Model output discussion - here comes the beast!

[MattTarrant]

1 minute ago, kold weather said:

No its not, I've changed it to cms not inches onthe settings. So it IS 5-7cms in the south and 10-15cms in the SW. Nothing to sneeze at still but its not quite the snow disaster some thought.

 

I was commenting on the 'WaswallWeather' image which was inches & shows what i was saying. Odd if cm setting would be different. 

[snowydog]

15 minutes ago, ukpaul said:

On the east coast of Northern Ireland and with your elevation I'd be very pleased at the output. Depending on wind direction that little stretch of water will do wonders in pepping up your snowfall.

Thanks. You’re a star. Trying my best to keep up with all the info ?

[kold weather]

2 minutes ago, Banbury said:

so 10cm of snow after a 2 day blizzard ermmmmmmmmmm

The air is too dry and the front gives up the ghost once its a little north of the M4. Only the south and SW get a really good dumping, by a line from Bristol to London it starts to rapidly weaken as the dry air cuts off the energy.

 

[Frosty.]

9 minutes ago, kold weather said:

Not as much snown as you'd think on the 12z ECM as the frontal system weakens as it hit the very cold and dry air. 5-7cms in the south, 10-15cms in the SW. Still neat but not as much snow as the 12z GFS.

Plenty of snow showers too for the n / e with longer spells of heavy snow and drifting..stunning Ecm 12z like so much other output today!

[Southender]

2 minutes ago, kold weather said:

No its not, I've changed it to cms not inches onthe settings. So it IS 5-7cms in the south and 10-15cms in the SW. Nothing to sneeze at still but its not quite the snow disaster some thought.

 

Meh. Either will do. Suspect it won’t even reach our shores, one for the backburner. All eyes on the convection potential first. What an unbelievable situation to be in. Cracking.

[kold weather]

2 minutes ago, MattTarrant said:

I was commenting on the 'WaswallWeather' image which was inches & shows what i was saying. Odd if cm setting would be different. 

https://weather.us/model-charts/euro/07-w-500-n/snow-depth/20180302-1800z.html

That is what I'm seeing and it DOES match up nicely the estimated radar returns at the time from the same website where the front decays rapidly.

With that being said, any chart like this needs a mammoth pinch of salt.

Edited February 23, 2018 by kold weather

[pages]

Still Cold very cold at T-240 interesting  that pressure starting to drop over Canada and Greenland, wonder if we would of seen the ravaged remains of Trop vortex start moving back over Greenland on T-264 chart and pressure start to rise to north East/north. Would only need week heights for next low to go under then would be at least 3 week freeze.

[supernova]

Think ECM just won the biggest BAFTA of the night (Bloody Amazing Frigid Troposphere Award). Not sure what happens after this chart but there’s still blocking in places we’re not used to seeing it. Am guessing the UK would remain iced for some time to come.

[Methuselah]

12 minutes ago, kold weather said:

Not as much snown as you'd think on the 12z ECM as the frontal system weakens as it hit the very cold and dry air. 5-7cms in the south, 10-15cms in the SW. Still neat but not as much snow as the 12z GFS.

Let's just hope that the LP takes a similar track to the one that closed out 1978. ..

[nick sussex]

I think it’s best at this stage to view any frontal snow as a bonus .

At least it’s not all or nothing there’s lots of snow potential before that even comes into range.

I’m still recovering from the shock of seeing these synoptics. The depth of cold forecast this late in the winter is incredible , we mustn’t forget it’s not mid winter .

 

 

[Severe Siberian icy blast]

2 minutes ago, chionomaniac said:

We have waited a long time to see this. Since the beginning of the internet age. We have all wanted to see these synoptics reel in and in and there is a bit of disbelief now it is happening,

Phenomenal is all I can say.

And to think that there was some that said that we would struggle to ever see these synoptics again. Well I guess that will be put to rest next week. Big time.

Normally to just get the -10ºC 850 isotherm over the country for a day is an achievement so to see multiple days forecast is amazing.

Look after any vulnerable neighbours whilst enjoying the freeze - but do enjoy what could be a once in a generation cold spell.

I'm sure that it is just a co-incidence that this follows a SSW lol!

Indeed chiono, I have to say hats off to you for getting this bang on  a strong easterly wind is never easy to pull off if it can go wrong it will, you have nailed this one.

I have stayed grounded all week with this because even with exceptional synoptics, some places will still miss out.

