Model Output Discussion - cold spell to end Autumn

[Frosty.]

Looking at tonight's Ecm 12z ensemble mean indicates increasingly cold and unsettled conditions from later next week onwards..no complaints there!

[feb1991blizzard]

2 minutes ago, bluearmy said:

An interesting one Feb - if the Atlantic ridge is ebbing too far north then the system coming around the top may be forced to run se to our east. A flatter pattern to our west allows the low to head se into the base of the troughing or drop far enough to the west which could mean warm sectors are avoided. the spread on the ecm days 8/10 reveals that we could see the Atlantic low coming in further west. The extended eps continuity good with nw European low anomoly and sceuro upper trough manitained. 

Yes, I did think afterwards (I posted at around or a bit more than 300 mark) that I might have been a bit picky, I just thought at the time though that the 0z was better, the further South the low anomaly can get, the more members likely show better cold /snow chances. but realise equally that you don't want it too far East either.

[Man With Beard]

11 minutes ago, phil nw. said:

Day 7 GFS mean-850's and the 2mtr temperature graph-Warks.

 

One word-cold.

Member 3 having its own little ice age there - here's a chart from it, not implausible the way output is going!

[SMU]

UKMO day 7 very Cold Northerly wind ! Bitter...

[Summer Sun]

Major difference between UKMO and ECM at t168

[A.J]

Model watching is all about looking for trends, and having looked really closely at the text and charts posted the past few days, I've noticed a trend that is really starting to stand out ......

 

That Steve Murr desperately needs one of these, can we organise a whip around or nice letter to Father Christmas?

 

I'll fetch me coat....

 

banter aside, some very good charts if one is of a cold persuasion, but as always are subject to change......and just goes to show how things can change model wise in 24 hours......can't wait for the 18z and overnight runs in the ongoing saga of 'Shortwave Wars - The Phantom Menace'

[Catacol]

27 minutes ago, Broadmayne blizzard said:

Can't help it but with Tamara's GP's and Catacols educated musings. Could it just be that Steve Murr's 1962 analog from a few days back might actually come close to the mark? Just wondering to myself that's all.

Actually there are similarities to the setup though we all know that every winter has a unique balance of forcings. However we are a long way from 62/63 yet. Huffman’s winter forecast is still stuck to my favourites bar - his reasoning was very good and his top 3 analogue years were 62/63, 84/85 and 95/96 - all good for winter synoptics in the UK. GP was hanging his coat on a 05/06 feel to things. Not remarkable you might think - but go run the Jan 2006 sequence. It was a very close call in terms of cold backing west. I wonder if he is still seeing that analogue as closest following the sudden surge in Pacific forcing so early on....

[LRD]

10 minutes ago, Man With Beard said:

Member 3 having its own little ice age there - here's a chart from it, not implausible the way output is going!

Not a million miles from what the last frame looks like on the 12z GFS operational. Hmmmmm...

Edited December 1, 2017 by LRD

[Snowy L]

13 minutes ago, Summer Sun said:

Major difference between UKMO and ECM at t168

Low pressure directly over Spain on UKMO. Nice westward shift there.

[SMU]

Taking the ECMs OP run aside the models mid term have indicated some desire for slider lows across the UK coming in at acute angle- these rarely deliver snow to the UK unless theres high pressure anchored over Scandi pumping Cold surface air across -

If you have a deep trough over scandi then on approach winds ahead of the slider low unless its very very shallow will always turn southerly or SW forcing a milder onshore flow in the south-

However the fact the models are developing these slider scenarios means that the jet is really getting rippled not only all the way back to the pacific but downstream towards russia- the closer the proximity the russian block comes to the atlantic high the greater the gradient becomes over a the UK...

Anyway ECM looks to be the elephant in the room this eve- lets see what the 18z brings... for now at least expect more crazy snow charts..

S

Edited December 1, 2017 by Steve Murr

[Pembroke Dangler]

3 minutes ago, Snowy L said:

Low pressure directly over Spain on UKMO. Nice westward shift there.

Definitely what we need to happen if snow for us southern folk is to be a realisation iv got everything crossed that the ukmo 168 chart verifies or as close to it as possible.

[East_England_Stormchaser91]

Jeez, I hope it's neap tides not Spring tides when that low corkscrews around in the S North Sea. Blizzards aplenty, but the more worrying thing would be the storm surge risk with 90mph northerlies tucking in, slamming the entire east coast. I hope that run for that sake gets binned! 

