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Model output discussion - proper cold spell inbound?

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Day 10 ECM. Do you reckon the Atlantic ridge will shoot up to Greenland if it went on another frame ?

IMG_1298.PNG

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1 hour ago, bluearmy said:

but note the 'shortwave' features develop as it heads towards the 'warm' north sea. we don't want uppers that low headed this way because im not sure they have a chance to make it past the Scandinavian coastline and the flow gets cut off. ironically, you don't want lower than -15 uppers headed west out of scandi

What about 1987?

 

Edit- didn't notice someone already picked it out!

Edited by ZK099

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10 minutes ago, ICE COLD said:

Day 10 ECM. Do you reckon the Atlantic ridge will shoot up to Greenland if it went on another frame ?

IMG_1298.PNG

No, I don't believe we'll see a Greenie high just yet.

I believe the trough will sink with the Atlantic ridge linking with a Scandi High.

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The Ecm 12z is not without interest...here are my highlights!:D:cold-emoji:

48_thickuk.png

96_thickuk.png

120_thickuk.png

144_thickuk.png

192_thickuk.png

Edited by Frosty.

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11 minutes ago, Steve Murr said:

Evening All 

Ice Cold hope your still with us ....

So the much touted SSW is coming into view & here’s my thoughts + timelines of when / where to expect it...

We have seen lots of posts & comments on it - but whats the reality likely to be -???

The Omni present warming in the GFS charts is usually due to the model & its poorer vertical resolution V the ECM, as a result there is an over reaction / over estimation of how much a warming is going to impact the zonal wind @10MB - so because of this 'bias' when viewing the mid / long term outputs churned out by the GFS we have to be a little on the sceptical side as these are normally moderated & scaled down even wiped out ! 

However we have now seen the evidence in the Berlin site that a downwelling SSW event will make it to the 10MB level & indeed go on to challenge the date record for the time lf year-

( this is NOT the same as the usual deceleration of the zonal wind we see at this time of year as that is more of a gentle reduction all the way to mid april when the vortex breaks its annual westerly influence )

So as highlighted we have passed the point of no return in the stratospheric modelling where a SSW is now just 5 days away for the 12th Feb *** Take note of this date --

The plots below show steep downward curve of a signature warming

6985F46D-C5CA-4B18-BEAD-BB3120E3E42F.thumb.jpeg.a6b0b8593226b69d18864f768937f865.jpeg

Note the main black line being Climo - but the ensemble mean from the GFS running out at mid -20 to -30 M/S...

The clustering is quite close - further backed up by the another illustration of the ensembles from the hannah attard site

7CBA0B3C-23C9-47E1-A719-9E3130FA7CC9.thumb.jpeg.9db935230d6f0bf9b5416e2db7b81c4d.jpeg

 

With the mean bottoming out at -32M/S

*The date record for this time is ~ -17 M/S

& the all time record low ( using Merra data ) is -35 M/S

The ECM berlin forecast below is not as bullish as the GFS coming out around -17 M/S @10MB but none the less still classed as significant event...

5FA5475F-18B4-4026-8E1B-39FF92721DE4.thumb.png.a04f50d0660a6604b738c0d3cca88321.png

So what we have in modelling terms of a SSW due is

* The first one in 9 years ( I dont think last year was classed without checking )

* Possible record breaking reversal of tge zonal wind...

If your thinking whats best in terms of impacting the UK its simple- The lower the negative number the better... - record breaker ? yeah I will take that please... Why?...

The bigger the negative number the stronger the easterly flow is across the mid lattitudes. !! ( think feb 63 / jan 85 & so on )

Whats the models churning out then?

The SSWs are classed as 2 types

- Wave 1 displaced vortex  or

- Wave 2 Split Vortex ..

