Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[bluearmy]

The 06z gefs looking more akin to yesterday's ECM extended with the low SLP end week 2 across nw Europe.

That's a pretty amazing mean and if you take the members on a diff tangent away ..............

[Cloud 10]

Expect to see fairly widespread snow warning's for Tuesday/Wednesday if the UKMO is on the money with plenty of precipitation around and cold air well embedded.

 

 

 

This is the raw version of the UKMO and maybe Ian will drop in with a more informed interpretation.

[Nick L]

Expect to see fairly widespread snow warning's for Tuesday/Wednesday if the UKMO is on the money with plenty of precipitation around and cold air well embedded.

 

P1_GZ_D5_PN_072_0000.gifTT_GZ_UU_VV_072_0850.gif

 

 

This is the raw version of the UKMO and maybe Ian will drop in with a more informed interpretation.

 

While there is plenty of precipitation, it is mostly light. The ECM has a similar picture, looks mostly light snowfall to me.

[Met4Cast]

I think the reason the models appear to be performing so badly in the short term is because of how marginal things are at the moment. When there's less than 1c between rain or snow the models only have to be off by a minuscule amount and we see pretty large outcomes.

 

Longer term it's clear the models don't have a handle on this yet, but then they never do. The seemingly poor (though not necessarily in reality poor) performance early term and the usual chaoticness in the longer term is getting people rather stressed. 

 

This mornings runs continued to show the cold being prolonged by a day or so, and if we can prolong the cold by 1 day with each run, I think most in here would be happy. As it stands, snow risk through the week still isn't nailed down, plenty more is likely to change. It's going to be a long week.

[Duane S.]

I know people might think that big high over Siberia on the GFS 00hrs looked good but its centred too far east, its better to develop a smaller high to the ne as this has a better chance of directing much colder air into the UK.

 

Don't worry if this run doesn't deliver , factor in that deep low, will it really be that strong, the most important thing is the earlier trend.

Absolutely Nick. I posted yesterday (and many times before) about these large blocks to our east. More often than not they serve to tease us throughout winter without ever extending westwards enough to directly feed continental to our shores. These smaller Scandi cells are often much more productive as often their duration with a propensity to ridge westwards through time is underplayed by the models. I think undercut could become the buzz word of the month (if it isn't already)

Interesting times ahead I think...

[J10]

You can of course look at historic charts and look at synoptics and CET comparisons etc 

 

However so many variables I do wonder that increase+  sea temp abnormalities may modify marginal situation which is the case for next week for many.

 

yet this gives a different outcome.

 

http://www.esrl.noaa.gov/psd/map/clim/sst.shtml

[bluearmy]

Going back to something Shaun posted earlier re the Siberian vortex segment, the gefs today are showing the arctic ridge n of Alaska preventing the Siberian vortex segment heading back to Canada across the pole. It has no choice but to head towards scandi. that would prevent the Russian ridge coming west in week 2. guess it's a win win scenario, given the choice between the Russian ridge coming west or the Siberian vortex headed sw. Fwiw, the Siberian headed sw co incides with the Canadian throwing out more lobes towards the n Atlantic which is what drives that mean I posted above.

Edited January 18, 2015 by bluearmy

[Daniel*]

Going the way we want it breakdown is not as easy... if you want the cold to prolong now looking cold still into next weekend, with a little sausage trying to exert a influence, on more recent 6z with a slider beckoning, promising. I will not be fooled with return to mild W'lies - I see this to be just the start of something more substantial...

12z

0z

6z

Wednesday frontal system:

More colder air in the mix less mixing out - enabling snow to fall further south.

Saturday

Struggling to reach above freezing for many ice day for some! All presenting the idea that cold signal is gaining ground - and will not leave home empty handed. ...I'd say a very cold February is on the way.

[chionomaniac]

Going back to something Shaun posted earlier re the Siberian vortex segment, the gefs today are showing the arctic ridge n of Alaska preventing the Siberian vortex segment heading back to Canada across the pole. It has no choice but to head towards scandi. that would prevent the Russian ridge coming west in week 2. guess it's a win win scenario, given the choice between the Russian ridge coming west or the Siberian vortex headed sw. Fwiw, the Siberian headed sw co incides with the Canadian throwing out more lobes towards the n Atlantic which is what drives that mean I posted above.

I am wondering whether the displacement of the strat PV to Siberia aids in this westward shift of the tropospheric Siberian high. Almost like squeezing a balloon from above- it squashes out to the sides and voila!

[blizzard81]

Going the way we want it breakdown is not as easy... if you want the cold to prolong now looking cold still into next weekend, with a little sausage trying to exert a influence, on more recent 6z with a slider beckoning, promising. I will not be fooled with return to mild W'lies - I see this to be just the start of something more substantial...

12z

image.jpg

0z

image.jpg

6z

image.jpg

Wednesday frontal system:

image.jpgimage.jpg

More colder air in the mix less mixing out - enabling snow to fall further south.

Saturday

image.jpg

Struggling to reach above freezing for many ice day for some! All presenting the idea that cold signal is gaining ground - and will not leave home empty handed. ...I'd say a very cold February is on the way.

Yes, I really do hope the gfs is onto something here. The 12z runs are awaited with great anticipation.

I am wondering whether the displacement of the strat PV to Siberia aids in this westward shift of the tropospheric Siberian high. Almost like squeezing a balloon from above- it squashes out to the sides and voila!

