Model Output Discussion 26/10 2012 >

[stewfox]

Hi all, Am I missing something, but to me the models look fairly uninspiring at the moment with HP to the south preventing any cold from traveling awer way.

Yes the previous 40 posts ?

Still lots to play for with nothing pinned post mid November, cant see how you see the 'potential' as uninspiring ?, not heard of a Barlett ones this week and a very mobile weather pattern coming up over the next few weeks with temps likely to below average. The CET starts the month 3c below average.

.

[Cloud 10]

Probably already noted, but new NAE loses snow signal for Sunday with more southerly track. UKMO considers only v low potential N and W flank dependent on ppn intensity.

Yes indeed,the 18z NAE has shifted Sunday's low a touch further south .

12z.. 18z..

The 18z GFS has other ideas though,with heavy precipitation and temps of 1c over parts of Wales!

[Geordiesnow]

I think a milder set up is nailed on now so it does look parts of next week will be milder with the exception of Monday where it will be chilly with a keen Northerly wind but it should be mainly sunny away from windward coasts!

Going into Mid-week, milder air will head in from the WNW'ly direction which will bring a lot more cloud with outbreaks of light-moderate rain heading across most parts of the UK and Wednesday looking like being the first day in a long while it seems of widespread double figures across the UK but it should be mainly cloudy however, despite this, I still expect some BBC forecasters having a bias of a more "favourable" tone to the outlook because it will be turning milder despite the outlook will turn more duller and wetter on a widespread scale! Will be interesting to watch the forecasts this week thats for sure.

The ECM height rises have not really been bought forward I feel, looks like its been tone down somewhat with the more interesting charts still around the 216-240 hour range - in other words FI! But some trends we may see a newfoundland high developing which may amplify the jet to allow another cooler shot from the NW if everything falls together of course.

[legritter]

still the same as i hinted at earlier ,looking at this evenings data charts . ridge moving in from west /s/west next week ,then fronts moving across the country with a gradual return to cold zonal or plane old atlantic .but its beyond this that current modells hint at a possible change on the horizon .now we are at T36 hrs sundays disturbance Crawls out of the woodwork ,but we knew it was a lurking .big iffs whether any higher ground gets anything wintry but one to watch as a system like this CAN deliver some impressive precipitation totals ,an interesting radar watch coming up ,cheers .

[Ice Day]

, not heard of a Barlett ones this week

Given some of the posters on here, you won't have to wait long!

I think the models are really rather exciting at the moment. As many of the more learned posters continue to allude, it's all about the trends. Just looking at the ECM at 168hrs, the Polar Vortex has split in all directions which is a big change from the same time last year (if my memory serves me correctly). A fragmented PV really increases chances of prolonged cold so long may it continue (if cold is your thing)

[Chess01]

Whos spiked the gfs 18z drink

[damianslaw]

Short term - more of the same, colder than normal for all especially northern parts with maxes in the range of 3-6 degrees in N England and Scotland, notably cold for early November where 7-10 degrees is the norm.

Both ECM and GFS are showing a weak ridge moving in early next week pulling in milder uppers and more settled conditions but also alot of cloud. Nothing especially mild it has to be said only just above average/near average, maxes of 10-13 degrees is preety normal for early-mid November. As we move beyond the reliable timeframe, subtle differences between ECM and GFS, but the overall theme remains the same, the trough looks like it quickly come back later next week to bring in further cold unsettled conditions as heights stay strong over Greenland. There are strong signals of retrogression of these heights, which depending on where the trough decides to sit could aid the development of height rises over West Russia into NE Europe as indicated by ECM, meaning very cyclonic conditions over the UK.. with cold building blocks establishing themselves to our NE. I don't see any zonal tropical maritime train.. its absence has been quite remarkable since well last winter!

[Costa Del Fal]

GFS 18z creates a vile day for the Midlands on Sunday with very cold rain. Just an afternoon temperature of 1c in the West Midlands!!! but no wintriness as uppers dont really support snow but it could be one truly nasty, cold and wet day!

[Isolated Frost]

On the top is the ECM hemispherical projection for today at +216, on 24 October, and on the bottom is it's actual verification.

Very, very similar. Good stuff ECM.. very similar in the projection of the zonal pattern, and the upper lows by the northwest territories, north of the uk and northern siberia. Note the kamchatka ridge being omnipresent..

