lorenzo

January 27

Thrawn - fine chookter word that SIS ! Lovely vid - we are so lucky !

January 26

Bit of a boring hiatus this, but some mad stuff ongoing - Spain Top Temps, the Jet Stream and Omega Block across the states is - one for the ages chart, just exceptional.

In the heart of the cold hangover and dreadful NWP output is a real 'meh' for excitement... But, lots of winter to go -- would normally leave that as .. a ha maybe stuff ahead..

But it is looking like being slow - burn and lagged... mid Feb is the one to watch ( even in the extended - for trends) vs. NWP right now.

January 21

Another nope..

January 21

948 on latest surface plot, some really powerful gusts here, strong winds right at the hook.

January 21

Some fierce gusts out there now, hang on to everything those out west, stay safe!

January 21

Oooft

January 21

Last visible on the in-flow before IR , fascinating dual low pressure structure.

January 21

The wrap up continues - nice satellite loop from yr.no to highlight

https://www.met.no/en/weather-and-climate/satellite-images

January 21

13 minutes ago, Starsail said:

I was just looking at the warning matrix on the met office amber warning. It is at it's highest level ( far right) in terms of impact. It is only likelihood that stops it from going red ( vertical axis).. As the track of the storm becomes more certain I would expect that some areas will go red. Sorry , don't know how to post the image.

Looks like things continue to evolve, @Jo Farrow added into the Storm Isha thread that the MetO warning matrix had been adjusted for Scotland to a lower likelihood re: impact. Small margins here one would think..

Starting to wrap up now https://www.met.no/en/weather-and-climate/satellite-images

January 21

Current Obs align well to the Met Office Fax from earlier, still some deepening to go on Isha, and this deepening phase happening right on our doorstep.

Another 10mb to drop and you can see the extent of the wind-field on UKV which has ushered in the Amber warnings for Englandshire / most of the UK ( hard to tell from the Met Office map given it's got so many overlaid warnings on it!)

Second pulse slams into Western Isles by midnight

January 21

Current Obs align well to the Met Office Fax from earlier, still some deepening to go on Isha, and this deepening phase happening right on our doorstep.

Another 10mb to drop and you can see the extent of the wind-field on UKV which has ushered in the Amber.

Second pulse slams into Western Isles by midnight

January 20

58 minutes ago, Mike Poole said:

I read that blog, but one thing that confused me with that picture, is that the often quoted (on here, anyway) Ural high, Aleutian low combo, as a SSW precursor, isn’t one of the two main patterns. Instead the two patterns are Aleutian low, North Atlantic high (for wave 1) and Aleutian high, Ural high (for wave 2)? In fact, the Aleutian low, Ural high is more similar to the left picture of what happened this year.

Can anyone explain/reconcile this, please? I am confused!

Had to rewind my mind back to 2009 - 2011 to get this one disentangled - there was a paper which referred to both the Ural High regime in combination with the Aleutian Low, and cited the NPAC low as a 'stratospheric starter pistol', a nice turn of phrase which sticks in the memory, which of the papers at the time examining precursors - have not been able to recall.

Looking at more recent analysis - found this paper which summarises both precursors and how they enhance wave activity / wave driving and create vortex perturbation.

It has been shown that pressure changes in certain regions, when in phase, can constructively interfere with the climatological wave-1 and wave-2 patterns and thus lead to an overall increase of wave driving (e.g. Garfinkel et al., 2010; Smith and Kushner, 2012). In particular, the Ural blocking pattern as part of a wave-1 anomaly has been recognised as a precursor pattern for SSWs (e.g. Garfinkel et al., 2010; Cohen and Jones, 2011). Moreover, this blocking pattern has recently received additional attention, as it plays an important role in dynamically linking Arctic amplification and sea-ice loss to changes in mid-latitude circulation patterns via a robust but highly intermittent stratospheric pathway (Jaiser et al., 2016; Hoshi et al., 2019; Cohen et al., 2020; Siew et al., 2020; Jaiser et al., 2023): The strong reduction of Arctic sea ice in autumn and winter, in particular in the Barents and Kara seas, and the associated heating of the overlying atmosphere favour more frequent blockingtype ridges over northwestern Eurasia in early winter, which facilitate the enhanced propagation of wave energy into the stratosphere, where wave breaking can lead to a disruption of the stratospheric polar vortex (Overland et al., 2016; Crasemann et al., 2017).
On the Pacific side, Ineson and Scaife (2009) demonstrate that a deeper Aleutian Low positively interferes with and strengthens the stationary wave-1 amplitude. Moreover, Bao et al. (2017) identify the positive phase of the Pacific–North American pattern (PNA) as a precursor of SSWs by means of constructive interference with the climatological planetary wave-1 pattern. Whereas the Ural blocking plays an important role in Arctic–mid-latitude linkages, the Aleutian Low and the PNA have been identified as a pathway connecting the tropical phenomenon of the El Niño– Southern Oscillation (ENSO) to the strength of the stratospheric polar vortex in winter (e.g. Ineson and Scaife, 2009; Domeisen et al., 2019).

