South West England Cold Spell Discussion

[Iceberg]

Iceberg, how early is that graphic? There seems to be a pesky 1 right on top of where I live!

That said, its a glorious day today, when I left there was a mini ice pack where the water was running down the road... now 3 inches thick and growing. Looks pretty impressive (more so that its just to the side of the road and passable... unless you fly around the corner )

It's from the latest 06Z, UK MESO model, and covers a 48 hr period, however I would say it's not going to be totally accurate so if you have a 4 on top of you, you might have a 2 by the 12Z or even a 7

The distribution of snow won't be fully known even tomorrow.

Hopefully people in the SW will start to believe though that there will be a good general covering for most of us, before the real heavy stuff comes fri/sat/sun .....

[Dartmoor_Matt]

It's from the latest 06Z, UK MESO model, and covers a 48 hr period, however I would say it's not going to be totally accurate so if you have a 4 on top of you, you might have a 2 by the 12Z or even a 7

The distribution of snow won't be fully known even tomorrow.

Hopefully people in the SW will start to believe though that there will be a good general covering for most of us, before the real heavy stuff comes fri/sat/sun .....

I was under the impression that event was fast fading from the horizon on the latest runs, or is that simply because the SE isn't getting the snowmageddon it thought it was? Take some things you read in the MO with a pinch of salt... or a gritter load (pardon the pun)

[Mark Parsons]

Morning all. Got down to -5.2 here in Bridport last night!

[theprophecyman]

Covering all bases then

South West England: Bath + NE Somerset Bournemouth Bristol Cornwall & Isles of Scilly Devon Dorset Gloucestershire N Somerset Plymouth Poole S Gloucestershire Somerset Swindon Torbay Wiltshire Widespread Icy Roads Tue 5 Jan There is a moderate risk of severe weather affecting Wales and southwest England. Outbreaks of rain, sleet and snow during Tuesday morning will fall onto subzero surfaces leading to widespread ice on untreated surfaces.

Issued at: 1114 Mon 4 Jan

[Ripeberry]

Well we can be sure of one thing...it will be a skating rink out there in the morning

I'm getting the tarpaulin out tonight and covering the car up as I don't fancy spending all of

tomorrow morning, chipping frozen rain off the car. It was -7.2c this morning at 7am and now at

11.30am it is still -3c with drifting freezing fog.

But it is so beautifull went you get out into the sunny spots as everything is white!

[03jtrickey]

Could well be an ice day today! Temp is still -1.8.

Off in a bit to the local nature reserve, to have a look at the rime-covered trees and may take some pics.

[dogs32]

For Tuesday

[03jtrickey]

Dogs - I bet the Midlanders are moaning incessantly at the nothingness that is shown over them!!!!

[Snowfan50]

I this pep on its way dosent fall as snow i give up. Was a cold night, -3 at about midnight kept waking up from the cold. 0c here now.

[kumquat]

So is that the front that can be seen over Northern Scotland now? What is the expected ETA of the front say to Bristol tomorrow? Any idea. Also about this wrap-around - does that mean we have two bands passing through?

Many thanks!

[Guest North Sea Snow Convection]

I was under the impression that event was fast fading from the horizon on the latest runs, or is that simply because the SE isn't getting the snowmageddon it thought it was? Take some things you read in the MO with a pinch of salt... or a gritter load (pardon the pun)

I'm actually hoping that the armegeddon doesn't materialise for the SE. Would be nice for life to carry on comfortably whilst enjoying the snow without the need for anything more extreme that cuts off our everyday essential needs.

There is going to plenty of snow over the coming few days anyway. And by the looks of things most of us will get snow at some stage

[Cakie]

I hope it doesn't fall as rain tomorrow. We had -6c at Exeter Airport this morning and if it falls as rain tomorrow there will be chaos on the roads

[MP-R]

Fantastic day for weather here today. Alternating spells of clear sunshine and thick drifting fog. As such the temperature is still well down at -2.9C. Perhaps we can keep it below freezing and have an ice day

Here's hoping for some more exciting weather over the coming days.

