Scottish Cold Spell Discussion 21:

[Scottish-Irish Skier]

Yeh that latest run on GSF is actually pretty good. SUre the details need firmed up but the cold holds on across Scotland and actually NE england. Could be lots of fun if the LP from the Atlantic pushes as far in as they think. Just hope those uppers are cold enough, got horrid feeling could be marginal east coast going with -7 / -8 rule. Intresting days lie ahead. Certainly nothing mild in reliable time

Just had a look and the uppers end of thye week are around -8 / -9. dam is around 527.......does this perhaps make any precip marginal ??

I'm hoping LSS will give us a summary at some point today, might clarify level of marginality.

From what I can make out from the model thread, we are still faced with -AO and -NAO with the main part of the jet heading for the med into next week. This is good for overall cold, although the positioning of blocks and offshoots of the jet are muddying the waters and putting us more on the edge of cold.

[Ross B]

BBC forecasts going for a period of snow across much of Scotland tomorrow before turning to rain

[GraemeB]

FI would appear to be T72/96 - I'm now trying to ignore anything beyond that, as last week, we were almost into Day After Tomorrow scenarios

Maybe they should split the model thread into 2 - discussions over what's happening 0-72, and another for post 72 apocalyptic doom talk.

I know which thread I'd sit in

Still, bright and cold here in Stirling - so no complaints (apart from the lack of snow)

[Richard Taylor]

Iight/mod snow shwr faIIing.

[Snowplough33]

This is brilliant..........how on earth is this possible with everything pointing towards the atlantic winning...

UK Outlook for Friday 5 Feb 2010 to Sunday 14 Feb 2010:

A spell of wet and windy weather affects the UK at the end of the first week of February with a chance of south or southeasterly winds reaching gale force in the north and west. Most places will have rain for a time with this most likely to be heaviest in the north and west. There is also a chance of sleet or snow in the northeast at first. It is likely to become drier by the end of the weekend although rain or showers continue in many places. Although there is still some uncertainty, the unsettled pattern of rain or showers, possibly of sleet or snow, is likely to continue throughout the second week of the month. Temperatures likely to start around normal becoming cold or rather cold later.

Updated: 1152 on Sun 31 Jan 2010

UKMO's own charts dont support this

Edited January 31, 2010 by Snowplough33

[Snooz]

This is brilliant..........how on earth is this possible with everything pointing towards the atlantic winning...

...

UKMO's own charts dont support this

because not everything is certain? and even if it is the eventual outcome it's not likely to happen at the flick of a switch

a couple of posts from Ian Ferguson (BBC Forecaster) on the Model thread give a little insight as to why the UK Outlook is as it is..

Yes, I've got to say I've seen no sign of any supposed 'back-tracking' from the medium range guys at Exeter in their briefings lately. The messy, mild(ish) set-up into this coming week has been a consistent theme over the past 48hrs of briefings (not least based on the GM) and as I posted yesterday, it's been the 10-15 day period where UKMO has focused any suggestion of a colder easterly returning. I'm awaiting the next detailed briefing notes but this abstract from the 00Z briefing makes the point well enough on behalf of the good folks at Ops Centre:

"4. Trend For Days 10-15: The low level flow is expected to back easterly with colder weather advecting westwards across the UK. Good deal of dry weather in the west, but increasing risk of snow showers for eastern and central areas and low PROB of sleet and snow in the far south later. Widespread frosts.

5. Discussion: There remains considerable uncertainty in the evolution during the coming week, with some models, including JMA, and some EPS members maintaining the block, whilst the main signal from the ensembles is for progression of Atlantic frontal systems into the UK. During the trend period, there remains a good signal for trough disruption over the Atlantic with a much colder easterly flow developing. This latter aspect has moderate confidence."

I do again stress this was a midnight briefing and will shortly be superceded!!!

