Model output discussions pm 31/12/15

[Geordiesnow]

I also have to add, i'm a bit confused about the talk of the UKMO 144 hour chart never comes to fruition, well of course it does not, no model chart at 144 hours comes to fruition whatever the weather set up, details will change from run to run. Will the UKMO be right in perhaps giving us a bit more of a potent shot or not, that would be my question on this evening outputs, perhaps tomorrow morning runs will tell us. 

[Cloud 10]

ECM op. run anomaly at day 10 versus ensemble mean day 10 anomaly.

 

[cuckoo]

The gulf stream continues up towards the arctic hindering ice formation.  Therefore the northerlies heading toward the UK are soon being warmed over the ocean.  As others have said areas of the mid-Atlantic / north east Pacific are much closer to frigid continental land masses e.g. Greenland and Northerly flows are subject to less modification prior to reaching the low latitudes.

[bobbydog]

18 minutes ago, CreweCold said:

That's not the issue though...I want to know when we do get N'lys why are we scraping by with uppers of -5 or -6 when any given location, even in the mid N Atlantic can easily achieve uppers much lower on a regular basis (as we saw in December). I'm not talking about the frequency of mean westerlys!

because thats just how it is mate. there must be a professional climatology explanation somewhere. however i must congratulate you on possibly the longest running off-topic rant that anyone has ever got away with in the mod thread!! lol

[Danielvn]

3 minutes ago, CreweCold said:

Maybe..

However take two northerlys..

One is a direct N'ly, straight from the pole affecting the UK

The second one is affecting somewhere in N Canada on our latitude

Now look at a globe and tell me why, at our latitude, the N'ly is watered down to nothing (despite not travelling far enough to actually modify all that much), whereas the Canadian N'ly is a mass of cold 5 times the size of our displaced cold pool which doesn't modify? At our latitude a -40 polar cold pool should not modify that much that we're left with uppers of -5 and a cold pool which is 5 times less large than it started out at!

Not to be funny, but that's what happened, complaining about it isn't going to make it better? Also, this isn't really model discussion?

[karlos1983]

7 minutes ago, winterof79 said:

You do find you have to skip a lot of negativity at this time but your post is straight to the point.Glasss 3/4 full.

 

6 minutes ago, bigsnow said:

Very interesting tweet that... some have said in here today and over the last couple of days that with a pattern change the models struggle to pin down whats going on and here we have it from the horse's mouth...  ( sorry Ian not implying your a horse)... think we need to chill a bit and take each run with a pinch of Rock Salt and see how things look at the weekend maybe then we may see the woods for the trees...

In my defence I've been boring everyone all day saying fl is about +96 and I'm sticking to it until I see evidence to suggest otherwise. From the models from my perspective that is. 

[northwestsnow]

1 minute ago, Cloud 10 said:

ECM op. run anomaly at day 10 versus ensemble mean day 10 anomaly.

 

The mean seems to be constantly 'better' than the op runs we are seeing over the last few days.

Not entirely sure what to make of that to be honest

[Cheshire Freeze]

Just now, bobbydog said:

because thats just how it is mate. there must be a professional climatology explanation somewhere. however i must congratulate you on possibly the longest running off-topic rant that anyone has ever got away with in the mod thread!! lol

Thanks, you know me

[chionomaniac]

1 minute ago, Steve Murr said:

Im afraid that ^^ second tweet cannot be said with any degree of certainty...

its a case of finely balanced on the hedge tonight ....

enough evidence to suggest that based on history theres a chance it will go either way but probabilty wise favours the milder scenario ( again based in statistics & uks law of sod averages )

i duly note the ECM op was milder for debilt at day 9 & 1 suggesting a slightly to flat a pattern....

 

s

Well having just looked at the EPS from days 10-15 I think that anything after days 5-6 is far from finalised and those proclaiming a two day toppler may be quite wide of the mark.

 

So to my eyes from days 10 + the positive anomaly for the Atlantic ridge is very strong and then this starts to retrogress west and towards a negative west NAO. It does not flatten out and let the Atlantic back in and the 850 anomalies start to become more negative again.

Message to all - don't react to the operationals - wait for the ensembles.

[blizzard81]

3 minutes ago, Greenland1080 said:

Sorry confused...meant lots of decades with cold flooding down into Atlantic...anyway off topic...18z soon.

 

What's more difficult than the weather is trying to remove a quote on here

Oh yes absolutely, many instances of -25 upper air getting into atlantic.

[winterof79]

10 minutes ago, blizzard81 said:

2010 and 2013 didn't see anything like -25 850's over the UK.

And lets put this to bed

http://www.meteociel.com/modeles/archives/archives.php?day=13&month=1&year=1987&hour=0&map=0&mode=0

[Methuselah]

10 minutes ago, CreweCold said:

Maybe..

However take two northerlys..