Edit: reading an earlier post, it looks like the worst case scenario would come to fruition. I wouldn't want to imagine the devastation that low would bring. Would be very comparable to 1953  

Edited December 1, 2017 by East_England_Stormchaser91

[comet]

Hoping the 18z does not wind the low up like the 12z it makes it less believable plus of course it introduces less cold uppers and higher dewpoints..

[Nick F]

Increasing confidence in another Nly at the end of next week into next weekend. To get the northerly, we need the upper trough over the NW Atlantic during the week to disrupt into a cut-off upper low, which will allow a ridge to build quickly to the west in wake of a ‘trigger low’ scooting across the UK from the west, this will allow a deep northerly flow from the arctic. This trough disruption likely due to the major amplification of a long-wave trough upstream over eastern N America.

But, like this weekend, it may be toppled from the NW after a few days, shorter if you believe 12z EC det., given the propensity for the trop PV over Canada to expand eastward toward Greenland and strengthen/flatten the jet downstream over the far N Atlantic at the same time.

However, looking at the extended ensemble guidance from EPS and GEFS so far today, there seems to be an appetite for ridging to rebuild / re-strengthen near/over Greenland again. Op highlights a marked +ve height anomaly over the arctic which is a response to a highly amplified PNA ridge along the west coast of N America, extending further and further north and warming up the uppers over the arctic and creating a -AO. This in turn reaching the over side of the pole toward Greenland and pushing cold vortices south into eastern N America and Europe.

This increasingly amplified and blocky wave pattern developing upstream, can be linked to the anomalously strong E Asia jet extending out to the NE Pacific weakening, likely a result of E Asia mountain torque event, which will buckle the zonal flow downstream over N America and slow it down, strengthening a west coast PNA ridge and then carving out a deepening long-wave trough over eastern N America. While this amplification of the wave lengths from the Pacific across N America will also likely lead to blocking re-strengthening around the Greenland area again – helped by some cross-polar ridging too.

Looking further ahead still into mid-late December, signs that the MJO could be in phase 7, which will further aid high latitude blocking and potential for cold patterns across parts of Europe including UK.

So, in conclusion, plenty for coldies to be upbeat about, though no prolonged cold and snowy patterns on the cards for now, protracted zonal and mild conditions in association with a strong PV over Greenland, which so often blight our weather in early winter, seem unlikely for a while IMO. The northern hemispheric pattern looks predisposed to amplification and high latitude blocking as we head through early December.

Edited December 1, 2017 by Nick F

[J-Man]

The low on the 18z looks even deeper.

[Pembroke Dangler]

So here we go a pub run special coming up. Will it continue with the cold hurricane? or something a little more sensible sliding into the continent with a wrap around northerly?? I for one will be looking for southward corrections on the trigger low over the next few outputs, if we can actually get the northerly nailed that is. 

[winterof79]

6 minutes ago, J-Man said:

The low on the 18z looks even deeper.

Really??Not any in the Atlantic that may influence our weather 

Edited December 1, 2017 by winterof79

[bobbydog]

well... just got in from work (a very loooonnnnng day....) and caught up with the models. GFS looks good, not too far away either, (ok, a million miles in current output terms!) very snowy for most, especially those who didnt get any this time round.

though i can confirm that here in sussex, we got a fair bit more snow than usual. in fact, though i missed  the blizzard, upon leaving for work, i spotted several of these on the bonnet of my land rover-

i selected low range and proceeded with caution.....

 

Edited December 1, 2017 by bobbydog

[bobbydog]

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Edited December 1, 2017 by bobbydog

[tinybill]

we  can only  hope!!!

 

[J-Man]

2 minutes ago, winterof79 said:

Really??Not any that influence our weather 

 

[winterof79]

4 minutes ago, J-Man said:

 

Is that not yesterdays out put?

Sorry Short beat me too it

Edited December 1, 2017 by winterof79

[Winter-Chaser]

3 minutes ago, J-Man said:

 

that"s yesterday's 18z

[J-Man]

2 minutes ago, Winter-Chaser said:

that"s yesterday's 18z

Too keen, too excited...apologies.

[Methuselah]

I'm quite confident that the 18Z will send the ECM's 850hPa temps onto the naughty step...hope these are not famous last words!