[03jtrickey]

Temp still low at -1.4. I think we are in for an ice day now, unless the temperature rises overnight ahead of the front. Yes, the wraparound means that some parts will have two bands of sleet/snow.

[Dartmoor_Matt]

If anything it feels colder now than earlier. Suffice to say if nothing else there will be plenty of surface cold around, I can't see how a warm sector will be present over the SW if the front has moved down over the UK with no warm sector so I'd say odds on for snow away from the extreme coastal regions?

[kumquat]

Temp still low at -1.4. I think we are in for an ice day now, unless the temperature rises overnight ahead of the front. Yes, the wraparound means that some parts will have two bands of sleet/snow.

Thanks JT!

[dogs32]

Dogs - I bet the Midlanders are moaning incessantly at the nothingness that is shown over them!!!!

yea...they are laughing...got to admit this is funny,Im sure it will change later..

[SteveB]

I just want some snow, will be happy with a light covering tomorrow, please don't be rain.

[dogs32]

I just want some snow, will be happy with a light covering tomorrow, please don't be rain.

Good chance of a small dumping I reckon....

Look forward to Ian comment's later.

Im going for 2cm-15cm in some places..

some places seeing the deadly Freezing Rain.

It's going to be luck of the draw

[yamkin]

I posted this on TWO earlier in relation to a very similar question.

"The latest 06Z GFS guidance soon to be updated with the 12Z release shows a Theta-e profile of +14 tied into the warm sector - which would lend an approximately 80% chance of snow to MSL under the assumption that PPN is moderate/heavy or prolonged for a period >30 minutes. Therefore ground above 100M or 75> would support a 98% chance of snowfall. Note the Theta-e +14 is only projected for Devon, Cornwall and the extreme coastal areas of Dorset at T+60 Tuesday 5th 18Z with cooler air still +12 slightly inland. The adjustment would take the 0oC isotherm down to 30M or less - basically to MSL. Through the period 5th January 18Z, 21Z, 00Z into 6th the Theta-e profile drops to +12 and +10 with the channel low projection simulating moderate to heavy PPN. This would almost certainly lead to snowfall inland across the South 1 mile or more away from the coast and it would only take 20 minutes or more of PPN falling near the coast at moderate intensity for the isotherm to lower 100M. It's all rather speculative of course at the minute because the specifics will change - but with a T850 BL wavering between -7/-8 and DP profiles in the region of 0 or -1 then it really does become less marginal than what one would assume. As for the far SW - I would imagine DP is a little higher - but snow to higher ground across Dartmoor would be likely and eventually after 30 minutes of PPN to lower levels being primarily transient - MSL snowfall would be possible. We await the 12Z to see if this channel low can verify 3/4 runs on GFS - also the 12Z NAE will be coming into resolution for this forecast period, at least the version we get will"

Although at first glance it would appear to be some-what complicated in nature - a good indicator of snowfall to the surface can be gauged by taking the Potential Equivalent (Theta-e) +14 as a marker. You do generally need to make some manual adjustments based on local variations such as surface tempertures projections, dew point and the topography (terrain) that is locally being forecast for - but a general rule of thumb is a theta-e gradient of +14 or Theta-WB +3 would deliver a 0oC isotherm to MSL (surface) in moderate intensity PPN events associated or tied into frontal systems that belong to a warm sector environment entrained in a depression. It's around 80% probability - ideally <12 Theta-e would indicate an almost perfect probability for PPN descending in hydrometeor form to turn to snow or a wintry varietal that will accumulate in nature. I often find that some-times the lower planetary layer of the atmosphere around 1000-850mb tends to have a high humidex profile - which again can hinder or slow down the transient nature or process of rain > snow. This is why, preferably in heavy PPN events it's advantageous to have a dry profile to enhance evaporative cooling induced by melting known as the isothermal melt layer. Anyway - current GFS 18Z guidance simulates Theta-e profiles T850 to be +14 tied into the warm sector - so you would assume that there is a warmer lower layer - so 100M isotherm could get eroded reasonably easy with a shower that is 10 minutes or more in length and of moderate intensity phasing.