In relation to the graphic it is clearly a different flavour of warming this year given it does not match the precursors shown, I do wonder if much of this is related to the Canadian Warming after effects from earlier in the season. We are either in a place where we have better tools to see CW type events more clearly - given the last few seasons has witnessed Nov / Dec wave activity akin to the CWs of early 80s, this season perhaps was a true CW event vs the prior seasons simply being early wave impacts on the developing vortex. It would be worthy of some re-analysis - am sure the boffins will be on the case and produce papers to examine the lead in to the short reversal over the next 12m.

Original post: https://community.netweather.tv/topic/99793-model-output-discussion-cold-spell-ending-what-next/?do=findComment&comment=5019786

January 20

Looking at GWO - you can see an argument for emergence from the circle of doom into a P4/5 circuit, the composites of which do advertise the initial scandi development , then into p5 heights building over Greenland.. Looking much further aloft day 10 sees the mid level vortex on it's travels to the Siberian side, we do have some grim charts on the face of things to muddle through in the immediacy, however the NWP will surely be toying with these type of solutions in earnest before too long..

January 20

2 hours ago, dryfie said:

Eyes now to the SW, with gales and much milder temperatures. Day max temperature records for rest of the month:

20th 13.3 Achnashellach 1970

21st 13.9 Onich 1937

22nd 14.5 Aboyne 2020

23rd 15.0 Girvan 2008 & Lossiemouth 1960

24th 16.5 Achnagart 2016 (whole UK record)

25th 15.8 Dunbar 2016 (whole UK record)

26th 18.3 Aboyne 2003 (whole UK record for date and month)

27th 16.7 Onich 1958

28th 15.0 Kinlochewe 1993

29th 15.5 Lossiemouth 1981 (whole UK record)

30th 14.2 Poolewe 2009

31st 14.8 Dyce 2007

I'd love to see the 26/1/2003 surface chart if anyone has the means?

Not a surface chart - but did find this https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/interesting/2003/record-breaking-maximum-temperatures---26_27-january-2003---met-office.pdf

January 20

58 minutes ago, Mike Poole said:

I read that blog, but one thing that confused me with that picture, is that the often quoted (on here, anyway) Ural high, Aleutian low combo, as a SSW precursor, isn’t one of the two main patterns. Instead the two patterns are Aleutian low, North Atlantic high (for wave 1) and Aleutian high, Ural high (for wave 2)? In fact, the Aleutian low, Ural high is more similar to the left picture of what happened this year.

Can anyone explain/reconcile this, please? I am confused!

Had to rewind my mind back to 2009 - 2011 to get this one disentangled - there was a paper which referred to both the Ural High regime in combination with the Aleutian Low, and cited the NPAC low as a 'stratospheric starter pistol', a nice turn of phrase which sticks in the memory, which of the papers at the time examining precursors - have not been able to recall.

Looking at more recent analysis - found this paper which summarises both precursors and how they enhance wave activity / wave driving and create vortex perturbation.

It has been shown that pressure changes in certain regions, when in phase, can constructively interfere with the climatological wave-1 and wave-2 patterns and thus lead to an overall increase of wave driving (e.g. Garfinkel et al., 2010; Smith and Kushner, 2012). In particular, the Ural blocking pattern as part of a wave-1 anomaly has been recognised as a precursor pattern for SSWs (e.g. Garfinkel et al., 2010; Cohen and Jones, 2011). Moreover, this blocking pattern has recently received additional attention, as it plays an important role in dynamically linking Arctic amplification and sea-ice loss to changes in mid-latitude circulation patterns via a robust but highly intermittent stratospheric pathway (Jaiser et al., 2016; Hoshi et al., 2019; Cohen et al., 2020; Siew et al., 2020; Jaiser et al., 2023): The strong reduction of Arctic sea ice in autumn and winter, in particular in the Barents and Kara seas, and the associated heating of the overlying atmosphere favour more frequent blockingtype ridges over northwestern Eurasia in early winter, which facilitate the enhanced propagation of wave energy into the stratosphere, where wave breaking can lead to a disruption of the stratospheric polar vortex (Overland et al., 2016; Crasemann et al., 2017).
On the Pacific side, Ineson and Scaife (2009) demonstrate that a deeper Aleutian Low positively interferes with and strengthens the stationary wave-1 amplitude. Moreover, Bao et al. (2017) identify the positive phase of the Pacific–North American pattern (PNA) as a precursor of SSWs by means of constructive interference with the climatological planetary wave-1 pattern. Whereas the Ural blocking plays an important role in Arctic–mid-latitude linkages, the Aleutian Low and the PNA have been identified as a pathway connecting the tropical phenomenon of the El Niño– Southern Oscillation (ENSO) to the strength of the stratospheric polar vortex in winter (e.g. Ineson and Scaife, 2009; Domeisen et al., 2019).

