Model output discussion pm 13/01/2016

[TomDav]

GFS Stratospheric output is consistent.

[BLAST FROM THE PAST]

Personally I'm looking at LPs of a deep nature affecting us over next ten days. I have seen hints that this could be the case and we need to look NNW and N for incoming cold turn of the month.   It does seem that the mild battle is underway and models are showing a bad cold outlook at present. I think the length of time of the bad outlook should look less over coming days, but some mild initially we have to accept.  

BFTP

[Derbyshire Snow]

4 minutes ago, TEITS said:

I beg to differ.

The models have been consistent with a positive NAO i.e low heights to our NW with high pressure to our S for many days now. The models have also been consistent with high pressure to our NE. The problem is even if we do see low pressure going underneath the high to our NE, the low heights towards Greenland are likely to prevent the block to our NE to extend W.

I seem to recall some forecasts based on teleconnections saying the end of Jan/early Feb is when winter will bite. Well at the moment I see no evidence of this in the output. Infact the current output is like something from a horror film. Maybe the forecasted cold spell will be put back to mid Feb.

 

I think there is some promise towards the end of this run. I know its FI . Because of the heights in North Atlantic and Greenland, not mega but enough to push  the PV east and we then begin to receive  a cold north westerly flow. Snow at time for many parts of the north particular on hills

[Ali1977]

5 minutes ago, TEITS said:

I beg to differ.

The models have been consistent with a positive NAO i.e low heights to our NW with high pressure to our S for many days now. The models have also been consistent with high pressure to our NE. The problem is even if we do see low pressure going underneath the high to our NE, the low heights towards Greenland are likely to prevent the block to our NE to extend W.

I seem to recall some forecasts based on teleconnections saying the end of Jan/early Feb is when winter will bite. Well at the moment I see no evidence of this in the output. Infact the current output is like something from a horror film. Maybe the forecasted cold spell will be put back to mid Feb.

 

Yes Teits, nothing cold before Atleast the start of Feb looks odds on - building blocks are in place regards slight weakening of the PV, and zonel wind reduction by then though - just need to build on that...METO have said 1st week in Feb not looking cold, but possibilities of a NW flow developing on into Feb - that's going to involve a weakening of the Euro High and vortex, so let's keep looking for that I'd say.

[bobbydog]

not to worry, hopefully the models will settle into consistent agreement and we will get the long awaited SSW, bringing us a decent easterly. by december....

[snowray]

2 minutes ago, bobbydog said:

not to worry, hopefully the models will settle into consistent agreement and we will get the long awaited SSW, bringing us a decent easterly. by december....

More likely a decent Easterly by late March, or April!

[markw2680]

11 minutes ago, TEITS said:

I beg to differ.

The models have been consistent with a positive NAO i.e low heights to our NW with high pressure to our S for many days now. The models have also been consistent with high pressure to our NE. The problem is even if we do see low pressure going underneath the high to our NE, the low heights towards Greenland are likely to prevent the block to our NE to extend W.

I seem to recall some forecasts based on teleconnections saying the end of Jan/early Feb is when winter will bite. Well at the moment I see no evidence of this in the output. Infact the current output is like something from a horror film. Maybe the forecasted cold spell will be put back to mid Feb.

 

When I say they are all over the place I mean there seems to be no consistency at all, one run shows one thing then the next one will show completely different, tbh I'm probably out of my depths here so I'll just leave it to the more knowledgeable 

[tight isobar]

Is this the first "hint" Synoptics" to GP,s torpedo??!

with modelled (as now) the mother Canadian vortex lobe being syphoned eastwards and the never decaying Russian peninsular (kara) heights, punching against the progression of the incoming vortex..and splitting through like a knife (torpedo) through butter and opening up at the western  seaboard Canada/USA..leaving a very displaced/deflated polar vortex...??!!! The Russian high has me not wanting take my eye off it!!!

Edited January 20, 2016 by tight isobar
Word love not lobe!!!

[snowray]

They are often like that Mark, more so the last couple of weeks though. Even full agreement at T96 or T120 can be wrong, although these about turns predominantly occur when they are showing cold and snow for the Southern 3/4 of the British Isles. 

[Derbyshire Snow]

These high pressure areas coming out of US i presume the models reacting to the odd prediction of NAO forecasts being right.

