Winter Model Output Discussion - 06Z 09/02/13 onwards

[bluearmy]

ecm ens continue the theme from yesterday. the undercut thurs looks quite good on the mean (time to view the stamps). thereafter, the op looks quite a good guide to the mean with two caveats - the support of euro trough to the south on the op will require an input of energy from somewhere which isnt clear on an ens mean and the sceuro part of the high at the end of fi looks increasingly like it will have a large trough dropping into it from the north east - hopefully cutting around it into europe and advecting our way as the main upper ridge builds towards iceland/se greenland. plenty to keep us interested.

[TEITS]

TETIS wont be happy about this blue box...

Yes livid this morning. S

Seriously though im looking at the predicted dewpoints at 12pm on the latest NAE of between 0C to 1C across E Anglia.

http://expert-images...021012_1006.gif

Considering dewpoints are currently around 2-3C across this region I would be staggered if the NAE is right. That for me is the issue with the NAE, it often predicts dewpoints that are too low which is why its OTT in predicting snow in these marginal conditions.

Latest NAE suggests the blue circle is further S and snow for me. I shall run around naked if its snowing in Peterborough at lunchtime as the NAE suggests/

http://expert-images...021018_1006.gif

Edited February 10, 2013 by THE EYE IN THE SKY

[Mark Parsons]

Looks like the sweet spot will be central southern england a fair bit in land from the coas

Why is there a blue rain area at midnight over parts of Cambs, and norfolk ? Is this signs

of a warm sector or less cold air being drawn in down the wash ? It then turns light pink

around dawn !?!

Best not to take those charts to seriously, they are not that accurate!

[johnholmes]

The immediate forecast for the rest of today is an absolute nightmare to get what falls in any one place accurate.

The models NAE or NMM will give a fair idea with more detail on Extra for how the immediate upper air, say to 10000ft is likely to change in the next 18 hours or so.

As to the actual track of the low the isollobars suggest a SE/SSE movement. (Isollobars are how much the pressure is rising or falling ahead and behind the low itsel)f. Currently at 0800 near Dublin.

Currently any snow is confined, it seems from a quick scout round observations and web cams, to be above 600ft or so, so the Peak district is getting a fair amount it would seem. We have 2 or 3 folk in that area; not yet looked in the weather reports for today but I am sure they and any others will keep us updated on what the weather is doing.

[Gibby]

Good morning. Here is the report of the 12z output from GFS, UKMO, GEM and ECM for today Sunday February 10th 2013.

All models show an active frontal system and developing depression moving in from the SW today. The fronts have milder weather in association with them but as they run into colder air over Northern and Eastern Britain they will turn the rain, some of which will be heavy to sleet and snow. This will be patchy at first but later in the day as the depression moves SE towards the English Channel colder air will be entrained to more and more areas with rain turning to snow more widely this evening and tonight at the same time as becoming lighter. It will be a cold day in a raw SE wind. Tomorrow shows the Low just to the South of the UK with sleet, snow and rain clearing away South through the day with a cold and raw East wind keeping things rather cloudy with the risk of some wintry showers towards Eastern coasts. By Wednesday a new trough of Low pressure will move in from the West with again a mix of snow and rain for all before it clears East on Thursday with less cold but blustery NW winds and showers the most likely outcome then.

GFS then shows an area of High pressure down to the SW with the remains of Thursdays trough down over the North Sea. Adjacent areas here could see further showers, perhaps wintry while other areas become dry and fine under the influence of slack High pressure. It would likely stay a little on the cold side though. The following week shows weak troughs crossing East to the North and down over the North Sea maintaining the risk of colder weather here with a few wintry showers or light rain at times while the South stays mainly dry and bright near to High pressure. Late in FI the trend is for High pressure to be centred near to the UK with plenty of fine and dry late winter weather with the usual caveats of frost by night and cloud cover encroaching into the NW at times from the Atlantic.

