Model Output Discussion 01/09/17

[ANYWEATHER]

Hello Folks....Is Armageddon coming??? The winter rollercoster has started with too may coldies on here setting the bar way too far high so early on as regards cold.  I think we all need to relax , sit back and enjoy whatever the weather throws up at us. Remember the weather wont follow computer models , its the the computer models trying to chase the chaos we call weather and they often get it grossly wrong . Looking at the next ten days, seasonal weather, yes mild at times but a fair share of cold weather, potential stormy weather too, But I did say yesterday morning , computer models will be grid locked in there output in the days ahead...Interesting times.....

[blizzard81]

4 minutes ago, CreweCold said:

What is of most concern (to me) is the omnipresent limpet heights either to our SW, S or SE. It's almost as if they're consistently being displaced N towards our shores. We saw last winter just how stubborn these heights are.

I would love to know what is causing these persistent Euro highs in winter. The models only ever seem to realise their existence at 6 to 7 days out. At days 8 to 10 these highs are nowhere to be seen.

[Dennis]

if the blocking succeed then watch if it will be broken.....

[blizzard81]

Any news on the ecm clusters? Maybe man with beard please? The ensembles don't look that great it has to be said.

[LRD]

13 minutes ago, blizzard81 said:

I would love to know what is causing these persistent Euro highs in winter. The models only ever seem to realise their existence at 6 to 7 days out. At days 8 to 10 these highs are nowhere to be seen.

I've mentioned this before on here. It's the expanded tropical high pressure belt (Hadley Cell) that includes the Azores High. It's not only in winter we experience this either. It's pretty rare to have a poor summer in the SE of England now due to the expanded tropical high cells having enough influence in summer too - even in the most unsettled summers. Even in 2012 the SE had a nice warm August. The models don't seem to have a handle on quite how dominant southern heights are becoming/have become and I'm not sure why. I really worry about winters in this country now (that is the first 'winter is over... forever' post!)

Edited November 14, 2017 by LRD

[blizzard81]

1 hour ago, Man With Beard said:

There's only one bet I'm going to place tonight, and that's to bet that we won't see conformity on all the op runs in the next 48 hours!!! We have a -AO and -NAO coming up, anyone who thinks the models have it nailed beyond D5 is very, very optimistic about their ability!!!

Great post. I think coldies shouldn't give up hope just yet for the reasons explained above. Very unusual synoptics and the models have the notoriously and famously unpredictable Arctic high to contend with. Good luck with that models.

[Cheshire Freeze]

4 minutes ago, LRD said:

I've mentioned this before on here. It's the expanded tropical high pressure belt (Hadley Cell) that includes the Azores High. It's not only in winter we experience this either. It's pretty rare to have a poor summer in the SE of England now due to the expanded tropical high cells having enough influence in summer too - even in the most unsettled summers. Even in 2012 the SE had a nice warm August. The models don't seem to have a handle on quite how dominant southern heights are becoming/have become and I'm not sure why. I really worry about winters in this country now (that is the first 'winter is over... forever' post!)

Spot on. 

I too have heard of this to be the reason for increased HP influence to the S. It really isn't good news as far as our winters go. It can't be surprising the modelling often fails to pick up on this too as naturally beyond a certain point they are more exposed to climatology bias. With this expansion of the Hadley cell being a rather recent occurrence, they won't have enough to go on RE most recent climatology trends. This is perhaps why we see them inflate the influence of these Euro heights closer to T0.

[bluearmy]

AO watch 12z

GFS -5

GEFS -4.5

EC  -4

EPS  -3.3

GEMS. -3.2

[karlos1983]

What about NAO watch ....how’s that looking? 

[LRD]

2 minutes ago, CreweCold said:

Spot on. 

I too have heard of this to be the reason for increased HP influence to the S. It really isn't good news as far as our winters go. It can't be surprising the modelling often fails to pick up on this too as naturally beyond a certain point they are more exposed to climatology bias. With this expansion of the Hadley cell being a rather recent occurrence, they won't have enough to go on RE most recent climatology trends. This is perhaps why we see them inflate the influence of these Euro heights closer to T0.

