Model Output Discussion - Into February

[Allseasons-Si]

"HOLY GRAIL ALERT"

this would be the perfect position to be in for a direct hit.

Edited February 11, 2023 by Allseasons-si

[That ECM]

Gfs gets a slating. Imo, sometimes correctly sometimes not but this is why I love it.

[Nick F]

MJO phase 7 10 day lag amplification or trop response to SSW displacement / reversal?

 

Edited February 11, 2023 by Nick F

[Allseasons-Si]

15 minutes ago, Nick F said:

MJO phase 7 10 lag amplification or trop response to SSW displacement / reversal?

 

I think both Nick but that looks like a QTR to me,landing date of phase 7 is the 14th with lag that would be the 24th> so that chart would be plausable

be interesting to see where it sits in the gefs ens soon,...i hope it's a better set than previous though.

Edited February 11, 2023 by Allseasons-si
typo/added text

[mulzy]

10 minutes ago, Nick F said:

MJO phase 7 10 lag amplification or trop response to SSW displacement / reversal?

 

Or just the GFS doing a random tease?

[andymusic]

And as if by magic a major reversal on the gfs 12z - yer we go

[Mike Poole]

24 minutes ago, Nick F said:

MJO phase 7 10 day lag amplification or trop response to SSW displacement / reversal?

 

I think if it was MJO it wouldn’t appear out of nowhere like that.  SSW effect, well we’re 4 days away from it now, we might expect the models to start to get to grips with all that the SSW entails, and make abrupt changes.  So my money’s on the SSW, vertical section of zonal winds plot later might give a clue?

[Nick F]

20 minutes ago, Mike Poole said:

I think if it was MJO it wouldn’t appear out of nowhere like that.  SSW effect, well we’re 4 days away from it now, we might expect the models to start to get to grips with all that the SSW entails, and make abrupt changes.  So my money’s on the SSW, vertical section of zonal winds plot later might give a clue?

Yeah maybe, we await the 12z GFS cross section on weatheriscool.com - but previous runs the downwelling of the reversal didn't appear to reach anywhere near the trop towards then.

The late Feb 2018 change in the trop that brought the BFTE not too dissimilar in area that +ve heights appeared over NE Atlantic up to Svalbard:

24th Feb 2018                                           12z GFS for Sun 26th

This was the 15th Feb 2018, note the strong TPV to the NW of UK like we're worried about in next few weeks:

Of course, we are dealing with a displacement this time, not a split like 2018, so I would expect it may take longer for a trop response to the sustained reversal way up and perhaps not as similar as 2018 response either, that's if high latitude blocking is the response!

Edited February 11, 2023 by Nick F

[Singularity]

19 minutes ago, Mike Poole said:

I think if it was MJO it wouldn’t appear out of nowhere like that.  SSW effect, well we’re 4 days away from it now, we might expect the models to start to get to grips with all that the SSW entails, and make abrupt changes.  So my money’s on the SSW, vertical section of zonal winds plot later might give a clue?

It would be highly unusual to see SSW impacts so soon after a displacement event. However, GFS has been subsequently splitting the vortex in two, so it's possible that it predicts a quick response from that, whether rightly or wrongly... such a quick downwell isn't usually a feature of post-displacement splits but the one GFS keeps coming up with looks atypical of those with a more distinct, strong secondary round of warming doing the job. So who knows, something peculiar might be on the cards. At this stage we can only wonder!

[minus10]

...yes an interesting pattern development in fi..

....a pincer movement between the west and east troughs with heights moving or being squeezed north...at last  something interesting to look at as i am isolating at home because of the dredded covid...yes...its still out there

[Stuie]

Going to get slayed for this but every winter there are 14 day charts showing a cold invasion. I do understand this `may` have legs but posting 14 day charts is just keeping the forum going.

[Mike Poole]

Well here’s the vertical cross section of zonal winds for the GFS 12z:

I’m not sure I’m any the wiser.  The plot on the left suggests it is trop led, maybe pointing to MJO.  But the anomaly plot on the right hints at more than an element of downwelling.  

