Spring Model Discussion 25th March 2013 012z onwards

[mushymanrob]

Face it our location is some kind of government anti-snow experimental testing site

Agree with CreweCold and Ian on this there are no winners on the ecm run tonight (unless you like cold rain of course)

I have to admit I'm not looking forward to any warm easterlies later in the season. The East coast shall ring to the sound of foghorns methinks.

im a winner, i dont like cold rain, or warm rain, but at least i can work in rain. i cant in frost and snow!

[Purga]

Looks like a gradual rise to me.

I was talking about in comparison to the 00z and 06z ens which favoured the return to mild much more, the shift is downwardsa on the 12z

[snowking]

This evenings Glasgow ensembles then - Tmax and Tmin:

12z ECM Tmean (red) with GFS 12z Tmean overlaid (green)

So both ensemble sets in fairly good agreement, a likely continuation of the cold, at least for Scotland from these.

And then the today vs yesterday comparison

ECM 12z today (red) vs 12z yesterday (black)

Very little change

GFS 12z today (Green) vs 12z yesterday (Black):

Trend downwards today

And to finish off (why not!) ECM 12z vs 0z:

Pretty much as you were, a slight trend upwards towards day 15 vs the 0z.

SK

[Nick F]

Although I'd rather it wasn't, got a feeling the 12z ECM deterministic today maybe on the mild side of the ENS spreads in the south, seems a little too bullish to bring less cold air north compared to most other model operationals this evening.

So will be interesting to see the London NCEP/ECM ENS comparison later.

Normally it's the GFS that is the more bullish in bringing in less cold air in these highly blocked situations. ECM maybe have a little wobble and it could be back in the freezer for all the UK tomorrow as we head into early April.

Edited March 25, 2013 by Nick F

[SnowBallz]

I was talking about in comparison to the 00z and 06z ens which favoured the return to mild much more, the shift is downwardsa on the 12z

Purga is bang on.

Relative to the previous run(s), the 12z is very much a stark moderation of previously advertised sharply milder theme, and more towards a flatter recovery. The direction may remain the same, but it's the trajectory and rate of decay which implies a continuation of the current pattern, for a little while longer yet anyway.

[john mac]

Can anyone imagine if the low coming in made it a little further north and then gets stuck in the north sea, it would be absolute carnage!!!

[Carlrg]

We'll be getting penguins in the Thames if this carries on! (yes i know they're from the southern hemisphere, they're good swimmers)

http://www.meteociel...&ech=216&size=2

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=7&ech=216&size=2

http://www.meteociel...&ech=216&size=2

Edited March 25, 2013 by Carlrg

[snowking]

The dutch ensembles this evening:

Det at the top end of the members once again, but the control following can often precede a swing in the ensembles. The 0z should be more telling, but some hope there I'm sure for Gavin (and many more of us I suspect from the current public mood!)

SK

[fergieweather]

I see that the channel low forecast of just 24 hours ago on the Meto office based Countryfile forecast has now been downgraded.

Ah well it was good while it lasted.

Erm, OK - I think caution needed here - and also on some other elements of detail later this week:

Let's consider the broader evolution towards late working week. We have a slack upper trough, extending west essentially from the Baltic, which will ultimately become cut-off into a vortex over the north of the British Isles. In turn, it then slips away south, later to interact with an upper front over southern parts of the country. In doing so, it becomes fundamentally important... it's very likely to play a cornerstone role in what remains (despite what latest NWP deterministic output might outwardly suggest) a very delicate balance, between current dominance of the blocked cold air from north, versus Atlantic system(s) trying to move-up from the SW. Given a third of MOGREPS members succeed in this push - at least some to the Midlands by Fri-Saturday - it remains foolhardly to assume this particular story is already a 'busted flush'. It needs careful monitoring and remains very much on a knife-edge.

Meanwhile, the FAX at T+72 holds potential for some disruptive snow into SE/E Anglia areas. Why? Well, we have upper forcing strongly signalled in the UKMO-GM for that timeframe (in 2 successive runs now, with now good 12z EC support but none - again - from GFS) as the aformentioned cut-off vortex merges with a vorticity strip... as the resultant trough then sharpens quite markedly, it deepens the boundary layer convection and indeed EURO4 now offers potential for a few cm's of snow, e.g., across the South Downs; E parts of Kent, Suffolk & Nortfolk which could (stress *could*) prove somewhat disruptive in places, albeit the threat is low.

