Model Output Discussion - early October

[The PIT]

You'll know what will happen by the time winter starts. All these lovely charts will be replaced by roaring mild south westerlies. Nice too see the vortex having a look in this direction rather than getting stuck across the pond.

[Mike Poole]

The T240 NH charts from the 12z suite (JMA is T192):

All over the place, but shredded trop vortex on all, and as noted in the discussion in the strat thread, maybe some interest up above too.  

Rant coming!   I've seen a number of comments regarding the seasonal models in various threads along the lines that all the models are lining up the same way, so this +NAO all winter thing is actually a dead cert, I think CANSIPS was the latest, "full house"! LOL!

No!  This is not what these models are saying. 

To use a non-analogy,  sure it is true that if some of the op models are showing an easterly at T120, we'll be sceptical, but if UKMO, GFS, ECM, GEM, JMA, FIM, the Russian one and ARPEGE are all progging it at T72, we buy it big time. That's fine for deterministic (single run) models.  

But the seasonal models are not like that, they are probabilistic, and what we see is just the average over runs, and worse still the average over 3 months as well in most cases.  The Met Office present their temperature results as 5 categories (equal 20% by climatology), and looking at the GloSea5 model, and what they say in the contingency planners forecast, the warmest category is 50% and the coldest 5%.  So that's the only model result you've seen....and then you look at another one, ECM maybe, it says the same, it's averaged charts look the same, does that make it worse for cold outcomes?  No, it makes it exactly the same.  It too has the same 5% very cold solutions.  etc.

This is one reason why the seasonal models results, especially taken all together, do not at all rule out cold winter weather, by any means.  Plenty to play for...we will see...

 

Edited November 1, 2019 by Mike Poole

[Man With Beard]

Back to the present... Are we underestimating this storm tonight? Up to 90mph gusts on the EURO4 even in a couple of built up areas like S Wales. There could be quite a bit of disruption, but media surprisingly blase? 

This mean wind speed chart has F10, close to F11 approaching S Wales for first thing tomorrow - very dodgy indeed 

Edited November 1, 2019 by Man With Beard

[Porto]

2 minutes ago, Man With Beard said:

Back to the present... Are we underestimating this storm tonight? Up to 90mph gusts on the EURO4 even in a couple of built up areas like S Wales. There could be quite a bit of disruption, but media surprisingly blase? 

There's definitely a lot of uncertainty to it, models don't have widespread agreement, and probably why the Met has their warnings so low on their Impact Matrix. ICON/EURO4/ECM all going for some pretty nasty storms, GFS and others less on board, although GFS definitely upped the speeds in its 12z run.

[Mike Poole]

45 minutes ago, Man With Beard said:

Back to the present... Are we underestimating this storm tonight? Up to 90mph gusts even in a couple of built up areas like S Wales. There could be quite a bit of disruption, but media surprisingly blase? 

That's well up towards the top end on the ARPEGE ensembles, here the 6z, 10%, 50% and 90% percentile of the probabilistic analysis, this was the peak at the time (charts are wind gusts km/h):

Edit, here's the AROME ensemble 92% i.e very top end of probability, at about its peak, 

I think MO has probably got it about right re risk level.

Edited November 1, 2019 by Mike Poole

[Ali1977]

No comments on the pub run, this isn’t far off being very good. Might come to nothing but -8 uppers into east Scotland at day 9, some snow showers off the North Sea there !! 

 

Scandy Hp refusing to budge and not much PV over Greeny, poss incoming WAA towards there through Newfoundland - Interesting FI coming up with reinforced Scandy HP!! 

 

and there you have it.

Edited November 1, 2019 by Ali1977

[Tim Bland]

Stonking  FI coming up 

Edited November 1, 2019 by Tim Bland

[feb1991blizzard]

Just couldn't get the frigid air in on that run - close but no cigar.

[Mapantz]

1 hour ago, Man With Beard said:

Back to the present... Are we underestimating this storm tonight? Up to 90mph gusts on the EURO4 even in a couple of built up areas like S Wales. There could be quite a bit of disruption, but media surprisingly blase? 

This mean wind speed chart has F10, close to F11 approaching S Wales for first thing tomorrow - very dodgy indeed 

A small discussion of this was taking place in our SW thread, MwB. It look's decidedly dodgy!

