Model Output Discussions 06z 04/11/16

[phil nw.]

That was quite an ending wrt Greenland heights on the 00z GFS run but looking at the London graph it looks out on it's own at the bottom end of the temp.ens.

That's not to say another colder spell is unlikely but perhaps not the amount of ridging in the Atlantic into a full blown Greenland block.

The GFS 06Z mean anomalies still showing an area of +ve heights to our nw and below normal 2m temperatures for the last 5 days of the run-towards month end.

showing a pattern on the cold side and the general flow from the north west.Some sort of mid-Atlantic high does look likely on the ens runs which with more amplification could develop into something more interesting i guess as it would draw colder air down from the north.

 

[fergieweather]

44 minutes ago, CreweCold said:

I don't bother looking at the percentage terciles...IMO they're about as much use as a chocolate fireguard given vagaries which show over and over again with temperature plotting and deviation from long term means in terms of anomalies presented. The only one I'd look at is the precipitation output. I'm personally much more interested in the MSLP anomalies...I can extrapolate probable surface conditions from that!

Yes, it's been the similarities between ECMWF and GloSea 500hPa GPH and MSLP anomalies that grab the eye foremost (GloSea's respective ENS mean fields and +ve anomaly probabilities below).

[Grimers]

3 minutes ago, fergieweather said:

Yes, it's been the similarities between ECMWF and GloSea 500hPa GPH and MSLP anomalies that grab the eye foremost (GloSea's respective ENS mean fields and +ve anomaly probabilities below).

Looking at this output, especially noting the lower than average pressure over the Atlantic, could mean a higher likelihood of snow events from Atlantic fronts rather than off the continent? This is just a theory which may suggest heavy but rare snow events.

Edited November 14, 2016 by Grimers

[Cheshire Freeze]

Just now, Grimers said:

Looking at this output, especially noting the lower than average pressure over the Atlantic, could mean we get a lot of fronts moving in from the Atlantic and creating snow events instead of snow from continent? This is just a theory which may suggest heavy but rare snow events.

As I said earlier, Will, The Jan-Mar anomalies for pressure look to me to be signalling the potential for a snow maker of a battleground between colder continental air and Atlantic LP systems. Just has that look. 

[Grimers]

1 minute ago, CreweCold said:

As I said earlier, Will, The Jan-Mar anomalies for pressure look to me to be signalling the potential for a snow maker of a battleground between colder continental air and Atlantic LP systems. Just has that look. 

Yes, I forgot about that. I think this is going to be a very interesting Winter.

[Methuselah]

2 minutes ago, CreweCold said:

As I said earlier, Will, The Jan-Mar anomalies for pressure look to me to be signalling the potential for a snow maker of a battleground between colder continental air and Atlantic LP systems. Just has that look. 

I tend to agree, CC...My memory of Jan-Mar 1963 was of, apart from 2 or 3 major snow-events, mostly quite dry weather with bouts of freezing fog? 

Having sad that, I do find some of the seasonals' outputs appear to lack much in the way of strong signals for temperature...I think Gavin P was a wee bit sceptical, as to how the models appear to be going for abundant Northern blocking, but with near-average temperatures...It seems to be wee bit self-contradictory?

I can't see how NW Europe can end-up that warm, given the extent and depth of snow-cover, over there, already?

[Ali1977]

I think the seasonal models always downplay colder weather in the UK as it is so hard to predict, and generally on the border of any cold/warm set ups.  Even when NW Europe is predicted to be in the freezer in the seasonals our little island often doesn't show the depths of cold shown in central France or even Belgium etc....This works with the opposite too, we are never in any extreme of any prediction - our little island is "sat on the fence" should we say.!!!

Anyway, 12z coming up - it'll show another scenario in FI no doubt - but lets see how it handles the medium term as this is where we should be looking.

[fergieweather]

17 minutes ago, Ali1977 said:

I think the seasonal models always downplay colder weather in the UK as it is so hard to predict, and generally on the border of any cold/warm set ups.  Even when NW Europe is predicted to be in the freezer in the seasonals our little island often doesn't show the depths of cold shown in central France or even Belgium etc....This works with the opposite too, we are never in any extreme of any prediction - our little island is "sat on the fence" should we say.!!!

Not always the case. When the signal for significantly colder temperatures is overwhelming, it can indeed be reflected. Take GloSea back in Nov 2010, for example:

...and equivalent probabilities:

Edited November 14, 2016 by fergieweather

[Tamara]

Latest MJO cycle has been progressing through the Pacific, with angular momentum well ramped up, as much expected previously.