The key thing here is that nothing can be taken for granted later this week, despite what might outwardly appear a rather tedious pattern on face-value of the charts. The fine balance I stressed earlier in this post is just that, and could literally tip either way.

[john mac]

Erm, OK - I think caution needed here - and also on some other elements of detail later this week:

Let's consider the broader evolution towards late working week. We have a slack upper trough, extending west essentially from the Baltic, which will ultimately become cut-off into a vortex over the north of the British Isles. In turn, it then slips away south, later to interact with an upper front over southern parts of the country. In doing so, it becomes fundamentally important... it's very likely to play a cornerstone role in what remains (despite what latest NWP deterministic output might outwardly suggest) a very delicate balance, between current dominance of the blocked cold air from north, versus Atlantic system(s) trying to move-up from the SW. Given a third of MOGREPS members succeed in this push - at least some to the Midlands by Fri-Saturday - it remains foolhardly to assume this particular story is already a 'busted flush'. It needs careful monitoring and remains very much on a knife-edge.

Meanwhile, the FAX at T+72 holds potential for some disruptive snow into SE/E Anglia areas. Why? Well, we have upper forcing strongly signalled in the UKMO-GM for that timeframe (in 2 successive runs now, with now good 12z EC support but none - again - from GFS) as the aformentioned cut-off vortex merges with a vorticity strip... as the resultant trough then sharpens quite markedly, it deepens the boundary layer convection and indeed EURO4 now offers potential for a few cm's of snow, e.g., across the South Downs; E parts of Kent, Suffolk & Nortfolk which could (stress *could*) prove somewhat disruptive in places, albeit the threat is low.

The key thing here is that nothing can be taken for granted later this week, despite what might outwardly appear a rather tedious pattern on face-value of the charts. The fine balance I stressed earlier in this post is just that, and could literally tip either way.

Fantastic and imformative post ian, thanks for that mate. An interesting weeks model watching to come

[Mark Parsons]

I see that the channel low forecast of just 24 hours ago on the Meto office based Countryfile forecast has now been downgraded.

Ah well it was good while it lasted.

Interesting response there mate from our learned friend! Still, miracles can happen!!

[Snowman.]

Erm, OK - I think caution needed here - and also on some other elements of detail later this week:

Let's consider the broader evolution towards late working week. We have a slack upper trough, extending west essentially from the Baltic, which will ultimately become cut-off into a vortex over the north of the British Isles. In turn, it then slips away south, later to interact with an upper front over southern parts of the country. In doing so, it becomes fundamentally important... it's very likely to play a cornerstone role in what remains (despite what latest NWP deterministic output might outwardly suggest) a very delicate balance, between current dominance of the blocked cold air from north, versus Atlantic system(s) trying to move-up from the SW. Given a third of MOGREPS members succeed in this push - at least some to the Midlands by Fri-Saturday - it remains foolhardly to assume this particular story is already a 'busted flush'. It needs careful monitoring and remains very much on a knife-edge.

Meanwhile, the FAX at T+72 holds potential for some disruptive snow into SE/E Anglia areas. Why? Well, we have upper forcing strongly signalled in the UKMO-GM for that timeframe (in 2 successive runs now, with now good 12z EC support but none - again - from GFS) as the aformentioned cut-off vortex merges with a vorticity strip... as the resultant trough then sharpens quite markedly, it deepens the boundary layer convection and indeed EURO4 now offers potential for a few cm's of snow, e.g., across the South Downs; E parts of Kent, Suffolk & Nortfolk which could (stress *could*) prove somewhat disruptive in places, albeit the threat is low.

The key thing here is that nothing can be taken for granted later this week, despite what might outwardly appear a rather tedious pattern on face-value of the charts. The fine balance I stressed earlier in this post is just that, and could literally tip either way.

Essex at all in that?

You went through half the East coast but missed me out which has me worried.

