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phil nw.

The Hunt for Cold continues 02/01/19

phil nw.

 

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

Some topic drift, humorous responses etc are fine

Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.

Posts which start with something like 'I know this is off topic but ...' are not ok.

Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

Message added by Paul

Message added by phil nw.

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Posted (edited)
20 minutes ago, karlos1983 said:

Was tongue in cheek 😜 and you are of course entitled to your opinion 😃

Moving on, we seem to have pretty good agreement at +96 just small differences really!

74A3A0FA-C19B-4F35-9AA5-32493CB9D575.thumb.png.f059797b92a10219a07c59054b3cf1dc.png04E39CAF-23D8-4305-BBA2-F1B9396DD6F8.thumb.png.5fdf5b37b7096ad64f2d9aff22d3e826.png2B24C319-D5DC-4381-86EF-E7C24212E5CD.thumb.gif.3cc73684c4a0a29360bb6d0f567653d5.gif

certainly a cold second half of the week is odds on! 👍 it’s what happens thereafter that’s got my attention! 

Oh yes, D4/D5 and beyond is where FI sits at the moment I think. Not convinced by the lack of wintry synoptics mentioned in the BBC longer-range forecasts, I think they'll soon be playing to coldies' tunes as the turnaround and blocked Atlantic signal takes up more prominence.

Edited by gottolovethisweather

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5 minutes ago, blizzard81 said:

Looks to be a downgrade on this morning's 10 day mean. 

EDH1-240 (1).gif

EDH1-240 (2).gif

If I was asked to describe the comparison between the 2 means I would say it’s like my front room. Not a lot in it.😄

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2 minutes ago, mulzy said:

Ext EPS looking good folks!  Trough over Europe and higher than normal heights Iceland and southern Greenland.  Tail-end of week 2 (days 10-15) looks good...

Interesting, Hopefully a decent sized cluster bringing in the goods starting next weekend or just after from the North. 

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1 hour ago, feb1991blizzard said:

come back in the middle of next week and tell me that.

I like the new positive Feb

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I'm pretty certain Ian Brown's WTF moment came before 2013...as we already had some decent cold winter spells before that and he was always harping on about 'large teapot'...maybe Dec 2010 perhaps?

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1 minute ago, Ramp said:

I like the new positive Feb

Can't see how a cold spell of some description can be avoided now, details massively up for grabs though, its positive yes but realistic, if the whole thing collapses then i will be the first to say.

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1 minute ago, Froze were the Days said:

I'm pretty certain Ian Brown's WTF moment came before 2013...as we already had some decent cold winter spells before that and he was always harping on about 'large teapot'...maybe Dec 2010 perhaps?

No it was around Jan 6th - 12th Jan 2013.

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35 minutes ago, More Snow said:

Was living at 300m in the Peak District during that winter and spring, stunning events that just kept on coming. March 2013 gave me the 2nd best Snaw event of my life, only bettered by feb/march 2018. will the UK see the like of it again? 

I remember one Friday night snawfall in March 2013, the estate I lived on in Lancashire was cutoff all Saturday.

 

Good times 😀

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3 minutes ago, feb1991blizzard said:

Can't see how a cold spell of some description can be avoided now, details massively up for grabs though, its positive yes but realistic, if the whole thing collapses then i will be the first to say.

You better get a good dumping in Uppermill this time lol 

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5 minutes ago, feb1991blizzard said:

No it was around Jan 6th - 12th Jan 2013.

This may be deleted but it was December 2010.

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1 minute ago, The Future said:

This may be deleted but it was December 2010.

No - it was definitely 2013.

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2 minutes ago, The Future said:

This may be deleted but it was December 2010.

It was 2013

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1 minute ago, CreweCold said:

It was 2013

Yes, it was a few days before you got a decent snow event - that battleground that failed to reach us, may have been a week or 10 days before.

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Posted (edited)
14 minutes ago, Froze were the Days said:

I'm pretty certain Ian Brown's WTF moment came before 2013...as we already had some decent cold winter spells before that and he was always harping on about 'large teapot'...maybe Dec 2010 perhaps?

Yep absolutely sure it was longer ago than 2013.

December 2010, maybe even late 2009.

Cant believe we are all arguing about that though 😂. Maybe he said it twice...

 

Edited by s4lancia

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We have a thread for chat & banter and it's right -------> HERE

Back to the models, please.

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Posted (edited)

LOOKING FOR SSW SURFACE IMPACTS NEAR THE POLE IN THE MODEL OUTPUT - COMPARISONS TO EARLIER EVENTS - PART 1:  2019 AND 2018

I'm writing this post for two weather forums (US and UK) but most of it is relevant to both N America and UK/Europe. I will be mainly drawing on charts produced by Meteoceil and these + archived charts from the NCEP reanalysis show the Northern Hemisphere from the UK perspective. 