Good to see some familiar faces on here.

Hi Thermohaline Conveyor, Very informative info. I would like to commend you on your latest null Weather Warning

This is a news release issued for the % risk of severe or extreme disruption during the period 5th - 15th January 2010. Major snowfall and extremely cold weather is on the way. This news release will be reviewed from the 7th with scope for an upgrade or update.

As many of you will be aware by now, the mercury is beginning to plunder and with it the risk of severe cold will increase as we move through into the weekend and more especially next week. We are now becoming increasingly confident that the main threat will be for Eastern areas of Britain with quite a high risk of significant snowfall, widespread severe frosts and at times blizzard conditions.

We have issued a moderate/high threat for many parts of the country including Central Southern/Southern England and some Central Areas for the possibility of Severe to Extreme disruption to travel networks, power and infrastructure. Right now the specifics remain unclear – but areas outlined are unlikely to change much.

We anticipate that numerous bands of snow will affect large portions of the United Kingdom – especially the North, East and South East. Temperatures will struggle to rise above freezing for many with severe to extreme frosts becoming a common feature. The concern is with temperatures so low during the day and at night, any snow that does fall will likely accumulate quickly and stick around for a long period.

Lengthy periods of snow on the ground will lead to major disruption and the extent of the snowfall depths although varying quite significantly at the moment – will in some locations be very deep. We would strongly advise to be prepared for a very difficult and challenging 10 days ahead. Please check with your local airport before flying and leave extra time before travelling. When possible, in the worst affected areas it is advisable to avoid travelling altogether. If avoiding travel is impossible then making sure you equip the car with winter essentials is strongly advisable.

[Lynxus]

I think i may put a blanket and shovel in my car this week, just to be safe. It looks like anything could happen at the moment.

[Jonesywilliteversnow]

i think we will be seeing a post from ian in the next 15 mins

[Iceberg]

and it will be good news, because the models 06Z are very good for the next 72 hrs.

[butler_son]

Hi Thermohaline Conveyor, Very informative info. I would like to commend you on your latest null Weather Warning

This is a news release issued for the % risk of severe or extreme disruption during the period 5th - 15th January 2010. Major snowfall and extremely cold weather is on the way. This news release will be reviewed from the 7th with scope for an upgrade or update.

As many of you will be aware by now, the mercury is beginning to plunder and with it the risk of severe cold will increase as we move through into the weekend and more especially next week. We are now becoming increasingly confident that the main threat will be for Eastern areas of Britain with quite a high risk of significant snowfall, widespread severe frosts and at times blizzard conditions.

We have issued a moderate/high threat for many parts of the country including Central Southern/Southern England and some Central Areas for the possibility of Severe to Extreme disruption to travel networks, power and infrastructure. Right now the specifics remain unclear – but areas outlined are unlikely to change much.

We anticipate that numerous bands of snow will affect large portions of the United Kingdom – especially the North, East and South East. Temperatures will struggle to rise above freezing for many with severe to extreme frosts becoming a common feature. The concern is with temperatures so low during the day and at night, any snow that does fall will likely accumulate quickly and stick around for a long period.

Lengthy periods of snow on the ground will lead to major disruption and the extent of the snowfall depths although varying quite significantly at the moment – will in some locations be very deep. We would strongly advise to be prepared for a very difficult and challenging 10 days ahead. Please check with your local airport before flying and leave extra time before travelling. When possible, in the worst affected areas it is advisable to avoid travelling altogether. If avoiding travel is impossible then making sure you equip the car with winter essentials is strongly advisable.

I've alluded to this on the Midlands thread, but I'm more worried by the violent theft being committed by the mercury! :unsure:

[slinky1989]

-1.4c in swindon. Could be an ice day?

Here at work in bath though, we seemed to be inside a snow cloud earlier as the air was thick with ice particles blowing around and leaving a white layer on most things.