Significant Snow Risk This Weekend - General Discussion

[kold weather]

OK I'll join the discussion. I'm often poor at these snow events: I remember many moons ago TEITS posting up a video link of him writing my name in the snow after I'd said it wouldn't!

However, although the cold pool is deep the angle of advance from the west is not one we'd generally favour for snow. Normally the centre of the low comes across the UK and there is big snow potential on the northern flank. As an alternative a low anchored south west has fronts stalling on a west-east axis, which again brings snow risk.

This north-south front suggests to me that any snow will readily turn to rain and I think there may be disappointments. The exception might be the far south-east if it holds on to the cold pooling and the front stalls.

Its a rare set-up thats for sure, but I think we have got a couple of things on our side. Firstly we already have a well established cold pool present at the surface. Many times with these set-ups we've had to hope we can import enough air and the air is marginal in the first place before the front arrives, this time dews/temps are plenty cold, especially the further east you go. Secondly is the timing. Because it comes during the eveing and overnight hours I think that will also make a big difference. Trust me WIB had it come during the daytime I'd be going along with you probably.

I'd like to think the high resolution models have a good grip on things and they are pretty keen on snow throughout for mostr central areas as well a the east.

I'm trying to think of one set-up in the past that has a shortwave developing through a high pressure zone whilst we have cold air present and coming down from the angle it does and I'm coming up with nothing. I'm sure there are some events in the past but the point I'm getting at is its rare.

[NickR]

Just one thing to remember there is very rarely any corrections EAST on the day- nearly always small increments west..

S

...which gives us some hope here in the NE.

[SMU]

Nick- do you have any altitude?? good lapse rates to start will ensure that altitude supports tomorrow

S

[NickR]

Nick- do you have any altitude?? good lapse rates to start will ensure that altitude supports tomorrow

S

Not really - about 80m, on a hill to the E of Durham CIty.

Is it looking poor for the NE do you think overall?

[Snowman31]

Do you think NW London a good spot to be in tomorrow night? really want some snow this winter

[picog]

Looks like central and eastern England may do well according to the NAE.

[kold weather]

Snowman31- Yes I think its a very good location, probably far enough east and north to not have too much to fear when it comes to it turning back to sleet/rain but far enough west to get the front whilst its still strong.

Great NAE at 42hrs by the way, snowline is way west still. Indeed good run for the west as well as it does give some snow for you. This is probably because the front is slower than it is on the NMM which is more marginal due to it coming earlier during the day.

PS, NAE has upgraded precip totals ALOT this run, precip amounts of 10-15mm showing up in a 3hr period now...good sign...VERY marginal though for central southern England upto say Oxford by 3am, so close to the GFS on thaty front, but precip is so intense that it probably will still be snow away from southern CS.

Edit- 48hrs chart is out, not a good one for the Midlands, temps rise a little probably to wrong side of marginal on the backend. SE/EA would likely hold onto the snow as dews and 850hpa profiles drop again behind the frontal zone by 6am, but elsewhere its a snow-rain event...though that being said a very BIG snow-rain event...

[Snowman31]

thanks for the reply Kold

Snowman31- Yes I think its a very good location, probably far enough east and north to not have too much to fear when it comes to it turning back to sleet/rain but far enough west to get the front whilst its still strong.

Great NAE at 42hrs by the way, snowline is way west still. Indeed good run for the west as well as it does give some snow for you. This is probably because the front is slower than it is on the NMM which is more marginal due to it coming earlier during the day.

PS, NAE has upgraded precip totals ALOT this run, precip amounts of 10-15mm showing up in a 3hr period now...good sign...VERY marginal though for central southern England upto say Oxford by 3am, so close to the GFS on thaty front, but precip is so intense that it probably will still be snow away from southern CS.

thanks for the reply Kold

[thegreat316]

Latest 6Z 42 and 48h NAE

A further shift east?

Edit:

This is the 0z 48h chart, compare with 06z 42 chart to see any shift

[MKN]

gfs 06z further east, fronts tilted more unfavourably

[i luv snow]

Further eastward shifts as opposed to westward ones so far this morning - twists and turns!