[UV-RAY]

Although I'd rather it wasn't, got a feeling the 12z ECM deterministic today maybe on the mild side of the ENS spreads in the south, seems a little too bullish to bring less cold air north compared to most other model operationals this evening.

So will be interesting to see the London NCEP/ECM ENS comparison later.

Normally it's the GFS that is the more bullish in bringing in less cold air in these highly blocked situations. ECM maybe have a little wobble and it could be back in the freezer for all the UK tomorrow as we head into early April.

I can't see any significant pattern change to milder comditions for the next two weeks at least, the long wave pattern has almost become set in stone. Looking at the CFS charts for the rest of spring and none of them scream warm, average at best, but after the last month average will feel like a heatwave.

[fergieweather]

Essex at all in that?

You went through half the East coast but missed me out which has me worried.

To be fair I could list innumerable places shown more than trace snow amounts in the EURO4 but that sort of detail pointless at this stage. Suffice to say some focus of snow amounts exists for some eastern districts in the prognosis.

[Isabellesnanny]

To be fair I could list innumerable places shown more than trace snow amounts in the EURO4 but that sort of detail pointless at this stage. Suffice to say some focus of snow amounts exists for some eastern districts in the prognosis.

What stage of the week are we looking at here - apologies the model reading still very poor ?

[Hotspur62]

What stage of the week are we looking at here - apologies the model reading still very poor ?

Think we are looking at Thursday/Friday period this week but if IF is correct i think you may be too far west to be affected.That said,i think matters will need to be monitored closely as these things are always subject to change at short notice.Hope this helps

[Cheshire Freeze]

As you were at 144...

Looks quite similar to the UKMO solution.

[Purga]

Thanks for an excellent and considered post Ian, so the South Downs (Sussex) could be in with a shout then for a few cm? I appreciate it's very marginal and uncertain but it's nice to at least be in the frame with a not insignificant percentage chance of snow. Thanks again.

[shaky]

As you were at 144...

Looks quite similar to the UKMO solution.

Frigid chart!!hopefully ecm will come to the party in the morning!!

[Bill davis]

I'm hoping we get some mild weather soon. Nothing enjoyable about seeing sheep and other live stock buried alive in snow, as seen on the news. Snow is fun, but not at the risk of life whether human or animal IMO

[peterf]

I'm hoping we get some mild weather soon. Nothing enjoyable about seeing sheep and other live stock buried alive in snow, as seen on the news. Snow is fun, but not at the risk of life whether human or animal IMO

Dont start until the 18th here,fingers crossed.

[Purga]

Looks like there may a bit of snow for the south / SE and NE over the next 24 hrs or so

Not a lot but nice to see.

Edited March 25, 2013 by Purga

[damianslaw]

The jet is forecast to stay on a very southerly course, are we about to exchange à easterly for a northerly i wonder, à polar low would top it all, and the chart above looks ripe for polar low developments, such synoptics are more likely in april than any other time of year, this is the time of year when the atlantic goes into slumber mode.

[Cheshire Freeze]

Looks like GFS wants to build heights further up towards Greenland possibly in further frames. Nice frigid cold pool to the N too.

I see Damianslaw has noted this above.

Edited March 25, 2013 by CreweCold

[snowking]

Just to follow on from Ian's very informative post from earlier.

If we take a look at the current set up:

Some low-ish heights, triggering off some snow flurries for a large part of NE England and E Scotland at present. Heres the accompanying Skew T from the ECMWF for midnight tonight for Newcastle:

Notice that there isn't really much height potential for the clouds from this - hence the snow flurries, but still an impressive amount of them about.

Now lets take a look at the setup for Thursday:

Heights even lower for this period, and the GFS suggestive of this, at least, too.

If we then take a look at the ECMWF Skew T for this period for London:

That cap on the cloud tops just that little bit higher. So we're not looking necessarily at anything major here, but certainly the potential for some more widespread (and slightly higher intensity than at the present moment) showers on Thursday, with the highest risk the further SE you head.

SK

EDIT: To demonstrate, the GFS Skew T's not as supportive of the slightly higher cloud tops, though still potentially enough there for some light flurries similar to those across the NE currently

Edited March 25, 2013 by snowking