I've now seen the updated (12z issue) UKMO 6-10 day briefing based on 00z runs and the 10-15 day guidance remains identical (to that cited above). I'm not going to abstract it here but instead offer just a key section, as follows: "....at this stage the continuity of the EC ensemble is compelling and a cold spell is indicated here, especially by the middle of next week.... Hence few changes are made here to the (midnight briefing) until greater confidence is shown by the operational models and their ensembles." All sounds simply like prudent science to me, rather than 'back-tracking'.....!

Edited January 31, 2010 by Snooz

[Scottish-Irish Skier]

because not everything is certain? and even if it is the eventual outcome it's not likely to happen at the flick of a switch

a couple of posts from Ian Ferguson (BBC Forecaster) on the Model thread give a little insight as to why the UK Outlook is as it is..

Nice post. What we like to hear and said sensibly by Ian.

[doctormog]

Interesting (and helpful input by Ian)

On the subject of interesting that cloud formation over the Northern Isles at the moment has caught my eye. I wonder if that is what associated with the forecast of increasingly frequent snow showers in the east (of the NE) later?

http://www.sat24.com/Region.aspx?country=gb&sat=ir&type=loop

The snow seems to be coming down nicely in Shetland at the moment:

http://www.shetland.org/60NTV/#

[Airedalejoe]

This is brilliant..........how on earth is this possible with everything pointing towards the atlantic winning...

UK Outlook for Friday 5 Feb 2010 to Sunday 14 Feb 2010:

A spell of wet and windy weather affects the UK at the end of the first week of February with a chance of south or southeasterly winds reaching gale force in the north and west. Most places will have rain for a time with this most likely to be heaviest in the north and west. There is also a chance of sleet or snow in the northeast at first. It is likely to become drier by the end of the weekend although rain or showers continue in many places. Although there is still some uncertainty, the unsettled pattern of rain or showers, possibly of sleet or snow, is likely to continue throughout the second week of the month. Temperatures likely to start around normal becoming cold or rather cold later.

Updated: 1152 on Sun 31 Jan 2010

UKMO's own charts dont support this

That's easy, the UKMO charts cover the coming week, the period referred to is for the end of this period onwards for another week or so. Currently the charts for next week point towards milder atlantic influenced air but beyond this I'm presuming indications are that we'll be drawing our air from a more continental source. All part of the ebb and flow of the weather.

[milkmaid]

it's still snowing on and off here has been all day

[Scottish-Irish Skier]

Starting to cloud over here; some of them fairly dark. Also some light prep developing over the Forth.

Hard to say, but looks like the showers to the North are pepping up a little? Maybe some might make it south.

Certainly some heavy cloud coming down from the north/up Iceland way.

[LomondSnowstorm]

This is brilliant..........how on earth is this possible with everything pointing towards the atlantic winning...

UK Outlook for Friday 5 Feb 2010 to Sunday 14 Feb 2010:

A spell of wet and windy weather affects the UK at the end of the first week of February with a chance of south or southeasterly winds reaching gale force in the north and west. Most places will have rain for a time with this most likely to be heaviest in the north and west. There is also a chance of sleet or snow in the northeast at first. It is likely to become drier by the end of the weekend although rain or showers continue in many places. Although there is still some uncertainty, the unsettled pattern of rain or showers, possibly of sleet or snow, is likely to continue throughout the second week of the month. Temperatures likely to start around normal becoming cold or rather cold later.

Updated: 1152 on Sun 31 Jan 2010

UKMO's own charts dont support this

Firstly, BFTP has informed us that this December and January period as a whole has been the coldest ON RECORD in Scotland. Although this sounds slightly implausible if you think about it most winters have either a December cold spell and late January mild spell (81/82) or have a very cold winter which only sets in at the beginning/middle of January(47, 62/63). Impressive to see this occur in this rapidly warming world where this isn't actually possible!

Anyway, that's enough tongue in cheek comments from me!

