Mid-Winter: Forecast and Model Discussion commentary

[TSNWK]

Pleased with ICON another jolt south and its game all for vast swathes of us and longevity less risky

Note Apearge is more north / but still showy - colder air uncutting… ?

[sheikhy]

I dare say this icon has moved to the ukmo solution!!

[Portadown Bhoy]

I keep saying to myself, right leave checking here for a few hours, go get a life or something. 
 

10 minutes later I’m back

[Mcconnor8]

Iberian high not perking up as much on ICON 12z compared to 0z, would help with longevity as well.

[TSNWK]

All very slack to our north east over scandi - room for slack scandi high?

[Mcconnor8]

Looks like a low breaking away from the ESB low at T156 and heading South of us, this is good.

[Mike Poole]

 wellington boot Good question, I wish we knew a definitive answer.  My experience is that the MJO seems more reluctant to pass through the cold phases (6, 7) at high amplitude in the heart of winter.  I also think whether it is helpful to the UK or not depends on the stratospheric polar vortex i.e. if that is strong and coupled with the tropospheric vortex it overrides the MJO effect, which itself might be weaker amplitude anyway.  

But I don’t know for certain at all, and my experience doesn’t go back far enough to know if this is a global warming thing, and it used to be different, or whether we are just in an unlucky period in terms of getting MJO assistance in the winter.  Anyone else have a take on it?

[Jacob]

ICON 12z rebuilds the TPV faster

[Battleground Snow]

 Jacob can help with building a scandi high when we have high pressure near uk and Iceland

[Mcconnor8]

GFS time, will it move South like ICON or was that a 1 off run from it?

[TEITS]

Overall i'm pleased with the ICON. The simple reason isn't because I expect that to be the outcome but at least the momentum N has stopped with this run and gone the other way. At the moment it's all about momentum in which direction the trend is heading.

 

[That GFS]

 Mcconnor8 It could take a couple of goes before the GFS reverts back to cold nirvana

[TSNWK]

Well Icon lifts the mood a little 15 mins.

time for a cuppa then by 4:00 we will have Good sense of GFS and UKM thoughts - I kinds of think ICON has corrected from a low point to meet the GFS / UKM if honest - but of course welcome similar shunts south by GFS / UKM.

[IDO]

By T174 at least three days of lying snow for those in the sweet spot at D4-5:

 

 

 

 

[phil nw.]

 TSNWK 

That yellow area is the spread covering the location of the battle zone.

The 850s would be below zero to the north and above zero to the south such as France.

Hope that clarifies things for you.

Anyway it will no doubt all change with new runs.

[nick sussex]

 Jacob

The earlier improvement is much more important . I’d not worry about the later output .

 

[Jacob]

How has the GH already downgraded on the 12z GFS at 6h 

[TSNWK]

 phil nw. thank you… 

it does..

[clark3r]

 Neilsouth are we confident of this happening? 

[Zaul]

 Jacob best compare 12z with the previous 12z, rather than looking at movements run to run.

[Johnp]

 Jacob that’s what’s called ‘over analysing’!

[Jacob]

 Johnp

[WYorksWeather]

Just to clarify a bit on my earlier post in the previous thread on the AIFS 6z - a few people taking my comment slightly the wrong way. I was simply saying that the AI model is now pretty consistent on a breakdown at day 10, whereas previously it looked much more optimistic in the medium term. As mentioned, day 10 is a long way away, so there's still time for a change.

That's all I was trying to get at, really. I want a cold and snowy outlook as well, but it doesn't make sense to stop posting a model just because it doesn't show what we want.

Anyway, on to the 12z runs!

[E17boy]

Icon has taken the shudders away a bit but still so much to be solved and still the big question will the southerners come into the game. I know a question that’s not going to be answered confidently yet. Really miserable here in NE London at the moment, but the winds have died down a lot from this morning. 

[nick sussex]

 Zaul

In this set up and when you’re dealing with a shorter timeframe yesterday’s 12hrs run is old fish and chip paper .