Model output discussion - deep cold inbound?

[CentralSouthernSnow]

4 minutes ago, Battleground Snow said:

Huge scatter on the GFS at 162 almost 17 degree range = GFS struggling to resolve the outcome...

It's probably it's biggest weakness. Atlantic being too progressive v a cold block, amplified by how cold the block and how big the low is.

I knew the GFS was having problems. That low isn’t going to blow up like that and I bet it shifts south... GFS is confused! 

[BLAST FROM THE PAST]

Just now, Scott Ingham said:

Locally is a figure spoken about.

The numbers i throw out arent wide spread and werent suggested as but ill be surprised if one poster from all those areas hasnt hit 20cm or 30cm in the soutb east by tuesday pm

I’ll hit it during my Supermarket delivery runs!!

 

BFTP

[sheikhy]

4 minutes ago, Battleground Snow said:

Huge scatter on the GFS at 162 almost 17 degree range = GFS struggling to resolve the outcome...

It's probably it's biggest weakness. Atlantic being too progressive v a cold block, amplified by how cold the block and how big the low is.

Big improvement on the op though!!the scatter begins at day 3!!some members go down to -14

[bluearmy]

1 minute ago, Kasim Awan said:

GFS snowfall accumulations initialized on 26th February for 28th Feb midday. Boy were they underestimations @Scott Ingham

That easterly came with some very low thicknesses - sub 510 dam for a period. This isn’t the same. 

[weirpig]

2 minutes ago, Scott Ingham said:

Locally is a figure spoken about.

The numbers i throw out arent wide spread and werent suggested as but ill be surprised if one poster from all those areas hasnt hit 20cm or 30cm in the soutb east by tuesday pm

I agree  maybe i miss read your post.   i read it like  most of the planet would be under a layer of snow  apart  from one area  of asia  were i pictured the Dali Lama bemoaning the unusually high dew points. 

As always  we shall see next week.

[Scott Ingham]

13 minutes ago, Nick L said:

There certainly is. But there is no evidence in either case to suggest the snowfall depths that were suggested there. There is no way that we're going to see in excess of a foot of snow through London and the SE on Sunday. If people want to post the evidence from the models that suggests otherwise then be my guest. EC has totals no higher than 10cm, GFS closer to 15cm, UKV could see closer to 20cm in places. Absolutely no evidence that I'm seeing to suggest in excess of a foot.

I'll be writing the forecast for TfL later, so if anyone wants to provide evidence for it I will gladly change my mind! 

Where did i quote sunday??

I said somewhere in that huge area by tuesday pm??? 

You telling me not one street will hit 30cm in the south east by tuesday pm?

Because i am certain one area will

One area in yorkshire will hit 20cm

One are in the midlands will hit 20cm

I respect your opinion but to ridicule mine is a tad premature in this set up

Forum do me a favour and if you hit any of these amounts by tuesday pm private message me

[Matt H]

By next Thursday the GEFS 18z ensemble spread ranges from -12.6C up to 1.8C, so it would take a brave person to predict when this cold spell might end. Fantastic model watching at the moment.

[Battleground Snow]

3 minutes ago, sheikhy said:

Big improvement on the op though!!the scatter begins at day 3!!some members go down to -14

By 186, there is a cluster which hold on to deep cold!

[GeordieX9v]

A good few days of uppers around -12c in my location

[95 Degrees]

2 minutes ago, Kasim Awan said:

GFS snowfall accumulations initialized on 26th February for 28th Feb midday. Only 4-5cm for most of the East Midlands, East Anglia, Essex. Boy were they underestimations @Scott Ingham

Also no snow showing whatsoever for Portsmouth when we got nearly 10CM! the GFS snowcasts are a good model to go on but not to be taken too seriously.

[Paul]

Come on folks enough of the willy waving, it's not a competition...

[MJB]

1 minute ago, Scott Ingham said:

Where did i quote sunday??

I said somewhere in that huge area by tuesday pm??? 

You telling me not one street will hit 30cm in the south east by tuesday pm?

Because i am certain one area will

One area in yorkshire will hit 20cm

One are in the midlands will hit 20cm

I respect your opinion but to ridicule mine is a tad premature in this set up

Forum do me a favour and if you hit any of these amounts by tuesday pm private message me

Fair play and without a doubt you can't be called right BUT you definitely can't be called wrong , let's just wait and see ..........so hard to call without a doubt  

[Mike Poole]

4 minutes ago, TEITS said:

Sometimes you need to use instinct and experience rather than simulated models. I have a very good idea of snowfall distribution across my area under the conditions suggested by the models for next week. Never forget how in the 80s an E,ly brought 1ft of snow in Peterborough in under 2hrs from a band of snow showers.

At times we can become too dependant on computer models. For example I just knew the GFS was way off with its handling of the low for this weekend. At one stage it even had the low move NW to Iceland against the huge block to our N. Instantly I knew this was wrong.

Me as well, TEITS ( and have liked your posts ever since i started following this thread in 2011). Given the output now, you would have to say no to the GFS, it is just not consistent with itself or with any other signal.  I think you mentioned a couple of days ago that the easterly would be in earlier if it was to happen, well it will happen, and it is in earlier.  Saturday is the start...

