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Early run up to Winter 2020/2021 discussion


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Pure guesswork predictions for Dublin (tmean, rainfall, sun). Though La Nina has some saying in them - I would have gone colder for Feb otherwise.

Dec - Sunnier than avg, cool and dry. (4C, 30mm, 65 hrs)

Jan - Wet with avg sun and temps. (5C, 80mm, 60 hrs)

Feb - Very dull (dullest since 1993), wet and mild. Not Feb 2020 standards but still stormy. (6C, 80mm, 50 hrs)

Have had 3 consecutive sunny Februaries (all 100 hrs+) so due a dull one and 2 dry Januaries too. 

Edited by BruenSryan
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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

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my expectations have slightly lowered reading about the differences between CP and EP La Ninas for Europe as we see ENSO 1.2 warming and 3.4 cooling. Modoki La Nina as was mentioned by @Snowy Hibbo almost beyond belief difference for us

FB_IMG_1600780684569.jpg

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1 hour ago, jules216 said:

my expectations have slightly lowered reading about the differences between CP and EP La Ninas for Europe as we see ENSO 1.2 warming and 3.4 cooling. Modoki La Nina as was mentioned by @Snowy Hibbo almost beyond belief difference for us

FB_IMG_1600780684569.jpg

I suspect this is a central based La nina. 

2cat_20200901_sst_months46_global_deter_public.png

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Dutch weer.nl published a couple of days ago their vision. On the background they get advise by World Climate Service.

https://www.weer.nl/nieuws/2020/winterverwachting-1e-versie-vroege-winter

Altough it's in Dutch, I presume you can read it or use translate google. https://translate.google.com/?hl=nl

The writer makes a reference to december 2010. 

1) much depends on the development of La Nina

2) there is chance the warmth in the north pacific will lessen 

Edited by sebastiaan1973
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8 minutes ago, sebastiaan1973 said:

I suspect this is a central based La nina. 

2cat_20200901_sst_months46_global_deter_public.png

Yes very much like CP Nina. Also the 500mb height anomalies from UKMO reflect CP La Nina winter anomalies. The NAO response is strogest in Jan/Feb with a very + look on CP Nina composite anomalies

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48 minutes ago, jules216 said:

Yes very much like CP Nina. Also the 500mb height anomalies from UKMO reflect CP La Nina winter anomalies. The NAO response is strogest in Jan/Feb with a very + look on CP Nina composite anomalies

So a front-loaded winter could be on the cards then?

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I'm pretty encouraged this year for cold prospects tbh. 

Some good signs but also against a colder winter than last year but I think it will be a more meandering(coming out of solar minimum) jet imo rather than flat,west to east.

 

Edited by joggs
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16 hours ago, Mr_Moreau said:

So a front-loaded winter could be on the cards then?

You never know,but November could be the most interesting month of the cold season, I would say now there is  EP Nina profile but cold waters will surface around region 3.4 to make it look like CP Nina unfortunately. It is hardly believable that there is such a dramatically different NAO response to those two Ninas. In November,well at least it the beginning  both exhibit a slight -NAO trend. The last winters have been so desperate,that I am almost ready to take a cold November and some part of December as a success, even though I am now located in central Europe which can have a good winter without -NAO support (2016/17)

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19 hours ago, jules216 said:

my expectations have slightly lowered reading about the differences between CP and EP La Ninas for Europe as we see ENSO 1.2 warming and 3.4 cooling. Modoki La Nina as was mentioned by @Snowy Hibbo almost beyond belief difference for us

FB_IMG_1600780684569.jpg

Jules, which article is this ? Thanks!