The GFS Ensembles show a period of uppers sustained around normal or slightly above, especially in the North. Though rain at times is shown there are no large amounts shown. The operational was a large cold outlier at the end under the UK based cold High. There is quite a large spread between the members from the middle of the run with values between +9 and -10 in the South and +10 and -10 in Scotland.

The Jet Stream shows the flow continuing to arch over the Atlantic and SE to the SW of the UK then on East from Spain across Southern Europe and North Africa, Later the flow breaks down in our neck of the woods as High pressure becomes prevalent near the UK.

UKMO shows a showery day on Thursday following Wednesdays band of rain and hill snow. It would of become somewhat less cold in the NW flow but there could still be a few wintry showers left in the North and East on Friday before High pressure takes control from Southern Britain to the Baltic and Russia. The South would become dry with bright days and night time frosts while the NW would become milder with rain at times on a SW breeze.

GEM today shows a similar disrupting trough on Wednesday not dissimilar to today with rain and snow becoming lodged over the UK through Thursday before winds swing Easterly and bring wintry showers to the East Coast as the rain and snow slip away South. High pressure becomes strong to the North and then slips down over the UK to end the run with cold and frosty late winter conditions with sharp night time frosts likely for most.

ECM shows a setup not unlike UKMO this morning with a blustery showery day on Thursday following Wednesdays rain and hill snow. High pressure then builds over the South and links to the Scandinavian model which quickly absorbs the UK wing to form a cold Easterly flow over Southern Britain later in the run with snow showers in the South to end.

In Summary this morning the first half of next week looks like being rather cold and raw but with little further snowfall behind our current feature. Midweek looks another tricky time for forecasting as a further front crosses the UK and runs into the cold air with hill snow again a possibility. Behind that there is good agreement on High pressure forming near to the UK but where is crucial to the type of conditions felt at the surface. The Euro's including GEM look favoured to keep High pressure nearer the North or Northeast with ECM setting up a chilly Easterly with snow showers for the South and East while. GFS is not a million miles away but instead parks High pressure over the UK eventually in very cold uppers before sinking it slowly South at the end of the run as the Jet rides over the top but all this far out in FI. There is no real route to mild weather this morning with a cold and frosty spell looking very possible and the chance of at least a little wintriness from wintry showers in the East.

[weather eater]

So still signs of heights rising to our N/NW on the GFS, different solutions cool/cold, being offered by the ECM, UKMO and GEM, NOGAPS is poor but overall an improving picture for wintery weather to continue, being picky I would still say I’m nevertheless underwhelmed at the moment but hopefully model evolutions will improve further.

Currently any snow is confined, it seems from a quick scout round observations and web cams, to be above 600ft or so, so the Peak district is getting a fair amount it would seem. We have 2 or 3 folk in that area; not yet looked in the weather reports for today but I am sure they and any others will keep us updated on what the weather is doing.

Snowing here rather fitfully but it’s been mostly rain so far so nothing on the ground, very slight precipitation, snow drizzle; we are about 180m here so maybe it’s better further up the A6 towards Buxton.

Edited February 10, 2013 by weather eater

[Severe Siberian icy blast]

Yes livid this morning. S

Seriously though im looking at the predicted dewpoints at 12pm on the latest NAE of between 0C to 1C across E Anglia.

http://expert-images...021012_1006.gif

Considering dewpoints are currently around 2-3C across this region I would be staggered if the NAE is right. That for me is the issue with the NAE, it often predicts dewpoints that are too low which is why its OTT in predicting snow in these marginal conditions.

Latest NAE suggests the blue circle is further S and snow for me. I shall run around naked if its snowing in Peterborough at lunchtime as the NAE suggests/

http://expert-images...021018_1006.gif

Morning TEITS

I may well be wrong but the way Iv always read the NAE is if its showing times for the period 12-18pm .then I normally look at it as if by 1800hrs it will be snow. Or anytime during that period, not necessarily at 12

[TEITS]

hope you post them on here!!!

