Model Output Discussions 06z 04/11/16

[igloo]

41 minutes ago, nick sussex said:

Bizarre. Looking at the outputs that forecast doesn't match especially with the UKMO updated at 11.56am, that tv forecast says updated an hour later and I suspect that was recorded much earlier or done the previous night.  Admittedly theres still some uncertainty given the models have been chopping and changing but theres simply no way the BBC can give that forecast without adding a caveat because its finely balanced. Indeed both the UKMO and BBC look too bullish either way and one wonders whats going on.

you a right does everyone remember a few years back when they gave seasonal forecasts which were on lines of barmy summers and mild winters which turned out to be the complete oppisite then they stoped them so im not sure why they are starting to ramp this stuff up again either they are super confident in there own models or they have forgoting the years prevoiusly either way this mornings ECM does not show this but my personal view is the ECM is a cold outlier and this evenings with be alot different

Edited November 26, 2016 by igloo

[Geordiesnow]

5 minutes ago, igloo said:

you a right does everyone remember a few years back when they gave seasonal forecasts which were on lines of barmy summers and mild winters which turned out to be the complete oppisite then they stoped them so im not sure why they are starting to ramp this stuff up again either they are super confident in there own models or they have forgoting the years prevoiusly either way this mornings ECM does not show this but my personal view is the ECM is a cold outlier and this evenings with be alot different

I think people need to know and be aware but the long range forecasts the BBC does is usually based on the 00Z UKMO run(on the nightly forecasts they may do a forecast based on data on the 12Z run if there is an ongoing weather event) and the 00Z UKMO run shows what that BBC forecast is saying.

Even the ECM is still a bit on the mild side for mid week next week, the question will be how much amplification will we actually see, I very much doubt we will see the GFS Northerly runs but hopefully we can get on the colder side of the jet.

[Man With Beard]

6 hours ago, Steve Murr said:

We know historically ( well many will ) that when it comes to energy within the jet & seperating different sequential areas of low pressure or even shortwaves the ECM will outperform the GFS every time- 

Here a good example from storm Angus -

Actual chart that verified

 

Nice post Steve, but just to be completely fair to the GFS! although this turned out to be a day ahead of the actual event, this goes to show it was sniffing around for the right conclusion several days before any other model was:

[ribster]

1 hour ago, beefy201 said:

I think this is the much more likely scenario (BBC) it is funny to see such cold ramps going on when the reality is so much diffrent

I think they suggested this was likely, not guaranteed, looking at the models today would suggest there is still uncertainty. 

[clark3r]

4 hours ago, Steve Murr said:

Will do a post @ 3pm today however dont under estimate the potential of what could happen at short notice this afternoon

BIG BIG DEVELOPMENTS..

Remember I mentioned the split energy scenario earlier in ECM at 120 & that was one of the important things to look for in todays models especially the GFS trending..

Heres the updated 120 06z Mean V the old 120 00z mean..

MORE AT 3

Then 162 v 168

 

Where's your 3pm update Steve? Hopefully it's a good one

[SMU]

Afternoon All-

So November 26th - 4 days to the start of Winter & for once we have started the run in on a 'seasonal' note, certainly a below average November about to land & generally the AO has been negative although perhaps not as negative as one would have expected V the strength of the vortex -

So we have already gone over why the NH height fields have been disrupted towards a more Postive height picture

- The total breakdown & non recovery of the vortex this April

- The Ice loss & subsequent reloss in October as the Cold seeped out to (mainly) Russia

- The record breaking SAI for 2016 

- The record breaking warmth in the Arctic... & so on..

Globally I believe 2017 will be a year like no other-

Anyway, the prime driver of the optimism has come from that zonal wind weakness -

The November average is Westerly @ 30 M/S & today we are running at exactly 8 M/S challenging the minimum record in 3/4 days of around 5 M/S-

So with this in mind I have disputed all along that the opportunity for deep cold could come before mid December & that opportunity peaked around 30th Nov in conjunction with a brief Easterly phase of the zonal wind - IE the chance 'globally' of there being a buckled jet around 60N - 

Its been a rollercoaster journey in the last 4 weeks with no significant cold present, however enough flirtations with polar air to see early snow for the North-

The peak weakness period of the jet circa Nov 30/Dec 1 should have been modelled as a blocky period however till today the models had produced elements of mid lattitude blocking - but nothing to sustainable-

Today however we do have something different in the mix. 

