12z Model discussion - rain, sleet or snow?

[wellington boot]

Does anyone have any satalite pictures of whats been going on to the system approaching us for thursday?

You can see the cloud massing

http://www.netweather.tv/pages/charts/noaa...061629-mcir.jpg

[surfersparks]

but thats not good news... if mild air does get in or near, the snow will readily melt at lower levels, assuming it settles at all..

sorry to be so cynical, but ill believe all this when i see it!

Much as I would love to see lots of snow I think this is a very healthy attitude to take and if you know whats good for you you'd do the same...saves you and your kids a lot of dissapointment. Despite that I'll still be up till early hours model ( and lamp post ) watching ...just in case

[wellington boot]

You can see the cloud massing

http://www.netweather.tv/pages/charts/noaa...061629-mcir.jpg

I hasten to add we're not looking at that block of cloud just of the south west with reagards to thursday. Thats tracking into france tonight and tomorrow i think. Its the general movement of a band of cloud comign up behind and into position which is relevant.

[Nick F]

Oh dear im ashamed :blush: . What a lapse. I thought they corresponded somehow, the colours and the DAM readings. Because if you actually use the colour coding, the number match up surprisingly accurately.

http://www.wetterzentrale.de/pics/Rtavn061.png

http://www.wetterzentrale.de/pics/Rtavn063.png

The '528' lines on both charts are almost in identical positions!

Anyway, thanks, thats an embarassing hole patched up.

Easy mistake to make, took me while until I realised a few years ago, but those colours showing 500mb heights on the WZ pressure charts are a different entity to the 500-1000mb thickness lines, such as the 528 DAM line, and shouldn't be thought as the same - even if the numbers for both do match,

for example, the 500mb geopotential height chart for t+96 shows an area of green between Iceland and Norway suggesting the 500mb pressure height is above 536 gpdm (or 5360m asl) - indicating high pressure at 500mb:

http://www.wetterzentrale.de/pics/Rtavn961.png

... while the 500-1000mb chart for t+96 shows the air is below 528 DAM - so the air below 500mb is cold with thicknesses low:

http://www.wetterzentrale.de/pics/Rtavn963.png

[swfc]

If i can make a post"without it being deleted for some biased reason", my take on thursdays snow is that the low will be towards the midlands max, and areas towards birmingham south will see a good fall of snow.Come saurday i think the models have probably got it right and any snow will be further north before it turns milder.Forty five years of forecasting and i know nothing, apparently. :blush: :blush:

[cheshire cat]

cartedj

Great link that pal

Edited February 6, 2007 by cheshire cat

[bennytes]

why are people so pessimistic?

TOTAL amateur on weather matters here, but over the few years I've lurked on here, I've seen LOADS of times when everyone gets all excited on here, only for the low to dive into France and give them the goods at the last moment.

IF, and I know it's only an IF at the moment, this low dives(maybe ''dives'' is the wrong word?) south as well, as it could well do based on past incidences, then yes, we in the south will get a battering, but the LONGER term prospects will improve for all of us, won't they?

or am I reading the situation wrong?

personally, I'm expecting it to take a more southerly track, based on gut instinct, nothing more.

sorry if I'm posting this on the wrong thread BTW, I know you mods are hot on that! :blush: :blush:

[ribster]

So where's west? I just wondered how far south his no snowfall prediction spreads, as parts of suffolk, such as Framlingham and Saxmundham have had significant, lying snowfall today. Or is that not far south enough.... :blush:

Edited February 6, 2007 by ribster

[Paul]

Will be locking this in around 30 mins to make way for the 18z's.

Just to let you know while I'm here, many of you have asked whether we can have a monthly option for radar access. Well now it's available - you can have full access to the 5 minute radar and all its features for just £3.49 a month. More information and instant access is available here:

https://www.netweather.tv/secure/cgi-bin/login.pl

There won't be a better way to follow the action this week!!!

[Nick F]

Looking at the 12z ECM/GFS 8-10 day height comparisons, the ECM suggests upper ridging between Greenland and Scandi up across the Barents Sea/Arctic with a slight retrogression of the PV over the Atlantic - possible fodder for a Scandi high down the line but also risk of some warm S'erlies across UK worse if the Scandi high doesn't ridge far enough West.