[Kasim Awan]

4 minutes ago, bluearmy said:

That easterly came with some very low thicknesses - sub 510 dam for a period. This isn’t the same. 

I see this pov. I still think this is factored into the model algorithm tho, so adjustments would still be appropriate.

[WINTRY WALES]

Sometimes this forum is easier to read in winters where there is no chance of snow...a lot less volatile for sure. 
We are all (99%) in the same army camp chaps! Get along

[danm]

All getting a bit heated in here over potential snow depths! Can we agree on this - no model is currently showing a foot of snow anywhere, so in a traditional forecast you wouldn’t use that figure, but on a forum where possibilities are being discussed then it can’t be ruled out? 

I suppose with convective streamers, which are notoriously difficult to forecast, it may be possible that some localised spots could see a foot under the right conditions and with being in the right place at the right time. However it’s also unlikely that a wide area of the country would see those values, probably more in the 5-15cm territory.

[Sully79]

1 hour ago, MattStoke said:

Brings an area of snow through the Midlands, as per the Met Office warnings and the UKV.

No-one seems to be paying any attention to that  

I thought that too but they do change them at last minute sometimes 

[Scott Ingham]

12 minutes ago, TEITS said:

Sometimes you need to use instinct and experience rather than simulated models. I have a very good idea of snowfall distribution across my area under the conditions suggested by the models for next week. Never forget how in the 80s an E,ly brought 1ft of snow in Peterborough in under 2hrs from a band of snow showers.

At times we can become too dependant on computer models. For example I just knew the GFS was way off with its handling of the low for this weekend. At one stage it even had the low move NW to Iceland against the huge block to our N. Instantly I knew this was wrong.

Yeah i get where nick is coming from though but i do forecast on instinct bias and past experiences.

I dont want to take up the thread guys but now you know my thoughts

To make it clear not wide spread 20-40cms

If by tuesday pm and you have reached this figure please pm me.

I wont reply to anymore quotes as its unfair to anyone else needing posting space

[Kasim Awan]

Just now, danm said:

All getting a bit heated in here over potential snow depths! Can we agree on this - no model is currently showing a foot of snow anywhere, so in a traditional forecast you wouldn’t use that figure, but on a forum where possibilities are being discussed then it can’t be ruled out? 

I suppose with convective streamers, which are notoriously difficult to forecast, it may be possible that some localised spots could see a foot under the right conditions and with being in the right place at the right time. However it’s also unlikely that a wide area of the country would see those values, probably more in the 5-15cm territory.

In 2010 the models were going for 10-15cm

Quite a large area outdid those totals

Streamers can cover hundreds of square miles

Anyway I agree, best to leave the snow forecast discussion for now

[Frosty.]

Maybe I’m tired so I could be wrong but I swear there are quite a few GEFS 18z members maintaining the deep entrenched cold, up to and including next Friday (12th Feb)...so I wouldn’t assume that the cold will be swept away in a weeks time...anyway...there’s a bitterly cold and for some, snowy spell to enjoy!..and I mean enjoy..don’t worry about the end, we haven’t even reached the beginning yet!   

[Paul T]

35 minutes ago, Scott Ingham said:

Yeah completely agree and its this micro scale abilities that make these my models of choice for streamers and showers. 

Excited for friday night and saturday mornings runs.

Yes the lack of instability keeps the flow cleaner, stops the formation of very small troughs in the flow cutting off the longevity of the easterly winds whilst we have just enough instability to create cloud tops capabale of proucing 75%/25% moderate snowfall but for a long period of time.

Dps being very low along with temperatured gives us a better moisture to snow ratio and even light showers will instantly stick

North midlands south yorkshire - 20-30cms

North east and North Yorkshire 20-30cms

Midlands and central southern england -20-30cms

South east and london - 30-40cms (due to a stalling front saturday night sunday morning)

All of this close of play tuesday with battleground snow to follow

Reading many posts, I think many have read Scotts post like those totals are by Sunday...as he references the stalling front on Sat night/Sunday (bold in quote). However, they are to Close of Play Tuesday and i guess that front is specifically reference as a significant contributor to those numbers

[That ECM]

Someone will definitely post 40cm depth cause most can’t measure snow depth and bend the measure

[Battleground Snow]

I've highlighted the 2 different clusters at day 8.

GFS OP is in the mild one.

[Allseasons-Si]

I will say this,we are all going to be in this cold spell,we would all probably see snow,...what does it matter how much we will get?

and there is every possibility that some places will see a good dumping from systems encroaching from the SW or they will totally miss us then if that happens the cold spell will be more prolonged

let's just enjoy the ride as this is the best spell coming up since 2018.

 

Edited February 4, 2021 by Allseasons-si
typo

[Duane S.]

I wish I had the time to properly go through the GEFS at around D7/8. Some really intriguing evolutions emerging ref that low. This has a long way left to run and I’m getting the distinct impression any warm up, should it even arrive, will be relatively short lived before we’re looking east again?