To explain why the UK outlook from the Met is as such, we must look at not the raw model output so much as the background - there is no raging zonality forecast (almost though on the UKMO), with the AO and NAO both negative, it is merely that we are in the wrong position to take advantage of it AT THE MOMENT. http://www.meteociel.fr/modeles/ecmwf/run/ECH1-120.GIF?31-12 High pressure to both our northwest and northeast is there, but because they refuse to link up due to the Scandi trough, we are stuck in yet another no man's land scenario, with neither the polar maritime air from the northwest or the continental air from the east dominating, though the atlantic isn't hugely dominant either (note the low is quite favourably tilted to undercut on the ECM +120). Also note the jet is tracking to the south, meaning that high pressure is less likely to build to our south and leave us in a b-word scenario. http://www.meteociel.fr/modeles/ecmwf/run/ECH4-144.GIF?31-12

So what does all that mean for us? Firstly we have a fairly wet afternoon and evening tomorrow, with a warm front moving across, bringing temporarily milder uppers and higher dewpoints. To start with, the first, weaker band might be snow or sleet for central areas, but this fizzles out fairly quickly

Behind this, the cold air floods back in - http://charts.netweather.tv/gfsimages/gfs.20100131/06/48/h850t850eu.png - bringing showers to the areas which have benefited from snow in the last few days http://charts.netweather.tv/gfsimages/gfs.20100131/06/51/ukprec.png.

Widespread frost on Tuesday night also http://charts.netweather.tv/gfsimages/gfs.20100131/06/75/ukmintemp.png

A dry cold day Wednesday with another harsh frost (harsher than suggested for some I expect) to follow http://charts.netweather.tv/gfsimages/gfs.20100131/06/96/ukmintemp.png

This is where the models diverge: GFS brings in southeasterly winds http://charts.netweather.tv/gfsimages/gfs.20100131/06/102/ukwind.png courtesy of this low http://charts.netweather.tv/gfsimages/gfs.20100131/06/108/h500slp.png

This brings a band of precipitation, which in this instance would be snow http://charts.netweather.tv/gfsimages/gfs.20100131/06/108/ukprec.png http://charts.netweather.tv/gfsimages/gfs.20100131/06/108/ukmaxtemp.png http://charts.netweather.tv/gfsimages/gfs.20100131/06/108/hgt500-1000.png

The ECM says the PPN will not get this far http://en.vedur.is/photos/atlant_evr_urkomuspa/100131_0000_114.png but due to a less favourable tilt the slightly less cold uppers do http://en.vedur.is/photos/atlant_evr_hitaspa/100131_0000_114.png

The UKMO doesn't just wreck our cold upper though, it sends milder air right across continental europe, something no other model supports http://www.wetterzentrale.de/pics/Rukm961.gif http://www.wetterzentrale.de/pics/Rukm1441.gif By +144 Euro high is almost inevitable.

The ECM at this stage, though hardly cold, has potential for a cold spell, with height rises to the north and lows looking to track to the south of the UK http://www.wetterzentrale.de/pics/Recm1441.gif.

The difference with the GFS is the better tilt of the low, which allows cold uppers to hang on across Scotland http://charts.netweather.tv/gfsimages/gfs.20100131/06/141/h850t850eu.png

http://charts.netweather.tv/gfsimages/gfs.20100131/06/141/ukprec.png

These showers would be quite marginal, but probably inland would be cold enough for snow. Of course, by this stage, the outlook is fairly uncertain, but slight changes in the angle of the trough and strength of blocking to the north are likely to completely change the 144 hour charts towards the mild UKMO or potentially snowy GFS, or perhaps the ECM's mid-ground scenario.

Starting to cloud over here; some of them fairly dark. Also some light prep developing over the Forth.

Hard to say, but looks like the showers to the North are pepping up a little? Maybe some might make it south.

Certainly some heavy cloud coming down from the north/up Iceland way.

