Scotland Regional Discussion - January 14th 2013>

[Guest]

Just as a point of interest - and by no means to dampen prospects for the coming days... its interesting that todays (admittedly relatively superficial) precip in the west wasn't really in the forecast over the previous 24-48 hours.

It makes no real change in the synoptic scheme of things. But just a salutary reminder that even short-term forecasts are subject to change by reality ... and that Lorenzo's nowcasting is both the wisest and best approach over the coming days.

The NAE showed it from Tuesday onwards, never amounting to much but there none the less:

http://www.weatheron...S=0&WMO==

Although it seemed to have a better idea at +48 than +24 :lol:

Edited January 16, 2013 by CatchMyDrift

[Highland Snow]

OOO err missus, am liking that, very tasty....

...and the weather chart's nae bad either

Snooz he may have the looks but does he have the touch!

[Penicuikblizzard]

Is the front on Friday likely to push right through with mild air behind or is it gonna stall then push back westwards???

[BleakMidwinter]

Strewth, my cosy skirt, big jumpers and rigger-boots* may keep most of me warm but jings I need to knit some gloves that aren't fingerless! Just been out and my fingers are stining like crazy as they warm up - a return to chilblains for younger folk, I wonder, if they don't know how to avoid 'em?

xc claims Embra is spot-on zero just now but it feels a lot nippier than that. And very dry-feeling air - cobbles and tarmac pale and dry for the first time in a few days.

*yep, Dickies' riggers, because I'm that trendy, me

[November13]

Is the front on Friday likely to push right through with mild air behind or is it gonna stall then push back westwards???

I have it on good authority that it will not win the battle and eventually be pushed back. Every model I have looked at suggests the cold is here to stay!

[over_the_rainbow]

I have it on good authority that it will not win the battle and eventually be pushed back. Every model I have looked at suggests the cold is here to stay!

So, in terms of snaw prospects further east it's a question of how far the front gets on Friday before the stall and then subsequent retreat?

[Bullseye]

BBC Scotland Weather looked epic for Friday almost covering all of Scotland! With added bonus of light snow at 3pm today...

[edo]

There were many better Pics Cheggers, went for the more clothes and Tartan !

Source of #snowmaggedon ramping is Laura Tobin @Lauratobin1. Definite coldie... er hottie, IYKFAM.

followed

[Buriedundersnow]

I have it on good authority that it will not win the battle and eventually be pushed back. Every model I have looked at suggests the cold is here to stay!

yeah it looks like it will make it in then pivot and move south which would allow the cold air to flood back in from the east to the north of the front

[edo]

Is the front on Friday likely to push right through with mild air behind or is it gonna stall then push back westwards???

million dollar question.... models say cold pushes back but the risk is always there

risk/reward situation

[BleakMidwinter]

I have it on good authority that it will not win the battle and eventually be pushed back.

Yes, but they said it would all be over by Christmas... no, wait, was that winter or the world war...?

[edo]

So, in terms of snaw prospects further east it's a question of how far the front gets on Friday before the stall and then subsequent retreat?

yup absolutely so get praying it reaches us then stalls

[LomondSnowstorm]

Ok, so what are the differences between what's likely to happen on Friday and what we saw happening on Sunday/Monday?

Firstly, the synoptics on Sunday/ Monday were not what I'd call conventional:

A low pressure system from the northwest ran into another low to the southeast after a day or two of moderate cold with a distinct warmer sector to the southwest of the low with a number of occlusions crossing the country generally northwest-southeast before finally stalling and heading south-southeastwards by Tuesday morning. This messiness can be good for snowfall but it becomes impossible to read until very close to the time and the dynamics are staggeringly complex. On Friday, while placement and tilt etc. of the front are still up for grabs, it looks at least a bit more conventional - milder air from the west runs into colder air from the east, an occlusion forms and then stalls because of the high temperature gradient between the airmasses and along this line there's a lot of snow because it's very cold at the surface and the flow is from the south or southeast where temperatures are pretty baltic at the moment. Evidence of this is from the 950hpas progged for Friday morning:

Even the western Isles and Tiree have sub zero 950s. Secondly, as the day goes on the front will pivot and we'll start to see the cold upper air temperatures come back at us from the southeast:

This will drag in lower dewpoints off the continent even in spite of a flow that will be trending ever more maritime for the east:

What happens next is up for debate, but it appears that we're likely to see an easterly flow develop, with an associated risk of snowfall both from convection and the front which is likely to still be straddling the country somewhere:

