South West & Central Southern England Regional Discussion 22/03/13 08z ----->

[khodds]

There looks to be a squall line developing coming up from France across to Cornwall on the radar.. Unless my eyes deceive me.

[coffee lover]

There looks to be a squall line developing coming up from France across to Cornwall on the radar.. Unless my eyes deceive me.

I see it as well....

[A.J]

GFS06z rolling out, and whilst some consider it the most unreliable run of the day, it has to be said that there are a few subtle variations on positioning and distribution of ppn/snowfall tonight/tomorrow for parts of the region.....To my eye, an increased risk of settling snow in Oxon/Gloucs/Wilts/Berks as the output shows PPN slightly further south on this run, with colder T850's undercutting from the NE more readily (The 0C T850 boundary line moves into BANES as well as the above mentioned areas later on tonight and into tomorrow thus turning precipitation more wintry.....Still rain I'm afraid for Devon/Cornwall/Dorset and most of Somerset, but this little analysis is just my view on this one particular model.....The hi-res NMM (due out in the next few minutes) and subsequent GFS/ECM/NAE runs this afternoon might add a different complexion

[khodds]

It's already very gusty... Not going to like it when it passes thru.. (If it does)

[khodds]

Rain just started here now

[Frosty_wsm]

Chucking it down here at the moment, cold and miserable out there!

Edited March 22, 2013 by Smartie

[Argyle1980]

Clearing up in Truro now. :-)

[jessandjon]

Will we get anything from this squall line?

[A.J]

Ok, the hi resolution 06z NMM is now out and I'll post a series of charts in time snapshot format to hopefully give an understanding of snow potential. Of course there will be some IMBYism to this post, but alas the snow risk as it currently stand does not make much inroads into our region on current modelling.....

All images © NetWeather.tv

ok, the first charts are for 0300z Saturday, and show PPN type, the height of the 0c isotherm (which gives a good indication of the altitude of the wet bulb freezing levels), Dew points, & lastly the lower atmosphere thickness known as the 850-1000 hpa thickness charts (this chart gives an indication as to how warm or cold the air in that layer is, in this case the lowest part of the atmosphere...the lower the figure the colder, the higher, the warmer.......to have a chance of snow the value needs to be lower than 1300m)..

Subsequent charts will be shown on a 2 hourly interval so you can see the subtle changes and trends towards more wintry precipitation as we move into saturday daytime

0300z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0500z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0700z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0900z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

1100z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

So in summary the NMM hi-res output concurs with the latest GFS run which subtle shifts south and east of the associated precipitation giving an increased risk IMO for snow to northern and eastern parts of the region as we move into saturday, whilst for the majority of the region the precipitation will fall as rain given the unfavourable atmospheric parameters for those parts of the region

[Costa Del Fal]

Yep brightening skies..ish in west Cornwall which is earlier than expected.

[coffee lover]

Will we get anything from this squall line?

Not sure, but become very windy here over the last half hour... with some very strong gusts...

[Mark Neal.]

Ok, the hi resolution 06z NMM is now out and I'll post a series of charts in time snapshot format to hopefully give an understanding of snow potential. Of course there will be some IMBYism to this post, but alas the snow risk as it currently stand does not make much inroads into our region on current modelling.....

All images © NetWeather.tv

ok, the first charts are for 0300z Saturday, and show PPN type, the height of the 0c isotherm (which gives a good indication of the altitude of the wet bulb freezing levels), Dew points, & lastly the lower atmosphere thickness known as the 850-1000 hpa thickness charts (this chart gives an indication as to how warm or cold the air in that layer is, in this case the lowest part of the atmosphere...the lower the figure the colder, the higher, the warmer.......to have a chance of snow the value needs to be lower than 1300m)..

