Hunt For Cold: Model Discussion - Heading Into Christmas

[Guest]

Update on the Background Signals and Looking at the Interaction between the Likely SSW Impacts and the Tropical Forcing

Firstly, that was an excellent update on the SSW on here by @lorenzo.

I have just posted on a US weather forum Teleconnections thread and I feel that this will put a little flesh on some of the points that I've made in some recent posts on this thread - I copy it below. I've edited it slightly to better fit the UK position but I do not have time to do a complete re-write. I will not explain everything again except the really key points. I posted this morning on here (on page 119) wrt to the model output and this post relates to some of those as well as my earlier comments - here's the link:  https://www.netweather.tv/forum/topic/91032-hunt-for-cold-model-discussion-heading-into-christmas/?do=findComment&comment=3948800

Just to add a little more to Tom's @Isotherm excellent update and several updates today - things do seem to be going very much according to plan with perhaps some real clarity likely to emerge during this week.  EDIT:  and while writing this I see that Tams @Tamara has just posted with some encouraging comments but with some wise words of caution too.  An excellent post as usual and an interesting comparison to the 2012/13 SSW and the key teleconnections at play back then compared to now.  Right on with my post and I'll make brief comments below each chart:

The total GLAAM (global atmospheric angular momentum) anomaly which has remained +ve all month but eased back recently is now rising again.  The strongest +ve anomaly is currently at the equator.  

The relative GLAAM tendency anomaly which spiked for 5 days, remains +ve but has levelled off. This has been in association with rising torques.  

FT (frictional torque) has been rising strongly. Note the orange colours (in the upper part of the chart) showing around 25N to 35N.  That's part of the poleward progression from the tropics (see below).   

GLMT (global mountain torque - the black line) has continued its recent spike and is now +ve.  Of the regional torques, the strongest rise showing is the highly important EAMT (East Asian mountain torque - red line) which is +ve and climbing steadily - this is exactly what I was hoping for, with perfect timing.  The highest values (red blobs) are once again being seen over the Tibetan Plateau and (with the 2 day time lag in these charts) is almost certainly over the Mongolian Mountains right now.  More below on this.

As I expected (well hypothesised) GWD should be rising in that same area just before EAMT is at its strongest and indeed it is and also around 35N to 50N.  More below on this.

Just a reminder of the GWO (global wind oscillation) phase chart as part of the GSDM (global synoptic dynamic model) which incorporates GLAAM and the torques and takes account of and influences (and is influenced by) the ENSO state and the MJO. The most recent GWO chart is below.

The GWO has stalled temporarily in neutral orbit (a bit like the COD on MJO charts) but looking set to emerge in phase 5.  With rising AAM and the torques we are likely to see the GWO rising though phase 5. I do note several comments on this with some views expressed going for a slightly longer delay in this progression and we'll need to see exactly what unfolds during this week. I feel that the key torque right now is EAMT but it is unwise to separate out any part of the whole GSDM process and we must consider all aspects together. So, I'll rephrase that and say that +ve EAMT has some very strong influences on planetary waves - lateral (eastwards impacting on the Pacific patterns downstream and beyond), northwards (to aid North Asian blocking) and vertically (strong uplifting often into the upper stratosphere and lower mesosphere).

I see that the latest MJO charts have been posted this afternoon and both the RMM phase charts as well as the VP200 output have been shown - so I won't repeat them here. I feel that both types of charts have their place and pros and cons  The GEFS bias corrected RMM version maintains its strong amp through phase 6 and into 7 before stalling there and maintaining amp. ECM continue to go for a faster progression through phases, 6, 7, 8 and at decreasing amp and entering the COD later than on recent runs. Most of the other models are somewhere in between the big 2 and there may well be greater convergence and model consensus as the timing of the pattern reset becomes clearer during this week.

