Model Output Discussions 12z 01/09/2016

[phil nw.]

3 minutes ago, Frosty. said:

I agree Phil, it's not that big of a deal at this time of year whether we miss the early cold or not but the charts are interestingly poised and it could go either way..I agree with BA.

Yes we would have a more extensive cold pool to draw on further into Winter,but the Polar profile is pretty good enabling an early dose of cold to some mid-latitudes already.The PV very much on the back foot as we head into November. 

[lorenzo]

Either way, I would call this next week high-end modelling debate - given it's timing early in the season - so good to have discussion here and now.

Previous incarnations of atmospheric dynamics have heralded much success here SAI / OPI correlation - we are in geomag declining phase, cloud 10 cleverly pointed out this analog may come back on line this year, truth is it is still geomag related to SSTs / Sea Ice... coincidental r when not SMax or S Min.

So where are we on geomag...

Declining phase - atmosphere written for a weakly prevalent positive NAO over DJF - yet canonical predictions, analogs all point elsewhere - that is why this early initial slow down at 60N is pivotal..

 This as I said could be the most fascinating period of modelling ahead this winter

a) for up close and northerly and b) for heralded impacts down the line...

make no mistake those over the last 36 months who have viewed this thread, this pattern is elusive to us old timers too...

[Frosty.]

By far this is the largest number of GEFS 12z perturbations showing varying degrees of cold heading our way both in terms of longevity and potency. We know that snow is possible in late october even in london since it occured in 2008 from an early Northerly so this coming weeks model watching will be even more interesting than it would normally be so early in the season.

[Summer Sun]

Changes from ECM this evening with the cooler / colder air not getting in on this run

Finely balanced which way it could go many more runs needed yet

[Singularity]

The start of November looks more important in terms of what's going on across the mid-high latitudes as a whole than how chilly - or not - we end up here in the U.K. So, little reason to despair if wintry conditions give us a miss at this early time of asking  

This will be my first winter issuing high-stakes long-range guidance. When it comes to timing...!

[bluearmy]

37 minutes ago, Singularity said:

The start of November looks more important in terms of what's going on across the mid-high latitudes as a whole than how chilly - or not - we end up here in the U.K. So, little reason to despair if wintry conditions give us a miss at this early time of asking  

This will be my first winter issuing high-stakes long-range guidance. When it comes to timing...!

Been bashing away at this point and I think in general that it's registered 

extened eps tell the same story as the previous runs. 

Also, 

GEFS: AO is  -4 end week 1 recovering to -2 by the end of week 2 

EPS: AO is a little short of -3 recovering to just short  of -2 by the end of week 2

GEPS: AO is around -2 end week 1 recovering to -1 by the end of week 2 

 

[johnholmes]

In terms of 6-10 then it will be interesting to see the output from EC-GFS in the morning. At last NOAA 6-10 AND 8-14 outputs, this evening, are much the same pattern. Quite some time since I saw this. I wait for the EC-GFS output but I think the pattern shown below on the 6-10 and 8-14 is about a 60 maybe 70% probability now.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

What happens beyond 14 maybe 16/17 days I have no idea. Read what other far more knowledgeable folk are posting. But PLEASE can we each post our view with charts to back that up and STOP digging at other folk. Doing it does 2 things, it confuses folk trying to learn what the models are showing and annoys the heck out of those who have been on the site a long time. It don't half make for a b----y long next 5 months as well as making a lot of unnecessary work for the team trying to keep things level headed.

link to NOAA output shown above, EC-GFS will be posted in the morning.

the caveat to above is no more major inputs into the north Atlantic from tropical storms/hurricanes.

Also my 60-70% is backed up by what other folk have posted about with data from other sources that seem to back up this view.

 

 

Edited October 24, 2016 by johnholmes

[knocker]

Well one can say there is no agreement between the GEFS and EPS this evening which is not a total surprise considering the det. outputs

[Frosty.]

1 hour ago, Summer Sun said:

Changes from ECM this evening with the cooler / colder air not getting in on this run

Finely balanced which way it could go many more runs needed yet

Yes Gavin spot on, however, there is currently more support than not for our first shot of cold air from the nw, n or ne in early november.