This is whats expected -

7A103303-5F39-472F-B48A-364BC8370A14.thumb.jpeg.1fb67b4b76e35c45fedd5b8c3a9fb857.jpeg

A classic wave 2 Split vortex- with 2 clear areas of poleward flux - over the far East & canada-

Now luckily for me the historic SSWs have already been classified -we are looking for la nina years / W2 / split vortex-

76A6AA8A-9AD0-4F40-9466-972E6225D7E8.thumb.jpeg.90f792a09189af51c78aae21649bbedf.jpeg

6 years appear as matches

- 28 Jan 1963

- 7   Jan 1968

- 18 Jan 1971

- 1   Jan 1985

- 21 Feb 1989

- 24 Jan  2009

Below are the 10MB increase in temps at the time when the zonal wind hits 0M/S

E950B5AB-BFE1-4961-931D-34A0C457ED7A.thumb.png.18b1dacd4f8e0bef3678ab5523c4670f.png7C172A0C-6256-4976-9A0C-38738541E322.thumb.png.37c9c093fe50dac61e724e89a87cd672.png0B84368C-7C0E-42D5-A98F-2D6DF1E10558.thumb.png.6d2e2535e81f7b807474b7f50044569f.pngACF12309-1137-4499-9B93-D8C9A31B8BEC.thumb.png.8b7d81843dfe4258b68689b6b7065eec.png062AE4C2-0CA5-4DBE-86BD-7F3FBA5F6EFC.thumb.png.7993950450a3f0a5783b78a7700c092c.png03B98343-0A38-414A-BD9E-DC0295160EFA.thumb.png.8f9f316d586058852d8cb6d66c697c9d.png

Obviously they all have 1 thing in common- The huge rise in temps across the pole -

Now the Date of the zonal Mean hitting 0M/S isnt the day of peak blocking -

Looking at the dates above peak blocking appeared 7 - 11 days post Reversal - see below day 11 charts from the above warmings ( 500 MB anomaly )

4DA8F1B3-83E5-49A4-90ED-E3EF47E3F5E1.thumb.png.c3ee45f8065667c25d9bb9e3ec95082f.png134B31F9-0120-46A6-A249-B3550E4151F8.thumb.png.96488e4884e229db30c093738d396078.pngE507AC96-7591-4B98-86B9-975A9BE8DC18.thumb.png.2cbb38c07acb1a599cc0dccacfa0a6ed.png1413215B-1985-4906-B849-F625BB46A709.thumb.png.f2d3fbfb22977ad1b9b5ac3698e74428.pngC08A30D3-1EDE-4828-B9A3-54F282B705DC.thumb.png.95461292f946936a73d9610c5be171df.png632D4FBD-C6FB-476E-83E4-17958B97B212.thumb.png.8b223709ab68f36edd2fc9ded124923e.png

Whats apparent is HLB is quite prevelent & most are centered ( for us ) around greenland & Western Scandi -

Also all 6 Splits have varying levels of troughing to the south - but all have an anomaly-

So that really leaves with a level of expectation that should at least give us some confidence for Feb over the following dates-

12 Febuary : is 'R' Day- as in the reversal of the 10MB zonal wind where the eastward progessional component is replaced by a westward one

13/14 Febuary : is peak 'R' days where we will know the magnitude of the warming & just how much westward ( reversal ) component there is - Sub -20 M/S is the date records & anything below is the jackpot -

16-18 Febuary - Mid to high lattitude transitioning - This is where depending on how lucky we are for our area we will see MLBs start migrating North to the pole as zonal wind lag filters through the lower layers of the atmosphere & support builds for HLB - look for the 3 key wave patterns ( atlantic / Scandi & pacific (-EPO)

The UK can get very cold in this period if the migrating highs are favourably positioned from the outset....

20-24 Feb - Peak HLB blocking across the NH - peak -AO signature & peak cold overall for the mid lattitudes ...

*** IF the GFS lands with the depth of negativity then Late Feb early march will be on a par with 2013 for AO negativity & possible / probable UK cold / snow....

if the negativity is watered down then the cold signature will be watered down & less dominent in western Europe...

 

Best

S

Amazing analysis there Steve and thanks for taking the time to do this? I have a young family and I just never get the time to do this length of post! 

But just a quick one, you say first ssw in 9 years, but jan 13 had one with a quick trip response which was the result of our snowy spell in mid Jan followed by another late ssw in mid/late Feb which bought about March 13, I'm not sure whether technically they were ssw's maybe some one can clarify?

