Model Output Discussion - 31/10/2014 and Beyond

[Duane S.]

The vortex has really got its work cut out this year. The upper Strat warming is still showing run after run and coming down towards the 10 day mark. Nothing spectacular but will further disrupt the vortex should it occur. A longwave wave Atlantic trough setup and a very unsettled spell often precedes UK cold spells so it could be the eggs to break for the omelette, as it were!

There is an early winter 2009 feeling about all of this. I think the end of the month going into December may be very interesting...

[Mucka]

Everyone is being far too sensible, time for a good old fashioned ramp.   

 

 

The highly amplified pattern being projected out to mid month is a classic pattern for setting up MLB/HLB. All that is preventing a block setting up around Greenland is the strength of the jet coming off the Eastern seaboard. As long as this pattern persists then it is only a matter of time before we get the type of blocking that can deliver cold to the UK. Yes there are caveats, cold in November is rare, even if we get good blocking it still needs to be in the right place and have the right orientation to bring cold and finally of course these charts are projections, we can't be sure we will see this pattern continue into mid month and beyond.

However the current synoptic raises the possibility of snow falling to lowland areas at some stage second half of November significantly over the average.

 

 

 

Of course such a synoptic is rare but we do have a very promising November pattern to raise the chances of cold second half of November/Early December.

[johnholmes]

I've knocked up a quick page which won't be widely publicised on the site, but thought it may be handy for those who follow the models, it allows a side-by-side comparison of the existing GFS and the parallel upgraded GFS. 

 

http://www.netweather.tv/index.cgi?action=gfscomp;sess=

 

It's only for a selection of timeslots, and chart types, plus only uses the 00z and 12z runs at the moment (I'll look at adding the 06z and 18z's next week), but hopefully it'll come in useful while the parallel is running.

 

very interesting Paul and thank you. Just a quick glance and it is around post 144h that really marked differences start to develop it seems, at least on this run?

[MR EXTREMES]

Everyone is being far too sensible, time for a good old fashioned ramp.   

 

 

The highly amplified pattern being projected out to mid month is a classic pattern for setting up MLB/HLB. All that is preventing a block setting up around Greenland is the strength of the jet coming off the Eastern seaboard. As long as this pattern persists then it is only a matter of time before we get the type of blocking that can deliver cold to the UK. Yes there are caveats, cold in November is rare, even if we get good blocking it still needs to be in the right place and have the right orientation to bring cold and finally of course these charts are projections, we can't be sure we will see this pattern continue into mid month and beyond.

However the current synoptic raises the possibility of snow falling to lowland areas at some stage second half of November significantly over the average.

 

 

 

Of course such a synoptic is rare but we do have a very promising November pattern to raise the chances of cold second half of November/Early December.

totally agree whats incredible is the models are very confident in there ideas and have been for a fair amount of time.

of coarse im not expecting nothing incredible right now and its pretty rare for a mega freeze in nov.

but if we go back to oct 2008 we had a potent arctic blast and this air source is typically the one type that brings cold enough air to bring snowfall to the uk even if it is not a lasting amount.

 

09/10 did bring small early warming and disruption to the stratosphere but theres certainly great interest this winter.

and from all the models there does seem to be a very strong push towards a cooler colder.

 

i think by end of nov into december things could well ramp up.

but for now much more in tune with seasonal average and feeling cold.

 

and the winning ramp chart is the gem but not likely to happen but best eye candy of 2014 

 

but most models see a push of systems south southeast which is a massive step forward in the right direction.

[Man With Beard]

Although this is a T384 chart, this it typical of the whole GFS(P) run, which shows a repeating pattern of lows tracking NW-SE underneath a block to our east - that could lead to a cold vs mild battle should it continue into late November. On the other hand, the pattern could lead to a lot of wind and rain in the near-term...

[Summer Sun]

Although this is a T384 chart, this it typical of the whole GFS(P) run, which shows a repeating pattern of lows tracking NW-SE underneath a block to our east - that could lead to a cold vs mild battle should it continue into late November. On the other hand, the pattern could lead to a lot of wind and rain in the near-term...