[feb1991blizzard]

The ECM op is surely an outlier for 850hpa temps over southern half of UK, either that or its picked out a new trend, FWIW I'm convinced that at some point during Autumn, we will have a stormy period (Second half of Nov), else would be the most stormless Autumn ive ever known, its just can what's happened so far and the next week or 2 leave enough of an imprint on the Northern hemisphere pattern (Strat and trop) such that a front loaded winter will still end up being blocked, cold and snowy from second week of December onwards.

Edited October 23, 2016 by feb1991blizzard

[blizzard81]

The ECM 12z op tonight reminded me of Fergie's repeated reminders over the last week that any UK wintry potential over the next week or two will largely depend on the location of low/high pressure cells in our locale. The ecm op tonight going for heights to stay quite high to our south hence stopping the arctic train from trailing south across the UK. 

[johnholmes]

17 minutes ago, knocker said:

Well one can say there is no agreement between the GEFS and EPS this evening which is not a total surprise considering the det. outputs

Yes they are not showing the same intensity of +ve heights and contour ridging but they are not in separate back yards so to speak. This is why, havong quoted the NOAA version earlier above, I am waiting to see what the EC-GFS version in the morning shows.

I don't think, on the evidence that we have, that the 6-14 day or so time scale will show, for instance an upper low where the current contour heights are, in simplistic terms?

[Ice Day]

Whilst not proper winter yet, we're seeing some really interesting charts at the moment.  For example, the ECM's view of next Saturday see's the PV in a state of enormous disarray.

.

This gives cause for optimism that winter 16/17 could hold more than a little interest for us cold lovers as these charts are a rare treat in recent years.  However, what has been a repeating pattern over the last few winters is that autumn has been a slow starter and tends to really ramp up November through December.  Last year the first 'named' storm (Abigail) didn't happen until around 10 November which heralded several weeks of stormy weather.  So while I'm keeping everything crossed that this year will be different, the return to status quo weather patterns is always just around the corner.  

Fingers crossed it's not for a while yet.  The next couple of weeks is going to be fascinating model watching, whatever the final outcome.

[knocker]

Today

A pretty quiet and dry day in most places the exception being the south west and south wales. where down pours could occur, perhaps thundery, especially in Cornwall and Devon, before dying out later in the day.

And the latest from the woodshed

The low pressure area currently to our south west slowly dissipates and moves south during the beginning of the week allowing high pressure to ridge north east. This HP tends not to encroach very far north as this movement is inhibited by troughs to the NW/N and this alignment of the LP and HP zones creates a very tight gradient with a jet of 160kts running west-east just north of Scotland. On the surface this pattern could well bring some wet and wind weather to the latter,

From here on amplification does occur with the trough to the north disrupting and swinging SE into eastern Europe and  simultaneously the high pressure amplifies in situ ridging north over the UK. With another trough to the west in the Atlantic we are looking at completely different pattern change to yesterday and the surface analysis reflects this with the HP cell to the SE and fronts to the west. Obviously with this evolution the cold air is over Poland.

Given the uncertainty concerning the way forward I'm not sure there is much point in concerning oneself with next week at the moment. In any case it's all very messy with what I can only describe as changeable but not mobile  Frankly it's all very much a pig's ear.

 

Edited October 24, 2016 by knocker

[knocker]

The GEFS is not adverse to the det run's take on the near time evolution. This is looking very much like a Dr. Francis meridional wave pattern.

Edited October 24, 2016 by knocker

[Ali1977]

17 minutes ago, knocker said:

The GEFS is not adverse to the det run's take on the near time evolution. This is looking very much like a Dr. Francis meridional wave pattern.

Yep, a different looking block this morning. Not sure if it'll swing back again but not the cold start to November that was showing up in the last few days - a big swing away in fact.  Blocking still showing throughout the run so all still very interesting, still with no PV.

[terrier]

Well certainly a big swing away for a cold start to November on the models this morning. Does looked blocked throughout still but In wrong place for uk. Seems like Ian f was right in his assumption of it all depends were block ends up. And blocking doesn't mean cold for the uk all the time. Maybe it will swing back again but we all been burnt before from the models. 

