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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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3 minutes ago, nick sussex said:

:D I think we need to get the UKMO onside . Early shortwave drama is unlikely that’s not the current issue as you’d see me moaning about it !

The UKMO has at least improved but I’m still mystified given the ECM mean is so close to the op how the former is still dragging its heels.

Lets hope the UKMO ditch their raw output and we see them modify that in the fax charts because that would suggest they think it’s gone rogue !

 

The milder side of the mogreps? , like the ecm was doing earlier this week with its own ensembles perhaps ?

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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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1 minute ago, Youcan'tbecirrus said:

Seeing comments Steve saying the models show a dry easterly. What are your expectations with regards how precipitation would form in this set up ? instability caused as the cold air crosses the north sea ? Re the 1987 event, I seem to recall there being a big low in Europe which led to 2 feet of snow where I live (below sea level).     

if we have -11/-12/-13 air with low heights then its a snow maker !! 

heights below 540 DAM or better

ECM 240 for london has -15c + 530 Heights & 515 DAM ( approx ) = huge snow showers

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1 minute ago, Raythan said:

The milder side of the mogreps? , like the ecm was doing earlier this week with its own ensembles perhaps ?

The UKMO do take account of the ECM op and it’s ensembles . They have been known to modify their raw output although to be honest the only people that look at those fax charts is us weather anoraks ! The main thing is the UKMO has improved from its 00 hrs run and at least it’s moving in the right direction.

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The Ecm 12z ensemble mean is another upgrade!! as means go this is superb if you want a prolonged very cold Easterly setting in with snow and severe frosts..BOOM!:D:cold-emoji:

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16 minutes ago, Fred Sykes said:

I would love to see this cold come off as much as the next person, BUT, If I had a penny for every time i've seen BOOM turn to GLOOM over the years, i'd have my own chalet in Courchevel and wouldn't need to read this thread! Caution still needed folks :)

Indeed, ! If I had a pound for every time the models were right in the outer reaches of the model output ,I would be a very poor man:rofl: BBC just mentioned Easterly winds later next week when yesterday they said the opposite:rofl: Anyway , the gfs 06z today and the 12 z , complete opposites , and the ecms 12z run tonight is a cold lovers dream, but given the high level of Shannon Entropy , nothing even five days away should be taken literally...:hi:

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1 minute ago, Youcan'tbecirrus said:

Seeing comments Steve saying the models show a dry easterly. What are your expectations with regards how precipitation would form in this set up ? instability caused as the cold air crosses the north sea ? Re the 1987 event, I seem to recall there being a big low in Europe which led to 2 feet of snow where I live (below sea level).     

We should be okay. Thing to watch is air pressure. Not an exact science but broadly below 1020 with that depth of cold and its probably boom time. 1025 - 1030 is okayish but once it gets much above that its flurries only. Deep cold doesn't always equal convection but in this case (as things stand) we would probably fair well enough.  

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Have we ever seen such a complete model divergence? The ECM and GFS ensemble suites are complete opposites it's quite remarkable, one model will never be trusted again... particularly if the ecm lets us down (as it's the cold hopeful)

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ECM ensembles have the first high pressure a little further south than is ideal for as first blast, but a large chunk are cold and dry. Still waiting to see what the more interesting part of the run looks like, think we are going to get some crazy ensemble members!

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2 minutes ago, lorenzo said:

ECM Ens are a win.. not in the same ball park as the failed 41/51 reversal either from a few years back.

Am just looking forward to the utterly manic run the 18z GFS will deliver, I thought a few days ago it would, but it will now for sure..

That is simply the only run that will eclipse tonight 12z - truly stunning ECM, it's late to the party, but in the big scheme of things the facts are - it is the best hi lid model, it's the best verifying model, it's the best model to 144, and, its the best model...

So, all in a massive plus for those on the hunt for cold, the vortex split dynamics have telegraphed the supply of cold, the trick is in the development of the block. Tonight sees the ECM move to resolve the split energy and recognise the break, perhaps to the outer envelope  or extreme cold solution tonight - but it is what one could expect to see given the stratospheric chasm and nuances into 150 hPA.

Further to this, regarding the initial QTR - the strat evolution plots and the dead drop bounce on u are mental to resolve. Probably the cause of the chaos of the last 48 hrs.

We know the u is in reversal , yet we see the deceleration on H Attard plots and acceleration again, no model will resolve this, until it plays through. 

Tonights ECM I think has seen that initial trop bounce, u wind rebound and play through and therefore it's higher top and resolution latch onto the 'truth' and the reality of the split hence the that x3 ecm run.

Just think now the ECM has 'got' this... what lies ahead for the other models...

Now that's what you call a RAMP:D

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I'm fascinated by this potential cold spell.  I (like many others I'm sure) have been following the model output since the SSW was forecast at the beginning of the month, and by today found myself giving frame by frame commentary in the MOD thread as the epic ECM 12z rolled out (not usual behaviour for me!). 

After today's 12z output and the Met Office views, I'm confident that something interesting is afoot.  But what?  There is in my opinion now say a 40% chance of a quite significant cold outbreak - and given it will stretch into March if it happens, it could make March 2013 look balmy! 

Very interesting times,let's see how it plays out.

(mods - meant to put this one in the cold spell thread, not sure why it ended up in here (beer possibly responsible!) please move if it's off topic.)

Edited by Mike Poole
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3 hours ago, carinthian said:

Just a further thought to the above, forecasts this evening from the computer models now all now showing cold outlook on the agenda. Now SSW has taken place, it sometimes takes up to 10 days for the full cold effect to take place. Our service provider think 70 % certainty now , which is in the high category . Of course timing and depth of cold is still on the cards. Still could switch quickly ( with 96h time ) or more likely Day 6 into the freezer. Fax viewing is now the best option to watch the developing cold and speed of advection. Short wave positioning to the East could also impact greatly as to source of cold ( ie) Arctic C or Continental flow ).

 C

Well, ECM going for Arctic Continental flow of the brutal kind into Central Europe. Don't think I will have experienced such cold as this if it came off !

 C

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6 minutes ago, Daniel Smith said:

Here we go again then. 

ICON an improvement at 66hrs, shortwave further South, Easterly flow developing a little earlier

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Trough disruption evident from the PV to the West as well this early.....

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