Model Output Discussions 06z 04/11/16

[damianslaw]

I said on Wednesday evening, expect lots of chopping and changing from the models over the next 4 days (up until Sunday evening), and as has played out we are seeing this. Always when we have high pressure on the scene and a rather weak jet, the models are prone to wild fluctuations from one run to the next, we see this throughout the year.

The ECM this morning is showing greater amplification and barely any westerly influence in the reliable timeframe, indeed not until the 8 day mark, with the trough digging further SE into eastern europe which has the affect of elongating the high on a more NW-SE axis, exposing the UK to colder uppers from the north for a time at least - its very plausible.

Longer term - all eyes on developments over NE Pacific, signs ridging will nose in towards the Pole, and it is this development that would be trigger to much more sustained colder evolutionary pattern as we head towards middle of December.

With that - no model watching for rest of today, as I feel it is going to be another one of those roller coaster days in here, with people's moods changing by the hour. Anyhow its a cracking day here in the Lake District.. time to get outside.

[snowbunting]

It wouldnt be the first nor the last time that GFS pulled something out of the metaphorical freezer in Fl just to throw it out at around 240hrs and for it to disappear then with a few days to go.... back again. It did this December 2010. mid month it wanted to go zonal with a high slipping south.. instead the greenie High, it was massive... together with a high over us slipped slightly more west. It allowed a dam line of 510 down over the south of England. In fact similar situation to the one Matt described in his above post. Its still all to play for. 

[Frosty.]

it's stating the obvious that we should expect lots of chopping and changing from the models on a run to run basis and its also obvious that we are looking at a more seasonal December..compared to the freakishly warm and wet hell last year.

[bluearmy]

just to say to anyone waking up and reading some of the comments, we aren't heading towards the GFS mega northerly blast runs of a few days ago.  a flick (potentially a transient kick) from the scandi trough and if the Atlantic amplifies enough then some pretty cold uppers for a time  to accentuate the cold. Thereafter quite uncertain and whils the higher anomolys and upper ridge look to take centre stage, I would say the eps mean/anomoly provides a wide enough envelope for just about anything to verify in the 8/14 day period. 

[Geordiesnow]

ECM is a little it of a surprise with its amplification but there was hints of it on both of yesterday runs that we may see a bit more amplification. So on this run we are just on the colder side of the jet and there is potential down the line on this run. Its encouraging too see as its the ECM and we are looking at the medium term here and not in la la land.

UKMO is still not playing all so some caution is needed as is the  GFS 06Z run as it has the tendacy to overdo blocking. Hopefully we will have a clearer picture by this evening and as per ever it will be interesting.

[lorenzo]

Models please folks, report buttons, PMs - all things that resolve stuff more effectively than open tit for tat posts - thank you!

[Nick L]

Numerous posts removed, if you have a problem with what someone has posted then either PM them, report it or PM a member of the team. Don't air your dirty laundry in here.

Cheers.

[SMU]

06z 120 shows the atlantic low having no positive tilt unlike the 00z which was about 15 degrees pos

06z is neutral so thats an improved profile...

[shaky]

Wow what a turnaround from last nights runs!!o6z gfs following the ecm rought!!low looks almost negatively tilted at 150 hours!!

[booferking]

This really is a forecasters nightmare John Hammond speaking last night of Milder Weather more likely to return for next week as they were more sure than the day before, now were back to square one again with this.

This really is brilliant model watching im loving every minute of it.

[Johnp]

Given the charts and the time of year, we may soon be talking about temperature inversions in the south with freezing days and nights, yet relatively mild uppers.

Scotland and Ireland probably less cold due to more breeze.

[Chris K]

2 minutes ago, Johnp said:

Given the charts and the time of year, we may soon be talking about temperature inversions in the south with freezing days and nights, yet relatively mild uppers.

Scotland and Ireland probably less cold due to more breeze.

Indeed...although hopefully it does not end up being a cloudy high with endless days of cold, grey skies...

Sunshine and frost please! 

[Summer Sun]

This high could be very hard to shift bar frost, fog and variable cloud not a lot looks like happening over the next couple of weeks

A big change from last year and all the flooding

[Johnp]

My hunch from the 6z and theta-w charts are it would be a 'frosty high'.

[Tim Bland]

Pray that 06z gfs FI is wrong as it is a long route to cold from there! 