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I have to say for my IMBY perspective some of the most notable snow/winter events I remember from recent past were achieved under +NAO and also CP La Nina, for example blizzard of February 1999 and November 1999, also January 2017 coldest since 1987, all CP NInas with lack of -NAO. NAO blocking of course helps western Europe and some parts of central Europe,but more outside my preferred region. I badly need Mediterranean low pressure activity then anything else, or even Black Sea low. Some charts from most memorable snow events IMBY 

archives-1999-2-12-12-0.png

archives-1999-11-20-0-0.png

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19 minutes ago, jules216 said:

I have to say for my IMBY perspective some of the most notable snow/winter events I remember from recent past were achieved under +NAO and also CP La Nina, for example blizzard of February 1999 and November 1999, also January 2017 coldest since 1987, all CP NInas with lack of -NAO. NAO blocking of course helps western Europe and some parts of central Europe,but more outside my preferred region. I badly need Mediterranean low pressure activity then anything else, or even Black Sea low. Some charts from most memorable snow events IMBY 

archives-1999-2-12-12-0.png

archives-1999-11-20-0-0.png

The first of these snowy spells in February 1999 hit us in the UK first with cold and sometimes snowy weather from 7th to 11th February and was part of a generally mild UK winter but with several cold shots from the Arctic which nearly all delivered some snow in them

The second one of these in November 1999 did little in the UK at all, sleet and hail at best and this led onto what was a poor winter overall for cold. In fact the only snow I remember was a bit of wet snow from showers early December before the two main colder episodes between 13th December and 21st December. After that I saw no more snow again until a brief cold snap early April 2000

Also +NAO can also be good for SE Europe and the Middle East for cold as the blocking high sets up in central Europe giving the UK and NW Europe an Atlantic onslaught and mild weather whilst SE Europe sees cold pooling out of Russia and Siberia.

-NAO usually works the opposite way with the block towards Iceland and Greenland giving W and NW Europe the cold and the low pressure sets up over central Europe pulling mild air up into SE Europe and Russia

Edited by SqueakheartLW
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CFS monthly anomaly chart analysis

This data is based on the daily updates to the monthly CFS anomaly chart on the weather outlook website. Here is the direct link to their charts page if you wish to have a look

https://www.theweatheroutlook.com/twodata/datmdlout.aspx

Just select CFS when you get there and you can view 500mb, 850mb and 1000mb heights as well as for the next few months ahead too.

I know this is all based on just 1 model, the CFS but some clear trends have already appeared during the summer. Now the equinox has passed I have ended this particular assessment for the summer period and will now concentrate on 2 week CFS blocks between now and the start of December to get a better idea of what the trends for winter are now we are much closer to it.

CFS 00Z 500hpa anomalies    Start 06/07/2020    Last 22/09/2020

Temps          Nov    Dec    Jan    Feb    Mar                    Precip          Nov    Dec    Jan    Feb    Mar

V Mild             0        1        1        1         0                      V Dry             0         0       3         2        0

Mild               23      16      15      15       15                     Dry                25       37     14       16      19

Average        26      24       29      30       43                    Average        34       24      31       20      26

Cold              30      38       33      28       18                    Wet               19       18      31       35      29

V Cold            0        0         2        4         3                    V Wet             1         0        1         5        5

          temps.thumb.jpg.1321dffa771b00520a2cef02ada43f78.jpg             precip.thumb.jpg.898f44d29ad02bf5277ac67110a04951.jpg

I have included my own generated line charts to make the various options easier to see

The clear CFS trends during summer for the November to March period came out with the following trends

November 2020

Temperatures - Close to or slightly below normal, probably a CET anomaly between 0.0C and -0.5C
Precipitation - Close to average overall with a slightly drier bias more likely

December 2020

Temperatures - Below normal temperatures predicted, probably a CET anomaly between -0.5C and -1.0C
Precipitation - Drier than average overall

January 2021

Temperatures - Slightly below normal temperatures predicted, probably a CET anomaly between -0.2C and -0.8C but with a small chance of something colder still at an anomaly of -1.0C or lower
Precipitation - Above normal precipitation predicted but not excessively so. Could be some snow events with the colder than average temps predicted too

February 2021

Temperatures - Similar to January 2021 with anomalies between -0.2C and -0.8C but like January a chance of something even colder than this at an anomaly of -1.0C or less
Precipitation - Wetter than average and a small chance it could be a very wet month. A real snow maker here if the colder anomalies come off too.