What a great way of putting it, I like that one lol,

[Frosty.]

When I read words like uncertain eastward progress it means the models are wobbling like jelly from later in the week ahead onwards so we just can't trust the output beyond say T+96 hours onwards, it's clear to me there has been a westward correction in the last 12 hours from the more progressive solutions shown last night. The way I see it, the outlook will stay generally unsettled with below average temperatures for the most part which means an ongoing risk of snow and no shortage of ice and frost..Much better than recently.

Edited January 18, 2015 by Frosty.

[bluearmy]

I am wondering whether the displacement of the strat PV to Siberia aids in this westward shift of the tropospheric Siberian high. Almost like squeezing a balloon from above- it squashes out to the sides and voila!

If the Siberian strat vortex verifies, will be a great watch of what the trop vortex does in response. could be interesting to see how the 'dancing' goes and who is leading who.

[Catacol]

Yep. Signs as posted last time that the siberian high might indeed be edging westwards - perhaps significantly so - with strat modelling supporting vortex realignment over Siberia. I have a gut feeling that the models all tend to have a bit of an atlantic westerly bias - in fact years of model watching have convinced me that this is the case,.. and whether it is new GFS or old GFS or ECM or whatever the loss of energy over Canada seems to be a factor that models dont deal with well in the medium term. With a jet running south and a block perhaps undermodelled in strength to our NE could we get lucky?

 

I'll throw another element into the mix. I have heard arguments one way and the other regarding solar flux: I am far from an expert in solar physics, and much more of an interested observer. But there has been a quite substantial drop off in solar flux over the last 10 days.... and to my mind this can only be a good thing. Again - observation has tended to suggest that increases in solar activity encourage westerly bursts: a reduction at this stage in winter in my opinion helps us.

 

Very interested to see where all this goes.

[bluearmy]

I'm at a bit of a loss as to why people think the Canadian vortex is weakening? There is no tropospheric evidence that this will be the case.

Perhaps beyond week 3 but that's just conjecture at this stage based on hoped for strat influences to downwell.

[chionomaniac]

I'm at a bit of a loss as to why people think the Canadian vortex is weakening? There is no tropospheric evidence that this will be the case.

Perhaps beyond week 3 but that's just conjecture at this stage based on hoped for strat influences to downwell.

It will be based on the strat displacement - as you said any weakening of the trop vortex will takes weeks to come through, but feasible.

[TonyH]

While there is plenty of precipitation, it is mostly light. The ECM has a similar picture, looks mostly light snowfall to me.

Those precipitation models often undercook, I think there will be local/ regional heavier falls.

[Rocheydub]

Those precipitation models often undercook, I think there will be local/ regional heavier falls.

Not trying to raise a separate discussion here, but they also often overcook them, can I ask why you think there will be more than suggested?

[swfc]

Slight shift to a longer cool-cold spell so far today.The next week looks staying that way but looking at the media the chance of any substantial snow looks to be slipping away altho that can change I guess.The fronts ete seem o be fizzling out threw the week but as many have said 48 hours is a lifetime atm regarding the mo

[Snowy L]

Snow accumulation by the end of Wednesday:

 

 

Massive accumulations in central Scotland and decent accumulations in Northern England and North Wales. Why are the met office warnings completely ignoring this, when the first of the 2 snow events begins in 1 and a half days?

 

 

 

 

[john mac]

We'll not long till the next round of entertainment. I'm expecting more possible upgrades in the 12z suites but we will see!! Wednesday is showing to be the day with most potential for some decent snowfall across the uk.

[bluearmy]

Snow accumulation by the end of Wednesday:

 

snow accumulation wednesday.gif

 

Massive accumulations in central Scotland and decent accumulations in Northern England and North Wales. Why are the met office warnings completely ignoring this, when the first of the 2 snow events begins in 1 and a half days?

Perhaps because most accs will be over hills and the models they trust dont show the same precip amounts in any case ???

[Skullzrulerz]

Awaiting the next set (12z) of runs I hope this is going to be a start of the upgrades and maybe the models will start to show a Scandinavian high more on the models in the mid-long term.

 

In all a good model watching period is soon to begin. 

Edited January 18, 2015 by Skulltheruler

[weather_it_will]

Snow accumulation by the end of Wednesday:

 

snow accumulation wednesday.gif

 

Massive accumulations in central Scotland and decent accumulations in Northern England and North Wales. Why are the met office warnings completely ignoring this, when the first of the 2 snow events begins in 1 and a half days?

Any snow event looks marginal this week on the models.

 

A single chart for accumulation is not proof that it will snow. It could be rain or sleet.

Edited January 18, 2015 by 'ColdIsBest'

[swfc]

Snow accumulation by the end of Wednesday:

 

snow accumulation wednesday.gif

 

Massive accumulations in central Scotland and decent accumulations in Northern England and North Wales. Why are the met office warnings completely ignoring this, when the first of the 2 snow events begins in 1 and a half days?

Look to the bottom left on that chart.Very slight accumilations tbh

[shaky]

Snow accumulation by the end of Wednesday:

 

snow accumulation wednesday.gif

 

Massive accumulations in central Scotland and decent accumulations in Northern England and North Wales. Why are the met office warnings completely ignoring this, when the first of the 2 snow events begins in 1 and a half days?

decent accumulations as far south as the midlands and northern home counties! !