Abbreviations used in this post:

SSW - Sudden Stratospheric Warming

SPV - Stratospheric Polar Vortex

TPV  - Troposheric Polar Vortex

HLB - High Latitude Blocking

QBO - Quasi Biennial Oscillation

MJO - Madden-Julian Oscillation

COD - Circle Of Death

SOI - Southern Oscillation Index

GWO - Global Wind oscillation

GLAAM - Global Atmospheric Angular Momentum

FT - Frictional Torque

MT - Mountain Torque

EAMT - East Asian Mountain Torque

What I want to examine are the surface pressure patterns and charts in relation to previous SSWs and to show what to look out for in the current output.  My focus will be for signs of the reversal propagating down to the surface in the high Arctic and close to the North Pole.  I will look at charts around the time each main SSW event started, at the time of the specific types developed (ie: the displacement and/or the split), the time that surface impacts were beginning to show up and one or more later chart(s) to see how blocking patterns fell into place.  I will divide this post into at least 3 parts over several days to cover separate SSW events.  In part 1, I will look briefly at the current set up and then focus on the February 2018 SSW.  In part 2 I'll focus on the 2013 SSW and in part 3, the 2009 SSW. Later on, I may move on to several earlier events - time permitting.

Firstly, we need to see the dates, type and length of each event.  I repeat this table for reference:

31z.thumb.PNG.b8ccd4c1a50c49dceae7ba453e5ee6bc.PNG

This only goes up to 2010. Malcolm @Blessed Weather has kindly helped me obtain similar data for the 2013 event and there is plenty of data available on the Feb 2018 event.  If nothing else, these posts will confirm that every SSW is different in many ways.  The type of warming with the displaced and/or split vortex events as we know are highly important with the latter "usually" leading to more extensive HLB.  The propagation and down welling of the wind reversal to the surface is often far from straight forward and precise timings are extremely difficult to nail down even within the D5 to D7 period.  

2019 SSW:  

SSW started in late December 2018 (precise date to be confirmed). Type - Split, circa January 3rd, 2019. MJO - phases 5 and 6 with 7 and 8 predicted at moderate amp; ENSO - weak El Nino developing (there is a minor blip right now but do not get hung up on the SOI and on some of the S Hem ENSO impacts);  wQBO (descending); solar - near minimum.

I'll start with the current "ongoing" event which I'll call the "2019 SSW" to avoid confusing it with the earlier 2018 event although the warming in the upper layers started in mid/late December 2018 with repeated attacks on the SPV. 

sswx.thumb.PNG.18612999be0ff00126c5ed53db89ea5a.PNG

GEFS and ECM are much more closely aligned now compared to the last couple of weeks but there is still some uncertainty over how fast the progression will be.  In the second half of January we would normally expect this to favour HLB.  As this SSW looks like being a long (or even very long) event it would not be too bad if the MJO misses out on its 1 to 4 phases and re-emerges in phase 5/6 again for a repeat performance (perhaps at higher amp) during February to give us a second bite of the cherry. I appreciate that on our side of the pond phases 7 and 8 (and 1) are better for blocking patterns while in N America phases 8 and 1 (and 2) are better.  

ssw19a.thumb.PNG.11d472d6e579f41f6af24a040fb1f9f0.PNG

The GWO is now strengthening again and progressing through phase 5 and looking set for phase 6 (if it's not there already with the 2 day chart time lag). The relative GLAAM tendency anomaly has been rising again as is total GLAAM.  That's encouraging for +ve tropical forcing but there has been a timing issue. Ideally, we would want to see the SSW surface impacts more or less coincide and it is not completely certain that GLAAM will be maintained in an elevated for more than the next 10 days or so.  It is, however, pretty likely that the GWO will perform in a similar way to the MJO and it has been on a repeat cycle since early November.  So we might see both January and February impacts.  FT (not shown) remains +ve.

30g.thumb.PNG.f7051657dbf91386f8e7760241f0067a.PNG

A reminder of the GWO phase chart.  

ssw19b.thumb.PNG.b8f531854e45a1ae6af43e9a3bb9fc74.PNG

Then we have further good news. Global MT (black line) is +ve and just recently, rising further.  This should prevent EAMT (red line) from falling back too far and it'll likely remain +ve for even longer.  The strongest signal is at 30N to 40N (the red blobs in the upper part of the chart) centred around the Tibetan Plateau (see my early posts for greater details on this). The +ve torques should assist in keeping GLAAM +ve for an extended period with perhaps only a short weaker or -ve blip.  