If I did the female members on this board will all be heading to Peterborough and im too busy today.

Widespread snow being predicted at midnight tonight, except the blue circle area.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/02/10/basis06/ukuk/prty/13021100_1006.gif

Let me clear this circle up. The NAE on many runs has suggested fingers of heavier precip and to be honest it would never occur like that. The circle area is within the zone of very light precip and to be honest I wouldn't pay much attention.

[The Northern Ramper]

It feels like we have been chasing Greenland height rises for months...........oh wait we have!

I guarantee we would not struggle to get them if it was June.

[Ryan Dutch Weatherman]

Controlle run is also wintry from the ECMWF 00z.

[snowmadchrisuk]

I know it's early, Chris; but are you sure that that's a circle?

Hehe , looks more like the BT man blowing his trumpet. Anyway things seem to be looking good for quite a few today, I have to head down to Gloucester later so may see something there . Only comment I would make this morning is as we head in to tonight .. the heaviest PPN seems to be held back West , so Jackpot area will probably be Gloucester / Cheltenham as they will be in the heaviest PPN ,and on the Snowline border so (Big flakes) .

Edited February 10, 2013 by snowmadchrisuk

[winterof79]

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

[Ryan Dutch Weatherman]

CMA 00z Cinese weather model is going towards the Greenalnd version like his previous runs from yesterday,.

Cptec 00z The Braziliaan model dont want b=nothing even from a interlude fas en has other version again cold , with a little slide low in for the UK en immediantely expanding Scandi H towards west .

Later i will post some charts , becouse both runs are still running , they are not finisch yet.

But i did some calculation .

Hang on for a wile it is very exiting wat is going on here,

[AWD]

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Control run is a mirror image of the Op. (Temperature wise).

Edited February 10, 2013 by AWD

[Coast]

Animated latest precip charts from Netweather's NMM, show a rain to snow and back to rain event overnight:

[TEITS]

I forgot to mention earlier that the predicted temps, dewpoints on the GFS are far more accurate than the NAE. Appears across my region they are going to drop from +2 to -3C by this evening. Awaiting the 06Z but im assuming it will show the same.

Based on GFS it appears around 6pm is the period when rain will turn to snow. At this stage the Midlands looks to me to be in the ideal position.

Edited February 10, 2013 by THE EYE IN THE SKY

[Summer Sun]

ECM full ensemble

Wednesday has the potential for a snow event especially for Scotland

Towards the end of the week both UKMO and ECM show pressure rising temperatures are likely to be below normal however if ECM was right if UKMO was to be right it would be brighter by day with frosts at night whilst the North west would be milder but wetter at times

Temperatures are likely be around 6c to 9c by the end of the week based on the 00z runs

Edited February 10, 2013 by Gavin.

[Blackjack10]

I literally have no idea what's going on here... I can't post any charts as I am on the iPad I'm afraid, but if you went by the GFS precipitation type charts on the 06Z, you'd see most areas north of the M4 getting some moderate snow from 6pm onwards. Compare this to the bbc and met office forecasts and all you see forecast for many areas is rain, and even this stops at around 6pm for many... Now as you may be able to tell, I am no expert. But can the GFS really be so wrong just 12 hours before an event? NAE shows decent snow opportunities too.... So the question (from a very confused beginner model watcher), am I reading the charts wrong, are the charts themselves wrong, or are the MetO/BBC likely to be wrong? My money is on me reading the models wrong

Hopefully somebody can help!

[bobbydog]

Animated latest precip charts from Netweather's NMM, show a rain to snow and back to rain event overnight:

looking at how the low develops (or is predicted to) on the GFS, that precip chart would suggest warm uppers being pulled back over the south east as the low wraps around, which may or may not happen. this could be very frustrating for us to the south of london. this will come down to a temp, dewpoint and lamppost watch!

[Tamara]

ECM maps at t168

Quite a mix of allsorts

Some have High pressure Scandinavia/Svalbard or towards iceland. The rest a mix of High pressure much further south and also some south westerlys.

To get to where the ECM operational and Control go to we need to see some favourable split energy later during this week - it all looks a bit half hearted atm and especially taking all the other modelling into consideration

Edited February 10, 2013 by Tamara Road

[johnholmes]

I think the BBC graphics give a fairly accurate picture of the best forecast available at the moment. To some extent it is going to be a hit and miss affair. Look at the detail on Extra for 850mb temps, dewpoints, zero C etc etc and height is the key to getting snow in this situation in terms of a genuine cover. I suggested 600ft in my first post I would amend that to 800-1000ft for now lowering through the day to 600 maybe 400ft in heavier precipitation. Places lower and where the intensity is highest will see wet snow at times.

The track of the low looking at the 09z chart suggests SSE as I commented on before to bring it somewhere just west of the Channel Isels later today. I have no idea how the Met O model is treating this feature but Extra (not looked at NMM) does not seem to have any real sign of colder 850mb air advecting south behind the low. It shows it happening erratically but not to any marked extent, more of a westerly movement it seems. By late evening the heaviest of the rainfall/snowfall looks to be over with not much sign of convection, so far on the 06z output, of wintry showers down the English N Se coast.

Of course in this type of situation this post will be out of date quite probably by the time the 12z run comes out!

But in summary a mainly higher ground snow pattern with temporary falls to very low levels for some.

Edited February 10, 2013 by johnholmes

[Ryan Dutch Weatherman]

There he is the Cptec 00z , Brazilian model.

End also he is up to something.

a ; No Atlantic.

b ; strong nord high pressure.

c; A westerly block.

d; He is pullig out the cold pv near Canada/greenland end place it heavier by Siberie /Nova Zembla /Kara sea .

e; low trough near Italie./ End another one 500 km wsw from south Ireland heading towards spain.

Brittain on the cold side of the pattern also west europe .

Dont shoot the pianist

[snowking]

GFS op, surprise surprise, all out on its own again this morning:

Mean heights 6-10 day ECM still not publishing, but heres the progression day by day:

Bulk of the height transfer from Scandinavia towards the Greenland locale, interestingly at day 6, the strongest heights look focused towards Iceland - indicative that the pattern may be a rather more east than west based -NAO, at least initially.

GEM has a rather more dilute signal this morning

Clearly a lot of spread looking at those. The GEM ensembles:

http://176.31.229.22...2&ville=Londres

Again, a less strong signal from the GEFS this morning:

Though if we follow the day by day progression:

We see the reason for the dilution in the 6-10 day signal, in that the heights continue heading further and further west (so theres no strong signal, necessarily, for heights in any one particular area through the 6-10 day period)

So, the risk from the GEFS is a more west based -NAO, as evidenced by the GEM at day 8 too:

Still plenty that could go wrong, but finally its beginning to look as though we can look towards Greenland (as commented earlier, it feels like we have been saying the same for some time now)

GWO heading into phases 4/5 from the looks of things:

So, we finally get a chance to use Recretos's fantastic GWO composites (a massive thanks to him!):

That more supportive of an East based -NAO (backing up the ECM EPS stance on things somewhat)

If we end up with amplitude >1:

Very similar story.

You begin to wonder whether the operationals are ove-reacting to an MJO phase 2 signal:

Which, thus far this winter, has been rather a false dawn.

So, plenty of positives heading into the the next couple of weeks

SK

[winterof79]

http://modeles.meteociel.fr/modeles/gfs/runs/2013021006/gfsnh-0-156.png?6 Steady that.

[ANYWEATHER]

I mentioned in the midlands thread yesterday upland areas of Derbyshire peak district may well do well out of this system later on today. I think for a lot of folk its tiddly-pip although perhaps some wet snow falling at times to lower levels more picticularly Brum northwards. More picticular concern is the intensity of the rain in one or two places at the moment,could give rise to some localized flooding and many rivers in southern Britain will be on the rise in the next 24hrs