[shaky]

And just like that the strong blocking over greenland has pretty much dissapeared this morning!!and with that maybe our chance of the first cold snap of the season for first week off novemeber maybe out the window aswell!!its unbelievable cos for the last 2 days we saw pretty much model agreement on that low in the atlantic to drive so waa towards greenland and head westwards!!its not all of a sudden changed its mind and gets dragged northeastwards!!couldnt make it up!!

[knocker]

I think there is a case to define what 'blocking throughout means'. I only mention it because although there is no rapid west -east movement the pattern is quite volatile and changeable, particularly in the latter stages of the run, where in fact the cold for the beginning of November does materialise. It's more case of pattern inertia within whch much is taking place. I suspect this discussion is purely academic in any case.

[Frosty.]

The main thing to notice this week on the Gfs 00z is how mild it will become once we lose the Ely flow off the north sea and winds swing SWly, especially further south from midweek until almost the middle of next week with temps of 17/18c under anticyclonic conditions across the south. The north turns milder too with spells of fine weather but with occasional fronts brushing across bringing some rain at times. Next week starts exceptionally mild in the south but it then becomes colder from the north.

Edited October 24, 2016 by Frosty.

[bluearmy]

Excellent hemispheric op runs continue (from a wintry winter perspective) although I suspect too many of you are still looking at the North Atlantic picture. 

In my opinion, the only thing that could scupper a cold December in the mid latitudes (far too early to start working out where) would be a sudden snap back of the strat vortex (which Matt referenced a few days ago). Looks unlikely at the moment but after so many years of  coldie optimism being replaced by disappointment as we head towards the first winter month, always worth keeping your eyes open for the fly in the ointment! 

Edited October 24, 2016 by bluearmy

[knocker]

9 minutes ago, bluearmy said:

Excellent hemispheric op runs continue (from a wintry winter perspective) although I suspect too many of you are still looking at the North Atlantic picture. 

 

I think it is permissible to look at both (or at least it used to be) and have the occasional post about the here and now and not the forthcoming winter. Or are you suggesting some of us needn't  bother posting?

Edited October 24, 2016 by knocker

[Severe Siberian icy blast]

38 minutes ago, shaky said:

And just like that the strong blocking over greenland has pretty much dissapeared this morning!!and with that maybe our chance of the first cold snap of the season for first week off novemeber maybe out the window aswell!!its unbelievable cos for the last 2 days we saw pretty much model agreement on that low in the atlantic to drive so waa towards greenland and head westwards!!its not all of a sudden changed its mind and gets dragged northeastwards!!couldnt make it up!!

Shaky the blocking over greenlands hasn't disappeared, the vortex is still non existent, and leaving the detail out and focusing on the bigger picture it's still very interesting, so if you thought the cold first of November was locked in by these last few days then unfortunately you haven't learnt a thing from the last 3 years,  the same applies if you now think that after one very messy gfs run with short waves and other areas of low pressure systems thrown in everywhere that it's our cold spell done for.

I for one minute didn't think it would clean sailing and in the deep freeze we go, because it's not in the reliable time frame , it's all been in the main t200+.

my humble opinion is we will get a colder spell, do I think a direct hit, no, but it's not even the first of November and the northern profile set up this year is poles apart from the last 3 years, I think we all need to focus on the bigger profile and look how fascinating it is to see such a weakened vortex been punched around the pole and critically how it's kept well away from our side of the pole. 

Edited October 24, 2016 by Severe Siberian icy blast

[feb1991blizzard]

In any case the ECM 240 chart still opens up the possibility of a quicker route to deep cold and still has blocking stretching right across the pole.

[bluearmy]

17 minutes ago, knocker said:

I think it is permissible to look at both (or at least it used to be) and have the occasional post about the here and now and not the forthcoming winter. Or are you suggesting some of us needn't  bother posting?

You not post knocks ?  Heaven forbid !

my post generally meant as an antidote to this mornings output closer to home and some of the less exposed visitors to the site who may not be used to the roller coaster that is model watching Nov to late march. 

 

Edited October 24, 2016 by bluearmy