What is positive about this is that the upper cold pool on both the GFS and ECM remains good, around -7C - -9C for Saturday evening, so we could be in for something very special if these hold up. Given the tendency for models to underestimate convection and also given the potential for this to interact with our occlusion Saturday evening for eastern Scotland could be very special. Before that of course central and western areas are more likely to bear the brunt on Friday, but at present it doesn't look like the milder air is going to make any inroads. On the GFS past +144 it manages to break in a bit but with the ECM showing uppers no higher than about -7C for eastern areas and around -5C for the west throughout the next ten days, which would almost guarantee that all precipitation remained as snow. I'll update again on the 12Zs but this one does look like the real deal.

[101_North]

yup absolutely so get praying it reaches us then stalls

And if it doesn't? That's not all bad news either if I seeing this right? Would leave us keeping the cold at least if it stalled further west? Would that give us a sniff at convective showers from the ease/south east?

Enough questions?

I generally don't rate frontal snow for this location but this could be good if it stalls in the right place. If given a choice though I'd prefer to keep the cold and have no snow than have this push right through and bring us milder air and a snow to rain mess - although that doesn't look like happening just now.

EDIT: Think LS just answered most of this - cheers

Edited January 16, 2013 by 101_North

[Scottish-Irish Skier]

Morn's ECM ensembles London surface T.

Mean stays well cold right out to end jan.

GFS on the mild side in FI

[Buriedundersnow]

wouldnt mind the nogaps verifying

78hr

84hr

96hr

108hr

120hr

132hr

144 hr

nice run and 850 temps dont get above -4 till the very end of the run which means this would be very snowy

[edo]

And if it doesn't? That's not all bad news either if I seeing this right? Would leave us keeping the cold at least if it stalled further west? Would that give us a sniff at convective showers from the ease/south east?

Enough questions?

I generally don't rate frontal snow for this location but this could be good if it stalls in the right place. If given a choice though I'd prefer to keep the cold and have no snow than have this push right through and bring us milder air and a snow to rain mess - although that doesn't look like happening just now.

EDIT: Think LS just answered most of this - cheers

absolutely 101 a lot of discussion about this last night and I favoured that solution until LS solution above.... i will have the stalled front followed by the easterly convection... cake and eat it

Im trying really hard not to ramp but its hard to see anything other than a very good winter spell where as ever some will do far better for snowfall but to be honest im happy with enough to let the kids sledge build a proper snowman and really stomp around in it..... 8 inches be fine

I think now no matter how it passes through it is going to head south east and drag easterly air in it is just a question of how potent the flow is.... LS explained this in perfect detail last night

Edited January 16, 2013 by edodfc

[BurntFishTrousers]

That's me away oot to panic buy again.

[LomondSnowstorm]

The NAE showed it from Tuesday onwards, never amounting to much but there none the less:

http://www.weatheron...S=0&WMO==

Although it seemed to have a better idea at +48 than +24

It had a better idea at +48 than at +3:

[TinyTim]

Well...

Excellent explanation by LSS as always... here's hoping that we get something out of this... It would be SO frustrating to be a few miles too far to the east in this setup!

Tim

Edited January 16, 2013 by TinyTim

[101_North]

absolutely 101 a lot of discussion about this last night and I favoured that solution until LS solution above.... i will have the stalled front followed by the easterly convection... cake and eat it

Im trying really hard not to ramp but its hard to see anything other than a very good winter spell where as ever some will do far better for snowfall but to be honest im happy with enough to let the kids sledge build a proper snowman and really stomp around in it..... 8 inches be fine

Like you I'm only wanting snow for the kids....honestly

[NUT]

Snow just starting to fall out the sky here (ableit very light)

[edo]

Well...

Excellent explanation by LSS as always... here's hoping that we get something out of this... It would be SO frustrating to be a few miles too far to the east in this setup!

Tim

Tim we may need to wait till sat night or Sunday but fairly confident we will then see plenty snow showers from the following Easterly even though you may feel frustrated if miss a large frontal drop (oooh errr misssus)

[TinyTim]

lol Edo

I'm really up for a 'large drop' right about now

Getting a little worried before today that this spell would go belly up before we received anything decent... but things do look like they are improving...

Tim

[M1245]

MO have released a picture of expected fresh snow cover on Friday but the 2-5cm line doesn't even reach fife and the east, while their warming covers most of Scotland...confusing.