That vast expanse of high pressure extends across almost all eastern, central, northern and western Asia , Russia and Siberia and has pushed even further westwards.  Strong blocking in this region is considered to be a key precursor for SSW impacts and very likely to assist with strat/trop coupling making the lowest layers more receptive to the lowest stages of the downward propagation.  This + the spiking EAMT and GWD are very encouraging right now and set to improve even further.

I posted this chart recently but the northern hemisphere snow cover has extended even further south and looks really impressive before we even consider the SSW and tropical forcing impacts. 

Global surface temps and particularly N Hem temps have fallen close to their lowest levels since Feb/Mar at the time of the last SSW. 

The trend in much of Europe and the UK is a downward one for the next 7 days but this is due to slightly greater amplification under the existing HP and not HLB (at this stage).  There are some low anomalies over Alaska and -ves over SE and parts of eastern CONUS.  The lowest anomalies of all are in the key North Asian/Russian/Siberian region with some parts seeing -ve anomalies approaching 20c below average.  I also note that the Arctic has turned much colder with overall -ve anomalies developing there (Greenland remains +ve).  The more cold to be displaced from the Arctic the better.  I will do an Arctic update within the next few days. 

It's not just global land temps that have been falling, global SSTs have continued to fall back steadily almost all month and if anything the trend is accelerating again. They are close to their lowest values for 5 years as shown below.

This may be a temporary trend and is something that we'll need to examine more closely on the Teleconnection thread but it's good to see some respite from the global warming trends.  

Overall, in the context of the SSW, the tropical forcing and the other key teleconnections there are some very encouraging signs and a lot might be revealed during this week.  Look out for what I suggested in my model post this morning.

David   

Edited December 30, 2018 by Guest
check charts and correct typos

[BLAST FROM THE PAST]

28 minutes ago, Catacol said:

Yes saw that yesterday, and NOAA report that the MJO has slowed in recent days as convection interacts with they call "strong" rossby wave activity. That would also account for a few more days later in terms of forcing....so a slightly delayed SSW and now a delayed MJO passage all adding up to a mid Jan scenario for continental cold rather than the week 1 transition that was seen by many when forecasting the pattern in early December. Strong rossby activity would only be good news too for our Hunt....

Problem is - people on this forum are going to start reaching for the bottle soon! I quite enjoy watching a slow progression (heightens the excitement!!) - but I'm also, like others, beginning to frown at the lack of good charts in the 10 day range. December 2018 is not going down as one of the better winter months down here - not sure we've had a single frost in the SW (we had 2 or 3 in November) and heavy drenching rain in the first half has now been replaced by mild and dull. Glad to see the end of the rain, but mightily unimpressed at double digit daytimes and mild nights. Not winter at all.

Something this winter will be remembered for...this winter ‘extreme’ is this HP.....it won’t go far for sometime....Not the cold HP I hoped for

 

BFTP

Edited December 30, 2018 by BLAST FROM THE PAST

[bluearmy]

Interesting ...... day 3/4 middle strat heights are imprinted on the ec mean 500hpa  day 9/10 .....

looking at the latter stages of ec strat run, the blocking probably just stays too close to expect the scrussian trough to get far enough west by day 15/16

spreads encouraging that the ridge can get far enough nw to allow a nor’easter ......tell tale sign of the light reds beginning to appear up the west side of Greenland on the 850 spreads late on  .......

Edited December 30, 2018 by bluearmy

[Bristawl Si]

8 minutes ago, BLAST FROM THE PAST said:

Something this winter will be remembered for...this winter ‘extreme’ is this HP.....it won’t go far for sometime....Not the cold HP I hoped for

 

BFTP

Blimey Blast you've changed your tune; you were continuously bullish over last few weeks.

[Methuselah]

15 minutes ago, karlos1983 said:

Steady on! GFS bashing is quite valid in my opinion, it’s been bloody useless! Said no to a split at 10hpa and eventually came wondering in with it’s tail between its legs! It also changes its mind 4 times a day! Don’t misconstrue my post please...  

Then again Karl, I wonder how the other models would fare, should they ever go all the way out do day 16?