Let's hope the north sea acts as the snow machine it can do. It reminds me so much of 1991, it's similar in so many ways, wonder if we will need low pressures to give organised snow or will the low uppers, low thickness values be enough to deliver for most on a strong east wind? 

[Sawel]

Even ol' misery-guts Arpege sneaks to the back of the line and says yes 

 

[Day 10]

See that little white dot that says Liverpool, that's pretty much where my house is, upto 0.2 inches

Heading into a sixth Winter without lying snow? Surely not.

[ChezWeather]

2 minutes ago, Day 10 said:

See that little white dot that says Liverpool, that's pretty much where my house is, upto 0.2 inches

Heading into a sixth Winter without lying snow? Surely not.

 

Don't take any precip accumulation chart as gospel at this range, they are all likely to be well off, wait until Sunday when the EURO4 comes into play 

Edited February 23, 2018 by ChezWeather

[Man With Beard]

30 minutes ago, WalsallWeather123 said:

South of England getting pasted if ECM came off aswell as NE England. Midlands least snowy. Good for me ll.

Sorry I don't buy it. When I view charts like we've seen tonight when the temperature is just above the threshold for snow, I expect an inch of rain, not an inch equivalent of snow.

[Frosty.]

This evening's Ecm 12z is nirvana / narnia for coldies!..these kind of spells don't come around often so enjoy it!...can't wait for tomorrow's upgrades

 

[Snowman.]

14 minutes ago, Banbury said:

Yes but same thing as 10cm = 4 inches ......I know I have confused things but the younger generation work in CM's anyway my poorly made point is with all that moisture coming up from the South somewhere will be battered and I mean battered, that isn't a system that would deliver just 10cm or 4 inches in Oxfordshire IMO

Hypothetical really as it might not even get here 

The SW gets some real good totals. Could be the angle of front might or the intensity, 

Edited February 23, 2018 by SN0WM4N

[AmershamMike]

3 minutes ago, Man With Beard said:

Sorry I don't buy it. When I view charts like we've seen tonight when the temperature is just above the threshold for snow, I expect an inch of rain, not an inch equivalent of snow.

Eh? Snow surely?

[SizzlingHeat]

Just now, AmershamMike said:

Eh? Snow surely?

Continental Easterly/south Easterly and uppers of between -7 and -10 widely = temps at 0 or below and dew points -3 to -6. Absolutely no marginality whatsoever even right on the coast.

[lamppost watcher]

Think man with beard means that the low in that picture would give 10 times what is shown as the same system in warmer temp would give an inch of rain. That's how I read it anyway

[phil nw.]

19 minutes ago, nick sussex said:

I think it’s best at this stage to view any frontal snow as a bonus .

At least it’s not all or nothing there’s lots of snow potential before that even comes into range.

I’m still recovering from the shock of seeing these synoptics. The depth of cold forecast this late in the winter is incredible , we mustn’t forget it’s not mid winter .

 

 

Incredible aren't they Nick i mean looking at the gefs 850s and 2mt temps

-15C and sub-zero daytime surface max's early March??.To see that mid-Winter would be eye catching they are something else !

[nick sussex]

2 minutes ago, phil nw. said:

Incredible aren't they Nick i mean looking at the gefs 850s and 2mt temps

-15C and sub-zero daytime surface max's early March??.To see that mid-Winter would be eye catching they are something else !

Yes Phil absolutely amazing.

Normally to just get the -10 line into the UK for a day is cause for celebration .

 

[BleakMidwinter]

36 minutes ago, kold weather said:

No its not, I've changed it to cms not inches onthe settings. So it IS 5-7cms in the south and 10-15cms in the SW. Nothing to sneeze at still but its not quite the snow disaster some thought.

 

But quite a few people in here have made the point that this is highly likely to be powdery dry snow which is thought to approximate c.3cm snow to 1mm of precipitation, rather than the usual 1mm ppn=1cm snow

In which case, triple everything...?

[Stuie]

4 minutes ago, BleakMidwinter said:

But quite a few people in here have made the point that this is highly likely to be powdery dry snow which is thought to approximate c.3cm snow to 1mm of precipitation, rather than the usual 1mm ppn=1cm snow

In which case, triple everything...?

I read that myself. I presume that being dry snow and falling on a dry cold surface there is no initial thaw/melt when settling on top.

[Man With Beard]

I don't know if perhaps this kind of micro-analysis of the snow potential needs moving into the dedicated cold spell thread ... but just thought I'd post the latest ARGEPE snow chart as to me it seems a reasonable idea of what to expect on the ground by Wednesday morning: