Model output discussion - into 2018

[Cheshire Freeze]

2 minutes ago, The Enforcer said:

12z Saturday: 

12z Sunday: 

12z Monday: 

12z Monday-

You used a different perspective for that last chart.

[The Enforcer]

4 minutes ago, CreweCold said:

12z Monday-

You used a different perspective for that last chart.

Yeah I was looking for the one you found cheers.

[Frosty.]

1 minute ago, Broadmayne blizzard said:

Always admire and enjoy your upbeat enthusiasm Frosty but snow up north with some elevation is pretty standard fair even in an average winter. When you live five miles from the English channel just north of Weymouth you something pretty spectacular and barring a polar low it don't come from the northwest for us.

Cheers, just trying to lift the gloom that's descended but I'm hopeful there could be some decent cold zonality from early next week onwards with some wintry surprises, not just across the north.❄❄❄❄❄❄❄❄

[SLEETY]

5 minutes ago, Chevron12345 said:

Chasing Artic Highs/Ridging in FI is the new theme. The Scandi High was the big theme in December then was witten off late December but actually did appear this week...confusing. Give me a Greenie High modelled at 72 by UKMET please.

The current output on the UKMET is not shifting the Scandi high as fast as people are predicting. The ECM has some agreement too.

Yes both models kept the high close by at 120 hrs with a se flow.We need to see this continue in the next set of runs,or it really is game over I think.

BTW where are TEITS AND SM they were the ones saying they expected the Easterly to win out,but they seemed to have stopped posting,which is annoying as it be nice to hear what they think of the recent runs.

[Panayiotis]

Ive been more of a lurker this winter regarding posting in this thread but heres a post on my thoughts. I think its fair to say (as mentioned by some) that the quest for a near-term easterly (which could deliver snow) is quickly becoming non-existent. The closest we get to a feed off the continent is from the SE which originates from Greece @120hrs and with no deep cold pooling over Europe, this is only likely to bring upper air temperatures just below 0C.

Looking at those charts from 120hrs, Im finding it difficult to see where a potential easterly (cold and snowy type) could come from. The centre of the high on all of the models is located over Russia, which is in completely the wrong place for the UK to benefit as the flow and subsequently colder temperatures are directed towards Turkey/Black Sea. Despite the MLB not directly delivering for the UK, I think it will help us in the longer term.

All the charts above also have another feature in common: a raging and circular PV over Greenland. Its after this point (120hrs) where there is developments for low pressure to move away from Greenland, and in doing so it faces the block to the east. Its this low pressure which delivers the polar maritime air mass forecast for the UK, and because its unable to move away due to the block, it keeps the PM feed for longer. The interesting trend which I'm picking up on is that the same low pressure which delivers the cold PM air to the UK is also responsible in driving away the PV from Greenland. Charts below are for 168hrs:

From experience when the PV moves away from Greenland, it is replaced by a pressure rise. Now if the low pressure can dig SE (as shown by the models) then we will see a movement of the heights from the MLB on the NE flank of the low. Hence what I'm looking for is a double 'attack' of pressure rises over Greenland, one from the east and one from the south. For an example of what could happen, I give the 00z run from the NASA model:

 

 

Edited January 8, 2018 by Panayiotis

[ANYWEATHER]

Evening All, so gloves are off and the battle between east and west For Now is finally settled ,before then nothing really mild on the cards even with the attempt of the Atlantic in the next few days with frost and fog to play with.....after that look west with some deep Polar Maritime air flooding our shores in the next ten days .

[Chesil View]

Just now, Frosty. said:

Cheers, just trying to lift the gloom that's descended but I'm hopeful there could be some decent cold zonality from early next week onwards with some wintry surprises, not just across the north.❄❄❄❄❄❄❄❄

Lets hope so Frosty followed by a greeny/scandi link up to give everyone a good chance of the white stuff. Keep posting Frosty because you definitely lift the mood my friend

[Johnp]

43 minutes ago, mulzy said:

No support from the mean - clusters may reveal more later.

Probably a rogue run from the control - it's day 15 and JFF.