See what tomorrow brings, i think surprises will appear more regular in the models  over the next few days

Edited January 21, 2016 by Derbyshire Snow

[igloo]

On 1/19/2016 at 7:01 PM, *Sub*Zero* said:

 

12 minutes ago, snowray said:

More likely a decent Easterly by late March, or April!

On 1/17/2016 at 6:18 PM, Jason M said:

forget them there condemned to the history charts. a 48h  northerly toppler and im more than pleased nowadays sad to say

  

[Ali1977]

This caught my eye...no support but nice all the same.

[Cheshire Freeze]

1 hour ago, Singularity said:

I've just realised that if you run the 12z and probably from the looks of it so far 18z GFS det. runs through +192 to +384 you can see how it basically decides to move the entire polar vortex from Canada across Greenland toward Europe as one consolidated feature - essentially following the stratospheric movement but lagged by a number of days. The process is slow enough that it's still not reached Europe as of the end of the 12z run, will the 18z be any faster I wonder?

How often does the vortex actually manage to move about like that in the troposphere without being at least stretched or even broken down? Not sure I can recall seeing it manage that any time since I started paying attention to the N. Hem charts in 2009.

I get the intense cyclogenesis element though, as deeply unstable air moves over the ocean during the transit process. The trouble is GFS has a simplistic approach with large, deep storms when it can be a whole lot messier. That's where the amplification of the pattern comes into it and why the MT event could make things interesting while the vortex makes its move.

The ECM 12z det. has the more disorganised look to the vortex that I'd expect to see.

I feel I have read too much into today's individual runs to be honest, despite Tamara's advice in this thread yesterday. I just can't help myself, I enjoy this kind of analysis too much! It's the making the forecast part that becomes less amusing 

Correct and reaffirms the assumption that the PV will eventually displace from the Canadian/Greenland sector over to our NE. What is being modelled is pretty much typical of what you'll see when the NWP transport the vortex across to the Scandinavian side....i.e increased gradient in the N Atlantic and a tightening of the jet stream and general zonal flow. Another response is to sharpen up the +NAO signal with increased heights to our S and lowered heights to our N. This is good (all part of the process)- and placed into context we will eventually see that this PV lobe becomes severed from the main vortex with a tanking AO and the severed vortex lobe eventually sinking to our east and providing the fuel tank for our next cold shot (as heights increase to our NW). This is the theory anyway.

Remember what I said about heights draining away slowly from the Greenland locale the other day? All we can do is sit back and wait...I have a feeling patience is wearing a little thin with some people.

I'd place a large sum of money on February coming in below average CET wise.....maybe around the 3C mark.

EDIT: just seen Ali's post above- yes something resembling that is what I'm talking about.

Edited January 21, 2016 by CreweCold

[Derbyshire Snow]

13 minutes ago, Ali1977 said:

This caught my eye...no support but nice all the same.

Thats a great chart to go to sleep on. SSW definitely taking a hand in that one

[Cheshire Freeze]

Let's take a look at an extreme solution to the pattern I've outlined above.

Perturbation 15.

Vortex on the move (on a more N'ly latitude than we may see) with low heights transferring E. Jet has tightened up well to our N

Moving on you can see the retrogressive nature of the high in tandem with the eastward propagation of the Greenland vortex lobe

Eventually western vortex segment is severed

The transported Greenland vortex then drops S to our E and becomes our cold reservoir as I mentioned in the post above

There's your cold Feb from an initially poor prognosis.

 

On balance, it won't be as smooth as this but I also don't think as much of a meal will be made out of the process as is currently shown amongst the ops and ensembles. Once the modelling finds the correct solution (i.e one which isn't flat zonal or super +NAO) you'll see the op runs start running with the idea of pressure rises to the NW.

Edited January 21, 2016 by CreweCold

[Timmytour]

I've had a few drinks, seen Spurs triumph and nearly had a heart attack pushing my brother's car back to his house.....so I'm in the mood for a bold prediction

On the GFS 18z at T96, watch the track of the low in the bottom left hand corner that takes it up to the north of the UK by T156.

T96      T156 

 

The prediction is that this track will be a whole lot different in the 0z and 6z runs....and a difference which will open up the prospect of much colder weather hitting the UK in a timeframe which the models are not currently showing us...