[Ali1977]

This would be good in Jan, but the Scandy high sank too early to tap into decent cold air - it’s only mid Nov so you need the perfect setup for anything really cold. As Feb says - close but no cigar !! 

[feb1991blizzard]

2 minutes ago, Ali1977 said:

This would be good in Jan, but the Scandy high sank too early to tap into decent cold air - it’s only mid Nov so you need the perfect setup for anything really cold. As Feb says - close but no cigar !! 

Yes, you need either a loop in the flow to back up far North East, either that or you need a 2 stage push, first a chunk of PV to snap off in Eastern Europe / Russia and just as the high re-orientates, to be on the same track as the flow into the UK, once you see the 500mb low heights retreating East or North East, even if you initially see the fairly cold 850's heading (too slowly) this way, that is usually a giveaway that you wont get a classic setup.

[Allseasons-Si]

1 minute ago, feb1991blizzard said:

Just couldn't get the frigid air in on that run - close but no cigar.

Late to the party

but yes Feb,the low needs to be further east towards Genoa area as this stops the med temps creeping up from the S/SE

the red X is where we don't want it,the black circle is where we want it

this is all academic at this range so i won't comment on it too much

i did like the 12z gfs run with low after low heading SE all through the run

0-192hrs 192-384hrs

there has been some great posts in here again today but  lets not get too carried away just yet.

 

[feb1991blizzard]

1 minute ago, Allseasons-si said:

Late to the party

but yes Feb,the low needs to be further east towards Genoa area as this stops the med temps creeping up from the S/SE

the red X is where we don't want it,the black circle is where we want it

 

this is all academic at this range so i won't comment on it too much

i did like the 12z gfs run with low after low heading SE all through the run

0-192hrs 192-384hrs

there has been some great posts in here again today but  lets not get too carried away just yet.

 

Yes, and preferably tilted on a NE-SW axis, particularly early or late in season, exception obviously is when we already have very cold air far South.

[Jordan S]

Arome bringing 70mph or so for the channel with 60-70mph for the southwest and south Wales and 50-60mph for the rest of southern England could be a little higher than this given some other model output going to be interesting to see wind gust reports later tonight in the south west. Rain will be heavy for a time too in similar areas. 

 

[Bristawl Si]

Soggy, and sometimes v windy November coming up; already kicked in here. Will last most, if not all, of month. You heard/read it hear first. Actually i wrote it one week ago in here, i think, but got 'told off'.

[Allseasons-Si]

Just for fun but this would raise an eyebrow or two if they kept on showing up on future runs

P12

[ICE COLD]

1 minute ago, Allseasons-si said:

Just for fun but this would raise an eyebrow or two if they kept on showing up on future runs

P12

Now that is perfecto . The purple blob heading straight for us . If only ay . But as you say just for fun for now . 

[Man With Beard]

Risk to S Wales drops on this EURO4 run but I would cancel a boat trip across Biscay this weekend, goodness me

[feb1991blizzard]

1 minute ago, Man With Beard said:

Risk to S Wales drops on this EURO4 run but I would cancel a boat trip across Biscay this weekend, goodness me

A cracker for S.Devon - gusting around 90+mph.

[ItNeverSnowsInWindsor]

We need the vortex in the charts to keep looking like the Bird of Prey to head us down some wintry weather 

[icykev]

18 minutes ago, Bristle boy said:

Soggy, and sometimes v windy November coming up; already kicked in here. Will last most, if not all, of month. You heard/read it hear first. Actually i wrote it one week ago in here, i think, but got 'told off'.

Looking @ the models I would say cold is a good bet.❄

[ItNeverSnowsInWindsor]

6 minutes ago, prolongedSnowLover said:

We need the vortex in the charts to keep looking like the Bird of Prey to head us down some wintry weather 

Something better than this though

[Geordiesnow]

That JMA chart above shows what could happen if we get enough ridging in the Atlantic but most runs from the main models don't suggest such a pronounce ridge. 

Next week meanwhile looks messy too me, very hard to pick out the details but there does seem to be a tendacy of the lows being reluctant to move ESEly thus any colder air from the north is struggling to make much inroads into the UK. 

Conditions up in the Arctic are looking interesting in respect how much the PV may split, the models do seem keen to sending down some sort of heights southwards from the Arctic but whether it will affect our weather is debatable. 

[MR EXTREMES]

[Bristawl Si]

Mr Extremes - your point is?