Yep agreed. Without wanting to start a climate change debate something has happened to inflate these highs and it can only be the warming climate and, as you say, the models have not yet adapted to that. I thought that modelling might have had the background warming and greater propensity for southern heights built into them but it appears not. The lesson for us is to treat modelled low pressure or low anomalies (to our south and south east) beyond days 6 or 7 with a very large pinch of salt. Might save us all some disappointment

[blizzard81]

1 minute ago, karlos1983 said:

What about NAO watch ....how’s that looking? 

No Arctic Onslaught!

[Dennis]

1 minute ago, karlos1983 said:

What about NAO watch ....how’s that looking? 

 

[bluearmy]

4 minutes ago, karlos1983 said:

What about NAO watch ....how’s that looking? 

Somewhere between -2 and -3

[LRD]

9 minutes ago, bluearmy said:

AO watch 12z

GFS -5

GEFS -4.5

EC  -4

EPS  -3.3

GEMS. -3.2

All those negative values and we are STILL staring down the barrel of SWly's! At least it looks as though we will have some actual weather though - just the wet and windy kind. But I'd rather that than the excrutiatingly tedious mild and dry that we experienced in October

[karlos1983]

I think we all know the AO is going negative, that’s not the issue, the NAO going negative and whether it’s west based or not is where we will or won’t hit the gold... imo anyway 

[damianslaw]

Alot of flip flopping from the models at the moment, always a sign they are struggling, and a reason to probably not get too hung up on anything past the 120-144hr tops, something that should be said at all times. We've had potent northerlies and northeasterlies, then easterlies, southerlies and southwesterlies and high pressure overhead all in the mix - what a mess!

Sticking to the reliable, becoming cool again over the weekend - a theme here, with northwesterly incursion, then signs the atlantic will return. That's as far I'm going with things - the models cannot handle short-term developments very well at all, and it is these that can suddenly make a mockery of them and cause them to do about u-turns. Stick to the reliable and you'll save yourself lots of frustration.

[LRD]

13 minutes ago, karlos1983 said:

I think we all know the AO is going negative, that’s not the issue, the NAO going negative and whether it’s west based or not is where we will or won’t hit the gold... imo anyway 

That's the point I was sort of making. All that -AO and -NAO and we find ourselves with a mild forecast.

I honestly don't know if the science works this way but is it because the southern heights are now so dominant (sorry to labour that point but we can't get away from it) that any Greenland heights will a) quickly collapse into the Azores or b) be pushed out towards East Canada for a west-based NAO by the more powerful high cell (the southern/Azores/Euro heights)? It's strange

Edited November 14, 2017 by LRD

[Dennis]

and its back   for 1 run .....

[I remember Atlantic 252]

At least GFS backtracking from washout Sunday, earlier runs today and yesterday showing horrid low, 

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[knocker]

2 hours ago, Man With Beard said:

There's only one bet I'm going to place tonight, and that's to bet that we won't see conformity on all the op runs in the next 48 hours!!! We have a -AO and -NAO coming up, anyone who thinks the models have it nailed beyond D5 is very, very optimistic about their ability!!!

Then equally obviously one would have to be very, I repeat, very. optimistic about their ability to correctly forecast a -AO and -NAO post day five.despite the sudden obsession with them in the thread.

Edited November 14, 2017 by knocker

[swfc]

Here we go!!!18z on the change again early doors

When will this be resolved

[karlos1983]

7 minutes ago, knocker said:

Then equally obviously one would have to be very, I repeat, very. optimistic about their ability to correctly forecast a -AO and -NAO post day five.despite the sudden obsession with them in the thread.

Totally agree Knocks, anyone who says they know what’s going to happen post D5 is a gambler. Wishes and hopes are for Christmas. 

[damianslaw]

Expect more flip flopping from the models in the next few runs, wouldn't be at all surprised to see many showing high pressure settling in and over the UK once again, jetstream profile looks rather ragged and broken, suggesting ridge development and heights will ridge through the country, low heights becoming squeezed and diffuse.

[blizzard81]

Seem to have been saying this for days now but tomorrow's 00z runs will be enlightening.

[Tracy Flick]

The JMA hints at an interesting north-south divide over the UK in the 240h+ range.