In relation to the graphic it is clearly a different flavour of warming this year given it does not match the precursors shown, I do wonder if much of this is related to the Canadian Warming after effects from earlier in the season. We are either in a place where we have better tools to see CW type events more clearly - given the last few seasons has witnessed Nov / Dec wave activity akin to the CWs of early 80s, this season perhaps was a true CW event vs the prior seasons simply being early wave impacts on the developing vortex. It would be worthy of some re-analysis - am sure the boffins will be on the case and produce papers to examine the lead in to the short reversal over the next 12m.

January 20

6 hours ago, snowking said:

Whilst that immediate signal in our locale at that snapshot is not the most appealing (although I have quite enjoyed the dry and sunny element this week I must say), if you’re looking for something to help nuke that great big purple blob then that’s a pretty decent Wave 2 precursor pattern - Russian high, Aleutian low.

Just adding this neat graphic from Amy Butler's recent blog to help visualise the above SK.

January 20

2 hours ago, Stormeh said:

Great news NS! Congratulations

Some very wild charts this morning for late tomorrow and early Monday. I think there is a possibility of a red warning being issued tomorrow if any of the following models were to verify.

In all seriousness, let's hope this downgrades a bit - that's pretty extreme.. Amber - yep, 100mph peak gust is surely red though?

January 20

Congratulations @Northern Strath !

January 20

Ridge solution

This view vs nwp - take a different look... February aint in GH anymore, just got some 5 day regime T.rash to wander through..

January 19

46 minutes ago, chionomaniac said:

Hi all

I know I don’t post often now but I’ve just realised that this winter is the 15th anniversary of the first Strat thread. How time flies!

I remember clearly that first year and a few years after. I was convinced that the stratosphere played an important role in influencing tropospheric impacts and thought I would monitor this throughout the winter season. Well, I couldn’t have chosen a better season. That winter, we saw a record breaking split SSW of the Strat that led to almost immediate tropospheric impacts early Feb in the form of a severe easterly cold outbreak.
Despite this being obvious to me, there were a lot of sceptics that still needed to be convinced.
Yep, I didn’t get everything right back then as I was still learning like the rest of us, but now when I look back I see that we on this forum were at the forefront of leading the way - maybe not ahead of the scientists - but more often than not ahead of the meteorologists who had never been taught the relationship between the Strat and trop in a way that we take for granted now!

I guess I am proud of the work we undertook on this forum and we led the way.

I don’t often post or tweet nowadays- I consider that the groundbreaking work was done back then and that there is little to add. However, I am still keeping a keen eye on things and understand a little bit more about the Strat trop interactions than I ever did.

And I am definitely keeping an eye on the first third of Feb for something interesting to develop- initially trop based but then affecting the strat. A few things will need to fall into place first, but keep an eye out.

Thanks to all those initial Strat believers

Ed

Gonna keep this short - the word you have not written above, but applies wholly to what you helped everyone see is - Visionary.

It's an amazing legacy and all over the frontier of predictabilty.

As you say job done sir !

January 19

IDK what to say HC other than - 100% agree ! Going to be quite a shift in regime ushered in with some really active stuff, that squall line will rattle a few windows in the early hours if it barrels through as predicted.

January 19

And in comes the Atlantic blowtorch..

January 19

Ha - well just in the last throes of things before the Atlantic gets savage - we got a 'dusting' of icing sugar

Here's hoping a real deal easterly can kick in during Feb to rescue winter !

MJO has lost a little juice this week according to VP Anoms, however blocking still advertised towards the end of the month.

January 17

Tremendous posts to read - what a joy, a complete pasting and ThunderSnaw tae boot ! Wow.

Wonder how this ranks among notable potent Northerlies? Can really sense the excitement in the posts too, great stuff !!

January 16

Just now, drm said:

Good to see, this was the thinking of a few members with regards background drivers without aid of assistance from an SSW of any type,if I recall

It is technically a SSW as the u wind has reversed, but also it really isn't a SSW in terms of after-effects, as the reversal to easterly happens so briefly - returning to Westerly within 24 hrs or so.

In terms of the super dynamic effects of a decent SSW, and the much hyped impacts rightly or wrongly thereafter - I think the Scandi development could be better teleconnected to AAM changes and MJO

(The troposphere taking the lead this season vs the stratosphere leading the dance as it were..).

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