Now to relate this to the models.  I prepared this post based on today's 0z and 6z output and I know that the 12z will be out by the time I've finished.  As there has been considerable run to run variability this does not really matter as output is likely to remain volatile for at least several more days and possibly rather longer than that.  What I noted however, was some remarkable "consistency" on the day 5 output (something not seen at all on previous runs with considerable disagreement):

sswz2.thumb.PNG.70e2f3b9c7cc0a257a6388c7487e13a4.PNG

I'll just show the GEFS 6z "mean" for today. The moderate amplification that we've seen so far has been related to the +ve GLAAM, torques and the MJO at decent amp through phase 6.  This has produced some quite stationary or slow moving ridges and troughs and the recent cold plunge into Europe which looks set to be repeated during next week. I'll leave it to other posters to comment on their shorter term "home" patterns be it UK, Europe or N America.  I'm really focusing on the high Arctic.  There are just hints of HP building closer to the North Pole.

sswz1.thumb.PNG.6308b5a498df82cb9e2b59191715932a.PNG

Now the January 9th chart.  HP is building right over the pole. and the TPV is looking set to split just to the south.  This is the mean chart but every GEFS ensemble member has HP over the pole at this time (see below), plus the control run + the GFS operational run.  Here's the panel: 

gens_panel_mjm1.png

EDIT:  I had saved the 6z but the gif updated to the 12z which still has all the members with HP building around the pole.

Moreover so do "all" the other main models - GFS (parallel), ECM, GEM, NAVGEM, JMA and ICON. As you'll see when I cover the 2018 and earlier SSWs, these are important early signs.  This coupled with the latest news on the stratosphere suggesting that the reversal is now down welling through the troposphere with several commentators suggesting that this may only be 3 or 4 days away. Now, please do not take this as definite - things can still go wrong or at least we may have further delays. The fact that all the models agree on around day 5 for the first signs of polar impacts is encouraging. Rather than pushing things back, if we can move things forward then we'll get the best combination of GLAAM and the torques with the tropical forcing with stronger HLB much more likely and assisting better strat-trop coupling. 

The full story is still in its early stages. Will the existing amplified pattern link up to HLB?  Will there be a transition of a few days with a flatter pattern?  Where will the blocking set up? How severe will the cold be and how long will it last?  "If" there is a further delay, things still look good into February.  So the 2019 SSW still teases us but I remain very optimistic of widespread cold weather going forward with some earlier rather than delayed impacts.

2018 SSW:

SSW started during February 2018. Type - Split, circa February 12th, 2018. MJO - phases 3, 4, 5 and 6 at increasing amp and entering phase 7 at around record high amp (see below); ENSO - moderate  La Nina (but with a weaker phase in January)  eQBO; solar - weak and falling.

SSW1.thumb.PNG.208480071072c9dcfd51a55291d8a085.PNG

Note that the MJO was in high amp phase up to the time of the initial triggering of the SSW on February 12th, then continued at weaker amp through to phase 8 (ignore the forecast "green" bit as I'm looking at what actually occurred). The time lagged impacts on HLB fitted in very nicely.

ssw18e.thumb.PNG.4b53998fb45daf7e1d76025609a3dc15.PNG

This chart from the archives (see below) shows that the MJO continued through phase 1 at increasing amp then onto phase 2 (good for N America which saw the SSW impacts a week to 10 days after the UK and Europe) and briefly into phase 3 before passing through the COD and back out to phase 7 towards the end of March.

Here's a link to the archived NOAA weekly reports going back to 2006 and these contain the phase charts and a lot more.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/ARCHIVE/PDF/

SSW2.thumb.PNG.51b01b775b7a5585e46aabfb4e81beb6.PNG

Unlike the current event, GLAAM had been strongly -ve through much of January 2018 and rose strongly at decent amp through phase 4 and 5 into early February and at moderate amp through phases 6 , 7 and into 8 by February 10th. So pretty strong and with +ve torques in the build up to the SSW. 

SSW4.thumb.PNG.0737cbf659f313137f015e6d9d1944ee.PNG

The spike in global MT and EAMT in early February and with that 10 to 14 day time lag almost certainly helped to trigger the SSW on February 12th. The next spike may well have assisted the secondary warming.  I covered this in more detail in my last post.

