Model output discussion - The Hunt For Cold

[MattStoke]

2 minutes ago, Mapantz said:

Doesn't the GFS have these occasions of throwing out a huge dartboard-low when it's trying to resolve the idea of something colder?

Almost always blows up Atlantic lows in low res. Even in short term it often overdoes them.

[summer blizzard]

Looking at the GFS around day 8 onwards and we can see that it develops the low off the south east coast of the US like the Euro and UKMO. This low allows the second go.

[lorenzo]

3 minutes ago, Mapantz said:

Doesn't the GFS have these occasions of throwing out a huge dartboard-low when it's trying to resolve the idea of something colder?

This is a great point - GFS has known 'swearing is not big or clever ups' or foibles to put it more politely -There is a CPC page someplace that reports it's bias - the dartboard low is a classic, the SSW on every 06z run is another - really progressive. Would be a good study right now with the Cubed model - exotic title of FV3 / GFS Para to compare whether this defect has been resolved..

It also flattens the jet in lower res - much to everyone's sheer annoyance - this makes watching stuff fun.... as in you have an exciting 18z to look forward to and on occasion it resorts to being 'difficult.'

( ECM has tended to amplify meridionally too as an aside), verification stats are useful, but what is also useful is as to what you are used to seeing, it's difficult to quality intuition at times...

On the other side of the coin though,it can sniff out easterly regimes, and when the ECM is on the switch given the time frame if variables fall in line it catches them, hence the 12z to 12z view is useful for the GFS.. this tried and tested method gives a clearer view vs the noise...

Here's the 12z GFS view of the Icelandic High ( I think propped by that GEFSBC MJO outlier earlier). Or it could be just considered mad in it's own right considering where it gets too later on...

Here are the last 4 runs of SLP combined - sorry, different time frames as the 18z ongoing.

Point is that the Op goes wild on the SLP anom vs the view with more data dampens Icelandic heights, click any point on this map by @SylvainTV to mess around with these.. http://www.meteociel.fr/modeles/gefs.php?carte=2

 

[Mucka]

Rememeber when we thought we were looking at something along these lines?

Well at least 2 18z ensemble members remember the dream

I actually think we will get something like this which is half way between the spoiler sinker of the Op and the clean retrogression of the runs above.

 

 

[Mike Poole]

FV3 at T156, not letting go is it, like a dog with a bone, this one...

[BlueHedgehog074]

42 minutes ago, feb1991blizzard said:

The other way as i've said before is for the Atlantic low to Phase with the scandi troughing and open the door from the North, thats how we could avoid the Atlantic trough spoiling things, still goes wrong and a low too deep and round ensues after this phasing on the 18z but it is possible to have a more favourable outcome from this scenario.

Must admit, I didn’t like that Low Pressure system approaching from the West of the U.K, thinking it was going to be a bad guy piling itself on top of the UK High and usher in South-Westerly winds.

But it sure did become a hero at the end going to our East (as you say, joining forces with the Scandinavian Low) with ridging building in behind it in the Atlantic.

I like that Low Pressure system. What a good guy it became. Despite it becoming stormy. Thanks, Low! And thanks Greenland blocking. 

In some ways, the models are like an episode of the London Paddington 24/7 train documentary. When something goes wrong, it goes wrong. And when things go right, it’s all okay, And even when things do go all wrong, it (often) all gets sorted at the end. Just like what happened on both the GFS 12Z and 18Z runs, tonight. 

(Of course, though, there are a few times where things keep going wrong right out to the end of the runs).

Edited November 17, 2018 by DiagonalRedLine
Adding little more

[Tim Bland]

Gfs(p) has a dusting of snow for many on Tuesday / weds. Will be a good test of this models accuracy for snow at short range 

[phil nw.]

Decent runs for coldies this evening.

Day 5 sees the re inflation of the Icelandic high from the Azores ridging which eventually helps to bring the colder air from the Scandinavian upper trough closer to us.

A promising run on tonight's GFS 18z up to day 8 with the bulk of the vortex heading over the top of the high towards Siberia,

adding to the cold pool to our ne..2mtr. ens charts for C.England continue to run around 3/5C daytime over this period.

We will see a rapidly cooling continent now so any flow which is not west of south will be quite cold.

Not too concerned about detail beyond next week as we will see different solutions in modelling with such a distressed vortex and continued wave action..The main theme is of a blocked Atlantic, a split jet with much of the energy heading south of the Uk.This a promising pattern for maintaining below average temperatures.

[Derecho]

Swingometers out for 18z's

More changes again, model fatigue...

But these are a slight improvement again. One or two arctic northerlies are creeping back again (P11 especially) and some of the anticyclonic members for November 25th are cold. Some have the UK stuck in no mans land on this date but still have high pressure to our north.

As ever more runs needed... but not a bad set.

Categories

Op and control - Anticyclonic

Parallel - Rather cold

[feb1991blizzard]

Improvement on the GEFS  - The only thing that is gonna stop us getting a really good pattern is that Atlantic low, if that behaved favourably, then the ensemble suite of the GEFS would have near enough 100% agreement on a flow N or NE, if we can somehow avoid that problem then it will be a Starship!