[AWD]

Both the ECM & GFS show a very tight thermal gradient over the Eastern Seaboard which would suggest deepening LP systems forming over there as we go into Mid Month;

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=168&mode=1&carte=1

http://www.meteociel.fr/modeles/ecmwf.php?ech=168&mode=0&map=1&type=0&archive=0

Which also helps to strengthen the Jet Stream over the Atlantic;

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=192&mode=5

Suggesting to me a rather "zonal" type outlook as we enter mid month. LP forming over the eastern seaboard, the Jet sending these systems up over Greenland as we have HP ridging in to the SW, then sending them down near the UK.

It all depends on the axis of the jet as to whether we end up with cool zonal or mild zonal. At the moment FI charts probably just about favour cool zonal but this could easily change on future runs;

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=300&mode=0&carte=1

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=300&code=0&mode=1&carte=1

Edited November 3, 2012 by AWD

[cold snap]

models shifting to a more zonal outlook,no deep cold geting into any part of europe,last weekend cold air had plunged into europe.now it looks like a retreat,very flat flow post 168 on both ecm and gfs this morning

Edited November 3, 2012 by cold snap

[Severe Siberian icy blast]

models shifting to a more zonal outlook,no deep cold geting into any part of europe,last weekend cold air had plunged into europe.now it looks like a retreat,very flat flow post 168 on both ecm and gfs this morning

Agreed, it looks very mobile on the gfs and ECM unfortunately , I'm looking at the last wk into the first wk of dec, not too bothered what happens inbetween.

[mountain shadow]

models shifting to a more zonal outlook,no deep cold geting into any part of europe,last weekend cold air had plunged into europe.now it looks like a retreat,very flat flow post 168 on both ecm and gfs this morning

As a positive the Polar vortex is still disrupted with HLB Still evident, just not in the right place.....yet.

[sebastiaan1973]

I didn't expect todays output at the later stage > 168h. BTW GEM is impressive. Especially over here in the Benelux.

[IDO]

The GFS 0z has the UK remaining within an Autumnal setup till late FI (trough, ridge, trough, each 3-4 days). No sign of sustained cold and even a lack of cold topplers. The PV is displaced slightly to our part of the NH (end FI):

npsh500.png

However there appears to be a strong HP setup in the Atlantic and even in Europe. Good synoptics on this run for a zonal flow, milder for the south UK, and cooler further North:

h500slp.png

MattHugo81

After being -ve for quite some time the AO (Arctic Oscillation) is about to become significantly positive! http://t.co/NEOXgDwW

The op run suggests, late in FI this zonal will be on the cool side, but 90% of the members have a milder flow down south, with four suggesting 850hPa's of over 5c and with the mean moving above 0c consistently (from T244). A change from recent output:

t850London.png

The current meridional pattern had to eventually subside, and 4-6 weeks is the usual average cycle for a UK pattern, based on recent Autumns/Winters. The next pattern, on current FI models, doesn't look like anything cold, but the next week should give us a stronger idea where we will be going till mid/late December. Too early for trends, so the current FI output, although poor for wintryness, is not yet of any statistically significance.

Edited November 3, 2012 by i'm dreaming of...

[Gibby]

Good morning. Here is my take on the 00zs from GFS, UKM and ECM this morrning Saturday November 3rd 2012.

All models show the current complex Low pressure hold influence over the UK for several more days with the centre transferring SE to Southern England tomorrow before moving off into Europe early next week and filling up. By Tuesday the Northerly flow behind the Low backs NW or West bringing less cold air with it but breezy conditions with Atlantic fronts bringing a spell of rain across through midweek.

GFS then moves out of the midweek period with Low pressure gathering strength out to the NW with winds backing off to the SW with rain reaching the North and West to give another short rather cold and wet spell in all areas over the weekend as the Low sinks SE over the UK. there would be a retur to snow on Northern hlls. Behind this feature another ridge bulds in from the Azores High Before FI becomes dominated by a more typical Atlantic setup I alluded to possibly likely to develop yesterday. That is that the Azores High firmly on its home ground with Low pressure over Iceland and Greenland with a fairly mild SW or West flow across the UK with troughs embedded giving spells of rain followed by slightly colder and more showery weather with the heaviest rain and strongest winds occurring in the North.

The GFS Ensembles show a return to average temperatures in a week's time with rain at times under a mostly Westerly wind. There is quite a lot of spread as usual at the end of the run but there seems little chance of anything significantly cold anywhere through the period of the output. Rain will occur throughout the period though amounts will not be sufficient to give anything other than normal amounts for November.