The extent of this rise, and the reflected passage of the Global Wind Oscillation through Nino Phases 5/6 (and on to 7) fully illustrate the magnitude of the starkly de-coupled state between -ve Pacific ocean anomalies and contrasting +AAM atmospheric profile.

.

A highly useful amplification ammunition store has been added to the atmospheric circulation - assisting poleward tropospheric wave breaking to keep hurting a weak early season polar stratospheric vortex. But, notwithstanding any start of winter cold potential, a follow-up is required to sustain the process of keeping adding an meridional aspect to NWP patterns. We have seen promising Eurasian snow cover profiles flatter before, but there has not been a pattern conducive to delivering the feedbacks.

As the forcing fades in completion of the latest tropical convection cycle, then accordingly the westerly wind additions that occurred in tandem with it, also fade and the weak ocean easterly wind (Nina) default re-emerges.  The passage of the tropical convection across the Pacific will have also served to further assist more cooling of the -ve SST anomalies across the central and western ENSO zones

With the ocean/atmosphere balance so highly stretched like elastic in opposite directions, the only way for angular momentum at present to head, is downwards. Frictional torque has already fallen to -ve 2SD - in contrast to AAM (as above) peaking at almost +2SD.

 Frictional torque will lead mountain torque and AAM tendency downwards from the latest peak. The GWO has already responded to this with an orbit through to Phase 8  (which will show on the soon to be updated WDT futures plots)

The question is where the floor limit lies.  In this respect, as much discussed in recent technical discussions, return of tropical forcing to the Maritimes restores the trend to being the friend and the next upturn in angular momentum and sets the -AO profile right back on course.  The low tidemark of this Nina thus far was in September with a positive index of 13 (indicative of Nina conditions).  SOI index has sure fallen some since them to weak -ve neutral territory

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/

 Logic would suggest that the atmospheric floor has higher limits since early autumn, but much depends if the atmosphere/ocean couples up to any greater extent in the upcoming lull in the tropics and in line with the cooling Pacific profile following the MJO passage. It continues to be my opinion to hope that it doesn't. if we want any early cold to rinse and repeat.

Amplification is the key word - and that amplification comes with a higher angular momentum state that in contrast to last winters super Nino, has much gentler forcing in tandem with a feeble vortex that suggests high latitude blocks are wholly capable with the assistance of the poleward Rossby waves that are created under these conditions.

Scepticism has reigned supreme so far from me about the development of La Nina. - but the coming weeks will tell a lot more about that and how much the atmospheric profile can take advantage of an early season vortex that is there for the taking and poised to provide some very interesting wintry potential to begin 16/17 proceedings.

This in turn, at least as far as I am concerned, will start to answer questions about how long lasting and how potent any early cold air advection may be, and whether or not it is the first of others to follow, 

In that sense any signal from the longe range seasonal big gun models of recurrent blocking would potentially offer encouragement.

But I will have to be forgiven, just for now, for continuing to ponder about exciting beginnings to further exciting things -  or flattering to deceive beyond an initial promising start. Been here with the T-shirt many times to get carried away, however things may appear.

 Here is to the next tropical cycle doing what it says on the tin on re-arrival in the Maritimes.

 

Edited November 14, 2016 by Tamara

[Rollo]

22 minutes ago, Ed Stone said:

I tend to agree, CC...My memory of Jan-Mar 1963 was of, apart from 2 or 3 major snow-events, mostly quite dry weather with bouts of freezing fog? 

Having sad that, I do find some of the seasonals' outputs appear to lack much in the way of strong signals for temperature...I think Gavin P was a wee bit sceptical, as to how the models appear to be going for abundant Northern blocking, but with near-average temperatures...It seems to be wee bit self-contradictory?

I can't see how NW Europe can end-up that warm, given the extent and depth of snow-cover, over there, already?

Nice to see that someone else was around for that epic winter. Our experience up here was of snow of and on from Boxing Day to around the end of the third week in February with little in the way of fogs. The run up to 62/63 winter did have a similar feel to this year but perhaps I am biased as in those far off days I was stupid enough to put my thoughts in a local paper!

[Daniel*]

 

1 hour ago, Grimers said:

According to the ECMWF model, it's music to the ears for cold lovers.

 

Honey G sort of music?  

I think some folk are getting ahead of theirselves and in all likelihood may end up getting disappointed. I think it's rather clear by now we're not going to see any deep cold in November. The charts above are flat and mobile, wet and cool, which has characterised a string of winters which we daren't speak of, I'm not quite sure what you're seeing - do not associate blues with cold especially with maritime sourced winds which offer very little, it's going to be a long winter, some composure is needed? 

