jhall
28 December 2019 22:01:57

Originally Posted by: four 



Not really, Start of March 2018 and all March 2013 were extremely cold with wind from the east.
Then there was December 2010, lots of selective memories coming out for some reason.

Several winters in the 1970s were practically snowless and generally mild.
And in the 50s, and in the 60s. And the 80s...

Winters in Western Europe are noteworthy for being generally mild considering out latitude, it is because there's a big warm Ocean on our doorstep and the prevailing wind is WSW.
/thread 



Indeed. People seem to regard a mild winter as somehow abnormal, whereas actually it's always been more normal than a cold one, at least since the end of the Little Ice Age.


For whatever reason, there seems to be a tendency for cold winters to occur in "clumps". The most recent set of cold winters brought us February 2009, winter 2009/10, December 2010, and January and March 2013. Since then, the winters have been predominantly mild, but we've had as long or longer runs of mild winters in the past, and I don't think that global warming can have changed things enough since 2013 to preclude cold winters in the future. After all, we have February and March 2018 fresh in the memory, which produced the March day with the lowest CET maximum on record for the month, showing that extreme cold is still possible.


Cranleigh, Surrey
Whether Idle
28 December 2019 22:10:06

...and back to the models...


ECM continuing in positive NAO territory here in the medium term -



 


Dover, 5m asl. Half a mile from the south coast.
doctormog
28 December 2019 22:17:57

And for a short while a couple of days prior to that

https://www.wetterzentrale.de/maps/GFSOPEU18_144_2.png



tallyho_83
28 December 2019 23:34:07

How did I guess that the 18z Op was a cold outlier compared to it's ENS:


 



Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
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Gandalf The White
28 December 2019 23:43:15

Originally Posted by: tallyho_83 


How did I guess that the 18z Op was a cold outlier compared to it's ENS:


 




It was not an outlier. That's when there is absolutely no support for the operational run in the ensembles: you can see from the chart that it was never out on it's own, just amongst the coldest options at the end of the run.


The control was also cold at the end but via an easterly, i.e. A completely different evolution to the Op.


Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


Chunky Pea
29 December 2019 00:44:19

Originally Posted by: doctormog 


And for a short while a couple of days prior to that

https://www.wetterzentrale.de/maps/GFSOPEU18_144_2.png




A lot of cold is set to be 'bottled up' over the southern regions of the Arctic (if that makes sense) over the next week or so, so a forecast chart like that would not surprise me if this pent up cold was to leak out a bit. 


Current Conditions
https://t.ly/MEYqg 


"You don't have to know anything to have an opinion"
--Roger P, 12/Oct/2022
DEW
  • DEW
  • Advanced Member
29 December 2019 07:41:55

Some weak movement of cold air westwards from Siberia but the air is well above normal temp so no excitement there. wxmaps.org/pix/temp4


Jetstream looping around in such a way as to encourage HP over UK until Sun 5th then resuming NW to SE over/S of the UK and very strong by Fri 10th so more stormy weather? https://www.netweather.tv/charts-and-data/jetstream - matches the forecast for a dry week followed by a distinctly wet one http://www.wxmaps.org/pix/prec4


GFS maintains HP to the SE of the UK until Thu 2nd Jan, then a mini-breakdown with some cold(-ish!) air coming south but the HP resuming, this time to the SW. Finally, to match the above, a deep and cold depression appears on Fri 10th (960mb over the Borders*) though after an unsettled few days the HP re-asserts itself.


ECM has less of a breakdown after 2nd Jan, but then rebuilds the HP with its centre over Poland


GEFS temps  well ageed on a drop to below seasonal average, even below a degree or two zero in the S, on Jan 4th, recovering to 3-4C above and the mean of the runs declining to near average by the 14th. By this time there are quite a few really cold runs to sustain the cold optimists. Very dry in the S though some activity 10th and after, a bit earlier in Scotland (doesn't seem to have picked up on the depth of the storm on the 10th).


10th Jan seems to be the day to watch but plenty could happen before then..


* Terminology - Scotland has Borders, Wales has Marches; I think our friends in the north might consider 'Scottish' Borders a bit Anglo-centric but correct me if I'm wrong 


 


War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Ally Pally Snowman
29 December 2019 07:46:24

P1 GEFS is fun this morning 47 style Snowmegeddon.  