[Frosty.]

Looking at the GEFS 12z postage stamps, the chances of snow increases as we head towards mid January  with some peachy cold potential..which as i understand it is in line with what exeter are saying on a daily basis!!..keep the faith coldies!

[bluearmy]

Extended eps finally more convincing in going where the 46 has been showing on occasion as the Azores low anomoly finally moves ne into the scrussian low anomoly  backing west with the high anomoly pulling nw into the mid Atlantic ......expect that smallest cluster on the Icelandic suite this morning to be larger later ??

Edited December 30, 2018 by bluearmy

[northwestsnow]

Just now, bluearmy said:

Extended eps finally going where the 46 has been showing on occasion as the Azores low anomoly finally moves ne into the scrussian low anomoly  backing west with the high anomoly pulling nw into the mid Atlantic ......expect that smallest cluster on the Icelandic suite this morning to be larger later ??

Now thats what coldies want to hear!!

Wondering if the stormy spell signposted for second week in Jan will be the trigger..

[karlos1983]

18 minutes ago, Ed Stone said:

Then again Karl, I wonder how the other models would fare, should they ever go all the way out do day 16?

Well the GFS struggled with the Strat in the same timeframes as the ECM Pete . But yes 16 Days is a big ask.... mind you the EC monthly did alright back in Feb for March..... In fact it pretty much nailed it!

[booferking]

The 10 Day mean hinting for heights NW.

[Radiating Dendrite]

27 minutes ago, Bristle boy said:

Blimey Blast you've changed your tune; you were continuously bullish over last few weeks.

Hopefully the opposite will happen - that has been the case so far with what BFTP has said this winter. 

[shotski]

38 minutes ago, Stonethecrows said:

Years ago people said global warming was a fad and look where we are now!! besides I think reminding everyone that a SSW doesn't always guarantee cold and snow is far more tedious as even the most novice of us are fully aware of that.

The cold is there, unfortunately for us it’s not here, yet! 

Cold weather geeks in Greece must pray for a UK high in winter like we do a greeny high LOL. Hopefully next time round the cards will fall for us in the uk. 

[bluearmy]

8 minutes ago, northwestsnow said:

Now thats what coldies want to hear!!

Wondering if the stormy spell signposted for second week in Jan will be the trigger..

Well the control is similar to the op and takes a system se through Shetland/w Norway  at day 15 as the ridge retrogresses 

[northwestsnow]

7 minutes ago, booferking said:

The 10 Day mean hinting for heights NW.

Thats a better mean !

[Man With Beard]

Not sure if this has been posted, but a very useful addition to the weather.us site - an overview of ECM ensembles data out to D15. Worth a bookmark! 

https://meteologix.com/ie/forecast/2643743-london/ensemble/euro/pressure

[bluearmy]

8 minutes ago, Man With Beard said:

Not sure if this has been posted, but a very useful addition to the weather.us site - an overview of ECM ensembles data out to D15. Worth a bookmark! 

https://meteologix.com/ie/forecast/2643743-london/ensemble/euro/pressure

Good find!

[MR EXTREMES]

2 hours ago, abbie123 said:

High pressure seems to pulling out west with cold air lurking to the north and east of U.K. This was  mentioned on BBC long range forecast high moving west and  towards the end of forecast she said there are indications. But video ended so don't no rest of it could be indications of colder weather to come???

I have a feeling that russian Siberian heights could be exactly what will help push our ridge of heights out west with segment of the PV dropping down into Scandinavian side.

So in other words bouncing between two blocks ours and russian/Siberian.

As long as our heights stick around this is a possibility for trend towards colder.

I'm not sure whether 7th of January is worth punting on again I've said the 7th for changes.

But after many Prozac moments recently I'm back in rehab having bit of faith in the weather god's,

and singing edd stones, chart topping snow tune lol.

Very interested to see where this goes.