[Cheshire Freeze]

I think the GEM is about to hit on a new pattern in upcoming runs...its 12z run looks slightly implausible to me out towards days 9 &10 *hint* attempted Icelandic blocking along with E European blocking divided by the skinniest trough you'll ever see...

[Grimers]

Just now, Daniel* said:

 

Honey G sort of music?  

I think some folk are getting ahead of theirselves and in all likelihood may end up getting disappointed. I think it's rather clear by now we're not going to see any deep cold in November. The charts above are flat and mobile, wet and cool, which has characterised a string of winters which we daren't speak of, I'm not quite sure what you're seeing - do not associate blues with cold especially with maritime sourced winds which offer very little, it's going to be a long winter, some composure is needed? 

I'm not getting ahead of myself, neither am I excited, I'm just describing what the charts show.

[Grimers]

The UKMO model is now picking up the idea from the GFS model of a potential storm on Sunday.

[Snowman.]

GFS and UKMO at 144

GFSUKMO

 

GFS even less heights over the pole than it's previous run. UKMO still has them strong. 

Edited November 14, 2016 by SN0WM4N

[Grimers]

Just now, SN0WM4N said:

GFS and UKMO at 144

GFSUKMO

Yes, as I said above, they're starting to agree, this could be a nasty storm...

[Nick L]

3 minutes ago, Grimers said:

Yes, as I said above, they're starting to agree, this could be a nasty storm...

Wouldn't even call it a storm on that, max gusts on the GFS are generally 35-40mph.

EC however does ramp it up with 60mph gusts quite widely.

Edited November 14, 2016 by Nick L

[feb1991blizzard]

The problem around 144-168 onwards is with that trough, instead of it slipping steadily Eastwards or sliding and disrupting SE, what happens is the cold just lifts out and it just becomes a ridge - this is modelled in every run now.

[Geordiesnow]

Just now, Daniel* said:

 

Honey G sort of music?  

I think some folk are getting ahead of theirselves and in all likelihood may end up getting disappointed. I think it's rather clear by now we're not going to see any deep cold in November. The charts above are flat and mobile, wet and cool, which has characterised a string of winters which we daren't speak of, I'm not quite sure what you're seeing - do not associate blues with cold especially with maritime sourced winds which offer very little, it's going to be a long winter, some composure is needed? 

Lets be fair here, he is not the only one in here to over ramp the prospects of cold and I'm sure I have read in the past week so every single day of look at this cold chart at D10 etc.

Bit of realism in here is much needed, i still see no real changes to the medium range trends, half hearted amplification, massive spoiler russian high with a trough near or over us and I am still not seeing much signs of the PV over Greenland being fully destroyed. Infact its not much of a surprise after this chilly snap during the latter part of next week, there are signals for the outlook to turn MILDER with the risk of a southerly flow thanks to hopefully what will be a trend of the russian high receding away and lower heights to try and take over western russia and scandi again.

As i said last night, I will still take the risk of the outlook turning milder again with a pinch of salt at this stage and I be interested if tonights ECM will go for that deep depression for Sunday as that will be the 3rd run in a row if it does.

[Ravelin]

2 minutes ago, Nick L said:

Wouldn't even call it a storm, max gusts on the GFS are generally 35-40mph.

I agree, way out to our West too...

Steady as she goes from the GFS so far, not much change from previous run out to d7...

6Z   12Z

Edited November 14, 2016 by Ravelin

[bluearmy]

The gfs 12z breaks the link to our east between the Atlantic and Russian ridges in fi so still continuity in the face of the ecm eps mean/anomaly 

 

[Grimers]

11 minutes ago, Nick L said:

Wouldn't even call it a storm on that, max gusts on the GFS are generally 35-40mph.

EC however does ramp it up with 60mph gusts quite widely.

Yes, hence why I said potential, and as the UKMO model has already developed the low, it could potentially develop further.

Edited November 14, 2016 by Grimers

[Geordiesnow]

5 minutes ago, Grimers said:

Yes, as I said above, they're starting to agree, this could be a nasty storm...

The GFS/UKMO don't really agree with the ECM on how deep the low goes but as we got airmasses clashing with the development of that low, you won't be surprised if the ECM is picking up on something. Certainly won't complain if it does as true Autuminal deep lows have been lacking this Autumn.

[shaky]

The low coming down from greenland has moved slightly furtther south and east compared to previous runs so could keep the colder air locked in for longer!!

[booferking]

4 minutes ago, Grimers said:

Yes, hence I said "potential", as the UKMO has already developed the low, that's quite interesting and could potentially develop further as typically happens with that model.

I thought it was the GFS that over develops lows into dartboard lows but by 162hr its a flabby low.  Your fence is save for another day