Model output discussion - after the beast, what next?

[sawan]

ICON 18Z brings the colder air in even quicker compared to 12Z, hits right in the middle of the country, BOOM!

[feb1991blizzard]

6 minutes ago, feb1991blizzard said:

The Icon 18z is going to be a stonker.

Heavy snow showers giving many inches of snow right the way down the Eastern half from Yorks to Sussex / Kent and not insignificant showers reaching further West either.

[JamesL]

27 minutes ago, Steve Murr said:

Nice post & just to add to this - Ive often thought of how to forecast snow without the aid of models due to there inability to quantify PPN totals from Streamers -

you can do the same for anywhere but The following parameters are important:

This is a very crude way -

A) Timeline of optimal instability - 24 hours

B)Max PPN rates from showers - ~2cm per hour

C)% of time You can optimise from the optimal instability time - max 75% (0.75) because the streamer locale usually changes.

This means the equation to the 'top out' values at sea level is A X B X C

so my forecast sweet spot at sea level would be 36cms within the window available.

In terms of elevation ( again crude ) based on reports I have seen from scotland then corresponding reports from Glencoe - that when sea level got a fall of 15cm, the Glencoe car park would be 2X (600M) ~ 30cm

So I would go with a 0.33 increase in depth per 100M

Tops of the downs are @ 200M Mostly - So 'top out' for the downs would be 59CM.

This is on a par with 2009 where low ground of NW kent got to 30-35cm in a 30 hour window & the high downs were in the 50's.

Taking the beast from the last week the GFS ppn rates/ snow depths look to be about 5-8X to low under convection where as the high res models like Hirlam / Aperge feel about 1.5X to short

Best

S

Remember that top out forecast. 36cm which is in the streamer sweet spot location TBC?

 

Thanks Steve and thanks for explaining your reasoning.

I find this absolutely fascinating and while I read your post in my home here in SE Wales (where we had 40cms plus 2 weeks ago) I have my parents (who still live in our family home in Kent) sitting here next to me panicking.

Esp as my father is travelling from Newnham over the Downs to Lenham and along to Gatwick very early Sunday morning to go......yep you've guessed it....skiing lol ? 

Could be Slightly ironic haha 

Edited March 14, 2018 by JamesL

[markw2680]

The beast part 2 lol, can’t believe we are looking at this again this winter/spring. Wonder if it will be powder drifting stuff again that just blows off the road. Looking at icon think quite a bit of the country will be in for a wack of the stuff

[Mike Poole]

ICON at T84, I'm interested in that small kink in the isobars in the channel, would be interested if this is picked up or developed by other models:

850s at same time:

[Summer Sun]

ICON 18z looking good for snow

[MattTarrant]

Just now, markw2680 said:

The beast part 2 lol, can’t believe we are looking at this again this winter/spring. Wonder if it will be powder drifting stuff again that just blows off the road. Looking at icon think quite a bit of the country will be in for a wack of the stuff

May not be as 'powdery' as the first spell but damn for mid march is will unimaginably powdery.  

[SMU]

Over the last 24 hours the cold spell has been extended at both edges - Cold coming in earlier & further North, & the exit point of the -8c line now seemingly late monday eve....

Talking of powder this was West Kingsdown on the last beast

Edited March 14, 2018 by Steve Murr

[tight isobar]

Icon-18z keeps the cold rolling....

And eyes snow deposit possibilities, to a large degree!

This is all going down the correct route.

@easterly #no-2...

[SMU]

19 minutes ago, Chertseystreamer79 said:

I was always rubbish at maths...! 

 

What regional thread you now in Steve?  The bookmark I had for the last beast is now closed. 

 

 

Cheers for the ever interesting input.

SE thread then the Kent / home counties thread when its split...

[snowfish1]

Is the Son of Beasterly a cert now ?

[Summer Sun]

1 minute ago, snowfish1 said:

Is the Son of Beasterly a cert now ?

I would say so maybe not as cold as beast 1 but not far off

[Derecho]

5 minutes ago, snowfish1 said:

Is the Son of Beasterly a cert now ?

I'd say very likely now, my swingometer was more volatile then the US stock market earlier but all the models are moving this back north to the UK again. Given we are getting closer to the event I can't see that changing.

The other thing to keep an eye on is whether the unstable cold air from the son of the beasterly can promote some instability to the SSW and stop high pressure from sinking in that direction. Unfortunately there is less energy down there then Steve Murr's phone battery as it stands. The ICON has the high sinking after a cold snowy weekend it would appear but this is still liable to change.

The most likely scenario at this point is an exceptionally cold weekend easterly (a bit less so then the original beast) followed by a settling down during the week with rather pleasent days but with the CET kept low thanks to chilly overnight minima.

Edited March 14, 2018 by Quicksilver1989

[Bob Lee]

Everybody saying not as cold or as long lived but the snow amounts quoted here seem to be higher. Is that wishful thinking? Metoffice saying an inch some here going way above that 

[kold weather]

The cold isn't quite as deep as the 1st shot from the east and the SSTs are colder, so lapse rates aren't quite as extreme, however we are still going to get a shot at the cold upper low. Last time this shot across N.England and some parts of the NE quater of the country got clobbered. I'd suggest something like that is probable, but maybe slightly more localised.Probably focused more to the south this time.

I'd watch for an embedded low to form in the flow, they usually do to some extent. CAN'T believe we may get near -15C isotherm AGAIN for the 2nd time in 2 weeks, yet alone for the 2nd time in MARCH, surely thats a record?!

[Summer Sun]

Early stages of the 18z and the -12 line looks a bit further north

18z

12z

[SMU]

6 minutes ago, Bob Lee said:

Everybody saying not as cold or as long lived but the snow amounts quoted here seem to be higher. Is that wishful thinking? Metoffice saying an inch some here going way above that 

The shortwave arriving from the east blocked the easterly flow for about 12-18 hours last time...

Anyway - boomtown on the 18z at 66

It looks like a historic chart from the 1800's

[Bob Lee]

Just now, Steve Murr said:

The shortwave arriving from the east blocked the easterly flow for about 12-18 hours last time...

Anyway - boomtown on the 18z at 66

It looks like a historic chart from the 1800's

NOT attacking by the way I admit readily to having a phobia about snow won't bore why so I am in a touch of a panic mode. Overall I want to educate myself about weather anyway

[kold weather]

1 minute ago, Steve Murr said:

The shortwave arriving from the east blocked the easterly flow for about 12-18 hours last time...

Anyway - boomtown on the 18z at 66

It looks like a historic chart from the 1800's

I think regardless of on the ground conditions, I'd argue that is a historic cold shot for the time of year, given SST's are surpressed from the earlier beast, could see some cold daily records go if we get enough snow on the ground during Saturday.

[snowray]

Well whats not to like about this chart, everything slightly further north again, -12c uppers widely and -14c uppers clipping the SE. This is turning more and more into a direct hit for the UK.

Lots of snow moving in from the east for all of us.

Edited March 14, 2018 by snowray

[Summer Sun]

-14 850's into parts of the SE at t78

 

Edited March 14, 2018 by Summer Sun

[seabreeze86]

Christ what a chart, the trend to push things south had been halted and now things are slowly creeping north again. Really amazing stuff convection will be rife especially the further south and east you are.

[IPredictASnowStorm]

That's more like it ?

[Snowmaggedon]

So just like the last Beast from the East things are upgrading nearer to the time. What a winter this has been. Time to dust off those sledges again that we only put away the other week!

[Ice Day]

Could be a snowy Sunday evening if the GFS precip charts are anywhere near accurate? 

Cracking end to winter, 2018 is going to be one of those years talked about in future winters