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Model output discussion - Post SSW - Will it turn cold?


Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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2 minutes ago, Neilsouth said:

Am I reading this right that the cold has been delayed yet again? Was weekend, then Monday now Tuesday?

Neil for us it's Wednesday night when the cold uppers move in they only continue dropping thereafter. Snowfall perhaps after Sunday and throughout following week hopefully Herne bay Thanet area will get loads it's about time 

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Cold - Yes Instability - Yes Prolonged - Yes I just wet myself - Yes!

I quite often agree with your sort of sentiment, as I'm one who opts to look at the most likely solution to fit the signals rather than the preferred one But, equally impartially and with intended

Sorry, I just thought I’d walked into the moans threa.. oh wait. <passes around a big bag of grips> No sooner do we get a cold spell within sight it astonishes me that time and time again some p

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9 minutes ago, Midlands Ice Age said:

 

Now I will try and put some figures on how rare this sequence might be.

 

Assume a beasterly occurs once in every 5 to 10 years.

Assume that a channel low might occur in a 1 in 10 chance (in bitterly cold air)..

Assume that a switch to a polar vortex low occurs as a 1 in 30 years occurrence ....

Note the above is roughly the figures for the UK.

 

Now normally the 'odds' are calculated by multiplying the numbers together.

 

 

This is not appropriate and misleading.  These are not independent variables, and will show some significant correlation - based in particular on the underlying synoptic pattern of high latitude blocking, so it is NOT appropriate to multiply them together.  The true odds of these things happening are much shorter than the 2250/1 you quote.

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4 minutes ago, Neilsouth said:

Am I reading this right that the cold has been delayed yet again? Was weekend, then Monday now Tuesday?

No, Sunday has been the transition day for the colder uppers for a good few days now, but there will always variability in the output.

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5 minutes ago, Mike Poole said:

 odf from This is not appropriate and misleading.  These are not independent variables, and will show some significant correlation - based in particular on the underlying synoptic pattern of high latitude blocking, so it is NOT appropriate to multiply them together.  The true odds of these things happening are much shorter than the 2250/1 you quote.

Mike...

If you read on I have stated that exactly,    and attempted to make an allowance for it, of from 200 to 500%!

 

MIA

Edited by Midlands Ice Age
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The 6z now developing a bigger cold pool as the cold flow hasn't been shut off in Siberia as was on the 0z, like the 0z ECM. Also Much like the ECM this morning it's short term 'pain' long term gain.

 

Nothing to worry about, just normal run to run variations.

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1 minute ago, Weathizard said:

The 6z now developing a bigger cold pool as the cold flow hasn't been shut off in Siberia as was on the 0z, much like the ECM. Much like the ECM this morning it's short term 'pain' long term gain.

 

Nothing to worry about, just normal run to run variations.

Its not even short term pain thats the beauty of it!!bar a 6 hour delay its brilliant throughout!!

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5 minutes ago, Catacol said:

As Steve has correctly said in an earlier post - we will need until Thursday before we can be 100% certain that the cold, as modelled, is going to hit. But I think we are 90% there, and my fears overly a potential southerly track are all but gone. There's barely a sniff of a southerly trajectory in any of the output, and as the models resolve the collapse of the Canadian vortex the HP is being moved into the most favourable of all positions.

I don't want to say - "unbelievable" - yet again... but somehow it does need to be said. BBC at 0750 did something I don't think I have ever seen before, and that was put up a graphic for next Tuesday illustrating daytime max temps at below freezing. 7 days away? Every model in line, MetO in line and all we are now left to talk about is snow depth.

Concerns over power, infrastructure, the old/homeless and general safety become real in this circumstance now. I hope the Met don't wait too long to put warnings out (its amazing how many people here at work have looked at me strangely when I said it was going to be extremely cold and possibly snow next week) and that everyone enjoys what comes AND tries to help those who will need it. Sleeping rough under -15 850s and heavy snow is not a combination to celebrate.

But on the positive side - wow. Back end of next week for the SW to see real fun as per this chart

ECM1-240.GIF?20-12

or this one

gem-0-222.png?00

or this one (so many to choose from!!)

gfs-0-252.png?0

but starting Sunday I will sit back and enjoy watching images of the east coast come under fire, and prepare for the best spell of weather since 1991/96 and quite possibly a spell that will outdo both of those, outdo 1987 for longevity and match 47/63 for severity. Big claims - but the model runs support such interpretation.

and yet the apps are still showing 2-4 degrees next week

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4 minutes ago, Catacol said:
5 minutes ago, Catacol said:

but starting Sunday I will sit back and enjoy watching images of the east coast come under fire, and prepare for the best spell of weather since 1991/96 and quite possibly a spell that will outdo both of those, outdo 1987 for longevity and match 47/63 for severity. Big claims - but the model runs support such interpretation.

Sorry cat but that last para belongs in the ramping thread because the available evidence just doesn’t support those claims, especially the 47/63 part.

I also need to go back and check Dec 2010 and parts of 12/13. 

 

 

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h850t850eu.png h850t850eu.png

00z v 06z. 

12 hours longer for the high to re-orientate means 12 hours more time for it to gather up deep cold from Siberia/C. Asia.

This to me is what the 00z ECM would have been had it not developed so many miniature disturbances in the deep cold flow while it was still some way east of us.

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Some posts have had to go, Please only discussion on what the Model Outputs are showing in here, And use the banter ramp thread or cold spell thread for everything else to keep the thread clean and constructive during these busy times.

Thanks as always, Please continue ☺

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