[Snowjokes92]

2 hours ago, Bring Back1962-63 said:

Update on the Background Signals and Looking at the Interaction between the Likely SSW Impacts and the Tropical Forcing

Firstly, that was an excellent update on the SSW on here by @lorenzo.

I have just posted on a US weather forum Teleconnections thread and I feel that this will put a little flesh on some of the points that I've made in some recent posts on this thread - I copy it below. I've edited it slightly to better fit the UK position but I do not have time to do a complete re-write. I will not explain everything again except the really key points. I posted this morning on here (on page 119) wrt to the model output and this post relates to some of those as well as my earlier comments - here's the link:  https://www.netweather.tv/forum/topic/91032-hunt-for-cold-model-discussion-heading-into-christmas/?do=findComment&comment=3948800

Just to add a little more to Tom's @Isotherm excellent update and several updates today - things do seem to be going very much according to plan with perhaps some real clarity likely to emerge during this week.  EDIT:  and while writing this I see that Tams @Tamara has just posted with some encouraging comments but with some wise words of caution too.  An excellent post as usual and an interesting comparison to the 2012/13 SSW and the key teleconnections at play back then compared to now.  Right on with my post and I'll make brief comments below each chart:

(SNIPPED)

David   

Which post by tamara are you referring to? I cant see it. There a good read like many of you

Edited December 30, 2018 by Blessed Weather
Snipped the post to shorten.

[karlos1983]

4 minutes ago, Snowjokes92 said:

Which post by tamara are you referring to? I cant see it. There a good read like many of you

I beg you and anyone replying to big posts, please not to quote the entire post hard work when on an iPhone

pretty Certain David was saying about Tamara’s post on a different forum. She doesn’t tend to post here much now, which is a massive loss, but I can’t blame her as she gets nothing but crap, which when you construct a post with such detail as she does, to have it dissected is ridiculous.

 

Edited December 30, 2018 by karlos1983

[Snowjokes92]

Just now, karlos1983 said:

I beg you and anyone replying to big posts, please not to quote the entire post hard work when on an iPhone

I would if i knew how to do it. Trust me i did try to find how to quote only a bit of the lengthy post

[Bobafet]

1 minute ago, karlos1983 said:

I beg you and anyone replying to big posts, please not to quote the entire post hard work when on an iPhone

@karlos1983 just click the little down arrow next to the time of the post and it condenses the quoted post, it makes it a lot easier to view from phone/tablet.

[Dancerwithwings]

2 hours ago, abbie123 said:

High pressure seems to pulling out west with cold air lurking to the north and east of U.K. This was  mentioned on BBC long range forecast high moving west and  towards the end of forecast she said there are indications. But video ended so don't no rest of it could be indications of colder weather to come???

That’s weird it’s just done the same on BBC news 24....10 day forcaste just before 10pm 

Same “the HP moving West and then there could be indications” then cut off....What’s that all about...Not Funny!!!

[Eskimo]

One thing's for sure, we do get some cold days with very cold nights, frosts, freezing fog etc courtesy of (whilst people don't like this term, even though I still believe it's very apt) 'faux cold' from this very stubborn high. 
 

[Snowjokes92]

4 minutes ago, karlos1983 said:

I beg you and anyone replying to big posts, please not to quote the entire post hard work when on an iPhone

pretty Certain David was saying about Tamara’s post on a different forum. She doesn’t tend to post here much now, which is a massive loss, but I can’t blame her as she gets nothing but crap, which when you construct a post with such detail as she does, to have it dissected is ridiculous.

 

Thank you. Its a shame really and always found her posts interesting and informative and non biased. @Bring Back1962-63 could you possibly link her post over to us? Thanks

[Blessed Weather]

11 minutes ago, Snowjokes92 said:

I would if i knew how to do it. Trust me i did try to find how to quote only a bit of the lengthy post

You can also just go into the quote and highlight and then delete the bits not required - as I've done above. Then come out of the quote box to write your post underneath it.

Edited December 30, 2018 by Blessed Weather