Now the models.  I'm using the excellent NCEP reanalysis charts from the archives.  You can trace the whole of the 2018 SSW and much more on this link:

http://www.meteociel.fr/modeles/archives/archives.php?day=12&month=2&hour=0&year=2018&map=4&region=&mode=2&type=ncep

ssw18a.thumb.PNG.34cf0219b0047853c9c6969ab742d4e5.PNG

The SPV split on February 12th and models were generally showing pretty mundane output (seems familiar?).  We had some polar maritime air in the UK and central/eastern CONUS and Canada had a "standard" (not SSW related) Arctic outbreak. 

ssw18bPNG.thumb.PNG.49c32e4120b3a6b9a88701b411ec99a0.PNG

Just one week later and the models were starting to sniff out something going on and there were signs of the pattern reversal impacting with the build of HP at the pole but only very modest amplification of the Azores HP.  Strong HP over central and northern Asia and building across from Alaska.  This post is already getting very long but for those of you who want to see how variable the model "forecast" output was a few days before, run through the archived "forecast" charts - here's a link:

http://www.meteociel.fr/modeles/gfse_cartes.php?jour=7&mois=2&annee=2018&heure=12&archive=1&mode=0&ech=6&runpara=0&carte=1

You can play around with all the output and reset the date ranges etc. 

ssw18c.thumb.PNG.8a0e746d2556adc70c019564ba2593ef.PNG

A further week on and it's getting very interesting.  Arctic HP extending to Iceland and Scandinavia.  The "Beast from the East" was just awakening over Europe and the UK. Note that the TPV was still over northern Canada but it was shortly to be on its journey across to Siberia.

ssw18z.thumb.PNG.ae7a9bba580978486f50a355b06a1def.PNG

Just 4 days later and the TPV had migrated across to Siberia. A true Greenland HP had developed. The surface flow reversal was now pushing on right through CONUS. The beast is at its most intense over western Europe and the UK.  

ssw18d.thumb.PNG.32f3cf4ab30f43c15d50e00b749338f5.PNG

Three more days later and the reversed flow at the surface shot through Europe, the UK, across the Atlantic, Newfoundland and through to central CONUS.

ssw18y.thumb.PNG.28341165497cfcb692b0588337a37d44.PNG

After weakening somewhat, the SSW (with its secondary warming impacts) is having another go.  The "Mini beast" (or beast 2) hits Europe and the UK

ssw18x.thumb.PNG.8e33ebdf6aa560a38382ceaaec70835a.PNG

Canada and central CONUS saw the most severe impacts during much of April 2018. 

Although the current and the February/March 2018 SSWs were both "split" SPV events you can see that the build up had some similarities but also many differences too.  One can see how quickly the model output changed and how dramatic these events can be.  I hope that we will see something very special from this event.  Watch out for those Arctic profiles and the HP building there.   

Next up in part 2 (tomorrow)  I'll look at the 2013 SSW which had a displaced and a split SSW with separate impacts over a prolonged period.  David  🙂 

 

Edited by Guest
check charts, links and correct typos

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Posted (edited)
9 minutes ago, Bring Back1962-63 said:

LOOKING FOR SSW SURFACE IMPACTS NEAR THE POLE IN THE MODEL OUTPUT - COMPARISONS TO EARLIER EVENTS - PART 1:  2019 AND 2018

Fantastic post,  All looking good .. can't wait for part 2.

Thanks 🖒❄

Edited by The BEAST From The East
Added

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5 minutes ago, The BEAST From The East said:

Fantastic post,  All looking good .. can't wait for part 2.

Thanks 🖒❄

Agreed, I couldn’t reply on my phone without quoting the entire post and infuriating the forum.

 

A stunningly informative post 62/63!

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Posted (edited)

Here's one for you...a what happens next?

JMA T192:

image.thumb.jpg.df19acbae9cda2f73e52dc53f48f4ed9.jpg

The T264 will appear about 11 pm, what would it show?  No answers on a postcard please!  But very interested to read your thoughts in here! (I'll post the actual chart tomorrow morning).

Edited by Mike Poole

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Posted (edited)
1 hour ago, feb1991blizzard said:

Yes, it was a few days before you got a decent snow event - that battleground that failed to reach us, may have been a week or 10 days before.

100% WTF was 2013! It wasn’t 2010 because I remember seeing it and I wasn’t on this forum back then! 

Onto the 18z, ICON stops at 120, but it looks almost identical to its 12z output. Things forming up on that front. 

5E2AD72C-8940-4FCF-8AE4-01E5979231E6.thumb.png.2a1715439a279d89e287fa6bc0d4e73d.png

Thanks for the amazing post David @Bring Back1962-63 👍

Edited by karlos1983

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1 minute ago, karlos1983 said:

100% WTF was 2013! It wasn’t 2010 because I remember seeing it and I wasn’t in this forum back then! 

Onto the 18z, ICON stops at 120, but it looks almost identical to its 12z output. Things forming up on that front. 

 

Thanks for the amazing post David @Bring Back1962-63 👍

GFS 18z a little bit worse than 12z though - only a little bit so would't be to down - little bit further East.

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