[jazzy]

Just wondering how accurate the GFS temps are as it has me down for +2 right now and it is actually -3, Am I straw clutching as if temps are lower tomorrow, might we have an ouside chance of the white stuff. Hohum.

[Liam J]

NAE 6z has brought in slightly milder 850 temps compared to the 00z also surface temps rising just above 0c for many instead of remaining below throughout. More twists to come over the next 12 hours with specific detail.

A stronger front will create more mixing of the air which isn't really what you want. This could be more marginal for the less favoured, elevation will be your friend.

[kold weather]

Yeah the 06z models aren't as good as the 00z runs thus far this morning for a vast majority of the country, though ironically there probably is more snow for most as the front is stronger, but a stronger front also brings with it higher dew points and even more marginal conditions. Think its going to be a nightmare to call whether it stasys as snow or turn to sleet/rain on the back-end for central and some eastern parts. SE/EA at the moment still far enough SE to probably be protected by the colder air, but any more shifts will also bring them into the snow-rain equation.

[TEITS]

Further eastward shifts as opposed to westward ones so far this morning - twists and turns!

Yes although for E Anglia/SE after the passage of the front the temps/dewpoints remain around -2C.

http://www.wetterzen...cs/Rmgfs514.gif

I agree with KW E Anglia/SE cannot really afford another shift E from the 12Zs.

[chris78]

Just wondering how accurate the GFS temps are as it has me down for +2 right now and it is actually -3, Am I straw clutching as if temps are lower tomorrow, might we have an ouside chance of the white stuff. Hohum.

crossed my mind too....also yesterday meto graphics gave 0 for nw tonight now the graphic says -8..big difference...but as you say is it straw clutching...

[TEITS]

Worth mentioning that yesterday the 06Zs moved slightly E but then the 12Zs shifted back W again and this includes the NAE.

[Bolton67]

I dont think people should panic, Feb 2009 is a prime example! it was even more marginal then. the outcome? take a look a TETIS sig.

[i luv snow]

Even for my location, where we are still shown by 6z to have snow throughout, would rather this shift westward a touch to keep it less marginal for other areas - alot of ppn ends up in North Sea anyway so this doesn't make as much difference for us in EA. I would imagine runs later today will show a westward shift so don't despair people Plus not only goes GFS over prog temps, but once snow is falling/on ground then this has a big effect.

[No Balls Like Snow Balls]

i think Oxfordshire will do well out of this. More snow Sunday night into Monday too?

[Beasterly]

i think Oxfordshire will do well out of this. More snow Sunday night into Monday too?

I think Oxford is borderline to this. Oxford will see heavy snowfall though dumping large amounts in short timeframe but turning to rain after!

[i luv snow]

Yes although for E Anglia/SE after the passage of the front the temps/dewpoints remain around -2C.

http://www.wetterzen...cs/Rmgfs514.gif

I agree with KW E Anglia/SE cannot really afford another shift E from the 12Zs.

Agreed here too! I would prefer it to shift a tad further W tbh... against this cold then this makes sense imo, so I would expect changers for later today. I genuinely think this will be a snow event further west also, and for a wider area than 6z would lead you to believe.

[Zakos]

Im thinking a small westward shift in pon aswell. As for the snow potential, this is changing wildly each run on the gfs, but the ecm has been very consistent of a much more widespread snow event than the gfs is showing. Even the NAE and ukmo still has the snow accumulation much further west than the gfs.

[No Balls Like Snow Balls]

I think Oxford is borderline to this. Oxford will see heavy snowfall though dumping large amounts in short timeframe but turning to rain after!

Still plenty of time for change, I just have that feeling we will stay as snow throughout and the milder air wont get that far East. fingers crossed.

[kold weather]

I think Oxford is borderline to this. Oxford will see heavy snowfall though dumping large amounts in short timeframe but turning to rain after!

Yes on the 06z it is very borderline, I suspect it stays as snow most of the way but stops settling once the core of the precip is past and that may indeed induce a slight and slow thaw as well.

The problem mainly is the models are actually strengthening the precip. This leads to a slight warm core developing which shifts SE and helps to tilt the odds for some areas that otherwise would get away with it. On the upside it does mean more snow before any transition IF that is what happens.

It very much will be a nowcasting event, could go either way still for alot of the country.