March 2021

Temperatures - Average temperatures expected with anomalies between -0.2C and +0.2C most likely
Precipitation - Slightly above normal precipitation predicted but no where near as wet as February 2021

Overall November to March period
Temperatures - Generally slightly below average, especially in January and February 2021. Overall anomaly for the period likely to be between -0.2C and -0.8C
Precipitation - Close to average overall with a drier start and becoming wetter later on

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21 minutes ago, SqueakheartLW said:

The first of these snowy spells in February 1999 hit us in the UK first with cold and sometimes snowy weather from 7th to 11th February and was part of a generally mild UK winter but with several cold shots from the Arctic which nearly all delivered some snow in them

The second one of these in November 1999 did little in the UK at all, sleet and hail at best and this led onto what was a poor winter overall for cold. In fact the only snow I remember was a bit of wet snow from showers early December before the two main colder episodes between 13th December and 21st December. After that I saw no more snow again until a brief cold snap early April 2000

Also +NAO can also be good for SE Europe and the Middle East for cold as the blocking high sets up in central Europe giving the UK and NW Europe an Atlantic onslaught and mild weather whilst SE Europe sees cold pooling out of Russia and Siberia.

-NAO usually works the opposite way with the block towards Iceland and Greenland giving W and NW Europe the cold and the low pressure sets up over central Europe pulling mild air up into SE Europe and Russia

February 1999 blizzards started exactly on the 12th and delivered most amount of snow in recent memory. That season had a very frosty November and large parts of December,then nothing in the hearth of winter before the February blizzards. Also November 1999 was cold in second half. Quite a few La Nina winters deliver very early on and then have a break before active February, interesting.

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4 hours ago, jules216 said:

I badly need Mediterranean low pressure activity then anything else, or even Black Sea low. 

You and me both, jules. But who knows how will it all come together in this new climate we are living in. I feel like analogues from the past provide less and less guidance in this warming world.

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Some form of Ural high pressure/blocking is still evident in the extended forecast period, would be great if it can persist as long as possible as according to recent study it is much better correlated with NAO blocking in Dec/Jan then Siberian snow cover extend. See abstract of study and extended GEFS anomaly  

Capture.PNG

gensnh-31-5-384.png

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On 23/09/2020 at 10:14, jules216 said:

You never know,but November could be the most interesting month of the cold season, I would say now there is  EP Nina profile but cold waters will surface around region 3.4 to make it look like CP Nina unfortunately. It is hardly believable that there is such a dramatically different NAO response to those two Ninas. In November,well at least it the beginning  both exhibit a slight -NAO trend. The last winters have been so desperate,that I am almost ready to take a cold November and some part of December as a success, even though I am now located in central Europe which can have a good winter without -NAO support (2016/17)

 

I would say, we have the coldest deeper seawater in the eastern Pacific. In a CP the core of the cold water is west of 160 W.

UyhJ9Zp (1).png

jswYGa4 (1).png

Edited by sebastiaan1973
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https://twitter.com/MattHugo81/status/1308668994094796800

 

East based #LaNina really getting going now, all eyes on this as one of the 'drivers' for potential influences on the winter pattern, a weak to moderate Nina potentially aiding in the risk of colder weather early in the winter. Some signs for a -ve IOD getting going too...

Edited by sebastiaan1973
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45 minutes ago, sebastiaan1973 said:

I would say, we have the coldest deeper seawater in the eastern Pacific. In a CP the core of the cold water is west of 160 W.