The Jet Stream forecast shows the general trend for weakening the current flow to the South of Britain as pressure builds in the Atlantic pulling the flow round the Northern periphery of the High and down over the UK from more Northern latitudes later next week.

UKMO for midnight on Friday shows High pressure over Italy and Low over Iceland with a weak SW flow around a ridge of High pressure over the South. A trough from the Icelandic Low would approach the West on Friday daytime with rain reaching the North and West through the day. Temperatures would be nearer to normal generally and in any sunshine in the SE perhaps a little milder.

ECM at 144hrs shows much more effects from a trough crossing the UK giving some rain as it leaves the East coast followed by a weak ridge covering the West at midnight. Thereafter as like GFS a more traditional Atlantic pattern develops as Low centres are pulled NE along with their troughs across and to the North of Britain meaning a more traditional NW/SE distribution of rainfall in temperatures well up to normal by then.

In Summary I think the most important point about today's output is the loss of Northern blocking around Greenland in a week or so. I did say in a comment on Netweather yesterday that this synoptic pattern was an easy threat and in this morning's output it has come to be from both GFS (latterly) and ECM from the end of next week. Things could swing back again over subsequent runs but from what I can see this morning after the next 3-4 days of rather cold and wet conditions move off into Europe by the middle of next week a period of milder weather is a possibility with more traditional wind and rain, heaviest in the North and West which given where the Jet moves could last for a fair while. It is true that GFS holds a colder phase to cover next weekend but it gets to milder looking synoptics too in FI and with the Ensembles having showed a gentle warming over recent days towards 850's nearer to normal in week 2 you wouldn't put too much money on against it happening.

[bluearmy]

Ths zonal increase appears to reflect the models wanting to push the kamchatkan heights further into the arctic which in turn, displaces the p/v towards ne Canada/ n Greenland. the subsequent increase in thermal gradient off the eastern seaboard ratchets up the jet. Not too bothered about this as we still have plenty of blocking evident in the NH. Will be a good test of the overall background pattern to see if it resets after a week or so.

[andymusic]

Probably already noted, but new NAE loses snow signal for Sunday with more southerly track. UKMO considers only v low potential N and W flank dependent on ppn intensity.

got a feeling Wales and it's mountains could be in for some wintry stuff tomorrow morning especially in the heavier precip!

[lindy2017]

got a feeling Wales and it's mountains could be in for some wintry stuff tomorrow morning especially in the heavier precip!

Thats got me covered then......

[AWD]

Both the AO & NAO look like going positive during mid month with only subtle hints of a drop back towards negative towards the end of the month.

[bluearmy]

Both the AO & NAO look like going positive during mid month with only subtle hints of a drop back towards negative towards the end of the month.

As has been pointed out before, those indices reflect the gefs headed for a less meridional and flatter pattern. They are derived from the model output. It would be odd to read the pots in here this morning and then see the NAO not going positive. If the week 2 modelling changes then so will those oscillation forecasts.

Incidentally, the less flipy floppy naefs doesn't downgrade the HLB at all week 2. Any high heights around Greenland are west based and into ne Canada but no sign of any low anomolys taking hold in Greenland. We remain firmly under the mean trough and little evidence that a strong p/v is taking root.

Edited November 3, 2012 by bluearmy

[BLAST FROM THE PAST]

Models will show different solutions as we look at a pattern change in FI so nothing surprising there. Sit back and enjoy the ride, lets see how it develops but quite interesting that a zonal picture is being thrown up. Will that happen or just what models do or are we seeing the start of waxing and waning that GP suggested?

BFTP

[Duane S.]

Indeed, always worth reminding that the AO / NAO are only reflections not drivers in their own right.

The 00z's cetainly are the most zonal / default looking we have seen so far this autumn. I just wonder if this is going to shake things up more than the 00z's would have us think... ?

[Chess01]

Just last week the models were showing the azores high for fi think there is time for change and i dont think the pattern that is shown now will stick its just to progressive of the change from what we are seeing now i think it will get slightly milder in the second week but not at the rate the gfs shows it

[bluearmy]

Indeed, always worth reminding that the AO / NAO are only reflections not drivers in their own right.

The 00z's cetainly are the most zonal / default looking we have seen so far this autumn. I just wonder if this is going to shake things up more than the 00z's would have us think... ?

that zonal wind chart from yesterday's ecm 12z run certainly is a polar drool with the reverse zonality making right up to the base of the strat. not even close to a positive AO chart. just shows that the ecm op run was likely a trop outlier.