One is a direct N'ly, straight from the pole affecting the UK

The second one is affecting somewhere in N Canada on our latitude

Now look at a globe and tell me why, at our latitude, the N'ly is watered down to nothing (despite not travelling far enough to actually modify all that much), whereas the Canadian N'ly is a mass of cold 5 times the size of our displaced cold pool which doesn't modify? At our latitude a -40 polar cold pool should not modify that much that we're left with uppers of -5 and a cold pool which is 5 times less large than it started out at!

You've answered your own question, I think...In Canada and the US, direct northerlies are hardly watered-down at all. The 'water' is either frozen, frozen and landlocked, or not there at all...

[blizzard81]

5 minutes ago, winterof79 said:

And lets put this to bed

http://www.meteociel.com/modeles/archives/archives.php?day=13&month=1&year=1987&hour=0&map=0&mode=0

We were talking about 2010 & 13

[Cheshire Freeze]

9 minutes ago, chionomaniac said:

Well having just looked at the EPS from days 10-15 I think that anything after days 5-6 is far from finalised and those proclaiming a two day toppler may be quite wide of the mark.

 

So to my eyes from days 10 + the positive anomaly for the Atlantic ridge is very strong and then this starts to retrogress west and towards a negative west NAO. It does not flatten out and let the Atlantic back in and the 850 anomalies start to become more negative again.

Message to all - don't react to the operationals - wait for the ensembles.

But the mean is heading in the WRONG direction Chiono?

A day or two back we had a proper Greenland high showing....here's what we have now at day 8

 

 

[Singularity]

I'm a bit late to the party but my impression is that GFS has produced a reasonable sort of run out to around +336 or so, as we see troughs disrupting as they come up against Greenland, which is a classic feature of negative AO setups. One also has to wonder what could be achieved if the heights between Iceland and Svalbard were higher at around +192 - a possibility if the models are underestimating the HLB as sometimes happens.

 

Now what about that ECM det. run... well, it seems hell-bent on merging the Canadian PV segment with low heights in the vicinity of Svalbard, seemingly exploiting the cross-polar flow - using it against us, in fact. 

That's made possible by a shortwave just west of Greenland at +144 hours which allows a U.S. low to move NE rather than N, preventing the mid-Atlantic ridge from linking with the Arctic Heights. GFS has no such shortwave, and no such drama. In fact it seems to have trended away from that idea since yesterday.

A head-scratcher for sure. Sure, the ECM run looks capable of pulling the Azores High back west soon after +240 with the Greenland trough diving southeast toward Europe, but the developments +168 to +240 do look a bit strange, as if the two main areas of low heights are somehow magnetised toward each other.

I'll now have a read back and see if that changes my view at all 

 

[Captain Shortwave]

Right, I think it is time for a fresh thread I feel. I will lock this in around 5 minutes once I have got the new one ready.

 

[ukpaul]

The twitter exchange between Matt Hugo and Ian Ferguson is infinitely more illuminating than the last couple of pages of this thread.....

https://twitter.com/MattHugo81/status/684479876812943360

[northwestsnow]

2 minutes ago, CreweCold said:

But the mean is heading in the WRONG direction Chiono?

A day or two back we had a proper Greenland high showing....here's what we have now at day 8

 

 

I think i only saw one ecm operational show a Greeny high.

So im not entirely sure why people are expecting one on the back of one op run.

[SMU]

17 minutes ago, bobbydog said:

because thats just how it is mate. there must be a professional climatology explanation somewhere. however i must congratulate you on possibly the longest running off-topic rant that anyone has ever got away with in the mod thread!! lol

 Er the clue is the sea & how the advection process takes place -

true cold air advection upper air movement is driven south by large High pressures over greenland ushering out south the deep cold off the greenland shelf -

where as atlantic ridges & transient northerlies from Iceland or just south of greenland dont start that cold- as they have been slightly mixed by warmer maritime air

The maximum cold air on tap for the UK in terms of a Northerly is about -15 for in Scotland & -12/-13 modified into the UK as long as driven south quite fast, if the process is slower maybe -10c

without a High pressure the air starting around -10 to -13 over iceland will already be moderated over the sea track up to -8s for scotland - hence the -5/-6c values over England-

If you take the Means of the models tonight -8/-9 into Scotland & -5/-6 to southern UK sounds about right-

its just the UKMO that lucks into the original cold pool over Scandi to sweep in -10s

 

id say for absolute coldest 850 temps for the Uk we could get is circa -20 to maybe -22c

it would require perfection in terms of synoptics from start to finish-

the coldest chart I have seen from the archives is -19c on 2 occasions- 1 was 12 jan 1987....

 

S

[joggs]

On the new thread can we please stick on topic.just had to read through some drivle last few pages.

Edited January 5, 2016 by joggs

[i luv snow]

 

Quote

 

Matthew Hugo ‏@MattHugo81 35m35 minutes ago

@fergieweather - Aye. I'm not sold on a true Greenland block, a 'middle ground', but not expecting a '2 day toppler' as the forums name it

 

Great tweet by Matt Hugo! not expecting a '2 day toppler' as the forums name it

[Captain Shortwave]

Thread locked, new thread here

https://forum.netweather.tv/topic/84791-model-output-discussion-05012016-18z-onwards/