UyhJ9Zp (1).png

jswYGa4 (1).png

This one looks a bit borderline between the EP and CP event. Will more likely get too strong or push into CP if we keep on posting SOI figures like we are doing on a regular basis at the moment

Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution

24 Sep 2020 14.26                        23 Sep 2020  7.43                          22 Sep 2020  12.72                       21 Sep 2020  14.32

20 Sep 2020  13.73                       19 Sep 2020  10.28                        18 Sep 2020  12.84

AVERAGE SOI 18TH TO 24TH SEP: 12.23

Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution

17 Sep 2020  17.89                       16 Sep 2020  14.09                        15 Sep 2020  7.67                          14 Sep 2020  2.14

13 Sep 2020  3.03                         12 Sep 2020  6.30                          11 Sep 2020  1.25

AVERAGE SOI 11TH TO 17TH SEP: 7.48

Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution

10 Sep 2020  0.12                         9 Sep 2020    -6.00                         8 Sep 2020    -2.61                         7 Sep 2020    13.31

6 Sep 2020    12.18                       5 Sep 2020    8.56                          4 Sep 2020    6.78

AVERAGE SOI 4TH TO 10TH SEP: 4.62

Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution     Date              Daily Contribution

3 Sep 2020    12.60                       2 Sep 2020    20.15                        1 Sep 2020    18.66                        31 Aug 2020  21.36

30 Aug 2020  22.70                       29 Aug 2020  18.63                        28 Aug 2020  9.65

AVERAGE SOI 28TH AUG to 3RD SEP: 17.68

I think in order to stop us from getting a CP La Nina we really need to post a few more negative SOI numbers to keep the La Nina focused in the EP to increase our chances of a colder winter and to also prevent the La Nina getting too strong

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59 minutes ago, sebastiaan1973 said:

I would say, we have the coldest deeper seawater in the eastern Pacific. In a CP the core of the cold water is west of 160 W.

UyhJ9Zp (1).png

jswYGa4 (1).png

Some seasonal models have it shifted towards west, like UKMO and it was also mentioned by @Snowy Hibbo in his initial winter blog. Right now of course it is very much like EP La Nina without doubt, as you can see on my attached images comparing current SST with both type of Ninas. @sebastiaan1973 intriguing stuff with the chaotic QBO,up for grabs Nina strength and positioning, IOD neither here or there,extra aerosol from wildfires in upper atomosphere, new solar cycle beginning which should correlate with more blocking also waters of the east coast of USA have cooled - another good news I think, now hints of Ural high pressuring early season vortex formation. I feel a lot more excitement then  this time last year for sure.

e7RefBvA.jpg

FN2f1eCX.jpg

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Looking ahead in to October now comparing with good analog years, so far I like 2005 the best. It also had a lot of named Atlantic storms, it was weak emerging La Nina after couple of weak Nino years, also had coming in to winter easterly QBO at lower levels and westerly at upper levels of stratosphere, this year might be similar at the top and very bottom of stratosphere.  Going by what models suggest the anomalies are kind of similar with occasional differences like always. We might disconnect more from that analog if Nina goes too far negative. 

Capture.PNG

e95qAmwHq8.png

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28 minutes ago, jules216 said:

Looking ahead in to October now comparing with good analog years, so far I like 2005 the best. It also had a lot of named Atlantic storms, it was weak emerging La Nina after couple of weak Nino years, also had coming in to winter easterly QBO at lower levels and westerly at upper levels of stratosphere, this year might be similar at the top and very bottom of stratosphere.  Going by what models suggest the anomalies are kind of similar with occasional differences like always. We might disconnect more from that analog if Nina goes too far negative. 

Capture.PNG

e95qAmwHq8.png

I noticed a nice Ural high on that October 2020 chart, good news if you want the polar vortex to struggle to get going with nice upwards wave activity impacting it from below, combine that with low solar activity and a current EP Nina then the vortex will very likely remain weaker than average into October 2020

October 2005 was a very mild month overall which continued on into the first half of November 2005 before a big flip took place and much colder settled conditions arrived before our first cold northerly shot near the end of the month. Was a taste of what could have been if winter 2005/06 had delivered on the potential it had.

Many factors were pointing to a colder winter that year but it didn't really come together until the end of February and into the March when the coldest CET anomalies on average came for the season. The only other really cold spell was just after Christmas 2005. Our deepest snow in N Lincs came from a frontal band in early March 2006.

For a Nina winter it was unusually back loaded, maybe due to the SSW that happened in January 2006

Edited by SqueakheartLW
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