Subsequent charts will be shown on a 2 hourly interval so you can see the subtle changes and trends towards more wintry precipitation as we move into saturday daytime

0300z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0500z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0700z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

0900z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

1100z

PPN type 0C isotherm height

Dewpoint 850-1000 thickness

So in summary the NMM hi-res output concurs with the latest GFS run which subtle shifts south and east of the associated precipitation giving an increased risk IMO for snow to northern and eastern parts of the region as we move into saturday, whilst for the majority of the region the precipitation will fall as rain given the unfavourable atmospheric parameters for those parts of the region

Thanks for that detailed explanation AJ

Looking good here, GFS,NAE and NMM all a upgrade for here this morning. Met Office going for 8 hours of heavy snow here through early hours and sat morning :-)

[A.J]

Thanks for that detailed explanation AJ

Looking good here, GFS,NAE and NMM all a upgrade for here this morning. Met Office going for 8 hours of heavy snow here through early hours and sat morning :-)

yes, looks very good for you Mark, substantial snow if the model output is correct...send it all 30 miles to your south west and I will be one very happy camper!

[Mark Neal.]

yes, looks very good for you Mark, substantial snow if the model output is correct...send it all 30 miles to your south west and I will be one very happy camper!

I'm happy to do that, we've had more than some of you lot as a whole this winter.

I hope we all get surprises!

[Severe Siberian icy blast]

yes, looks very good for you Mark, substantial snow if the model output is correct...send it all 30 miles to your south west and I will be one very happy camper!

To be honest I think you will get some . Last night was meant to be rain all the way , I had an inch . Tonight we have cold air undercutting the ppn , the met o seem confindent of their warnings , so I expect Gloucestershire , Oxfordshire , will do very well , higher up the better , but I also expect snow lower down and into the areas further south , Im saying m4 north , maybe wet snow into Bristol area by dawn.

[03jtrickey]

I cycled from Oxford to Cheltenham last night and it was snowing heavily on the tops of the Cotswolds but not settling. Will be returning this afternoon.

[Bobd29]

To be honest I think you will get some . Last night was meant to be rain all the way , I had an inch . Tonight we have cold air undercutting the ppn , the met o seem confindent of their warnings , so I expect Gloucestershire , Oxfordshire , will do very well , higher up the better , but I also expect snow lower down and into the areas further south , Im saying m4 north , maybe wet snow into Bristol area by dawn.

cold front moving in slowly, main event after dark, strong easterly/sely wind, low dew points....nothing marginal at all for anyone north of the M4 and places like Cotswolds/Oxford/Warks could be quite interesting by Saturday lunchtime; not a day for travelling for sure stay safe people

[AWD]

I know this isn't our region, but I'm not exactly devastated missing out on the current conditions in the NW of the UK. This is the M6 in Lancashire;

That's a dangerous millimetre of wet snow there! :p

[Mapantz]

It was forecasted to be raining here all night and today, it stopped at 2am and we've had a brief spell of rain 15 minute ago, certainly not what they were forecasting.

[A.J]

I know this isn't our region, but I'm not exactly devastated missing out on the current conditions in the NW of the UK. This is the M6 in Lancashire;

That's a dangerous millimetre of wet snow there!

you still travelling up to Tamworth later on?...could be an interesting drive!

.

jack-knifed lorry?, awful weather?, cars bumper to bumper?........just your average friday afternoon on the M6....lol

Edited March 22, 2013 by ajpoolshark

[AWD]

you still travelling up to Tamworth later on?...could be an interesting drive!

Yeah. Got family up there so am going to see them anyway. Was going to go for the weekend but unless the snow situation improves up there and I get stranded there, I'll probably come back Saturday. If I can drive back, the snow has failed.

[noonoo418]

Don't know how people are reaching the conclusion that snow will be m4 north tonight. Met Office forecast for this area is very firmly rain.

[Mapantz]

Poor old Devon and Cornwall ..

Last 24 hour accumulations;

I've had 29.4mm since 7am yesterday and 23.4mm in the last 24hrs. It seems to tie up with the radar accumulative map.

[Andy Bown]

I was thinking while out working earlier that with some bright sunshine for an hour allied to a bitter SE gale force gusting wind that we need a new name for this late Winter/early Spring period.

So, do you prefer Sprinter or Wing?

Actually a little milder at the mo at 6.1c with rain easing off after a very heavy downpour for 45 minutes.

[Mapantz]

I was thinking while out working earlier that with some bright sunshine for an hour allied to a bitter SE gale force gusting wind that we need a new name for this late Winter/early Spring period.

So, do you prefer Sprinter or Wing?

Actually a little milder at the mo at 6.1c with rain easing off after a very heavy downpour for 45 minutes.

Sprinter and Sprummer for me!

Edited March 22, 2013 by Mapantz