[Mokidugway]

6 minutes ago, Tim Bland said:

Gfs(p) has a dusting of snow for many on Tuesday / weds. Will be a good test of this models accuracy for snow at short range 

Seems  to be showing a streamer ,SSTs to high though 

[northwestsnow]

7 minutes ago, feb1991blizzard said:

Improvement on the GEFS  - The only thing that is gonna stop us getting a really good pattern is that Atlantic low, if that behaved favourably, then the ensemble suite of the GEFS would have near enough 100% agreement on a flow N or NE, if we can somehow avoid that problem then it will be a Starship!

100% agreed!!
Think we have pretty decent agreement that the scandy high will retrogress and become cut off, the low to the SW is indeed the elephant in the room.18Z turned out good with a cold north westerly but i'm far from convinced with that, far too many variables at play..

I'm happy UKMO called the 120-144 period correctly but the tricky part will follow,the pattern could easily become a horrid West based -NAO, the natural progression would be a Euro high and big +NAO setting up..equally something along the lines of 18z could materialize longer term...

I'm still 50/50 - FG might copa dusting wed at 300m ..

 

Edited November 17, 2018 by northwestsnow

[feb1991blizzard]

4 minutes ago, DiagonalRedLine said:

Must admit, I didn’t like that Low Pressure system approaching from the West of the U.K, thinking it was going to be a bad guy piling itself on top of the UK High and usher in South-Westerly winds.

Z runs, tonight. 

Yes - see my post below and look at the GEFS in full and it will show you how important that low is - look at the GEFS in detail and it will show you. some members phase it with upstream troughing - either way, you dont want it just sitting there in the Atlantic.

[Cheshire Freeze]

Couldn't make this up...

Stonking GEFS mean right into deep FI

[BlueHedgehog074]

3 minutes ago, feb1991blizzard said:

Yes - see my post below and look at the GEFS in full and it will show you how important that low is - look at the GEFS in detail and it will show you. some members phase it with upstream troughing - either way, you dont want it just sitting there in the Atlantic.

Will have a look. And agreed. Having it just sit in the Atlantic would just causes problems. 

[Geordiesnow]

Just now, northwestsnow said:

100% agreed!!
Think we have pretty decent agreement that the scandy high will retrogress and become cut off, the low to the SW is indeed the elephant in the room.18Z turned out good with a cold north westerly but i'm far from convinced with that, far too many variables at play..

I'm happy UKMO called the 120-144 period correctly but the tricky part will follow,the pattern could easily become a horrid West based -NAO, the natural progression would be a Euro high and big +NAO setting up..equally something along the lines of 18z could materialize longer term...

 

That is the risk when you see forecasts of the PV leaving Canada but some runs had the high sinking somewhat, I think I rather take the risk of a possible west based NAO especially as you know with the models, they like to edge the pattern eastwards in anycase.

[northwestsnow]

Just now, DiagonalRedLine said:

Will have a look. And agreed. Having it just sit in the Atlantic would just causes problems. 

Yyup- we need some energy to go under us, its a fine line we are treading moving forward, the high drifts too far west and we 're in trouble..

[Man With Beard]

The parallel keeps plugging away at a cold week 2

But the ecm ensembles are less good tonight with a heights increasing over Europe on the top two clusters by D10 - which I see as the most significant development of the day

Edited November 17, 2018 by Man With Beard

[Allseasons-Si]

The control at the end is not bad either

as long as we keep on seeing these amplified patterns then there is nothing to worry about

the NAO/AO is still tanking neg

this will keep the pv on the ropes/displaced and the atlantic dead

i mean...look at this

there are segments all over the shop.

[Ladyofthestorm]

It seems to me that the GFS is doing its classic dropping a trend and firing out a deep Atlantic low in the longer range. What's the chances(again) of it  modelling back to the NEly in a few days time. 

The Ensembles runs in the longer run are all over the place and the GFS longer-term looks like an outlier.  Do best ignored. Blocking to the north everyone. Europe is suddenly going into the freezer.  And the NAO and AO are very negative. 

No Atlantic weather anytime soon. 

[blizzard81]

9 minutes ago, CreweCold said:

Couldn't make this up...

Stonking GEFS mean right into deep FI

Don't give up on December just yet

[Allseasons-Si]

That's better,most of the mild members at the end are gone compared to the earlier sets

 

[Man With Beard]

Longer term... well the height anomalies are always N and W, this is D14 clusters. Looks like we'll be "in the game" for a while. 

[feb1991blizzard]

12 minutes ago, Man With Beard said:

 

 

But the ecm ensembles are less good tonight with a heights increasing over Europe on the top two clusters by D10 - which I see as the most significant development of the day

 

Unfortunately i agree with you.

[Mike Poole]

FV3 T240:

I think this is a good pattern hemispherically, maybe on this occasion, the high has ended up extending over the UK, with the deep cold flowing a tad south, that could change.    Considering where we were this morning, I'll take this at close of play! 

Edited November 18, 2018 by Mike Poole