Meanwhile in the mild reality somewhere in Scotland could break the date record today 16.1c to beat.


 


Bishop's Stortford 85m ASL.
DEW
  • DEW
  • Advanced Member
29 December 2019 07:52:30

Originally Posted by: Ally Pally Snowman 


P1 GEFS is fun this morning 47 style Snowmegeddon.  


Meanwhile in the mild reality somewhere in Scotland could break the date record today 16.1c to beat. 



Not on the TWO chart viewer out to T+180


War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Brian Gaze
29 December 2019 07:55:19

GFS 00z op was one of the colder runs later on.  



Brian Gaze
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Ally Pally Snowman
29 December 2019 08:03:54

Originally Posted by: DEW 


 


Not on the TWO chart viewer out to T+180



 


Have a look on wetterzentrale 240h +. 


Bishop's Stortford 85m ASL.
Brian Gaze
29 December 2019 08:08:28

Originally Posted by: Ally Pally Snowman 


 


 


Have a look on wetterzentrale 240h +. 



TWO link is 


https://www.theweatheroutlook.com/twodata/gefs.aspx?run=na&charthour=240&chartname=500mb&chartregion=na-region&p=1&charttag=500hPa%20GPDM


 


Brian Gaze
Berkhamsted
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Ally Pally Snowman
29 December 2019 08:10:39

Originally Posted by: Brian Gaze 


 


TWO link is 


https://www.theweatheroutlook.com/twodata/gefs.aspx?run=na&charthour=240&chartname=500mb&chartregion=na-region&p=1&charttag=500hPa%20GPDM


 



 


Yes ends in spectacular style all Coldies should take a look.


 


Bishop's Stortford 85m ASL.
Brian Gaze
29 December 2019 08:15:18

Originally Posted by: Ally Pally Snowman 


P1 GEFS is fun this morning 47 style Snowmegeddon.  


Meanwhile in the mild reality somewhere in Scotland could break the date record today 16.1c to beat.


 



It has already gone. 16.2C was recorded at Achnagart at 01:00 today. Astonishing. 


Brian Gaze
Berkhamsted
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Rob K
29 December 2019 08:19:42

Originally Posted by: Brian Gaze 


 


It has already gone. 16.2C was recorded at Achnagart at 01:00 today. Astonishing. 



Does that count for today or yesterday? I can never remember how the official temperatures are assigned for the overnight period!


IIRC the 9am-9am max gets assigned to the first day of the period but the min gets assigned to the second day, is that right?


Yateley, NE Hampshire, 73m asl
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JACKO4EVER
29 December 2019 08:23:28

Originally Posted by: Brian Gaze 


 


It has already gone. 16.2C was recorded at Achnagart at 01:00 today. Astonishing. 



thats truly astonishing. 
meanwhile some fun and games in FI, otherwise as you were in the reliable. 


 

Brian Gaze
29 December 2019 08:33:04

Originally Posted by: Rob K 


 


Does that count for today or yesterday? I can never remember how the official temperatures are assigned for the overnight period!


IIRC the 9am-9am max gets assigned to the first day of the period but the min gets assigned to the second day, is that right?



You could be we'll be right. I can't remember either. 


Brian Gaze
Berkhamsted
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doctormog
29 December 2019 08:34:48
Blink and you’ll miss it but the GFS op run has 515dam air here at 138hr on the 00z output, compared with the remarkable 556dam today!
DEW
  • DEW
  • Advanced Member
29 December 2019 08:51:37

Originally Posted by: Ally Pally Snowman 


 


 


Yes ends in spectacular style all Coldies should take a look.


 



OK,as above, seems indeed that the 10th Jan is the date when things might kick off


War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Lionel Hutz
29 December 2019 09:18:31

Originally Posted by: DEW 


 


OK,as above, seems indeed that the 10th Jan is the date when things might kick off



Correct me if I'm wrong but sadly that outcome seems to be a real outlier on the ensembles. Nice eye candy though.


Lionel Hutz
Nr.Waterford , S E Ireland
68m ASL



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