a66a53eb80de8c849a37c18f.png

Edited by knocker
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The medium term mean GEFS anomaly still looking pretty benign with maybe some cooler intervals in the north. But under pressure from the east bound energy which wins out in the end. My cup runneth over

gefs_z500a_5d_nh_55.thumb.png.951e7b4e0eafc8ad5030eec6dc9c1e27.png

Edited by knocker
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