 

GFS (P) rain totals to the 10th shows the west taking the brunt of the rain parts of east see very little rain

 

[summer blizzard]

Although this is a T384 chart, this it typical of the whole GFS(P) run, which shows a repeating pattern of lows tracking NW-SE underneath a block to our east - that could lead to a cold vs mild battle should it continue into late November. On the other hand, the pattern could lead to a lot of wind and rain in the near-term...

 

The general angle (backed by the Euro in the latter stages) would suggest a potential easterly down the road if retrogression continued. No guarantee we'd have the cold air though.

[SMU]

Afternoon All-

 

Theres probably a lot of confusd members on here this morning- LOTS of mixed messages or perhaps lots of mixed interpetations.

 

What I would suggest, if your new to the forum & are looking for clarify or trying to make head / tail of the situation then stick to ONE model- rather than the procession of images put up from various websites which is possibly confusing.- I would go with the UKMO on that basis if your leaning towards the next 4-6 days as there is no timeline past that on the UKMO run & less volatility.

 

Today marks the day where Summer weather is OVER.

 

Look at the Theta charts & changing airmass effecting the UK from yesterday to this afternoon.

 

Saturday saw the warm air clinging on just long enough to give SOME a crystal clear warm firework eve-

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110100-6-6.png?0

 

Today its long since been swept away-

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-18.png?0   just the last dregs exiting Norfolk late this afternoon.

 

Tomorrow we are into true autumn air-

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-42.png?0

 

With Tues, Weds & Thurs retaining the cold airmass delivering some frost-

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-66.png?0

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-90.png?0

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-102.png?0

 

Post that some flirtation back with the atlantic,- its important now though as we head into November to see when westerly fronts are stalling into the UK how much of the Cold air is actually mixed out- as what appears a 'mild' chart' still may be cold at the surface-  its no good looking for surface temps at the 500 MB level.

 

So the 500 MB chart for Friday looks MILD- with a decent southerly draw-

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-0-120.png?0

But the theta chart shows the its not mixing the cold air out sufficiently as its stalled out.

 

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014110200-6-120.png?0

 

GFS predicted surface temps-

http://modeles2.meteociel.fr/modeles_gfs/runs/2014110206/126-580.GIF?02-6

 

As we can see where the front struggles across England the cold air is still at the surface.

 

 

So where we keep seeing repetative patterns of lows hitting the UK & stalling that is often not as mild as some may think, especially if a polar Northwesterly is chasing along behind because eventually the mild air gets mixed out from the back anyway....

 

 

The first 7days of November look to pan out about average, maybe a tick above, however the backdrop is that day 1 was probably 4 or 5 degrees above average, & the following 6 a tad below evening it out.

 

We are not concerned with the overall developments in H1 of November - especially over Europe, however as we get past the 15th ( or slightly before ) the availability of cold air + the low sun indicates that snow can now fall to all low levels in england ( yes there is October exceptions ) what I am referring to is ability of something more wisdespread having the opportunity to deliver.

 

As many know I love the NOAA AO ensemble link, as often I open it up with the expectation that the GFS has failed like it usually does, however today there is some noteable trending on a par with the ECM operational.

 

The MEAN from the 00z suite certainly agrees with the ECM in terms of a significant drop in the AO in week 2.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

 

Mean wise probably -1/5 to -2, however some runs probably lower than -3- certainly of the ilk of the ECM which I think would have delivered a sub -3 on the operational.

 

If you could plot the LONG TERM November MEAN onto that chart id (1948-current) imagine that it would probably average out between +1.5 & 2, so statistically to be seeing values of -2 or below correlates well with an inverse polar height pattern developing week 2 in the models.

 

Eventually this will catch up with the UK because with such a strong nehative AO you induce whats called either a 3 or 4 wave pattern, which is 3 or 4 clear standing waves around 60N & the pole, a pattern stuck solid,

At first ( especially out to day 10) we could be on the very western tip of the positive anomaly - which is currently effecting central europe.- However once we get some positive height anomalies over Greenland - so that should induce some troughing to sink south into Scandi reversing the pattern & reversing the 4 wave pattern about 30-40 degrees west.- which in essence would push the large heat anomly up to greenland - displacing cold air south towards the UK.