I know it's almost pointless discussing it, but what kind of evolution does it follow to get there?

[The Enforcer]

Sunday 12z: 

Monday 12z: 

Cold 850s being undermined, but they are still there.

[Scandinavian High.]

BBC weather outlook not very confident when will westerly will break down high to the east high looks like putting up more a fight than previously thought I think models are being progressive..

Edited January 8, 2018 by abbie123

[SLEETY]

1 minute ago, abbie123 said:

BBC weather outlook not very confident when will westerly will break down high to the east high looks like putting up more a fight than previously thought I think models are being progressive..

Yes I’m not surprised when you look at 120 hours on ukmo and ecm.people ignoring the earlier time frame again

[bluearmy]

Big temps difference  on the latest ec op for ththe end of the week down here compared to previous runs

Not much above freezing here Thursday and fri now 

Edited January 8, 2018 by bluearmy

[Bogman]

6 minutes ago, bluearmy said:

Big temps difference  on the latest ec op for ththe end of the week down here compared to previous runs

Not much above freezing here Thursday and fri now 

As in, round these parts? Two hours ago local weather showed 9 degrees

[mulzy]

28 minutes ago, Johnp said:

I know it's almost pointless discussing it, but what kind of evolution does it follow to get there?

Similar to the op to day 10 then little channel runner by day 11 and then main trough digs into Europe with Scandi high forming - all academic of course...

[ANYWEATHER]

22 minutes ago, abbie123 said:

BBC weather outlook not very confident when will westerly will break down high to the east high looks like putting up more a fight than previously thought I think models are being progressive..

BBC

[Catacol]

Not got time to check back through the thread tonight - but this is a glaring GWO chart if noone else has noted it:

For neartime amplification pretty dire (hence atlantic breakthrough coming up) - but for the degree of "stretch" in the atmospheric elastic band this is setting us up for a decent ping-back. Think of atmospheric momentum budgets like a band - constantly stretching out of alignment but then coming back to neutral as the band pulls things together. Here we have an extreme GWO 1 orbit in low AAM tendency... and the elastic band is going to want to bring things back to neutral pronto. End result - bigger chance of a decent spike when it comes. 

As noted yesterday in posted charts - MJO stalled in phase 2 but CPC predict (again) a move to phase 3 next week. Have to think it will happen this time... in conjunction with rising frictional torques. 

So not a lot of change from yesterday - but that GWO chart was worth looking at. Timing of amplification and return of scandy high on course. Some interesting charts will start to appear at T+240 in the next few days...

Edited January 8, 2018 by Catacol

[SMU]

Evening campers

A busy day leaves me with just 1 post count for the day

The last 5 days have been run in almost slow motion, it’s like we have been walking forward on a conveyor belt that’s going the other way at the same speed-

In terms of forecast the notion & expectation that the models would move to a cold Easterly has made the journey about 85% & credit to the UKMO in support of that- it had the long @ shortwave pattern pretty much nailed well ahead of the GFS / ECM ( poss 2 days )

The only criticism it can take is it was to deep with the Italian low prolong up the high

so just for fairness & commentary you can be your own judge

this is today’s ECM 120 which feels about right

Thats a fair shout of a forecast 7/8 days out ( also strat indicators for 7th Jan almost 3 weeks out )

for ref the 2 days proceeding 144 & 168 for the big 3 ( just 1 UKMO )

GFS - made a very abrupt change over 24 hours 168 then 144

ECM was closer but to progressive

UKMO 144 yesterday 

 

I think overall the UKMO was best online with forecast - with just 1 run that was to deep in an easterly flow-

ECM was very poor & progressive on many occasions & GFS couldn’t resolve the shortwave split in energy.

