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Early run up to Winter 2020/2021 discussion


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On 19/09/2020 at 14:43, Froze were the Days said:

No silly stories in the papers (Express) or musings from Joe Bastardi about the impending coldest winter in 30 years or 'snowmaggedon' to come as of yet which usually occurs sometime in September. Not sure whether there was any garbage journalism last Autumn about the 2019/20?

Piers Corbyn's too busy spouting Covid conspiracy theories to get his annual snowmageddon article into the Daily Express

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Just a post for any newbies who have just joined. Musings and posts you WILL regularly come across in the months ahead and going into a winter: 1. October: 'This winter will be front loaded or ba

Says it up top 02/10.   Hot off the press Met office seasonal update OCT 20 for NDJ Considerable changes in favour of a colder Front loaded winter. Gone is the negative low pressur

Last time Liverpool lost 7-2 was apparently in 1962/3. Lets hope the weather remembers

Posted Images

20 minutes ago, sebastiaan1973 said:

November anomaly charts in La Nina years since 2005.

UczMPB81xg.png

november 2007.png

nov 2008.png

eRkx0_VjhP.png

november 2011.png

a9zHT7h0IO.png

Yes i noted myself the signal for a blocked October over/east of the UK, ridging near Greenland in November and a little west of the UK in December. The signal does not actually change that much in Q4 whether weak or strong either. 

Granted i only use first year analogues since 1950 and filtered out +PDO years.

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I was about to enquire, what, if any, is the interest in Ural blocking, but had a quick search and found 

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL082097

Ural Blocking as a Driver of Early‐Winter Stratospheric Warmings

Not sure I'm any wiser... 

There's a bit of chatter on social media by some of the usual suspects, suggesting I can be potentially disruptive to the PV

Another piece of the puzzle or a dead cat? 

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Griff. this is an article about november

This study explores the early‐winter atmospheric response to Ural blocking anomalies in November, using a nudging technique to constrain the temperature and dynamics in a high‐top atmospheric model. Persistent Ural blocking anomalies in November are associated with a warm Arctic/cold Siberia pattern and increased upward planetary waves entering the stratosphere, leading to a warming of the polar vortex. This stratospheric response then propagates in the troposphere, leading to increased occurrence of the negative North Atlantic Oscillation in December and January. In contrast, simulations with perturbed Barents‐Kara sea ice and Siberian snow in November do not reproduce a significant atmospheric response. In simulations including a slab ocean, the Ural blocking induces Barents‐Kara sea ice and Siberia snow anomalies that resemble composite analyses from observations. These results highlight Ural blocking variability in November as a robust driver of early‐winter stratospheric warming while questioning causality between sea ice/snow and Ural blocking anomalies.

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Thanks @sebastiaan1973  et al!

Nice and clear explanation. 

The usual suspects have promised me cold and snow at various times over the last winter only to disappoint... Perhaps it should be he who's name we don't speak? 😂 

 

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https://www.researchgate.net/publication/335465874_Towards_understanding_the_global_and_regional_climatic_impacts_of_Modoki_magnitude

Earlier studies suggest that the frequency and the strength of ENSO Modoki events increased considerably since last few decades (1970-2010) resulting in a need to revisit the climatic impacts of varying magnitude of ENSO Modoki. Hence, to better understand the impact of ENSO Modoki amplitude over the tropical and extra-tropical regions, especially in the Pacific, Asian and African regions, we conducted ENSO Modoki sensitivity experiments using ICTP-AGCM (SPEEDY). One of the main interests of this study is to see how ICTP-AGCM can reproduce teleconnections induced by ENSO Modoki events and how sensitive is the global and regional climate to ENSO Modoki strength. SPEEDY model qualitatively reproduces the impact of ENSO Modoki over the Pacific, Atlantic, North and South America and African regions very well. However, it underestimates ENSO Modoki-induced teleconnection patterns and associated changes in South Asia, particularly in the Indian region. This study suggests a nonlinear climatic response to increased magnitude of ENSO Modoki. Our results reveal that like conventional ENSO, ENSO Modoki also induces considerable impact over North Pacific (Atlantic) region and initiates strong PNA (NAO) like response. ENSO Modoki-induced negative/positive NAO-like response and associated changes in Southern Europe and North Africa region get significantly strong following increased intensity of El Niño/La Niña Modoki in the boreal winter. We further find that ENSO Modoki magnitude significantly impacts tropical and high latitude circulation cells. The positive phase of ENSO (El Niño) overall strengthens Hadley Cell and a reverse is true for La Niña phase. ENSO Modoki-induced strengthening and weakening of Hadley Cell induce significant impact over South Asian and African ITCZ convective regions through modification of ITCZ/monsoon circulation system.

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Not sure which thread to post these charts in so this thread will do, just looked through the CFS and I bet you will all be happy if something like this was to happen during Winter 20/21...

cfs-0-3750.thumb.png.229d747a808197ca38b077acdb5e4a71.png   cfs-2-3750.thumb.png.e84e5580715f46dad5dc8fab49203aa9.png

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4 hours ago, Zak M said:

Not sure which thread to post these charts in so this thread will do, just looked through the CFS and I bet you will all be happy if something like this was to happen during Winter 20/21...

cfs-0-3750.thumb.png.229d747a808197ca38b077acdb5e4a71.png   cfs-2-3750.thumb.png.e84e5580715f46dad5dc8fab49203aa9.png

Not a million miles away from the modelling late this week ...

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1 hour ago, Steve Murr said:

Continued blocking over Northern Europe retrogressing towards Greenland allows the AO to tank to Sub -3

A long way to challenge the record of -5 which was Oct 2002...