 

 

Relating to my winter Forecast & the OPI, we continue on the path of hemispheric patterns that is to be expecting, if anything the pattern mode is of a higher index than I was expecting already- meaning that where mid December would be the starting point to think about those X rated snow charts, we could be considering a Nov / Dec 2010 type scenario mid to late in the month.

Its not 100%, however should the polar height field change like predicted in week 2 then we are in the game from the tail end of week 2 & into week 3.

 

Patience, as ever is needed but I feel the excitment beginning to build - especially in terms of cold prospects down the line.....

 

CIAO.

S

PS sorry for spelling- on WK PC

Edited November 2, 2014 by Steve Murr

[Summer Sun]

1060mb high over Greenland on this mornings GEM with high pressure also to our east any low pressure systems which head our way could take some time to move resulting in a lot of rain for some along with strong winds

 

[Tom Jarvis]

Hi all I'm back again after a summer hibernation. Things look more promising this year than last year as we already have a very disrupted polar vortex.

Edited November 2, 2014 by Tom Jarvis

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=6

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

 

hi  all after the summer slumbers  November  at  the  moment   looking it could  get  a   bit  wet  in places   if  things carry on as  they are  December  could  be very interesting

[IDO]

^^^  Yes background signals are a lot better if wintry stuff is your cup of tea. Anyway November shouldn't be too bad for the E/SE/S if the pattern keeps repeating. For instance touched 15c this afternoon despite this morning's ECM forecast of around 12-13c. The latest UKMO update suggests average temps for the second half of the month and a continuation of the current set up: http://www.metoffice.gov.uk/public/weather/forecast. 

 

The GFS 12z less amplified than the 0z; D6: 

[Mucka]

Yeah GFS 12z a bit out there and over progressive by the look of it. Let's see what the parallel looks like by day 7 but here is the UKMO for comparison.

 

 

Regardless we are really looking into the bigger picture and the groundwork being laid for possible blocking later in the month.

[Backtrack]

According to high res its a very unsettled picture indeed, more so for the north western parts however according to this:

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=150&mode=0

To me we can't look outside high res at the moment all I can say is up until the chart I've posted it looks chilly and not as warm as it has been.

 

When is it ever acceptable to look outside of high-res, and take it as a gospel though?

 

It's looking chillier, with the warmer air pushed eastwards now over Europe. A shame really, if it could of stuck around for just one more day then we would of had a new temperature record for November (previous 21C). 

It was only a few days ago that the models were keen on a widespread snow event around Bonfire Night, quite fickle a the minute, with temperatures and indeed the weather itself, now fully into Autumn mode.

Edited November 2, 2014 by Backtrack

[Ali1977]

This is good model watching, the PV is definitely not gathering pace. Plenty of potential mid Nov onwards.

[Barry12]

The Polar Vortex has been massacred on day 9 and 10 on ECM

 

[IDO]

ECM D10 tonight a bit more sensible than the 0z: 12z > and the 0z > 

 

Still not a bad Arctic profile, but maybe again overdone. The AO (on twitter) for this morning's run showed how unreal it was, compared to previous runs:

 

 Though the 12z should also be similar.

 

ECM in good agreement with other models for the long wave pattern to continue as we head into mid November. The upper flow is slack so showers rather than frontal rain and temps look close to average, though model to model that varies a bit either way.

 

GEM at D10:  GFS Parallel: 

 

Both continue to make less of any HLBs. Looking at the GEFS at D16 for the PV profile there is a continued trend for the PV to become more organised but Siberia is now favoured more than Greenland/NE Canada, though it remains for the vast majority a split PV.

 

The mean at D16: 

 

With the volatility of output very little significance in my opinion but worth keeping an eye on.

Edited November 2, 2014 by i'm dreaming of...

[snowking]

The Polar Vortex has been massacred on day 9 and 10 on ECM

 

If ever you wanted an example of Cohen's theory in practice, those charts would be it.