[Geordiesnow]

I see people are saying nothing cold until the start of Feb but there has been hints of potentially a strong polar maritime airflow for some time next week if albeit probably not for very long although details at this range would be pointless too look into so it might not be the totally mild/very mild story as people are suggesting. 

It does look like Sunday and into Monday will be the peak of this very mild weather, what happens after detail wise will be uncertain because low pressure will be edging in and perhaps trying to introduce some way of colder air for a while. 

In terms of another cold spell, we do look a bit of a long way off at the moment and maybe patience is what will be needed. I agree with Blast in respect there is a chance of a very deep low forming, especially if that very strong PV drops out of Canada into the Atlantic. 

Of course, whilst you got blocking you can never rule anything out but any cold weather from the East looks very unlikely at the moment. 

[Cheshire Freeze]

Lovely chart...watch that swathe of HP get hoovered up to the NW as the vortex transfers E...

EDIT: vortex doesn't break favourably for us and we end up with a segment remaining over Greenland. AO does look to go negative though

The potential is there days 9&10 if we can get a clean displacement of the vortex. One to monitor!

Edited January 21, 2016 by CreweCold

[snowfish1]

6 hours ago, Singularity said:

I've just realised that if you run the 12z and probably from the looks of it so far 18z GFS det. runs through +192 to +384 you can see how it basically decides to move the entire polar vortex from Canada across Greenland toward Europe as one consolidated feature - essentially following the stratospheric movement but lagged by a number of days. The process is slow enough that it's still not reached Europe as of the end of the 12z run, will the 18z be any faster I wonder?

How often does the vortex actually manage to move about like that in the troposphere without being at least stretched or even broken down? Not sure I can recall seeing it manage that any time since I started paying attention to the N. Hem charts in 2009.

I get the intense cyclogenesis element though, as deeply unstable air moves over the ocean during the transit process. The trouble is GFS has a simplistic approach with large, deep storms when it can be a whole lot messier. That's where the amplification of the pattern comes into it and why the MT event could make things interesting while the vortex makes its move.

The ECM 12z det. has the more disorganised look to the vortex that I'd expect to see.

I feel I have read too much into today's individual runs to be honest, despite Tamara's advice in this thread yesterday. I just can't help myself, I enjoy this kind of analysis too much! It's the making the forecast part that becomes less amusing 

...which only serves to make your post much more interesting on our interpretation of the models and associated influences so thank you. It's a bit like Johnny Ball and maths lol

Edited January 21, 2016 by snowfish1

[Ali1977]

ECM at day 10 much better than yesterday, nothing cold just yet but the NH is looking much more favourable as we head into Feb, wouldn't take much to fire WAAup into Greenland as the PV splits in the area!!

The GFS Ens starting to get a few colder runs going again also.

[Frosty.]

It's starting to look like we are looking at a mild / very mild outlook through to the end of Jan and into feb guys...so at least the daffs will be happy!

[mountain shadow]

11 minutes ago, Frosty. said:

It's starting to look like we are looking at a mild / very mild outlook through to the end of Jan and into feb guys...so at least the daffs will be happy!

Cohens temp anomaly for February is the complete opposite of that. 

Let's hope for a quick turnaround next month. 

[joggs]

26 minutes ago, Frosty. said:

It's starting to look like we are looking at a mild / very mild outlook through to the end of Jan and into feb guys...so at least the daffs will be happy!

GP stated a few days ago,anyone thinking a mild shot early Feb might be in for a shock.

[Frosty.]

5 minutes ago, joggs said:

GP stated a few days ago,anyone thinking a mild shot early Feb might be in for a shock.

Well looking at the reliable timeframe it's going to become much milder with temps up to 11c tomorrow and then very mild through the weekend into next week according to the models!

[Yarmy]

ECM trying to build an Atlantic ridge at the end of its run and drop a Scandi trough into Europe. This would be more in line with what GP has been suggesting (as I understand it anyway). I think IanF commented on NW/N flow possiblities too, but that may have been for later into February.

The NOAA anomaly chart also has increased the +ve height anomaly over the mid-Atlantic and has shifted the -ve height anomaly over Greenland towards Canada. Not much sign of a Scandi trough, though.