Odd run this, we get a split at the end, but not in the same place as previous splits, both lobes on Europe/Asia side.

[Met4Cast]

The GFS performance of late has been nothing short of awful. I genuinely don’t think i’ve seen a model perform this terribly before. 

Might be worth factoring this in when looking at the extended range runs. I doubt dealing with the fallout of an SSW is going to improve it. 

Edited February 11, 2023 by Met4Cast

[andymusic]

5 minutes ago, Stuie W said:

Going to get slayed for this but every winter there are 14 day charts showing a cold invasion. I do understand this `may` have legs but posting 14 day charts is just keeping the forum going.

But it's what we are looking out for right now in conjunction with the ssw towards the end of this month beginning of next

[phil nw.]

We are forecasted successive warmings which will prevent the spv relocating to the pole.

At least this will extend reversal of the zonal winds higher up and continue to weaken them down to mid level.

I am thinking the eastward moving MJO lag effects could be the final blow to a vortex already weakened and displaced.

Probably still outside nwp range yet if we expect a dramatic turn around to a negative nao/ao.come  early March.

Of course we still need the good fortune to end up on a cold side of any blocking.

It's an interesting watch for now though not knowing how this will pan out.

[Purga]

A nice chart in deep FI on the face of it. Doesn't yield any snow (sod all even in the Highlands) and daytime temps around 4C not very exciting..

   

[Eagle Eye]

@MATT TATTOO Wish you all the best and hope to see you here soon.

It's clear we're entering the SSW period now with the zonal winds already pushing down, now is the waiting game as we see what happens between the Strat and the Trop.

"The SPV is currently weaker than ERA5 average 
and is forecasted to remain weaker than average (according to GEFS-mean)
0 of 31 members have stronger vortex than average at the last forecast step (2023-02-26 06:00:00)

The SSW probability in GEFS is: 100%

The zonal mean zonal wind at 10 hPa 60N is today (GFS analysis): 13.2 m/s"

The setup for 10hPa appears to be better than 2019 though worse than 2018, it's sort of in the middle between the two making it almost a nail biting game to see if it can downwell properly.

I mean even 250 hPa whilst not reversing slowly loses the zonal wind speed strength though the Trop is of course handled worse than the Strat.

Oh and if anyone's interested, there's a Wave-2 event looking likely around the 25th which may or may not help with downwelling I'm not exactly sure.

[Stuie]

This ECM run does tie in with the AO sharp drop towards neutral.

Edited February 11, 2023 by Stuie W

[Bricriu]

So the wave 2 second warming could lead to the vortex splitting?  Will the daughter vortices move to the wrong place though? 

[bluearmy]

3 hours ago, Nick F said:

MJO phase 7 10 day lag amplification or trop response to SSW displacement / reversal?

 

That’s a combo of both !  Winds actually reverse in the trop late on and the reversal high up makes it down below 100hpa at the end of the run 

whilst the trop is probably wrong at that range, it’s notable to see the downwelling from the strat …

Edited February 11, 2023 by bluearmy

[Vikos]

http://178.62.112.79/prod/gfs/vertical_cross/umedel60.png

looks promising

 

Edited February 11, 2023 by Vikos

[Ali1977]

Looking at the EC ENS it’s all very boring to about T300 then everything starts getting interesting, lots of blocking but obviously no real consistency as to where at this stage. So like the GFS Op it looks like around day 14 things could take off - around the same time as the BFTE then

Edited February 11, 2023 by Ali1977

[ANYWEATHER]

Tbh, I couldn't care what the MJO or the PDO  ,the AMO, or the ENSO, and the NAO, Along with the SSW And Polar vortex ,and of course cosmic bloody rays , the UK is going to experience some boring February weather....

[ItNeverSnowsInWindsor]

Looking good for some snowfall top ups in Norway!

FA2DCF01-4A56-4B45-99CA-03D148EFE4A7.webp

[pinball wizard]