First & foremost I'n not saying this will happen - however from experience this is where 'some' if not most of our decent snowy cold spells have come from.

What we see at 120 is an opportunity to further reduce the atlantic push east as height rises try to head N/NE towards Greenland-

Remember the Criteria for a decent Greenland block-

* Azores High Ridging North 

* Scandi High ridging West  

or both -

The key location as EVER is whether the 552 Line can get North of the west coast of Greenland-

This is usually the cut off point where the jet & low pressure has been deviated so much off track that its past the point of return- any lack of upper blocking that doesnt get into that locale usually means that we have enough positive tilt in the jet to over ride the high & the subsequent block wont be far enough NW to get the deep cold in ( usually it skirts the NE coast ) as it drifts past.

What I have seen this morning is exactly the same as how 7th March 2013 blocking started with a wedge of high pressure forcing its way North west & the cold plume getting forced west underneath-

At that time the models especially the GFS struggled with the magnitude of the high & blocking till about 144 where all of a sudden the energy went underneath & the 554 line made is past greenland -

looking at the ECM today were not quite there

- Should we get just a bit more amplitude in the wave & a higher lattitude block the Ensembles will crash towards -10c....

So lets look at the date for Dec 3 ( transition period 30-2nd) in the Ensembles for 2 locations & monitor the 'means' movement

Aberdeen & London 

Aberdeen -3

London 0

- Areas to look at 120-144 for more negative tilt bit also more amplitude in the wave...

Cheers

S

 

 

[Mucka]

Another little step back toward colder from GFS. This maybe the new middle ground.

Certainly UKMO moving back toward a more amplified pattern too. 12z comparison today/yesterday

 

Seems now that ECM was definitely onto something this morning.

 

Edited November 26, 2016 by Mucka

[Tom Jarvis]

Well well well. Going under

I sense the famous murr sausage is about to appear

Edited November 26, 2016 by Tom Jarvis

[Singularity]

 

 

Notable to see the ridge, hence jet and indeed the 552 line adjusted to reach further NW on the 12z (right) compared to the 06z (left).

2m temps actually turn out a little higher in the south for Wednesday night and Thursday which seems to be due to clearer conditions (less low cloud or fog) but with a typical overlooking of early-morning cooling potential by the model (the number of times I've seen a dip in temp 2-3*C below the GFS min between 7 and 9am... it's ridiculous).

 

Nice trough angle on the 12z UKMO, as many anticipated from the Met Office update (but not the out-of-date BBC one!)

[shaky]

Now its getting interesting!!low looks like its attempting to slide under at 150 hours!!gota keep these upgrades coming though!!

[igloo]

cant post pics as im on a android tv box but the UKMO looks alot better at 120h very similar to the ECM and GFS so ot looks like it is backtracking good sign

Edited November 26, 2016 by igloo

[Singularity]

3 minutes ago, Tom Jarvis said:

Well well well. Going under

There's now actually a break in the jet stream south of Greenland which indicates some decent upper level convergence going on in the mid-Atlantic, supportive of strong ridge development.

+144 UKMO... sudden loss of about 10 mb of ridge magnitude across the UK which is strange given the very negative tilt to the Atlantic trough at +120. Route going forward not exactly clear but greatly improved from the 00z perspective. 

These days where you get a flurry of runs adjusting toward a colder outcome via tweaks to the longwave pattern (waves in the jet stream) toward something sharper with the jet angling NNW or even NW at times... they're the ones most people come here to enjoy the most.

Often it continues until desirable conditions are at around +96 hours, then some sudden downgrades to the detail occur 

Edited November 26, 2016 by Singularity

[karlos1983]

UKMO and GFS both looking great, negatively tilted low, heights building. Things looking good to my eyes!!

 

Edited November 26, 2016 by karlos1983

[Daniel*]

this is looking reasonable a wedge of +ve heights to the west of Ireland lows going SE which should help prompt the 'block'. 

 

[Mucka]

4 minutes ago, karlos1983 said:

UKMO and GFS both looking great, negatively tilted low, heights building. Things looking good to my eyes!!

 

Yes pretty good agreement there out to 144 Karlos

If we can back the pattern West a la this mornings ECM and then get the undercut we will be in for some exciting winter charts.