Big Aleutian low, Scandinavian/Sceuro high. The result (if it were to come to fruition of course - this is still a set of forecast charts) would likely be some impressive wave activity heading in to the Stratosphere.

SK

[Man With Beard]

The Polar Vortex has been massacred on day 9 and 10 on ECM

 

 

 

And that little blue blob over Ukraine - maybe just maybe could be one to watch if T192 onwards verifies - the way things are setting up by this point, an easterly could set up fetching from the region. It's a developing cold pool:

Great post from Steve above btw, you can see how it could happen - though caution everyone, it is one of those "if everything works out" scenarios if we're talking getting everything in place for the end of November. Saying that, I just can't imagine we won't get at least one brief swipe of cold before the end of 2014, though, unless the PV can somehow get its act together and fast! 

[Cloud 10]

That day 10 ECM chart looks mighty impressive anomaly wise,and gives the first "black hole" of the season over Northern Scandi.

 

[Nick F]

The medium range output from ECMWF, GFS and GEM has been remarkably stable over the last few days for the mean 500mb pattern for the next 10 days, both across the Atlantic/Europe but also upstream across N America.

 

 

An increasingly sluggish upper wave pattern for early November with a mean trough amplifying deep across western Europe/Ern N Altantic including the UK, with the polar front jet sent way southeast towards Morocco before returning polward on the forwardside of the trough across France, Low Countries and the North Sea, central and eastern Europe seeing WAA on the western flank of blocking high over NW Russia - which could become quite a persistent and dominate feature through November.

 

A look at the northern hemisphere from ECM and GFS and blocking is evident over the arctic including Greenland into the medium range, the upper lows/trouhs are rather fragmented this side of the pole across N America and N Atlantic sectors with PV most dominant across eastern Siberia and Alaska.

 

Good early building blocks for something wintry to develop further down the line perhaps, with the upper lows displaced south from high latitudes with HLBs in their place. But we still need to wait for a cool down to our NE for any hope of an easterly delivering later in the month. Northerlies the best bet for coldest air this early on in the cold season. Still potential for the PV to re-organise to our NW in next few weeks, but interesting upper patterns developing at the moment.

 

Patience required from coldies though, the cold ain't going to come quickly with such a stagnant wave pattern as coming over the next 10 days or so.

Edited November 2, 2014 by Nick F

[Captain Shortwave]

Real beast of a high to our east, the CFS is showing a constant battle over the UK between Atlantic fronts pushing against this block. Even come the end of the month we seem to retain the same longwave pattern. 

Day 10 GFS mean

Expect to see this a lot over the coming weeks.

A classic route to cold does lie there with the pattern almost at a stalemate potentially for a good couple of weeks. We must play the waiting game and for the west, prepare yourselves for a soaking, the east looks a little drier with near average temperatures. Like Steve Murr says, temperatures should be around or slightly above average just down the fairly mild southerly flow.

[Man With Beard]

Right ... I've been trying to make a point for a couple of weeks that the models have been backtracking on attempts to relocate the PV to Greenland/Canada. I present another piece of evidence in my case. Three days ago I posted these T240 charts:

 

 

 

And here's where the same models stand for the same day/time, but now at T168:

 

 

The trend is one-way traffic at the moment - the PV is getting nowhere, particularly over Greenland. SM's post above covers what the ramifications of this may be.

[ANYWEATHER]

The significant pattern change continues to really normal British November weather in the week ahead. Rather cold and wet at times ,with snow for the mountains of Scotland and in the quieter times potential for frost and fog overnight for some. With low pressure anchored to the northwest of Scotland this week , little chance of any milder spells

[Weather-history]

1060mb high over Greenland on this mornings GEM with high pressure also to our east any low pressure systems which head our way could take some time to move resulting in a lot of rain for some along with strong winds

 

This is often pointed out at this time of the year but you need to treat pressure modelling over Greenland with a pinch of salt, there are problems, something to do with the height of the plateau? It may show a 1060mb high but you can tell by that chart that the model has exaggerated the prediction.