75296091-4821-4E5F-B629-2DC0F46AB9B8.thumb.jpeg.da6875c0bfc88384fe860ded8f10794a.jpeg

Whats the net fallout?

The jet straddling the UK > Wet windy & chilly!

What kind of winter followed the record -5 in October 2002🤔

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7 minutes ago, Sunny76 said:

I don’t think we will see anything wintry until after Christmas. Then a very cold January and the coldest one for many years.

I think it'll be the opposite way round. La Nina winters tend to be front loaded favouring a cold November / December at times with a signal for milder than average conditions later in the winter.

We also have warmer than average SSTs in the tropical Atlantic too. This may well favour lower pressure over the Azores but will we see lower pressure over southern Europe too?

We shall see, I have a hunch that December will be colder than average with January transitional, February and March mild.

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9 hours ago, Penicuikblizzard said:

What kind of winter followed the record -5 in October 2002🤔

December 2002 was mild overall but January and February 2003 weren't too far from average, at least for the CET. Depended on location what you thought of that winter, London had snow in early January and there was the M11 snow fiasco that stranded many drivers at the end of the month. Only a couple of days or so before it was exceptionally mild, the record maximum temperature for January was equalled. Personally, it was typical of those winters of that period of 1997-98-to 2007-2008, not particularly snowy with only short cold periods

Edited by Weather-history
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10 hours ago, Quicksilver1989 said:

I think it'll be the opposite way round. La Nina winters tend to be front loaded favouring a cold November / December at times with a signal for milder than average conditions later in the winter.

We also have warmer than average SSTs in the tropical Atlantic too. This may well favour lower pressure over the Azores but will we see lower pressure over southern Europe too?

We shall see, I have a hunch that December will be colder than average with January transitional, February and March mild.

I think front loaded winters are better. You get the cold in nice and early when the days are short and the sun is at its weakest meaning snow and frost are much more likely to stick around throughout daylight hours and if the pattern gets locked in enough it can take some shifting.

Also with a front loaded winter there always remains the chance of a SSW which can then add a back loaded element to the winter too.

2017/18 was a good example of this with some early snow chances and events late November 2017 into December 2017 before the milder January and then the SSW happened that delivered Beast from the East at end of February 2018 and then Beast from the East part 2 in mid March 2018

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11 hours ago, Quicksilver1989 said:

I think it'll be the opposite way round. La Nina winters tend to be front loaded favouring a cold November / December at times with a signal for milder than average conditions later in the winter.

We also have warmer than average SSTs in the tropical Atlantic too. This may well favour lower pressure over the Azores but will we see lower pressure over southern Europe too?

We shall see, I have a hunch that December will be colder than average with January transitional, February and March mild.

It could go that way. One thing we can agree on, it’s going to be a colder winter than the last two.

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13 minutes ago, SqueakheartLW said:

I think front loaded winters are better. You get the cold in nice and early when the days are short and the sun is at its weakest meaning snow and frost are much more likely to stick around throughout daylight hours and if the pattern gets locked in enough it can take some shifting.

Also with a front loaded winter there always remains the chance of a SSW which can then add a back loaded element to the winter too.

2017/18 was a good example of this with some early snow chances and events late November 2017 into December 2017 before the milder January and then the SSW happened that delivered Beast from the East at end of February 2018 and then Beast from the East part 2 in mid March 2018

2017/18 was a modern classic. Nothing special, but enough variety of cold days, with a few mild days in between. It was also a dry winter from memory. 

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12 hours ago, Penicuikblizzard said:

What kind of winter followed the record -5 in October 2002🤔

I had one air frost that winter before the end of December. -0.1c.

2002 as a whole had -5 in the early hours of Jan 1, then two more that winter -0.2c, -0.1c, then the one in December.

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Morning peeps,

Oh dear oh dear I was feeling really optimistic about this coming winter untill I caught up with Gavs first seasonal model roundup which was released yesterday, after listening to It wish I hadn'tI must admit my heart sunk because it's a horror forcast from the models for us coldies. The met office are forecasting a mild or very mild winter for the northern hemisphere together with several other models. I know it's very early days and it was the first seasonal roundup but for god mighty I hope it's not a picture of things that are to come this winter. Has anyone got any idea of how reliable the met seasonal model is going by past years?

I know it's very early days and these seasonal model forecasts are to be taken by pinch of salt, but it does shock the system a bit and it does make you start doubting your hopes.

hope you all have a great Sunday

kind regards 😊

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2 minutes ago, E17boy said:

Morning peeps,

Oh dear oh dear I was feeling really optimistic about this coming winter untill I caught up with Gavs first seasonal model roundup which was released yesterday, after listening to It wish I hadn'tI must admit my heart sunk because it's a horror forcast from the models for us coldies. The met office are forecasting a mild or very mild winter for the northern hemisphere together with several other models. I know it's very early days and it was the first seasonal roundup but for god mighty I hope it's not a picture of things that are to come this winter. Has anyone got any idea of how reliable the met seasonal model is going by past years?

I know it's very early days and these seasonal model forecasts are to be taken by pinch of salt, but it does shock the system a bit and it does make you start doubting your hopes.

hope you all have a great Sunday

kind regards 😊

Have faith. He predicted a poor summer for 2018, based on the previous years ending in 8, having poor summers. 1978, 88, 98, and 2008 were all poor, but 18 bucked the trend.

I tend to look at how the weather pans out in late October and during November, which often points to a cold or mild winter.

Sometimes it’s more exciting when you just observe the change in the weather, without relying on long range forecasting.

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