[Ventnor Viking]

I appear to be the only one that doesn't see this as an upgrade?

[karlos1983]

1 minute ago, Mucka said:

Yes pretty good agreement there out to 144 Karlos

If we can back the pattern West a la this mornings ECM and then get the undercut we will be in for some exciting winter charts.

As long as we see the ECM show something similar, we can start looking for upgrades. We still have a chance in the time frames we are talking. So far so good this afternoon. 

[Banbury]

Just looking at what the charts are churning out they seem to show something different to what N Miller has just said

 " as the week goes on it will turn less cold "  I know these charts aren't that great BUT

Also the UKMO 12z run would suggest some chilly days ,  today has been 9c , seems an odd comment from Nicky boy

[karlos1983]

6 minutes ago, ShaftsburySnow said:

I appear to be the only one that doesn't see this as an upgrade?

Wouldn't say upgrade just yet, but we have an opportunity now for upgrades. Lows pressure going south east and a building ridge. That's a good platform to build from

edit: if it's potential cold you're after of course

Edited November 26, 2016 by karlos1983

[Singularity]

Very funny (!).

The ridge just didn't gain enough solidarity, despite the supportive upper level environment I mentioned a few moments ago. 

I swear, someone has implemented Sod's Law into the models since the last decent winter spell we had .

Interesting N. Hem profile, as long as you don't mind doing your waiting under settled conditions; look at that ridge almost to the N. Pole from the Pacific. A big change from the 06z though so the usual caveats apply.

Edited November 26, 2016 by Singularity

[Ventnor Viking]

2 minutes ago, karlos1983 said:

Wouldn't say upgrade just yet, but we have an opportunity now for upgrades. Lows pressure going south east and a building ridge. That's a good platform to build from

I think many in here are looking for cold. Under the HP there are chilly days ahead and frosty nights but nothing sustainable long term. Additionally its surface cold so wouldn't take much to shift all in all seasonable weather and more importantly for many it remains dry!

If its wintry weather all is after the HP is too weak to our SW and upstream patter doesn't allow for any ridge to build in a favourable position.

[Ali1977]

So far a positive day for coldies, whilst no FI Stella runs things are moving in the right direction. I feel sat by day improvements could be the way we travel - this time next week i think we'all be looking winter square in the face with some great medium term patterns setting in!! 

[IDO]

26 minutes ago, karlos1983 said:

Wouldn't say upgrade just yet, but we have an opportunity now for upgrades. Lows pressure going south east and a building ridge. That's a good platform to build from

edit: if it's potential cold you're after of course

Not really seeing anything unusually cold in the next 7 days. The trend looks to push the cold upper flow too far east for snow (nominal chance now) and still a small chance of a dry northerly. The high has been consistently modelled to sink SE and in this run it does. That high is not going to just sit there IMO as the models are not even entertaining that. The Azores then pushes in bringing milder air from around D9.

I see no upstream amplification to stop the mobility of the flow and there is absolutely no WAA worth its salt other than transient topplers other than to ML's. Very little potential showing up in the runs and unless the models flip soon its wait it out till mid-Dec.

At around D9 on the GEM and GEFS: 

Mild more likely in the mid term with 14c after D10 possible with that Azores push.

We have a PV in disarray and there is just no forcing to take advantage of this, even if its just Rossby wave action to kick the strat PV; really a missed opportunity despite the potential further down the line. Thankfully the trop PV still showing no trend to regroup so maybe in a couple of weeks we will get some forcing but certainly zero consistent cold runs coming from the GFS and that is not good when so much is in our favour.

Edited November 26, 2016 by IDO

[nick sussex]

Given where we were yesterday and the huge changes especially in the UKMO output we've at least reached base camp!

Where we go from here depends on how much energy can disrupt off the troughing to the west, we don't want to see the bowling ball low as per the UKMO T144hrs output.

You preferably want the weaker shortwave as shown in the GFS, we still don't manage to get those lower heights far enough east towards northern Italy. That's really what we need to see going forward.

[knocker]

The GFS retains the amplified Aleutian ridge and energy zipping out of the southern States on a strong jet with an increasingly influential trough in the western Atlantic which keeps the Azores ridging in check and induces WAA by the 6th