[blizzard81]

Really enjoying watching this blocked set up from the models. So seasonal and uplifting. No one having to worry about flooding issues.

[Johnp]

3 minutes ago, Tim Bland said:

Pray that 06z gfs FI is wrong as it is a long route to cold from there! 

I was looking at some charts from Nov and Dec '62 yesterday and there were plenty like that. It's not much of a stretch to get a Scandi high out of that setup imo.

[blizzard81]

Just now, Tim Bland said:

Pray that 06z gfs FI is wrong as it is a long route to cold from there! 

Not as long as you might think. The models are starting to toy about with the possibility of cross polar ridging. You can see this beginning to take shape in the chart above. At this point, the models will not be sure where this ridging takes place. It may be further to our north west on the 12z run. Who knows?

[SMU]

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

 

Edited November 26, 2016 by Steve Murr

[feb1991blizzard]

Just now, 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

 

There' a very significant difference at 150+ now, trough to the south of GL held further back west on the 6z and subsequently the upper ridging much further North and sharper for such a timeframe on an ens mean.

[Methuselah]

10 minutes 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

 

Either we're in for something utterly stupendous, Steve, or the GFS is still three sheets to the wind, following last evening's pub run?

Edited November 26, 2016 by Ed Stone

[Derecho]

So we won't get the northerly modelled a few days ago but high pressure staying firmly in charge. The next week or so actually looks pretty cold with the Meto forecasting a low of -4C near the south coast on Tuesday night....

We have a differing set of model runs this morning the UKMO keeps high pressure over us while the ECM and GFS attempt to move the high pressure north. Although both runs eventually sink the high pressure there would be a rather cold opening week to December if either verified. Surface cold quickly develops at this time of the year.

Perhaps a slim possibility but the 06z GFS shows potential for heights to build over Scandi

Watch out for this in the next few runs maybe, December 2009 springs to mind. High presssure kept being forecast over Central Europe, but then the hint of northwards ridging came along....

[nick sussex]

Wow what drama, the models listened to my plea  to send some energy se and amplify the low to the west.

We could still do with a bit more but this is a big turnaround given the timeframes and the ECM already is going to develop a better high at just T120hrs.

I think we're seeing a reaction to events over the USA which crucially hold back that central USA low and are a bit more amplified at a key timeframe. This downstream helps clear the shortwave energy to the north of the UK and as in the ECM amplify that low.

You can see the difference here that's why I've been  droning on about that central US trough and bored everyone to tears for the last few days!

So this is yesterday mornings ECM 00hrs run to T144hrs, note the low over the central USA, much flatter and the downstream response with the low in the Atlantic. And then look at the change in todays T120hrs to the same time, that's why that central portion of the USA is crucial to events down stream:

Yesterdays  ECM 00hrs to T144hrs:                  Todays ECM00hrs to T120hrs:

The more amplitude we can squeeze out upstream the better chance of getting the more favourable cut back in the jet towards the UK later in the run and more chance of advecting some colder air in from the e/ne.

For newcomers to the thread the changes in todays outputs are a great example of how much impact changes upstream can have on us in Europe. Its also always best to view the models from the NH perspective because it gives a much better idea of the connectivity between us in Europe and upstream in the USA. You can see that the overall NH pattern is very similar but just that smallish change upstream can manifest itself much greater down the line.

 

         

 

 

Edited November 26, 2016 by nick sussex

[SMU]

NAVGEM 06z 138 

nearly reaches the point of no return...

[Devonshire]

7 minutes ago, nick sussex said:

So this is yesterday mornings ECM 00hrs run to T144hrs, note the low over the central USA, much flatter and the downstream response with the low in the Atlantic. And then look at the change in todays T120hrs to the same time, that's why that central portion of the USA is crucial to events down stream:

Yesterdays  ECM 00hrs to T144hrs:                  Todays ECM00hrs to T120hrs:

The more amplitude we can squeeze out upstream the better chance of getting the more favourable cut back in the jet towards the UK later in the run and more chance of advecting some colder air in from the e/ne.

Thank you Nick, that is just the type of model commentary that I come to this forum for: informative as to what is going on and maybe in the pipeline for us, while also educational for a newbie like me - more please! (and yes - I am learning lots from a few other posters too!)