 

But needless to say a very exciting Feb and March coming up, but I suggest people just hold on to a couple of the eggs despite the positive outlook because if it can go wrong, it most deffinately will! 

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I don't think ECM is very likely to verify. Can't see a lobe of the PV moving South East and staying so organised as this.

ECH1-192.GIF?07-0

Expect tomorrow's runs to look very different for the same date.

JMA is  better in that respect and much more probably synoptic IMO

JN192-21.GIF?07-12

Also the potential for heavy snow is outlined again for around the 13th - it all looks marginal and the North looks best but something I think is being overlooked in the excitement of potential wintry weather further down the line.

Edited by Mucka

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7 minutes ago, Severe Siberian icy blast said:

Amazing analysis there Steve and thanks for taking the time to do this? I have a young family and I just never get the time to do this length of post! 

But just a quick one, you say first ssw in 9 years, but jan 13 had one with a quick trip response which was the result of our snowy spell in mid Jan followed by another late ssw in mid/late Feb which bought about March 13, I'm not sure whether technically they were ssw's maybe some one can clarify?

 

But needless to say a very exciting Feb and March coming up, but I suggest people just hold on to a couple of the eggs despite the positive outlook because if it can go wrong, it most deffinately will! 

hi

it was nino neutral so not on the list..

only analogued la nina winters..

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26 minutes ago, ICE COLD said:

Day 10 ECM. Do you reckon the Atlantic ridge will shoot up to Greenland if it went on another frame ?

IMG_1298.PNG

I think I'm well named to answer your query, YES a big fat Greenland high with snow of epic proportions blanketing the country! :D

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4 minutes ago, Steve Murr said:

hi

it was nino neutral so not on the list..

only analogued la nina winters..

does a major SSW not over-ride the la nina signal? if so, could another few be added to the list?

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UKMO extended again shows a potentially very wet and windy spell at t168

ukm2.2018021412_168_lant.troplant_prp_fcst.gentracker.thumb.png.ac23271ab5d5e6b61420a155e4cd20f6.png

Miles away from what GFS shows at the same time

gfs2.2018021412_168_lant.troplant_prp_fcst.gentracker.thumb.png.0d9c8c4a6a6f406e484de5b1f14ec2e5.png

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1 minute ago, Steve Murr said:

To be honest - I coukd have spent 8 hours looking through the list-

you could argue that all SSWS that have occured have made it through the barriers & that all should be included as the immediate tropospheric response signal woukd overide the background nino signal-

however or took 3 hrs to do that 1 post so I stuck with Nina... If you have a spare 3-4 hours then whack them all through the system to generate the temps then day 11 anomaly ! :)

or you could do 1 chart- the super chart if you like of all SSWs at day 10 500MB anomaly would be an OK match...

erm... i think we'll stick with nina years then... :shok:

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4 minutes ago, Steve Murr said:

To be honest - I coukd have spent 8 hours looking through the list-

you could argue that all SSWS that have occured have made it through the barriers & that all should be included as the immediate tropospheric response signal woukd overide the background nino signal-

however or took 3 hrs to do that 1 post so I stuck with Nina... If you have a spare 3-4 hours then whack them all through the system to generate the temps then day 11 anomaly ! :)

or you could do 1 chart- the super chart if you like of all SSWs at day 10 500MB anomaly would be an OK match...

Appreciate you time and effort mate, absolutely top draw and so informative.👍

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What’s encouraging with today’s outputs is that any mild outburst look brief in the next 10 days and then after that in fi (but not your normal fi) most outputs are favouring some sort of blocking near to our north. The best thing is there is growing ensemble support showing, we have the met office still on board as if the chief forecaster is a cold ramper, so I now believe this will happen and possibly could be memorable. Cant remember there being such a big signal for blocking to our north since the 2010 classic. Think it was like 2 weeks before it happened the met prodicted it and it came to fruition just saying. 