So in all probability we will miss the deep cold although having said that I’m still of the opinion the progress from 120-72 still holds some sharper charts relating to the continental flow & we still could scrape that all important -6c over the UK

 

Post that - again what’s been apparent is the models willingness to push the Atlantic through before backtracking over the next 24 hours-

Here’s a good example -

yesterdays 12z GFS 168 next to today’s 144

Note the retraction west of the vortex struggling to make inroads

also the wave height of the Scandi block is higher amplitude -

So I expect the Atlantic to mount a big attack around 156-168 however the more robust the block the weaker the Easterly progression with ‘Sliding type scenarios’ in the mix- as it is buffered by the Scandi & Arctic high which was mentioned 24/36 hours ago.

also watch out for the cut off low that could reinforce the continental flow with possible snow if it stays shallow enough ( about T120 )

Just an aside the strat forecasts ( **GFS derives ** ) show a SSW/ zonal reversal early Feb with good continuity from the CFS control & Pterbed runs all showing very similar characteristics...

Anyway enough for now- I think this weeks been a worthwhile investment of time at least to show & dismantle the GFS performance around split energy!

S

 

 

 

Edited January 8, 2018 by Steve Murr

[SMU]

21 minutes ago, bluearmy said:

Big temps difference  on the latest ec op for ththe end of the week down here compared to previous runs

Not much above freezing here Thursday and fri now 

Continental SE flow - low Theta E values ...

[chionomaniac]

Just a point to take note of how continental air mass can influence temperatures. Pretty cold here now with a SE flow off the continent:

 

The 850 temps though are a lot higher though- towards 8 and later 10 degrees :

So one can imagine that if 850 temps were even just below 0 then the surface temperature could still be conducive for snow if precipitation was forecast.

 

[Kentish Snowman in Yorks]

I am not for one minute suggesting anything bitterly cold or snowy will come from it but I am less and less convinced that the Atlantic will properly break through looking at the model output as a whole today.

The breakdown appears to be stuck at Day 6 and moving no nearer.  The ECM in particular is eye opening in this regard.  I appreciate the Atlantic is full steam ahead at the moment but it does not really have anywhere to go except SE with more and more of the output suggesting that heights are to retrogress NW out of Scandi.

Is The Beast stirring after all?

[shaky]

11 minutes ago, Steve Murr said:

Continental SE flow - low Theta E values ...

Lets see if 18z is more stubborn with the block!!

[Weathizard]

6 minutes ago, chionomaniac said:

Just a point to take note of how continental air mass can influence temperatures. Pretty cold here now with a SE flow off the continent:

 

The 850 temps though are a lot higher though- towards 8 and later 10 degrees :

So one can imagine that if 850 temps were even just below 0 then the surface temperature could still be conducive for snow if precipitation was forecast.

 

Indeed it's bloody freezing down here! That being said, that might be because it's been a fairly mild winter for us so far.

 

iPersonally I'm not buying any Atlantic onslaught, probably no beasterly but I can't see a washout, I hope not anyway... hasn't bloody stopped raining recently! 

[Chris101]

What gets my interest is the constant modeling of lots of areas of weak heights all around our North and Northeast, some don't even seem to be able to pinpoint where these heights are even coming from.

With our now rather hated Scandi still on the board i still have high hopes for a big surprise.

Ecm and Gem very early on had a fleeting glimpse of heights in a large area across our N/NE in the shape of a tantalising high and Easterly which was soon to disappear.

That whole area is going to be fun to watch between now and the weekend. 

[January Snowstorm]

I think Steve's post above asserts the opinion that rather then any model being right or wrong a mix of all 3 is quite often the resultant outcome.

Let folk be their own judge of the last 7 days. For me the GFS was most reliable in eroding the block enough that it wouldn't play a part for now......

In the meantime the trend is gathering pace of a colder spell towards the latter half of January 

[doctor32]

1 minute ago, January Snowstorm said:

I think Steve's post above asserts the opinion that rather then any model being right or wrong a mix of all 3 is quite often the resultant outcome.

Let folk be their own judge of the last 7 days. For me the GFS was most reliable in eroding the block enough that it wouldn't play a part for now......

In the meantime the trend is gathering pace of a colder spell towards the latter half of January 

Funny how we see things different, i see the gfs constantly delaying the atlantic breakthrough due to the block being more stubborn. So very much playing a part in this setup. 

If gfs was correct some days ago we would be in the westerly flow now with low pressure over us.