GFS less keen on such strong ridging and keeps the PV close to our West fuelling cyclogenesis and milder wet and windy weather into the medium term. It's advantge though maybe that it would steer the jet further South than the ECM.

With FI rather close atm, it's hard to say where things will progress towards, but with heights staying fairly high to our NE and over the Arctic, with not too much sign of the PV returning to it's favoured postion over the poles, I think there's plenty to be optimistic about for February.

[PB22]

So where's west? I just wondered how far south his no snowfall prediction spreads, as parts of suffolk, such as Framlingham and Saxmundham have had significant, lying snowfall today. Or is that not far south enough....

Sorry, off topic, but yes, have 2cm of lying snow tonight here.

[wellington boot]

cartedj

Great link that pal

Yes thats a really nice link. Cheers matey

[pinball wizard]

Im really confused looking at the models, I dont pretend to be anything more than an enthusiast, and am certainly no expert though I do try and learn more about reading charts and forecasting. I'm really not sure about prospects for Suffolk, my head is telling me im going to be on the wrong side of marginal, and probably receive sleet, whilst further north into Norfolk and westwards they will see snow. I know someone said earlier that the 528 was not the be an end all, but it always cited as a good marker. Looking at progged temps and the 0c isotherm it would seem like it may be cold enough if the ppn hits in the night time, but that it would rapidly turn more mushy later. Anyone care to offer some expert or more expert opinion to this situation here in East Anglia?

[wellington boot]

Easy mistake to make, took me while until I realised a few years ago, but those colours showing 500mb heights on the WZ pressure charts are a different entity to the 500-1000mb thickness lines, such as the 528 DAM line, and shouldn't be thought as the same - even if the numbers for both do match,

for example, the 500mb geopotential height chart for t+96 shows an area of green between Iceland and Norway suggesting the 500mb pressure height is above 536 gpdm (or 5360m asl) - indicating high pressure at 500mb:

http://www.wetterzentrale.de/pics/Rtavn961.png

... while the 500-1000mb chart for t+96 shows the air is below 528 DAM - so the air below 500mb is cold with thicknesses low:

http://www.wetterzentrale.de/pics/Rtavn963.png

Thanks for the clearing up. I guess i just never looked closely enough/though hard enough about it before to work out what was going on.

[Surrey Snowstorm]

Is there any chance the snow band could be pushed south again later in the day?

[scotto]

How far north would people expect this snowband on thursday to extend, as i am new to this and not sure what to expect for my part of the world in south Lincolnshire.

[Bobby]

How far north would people expect this snowband on thursday to extend, as i am new to this and not sure what to expect for my part of the world in south Lincolnshire.

It will move North up through the UK but the worst hit areas will be Wales and Midlands - the band will weaken quickly as it moves North. Can't see much from say Newcastle north.

[Surrey Snowstorm]

But could it push south again?

[PB22]

Im really confused looking at the models, I dont pretend to be anything more than an enthusiast, and am certainly no expert though I do try and learn more about reading charts and forecasting. I'm really not sure about prospects for Suffolk, my head is telling me im going to be on the wrong side of marginal, and probably receive sleet, whilst further north into Norfolk and westwards they will see snow. I know someone said earlier that the 528 was not the be an end all, but it always cited as a good marker. Looking at progged temps and the 0c isotherm it would seem like it may be cold enough if the ppn hits in the night time, but that it would rapidly turn more mushy later. Anyone care to offer some expert or more expert opinion to this situation here in East Anglia?

Its hard to call! I would say it will start as snow at least, then its a case of how quickly it turns to rain...if it does. Its beginning to look like it will get as far as Norfolk and Suffolk before dying out, and the colder air moves back south again. I would suggest some snow, before easing off to drizzle.

[Bobby]

But could it push south again?

Hmm, a small possibility. But if it did it would be very weak and probably only just bring cloud or light patchy flurries.

[Paul]

Locking this one now - new thread for the 18z's:

http://www.netweather.tv/forum/index.php?showtopic=36257