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3 minutes ago, Steve Murr said:

To be honest - I coukd have spent 8 hours looking through the list-

you could argue that all SSWS that have occured have made it through the barriers & that all should be included as the immediate tropospheric response signal woukd overide the background nino signal-

however or took 3 hrs to do that 1 post so I stuck with Nina... If you have a spare 3-4 hours then whack them all through the system to generate the temps then day 11 anomaly ! :)

or you could do 1 chart- the super chart if you like of all SSWs at day 10 500MB anomaly would be an OK match...

Steve I have heard that sometimes a second SSW can actually ruin the Synoptics in the troposphere of an original SSW is this a possibility if the second major SSW over Canada comes to fruition and if so do you know the likeliness of that happening?

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A question. What’s the chances of the cold air undercutting the weather front that crosses the country tomorrow night?

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This time last year and today's 12z for comparrison 

Screenshot_20180207-194737.png

Screenshot_20180207-194859.png

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Unfortunately John M, it looks today like the cold air is lagging behind much more so where I was really positive last night, today I am more resigned to a wet affair Friday. 

Edit:

This chart shows HOW annoying this whole thing is. The precipitation easily turns to snow over Northern France. 

arpegeeur-2-45.png?12

Edited by Stuie W
data

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33 minutes ago, Summer Sun said:

UKMO extended again shows a potentially very wet and windy spell at t168

ukm2.2018021412_168_lant.troplant_prp_fcst.gentracker.thumb.png.ac23271ab5d5e6b61420a155e4cd20f6.png

Miles away from what GFS shows at the same time

gfs2.2018021412_168_lant.troplant_prp_fcst.gentracker.thumb.png.0d9c8c4a6a6f406e484de5b1f14ec2e5.png

Overall they aren’t a million miles away? Both have troughing approaching us on a nice angle/ latitude with height rises/ridging showing in the Atlantic well west of us which probably will stop the Atlantic flow?

looks a good development to me with general direction agreed.  If they are poles apart then I’m happy for that to be explained to me.

 

BFTP

Edited by BLAST FROM THE PAST

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In the shorter term, Friday and Sunday both look fairly wintry. The GFS shows showers pushing quite well in land in the NW flow. Although obviously the further south and east you are the more sheltered you will be. Both the GFS and ECM have -8 uppers across the UK. Should be cold enough for snow, particularly if precipitation is heavy enough.

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28 minutes ago, winterof79 said:

This time last year and today's 12z for comparrison 

Screenshot_20180207-194737.png

Screenshot_20180207-194859.png

That's a worry. Broadly similar and last year's winter was complete toss (much like so many before it since the great Eastern snowstorm of 2010!)

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The GEFs in week two seem to want to send low pressure south east through the UK with those deep low heights to our north west relenting as the trough disrupts. The extended outlook does suggest an easterly flow is certain possible.

gensnh-21-5-240.png   gensnh-21-5-300.png   gensnh-21-5-360.png

Certainly a consistent and positive trend across the GFS suite as of later. So what about the ECM?

ECH1-144.GIF?07-0   ECH1-192.GIF?07-0   ECH1-240.GIF?07-0

The idea is there with low heights steadily drain south east, you could see the GFS like evolution happening after day ten with the low over the UK sinking south east with heights in the Atlantic building and re-enforcing those weak heights to our north. So an easterly looks possible further down the line.

ECM ens anomaly at day 10 isn't far from the GEFs solution.

EDH101-240.GIF?07-0

I agree with others in the thinking that the 19th/20th could be when we could see a blocking type scenario develop near the UK. I won't say cold as firstly we will see quite cold weather at times before this point and secondly there is no guarantees that we will get a block/cold solution though the dominoes do seem to be falling in the right direction at least.

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7 minutes ago, supernova said:

That's a worry. Broadly similar and last year's winter was complete toss (much like so many before it since the great Eastern snowstorm of 2010!)

2013 too. Top of our road

The mean is a good -2 lower though throughout and we have an SSW:wink:

March snow 011.JPG

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Fairly solid agreement for the ECM ens and op to Monday  into next week the mean gradually levels off staying around -3

graphe_ens3_php.thumb.png.9eb32ab1a158df555f718b4670279432.png

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