I've been tracking a few showers heading towards Perth, but they are fast fizzling out - still might see a few flakes though. They do appear to be a bit heavier and in lines running from the Northwest highlands southeast, but the highlands will take the brunt as usual I suspect.

[LadyPakal]

Well, I timed that badly... I let the cats out for a first wander in their new garden, figuring the snow would stop them wandering too far (neither are that keen on it). Sun was shining, both headed next door (d'oh!).

Anyway, she came in when the first heavy snow came (sensible girl). No sign of him through the second fall - despite me calling. My neighbours now probably think I am loopy as I wandered about in the garden in a snow storm calling 'Ralphie'. Anyway he finally came back in the middle of the third snowfall - almost totally white (hard to do on a long haired dark brown tabby). He's not showing any inclination to want to go back outside at the moment.... Besides he's busy cleaning the mud off his tummy - no idea where he managed to find mud... I guess they are like kids in that respect.

SOme of these snow showers are really quite heavy - bright sunshine one second, snow storm the next - I like!

[Highland Snow]

Snow flurries in Perth. Temp. +3.2C DP -2.6C.

[Snowplough33]

If the latest GSF offering is correct........fear not.............

Remember December time was ace!!!

[Northernlights]

Some serious looking snow showers coming of the Firth from the north towards us and heard a warning for snow and on the tractor 40 minutes ago from the local radio station for Invernes, Moray and Aberdeenshire.Currently 0c and Nw wind strengthening.

[Snowplough33]

WOW, this is the Huntly cam at 1730......

[Sunny Leith]

Thanks for that LS ... bloody hell thats a comprehensive piece of work you've put together there !

I don't think we need any kind of vote from the Scottish thread to appoint you as our model representative, just consider yourself elected :lol::lol:

Firstly, BFTP has informed us that this December and January period as a whole has been the coldest ON RECORD in Scotland. Although this sounds slightly implausible if you think about it most winters have either a December cold spell and late January mild spell (81/82) or have a very cold winter which only sets in at the beginning/middle of January(47, 62/63). Impressive to see this occur in this rapidly warming world where this isn't actually possible!

Anyway, that's enough tongue in cheek comments from me!

To explain why the UK outlook from the Met is as such, we must look at not the raw model output so much as the background - there is no raging zonality forecast (almost though on the UKMO), with the AO and NAO both negative, it is merely that we are in the wrong position to take advantage of it AT THE MOMENT. http://www.meteociel...1-120.GIF?31-12 High pressure to both our northwest and northeast is there, but because they refuse to link up due to the Scandi trough, we are stuck in yet another no man's land scenario, with neither the polar maritime air from the northwest or the continental air from the east dominating, though the atlantic isn't hugely dominant either (note the low is quite favourably tilted to undercut on the ECM +120). Also note the jet is tracking to the south, meaning that high pressure is less likely to build to our south and leave us in a b-word scenario. http://www.meteociel...4-144.GIF?31-12

So what does all that mean for us? Firstly we have a fairly wet afternoon and evening tomorrow, with a warm front moving across, bringing temporarily milder uppers and higher dewpoints. To start with, the first, weaker band might be snow or sleet for central areas, but this fizzles out fairly quickly

Behind this, the cold air floods back in - http://charts.netwea.../h850t850eu.png - bringing showers to the areas which have benefited from snow in the last few days http://charts.netwea...6/51/ukprec.png.

Widespread frost on Tuesday night also http://charts.netwea...5/ukmintemp.png

A dry cold day Wednesday with another harsh frost (harsher than suggested for some I expect) to follow http://charts.netwea...6/ukmintemp.png

This is where the models diverge: GFS brings in southeasterly winds http://charts.netwea.../102/ukwind.png courtesy of this low http://charts.netwea...108/h500slp.png

This brings a band of precipitation, which in this instance would be snow http://charts.netwea.../108/ukprec.png http://charts.netwea...8/ukmaxtemp.png http://charts.netwea...hgt500-1000.png

The ECM says the PPN will not get this far http://en.vedur.is/p...31_0000_114.png but due to a less favourable tilt the slightly less cold uppers do http://en.vedur.is/p...31_0000_114.png

The UKMO doesn't just wreck our cold upper though, it sends milder air right across continental europe, something no other model supports http://www.wetterzen...ics/Rukm961.gif http://www.wetterzen...cs/Rukm1441.gif By +144 Euro high is almost inevitable.

The ECM at this stage, though hardly cold, has potential for a cold spell, with height rises to the north and lows looking to track to the south of the UK http://www.wetterzen...cs/Recm1441.gif.

The difference with the GFS is the better tilt of the low, which allows cold uppers to hang on across Scotland http://charts.netwea.../h850t850eu.png

http://charts.netwea.../141/ukprec.png

These showers would be quite marginal, but probably inland would be cold enough for snow. Of course, by this stage, the outlook is fairly uncertain, but slight changes in the angle of the trough and strength of blocking to the north are likely to completely change the 144 hour charts towards the mild UKMO or potentially snowy GFS, or perhaps the ECM's mid-ground scenario.

I've been tracking a few showers heading towards Perth, but they are fast fizzling out - still might see a few flakes though. They do appear to be a bit heavier and in lines running from the Northwest highlands southeast, but the highlands will take the brunt as usual I suspect.

[LomondSnowstorm]

Thanks for that LS ... bloody hell thats a comprehensive piece of work you've put together there !

I don't think we need any kind of vote from the Scottish thread to appoint you as our model representative, just consider yourself elected

Lol, the funny thing is, it's totally out of date now!

[Sunny Leith]

I have to come clean SP33 ... we'd scraped our pennies together to head off to Tenerife in a couple of weeks...

All that GFS reverse zonality that might have" shut down the UK" (to quote one of the more rabid model watchers) ... was looking like throwing the southern jet right over the Canary Islands. Now that armageddon scenario is looking unlikely I can think about drinking cold lager on the beach-front again.

Phew ... throw another shrimp on the barbie and someone throw me a cold one :lol:

If the latest GSF offering is correct........fear not.............

Remember December time was ace!!!

[Snowplough33]

The A90 southbound of Aberdeen is down to single track.

[

Phew ... throw another shrimp on the barbie and someone throw me a cold one

[LadyPakal]

The A90 southbound of Aberdeen is down to single track.

Yes, there have been a successsion of heavy showers in the last few hours. :lol:

[Snowplough33]

Yes, there have been a successsion of heavy showers in the last few hours.

Heaps of them pushing down on the radar.........enjoy!!

Actually, they have made it as far as Laurencekirk. LSS...........eyes to the radar!!!!!!!!

Edited January 31, 2010 by Snowplough33

[Cheggers]

Not sure what is going to happen here over night, in last hour cloud came went, temp went from 0.3 to 1.5 and now back to 0.1!!!!!

Great update LS, can safely say with you around who needs the temper tantrum thread.

[Scottish-Irish Skier]

I've been tracking a few showers heading towards Perth, but they are fast fizzling out - still might see a few flakes though. They do appear to be a bit heavier and in lines running from the Northwest highlands southeast, but the highlands will take the brunt as usual I suspect.

Excellent summary LSS. Such well balanced views with all options on the table are sadly missing from the model thread most of the time.

Seems the showers are getting further south since I last checked. Fun now reaching some in the Perthshire area.

Lol, the funny thing is, it's totally out of date now!

Lol.

A bit like painting the forth bridge eh?

You just post your in-depth analysis of the models at the moment the next lot of predicitons come out, all showing completely the opposite.

A definite swirl in that heavy cloud near orkney at the mo; the source of some heavy showers. Is that the evening express from spitzbergen? Just hoping it's not a part route only.

Edited January 31, 2010 by scottish skier