Model Output Discussion 12z 18/10/2012

[Cloud 10]

weather master you images show the difference in trough axis over the states on 12z V 18z

S

snow maps ecm

WunderMap® | Interactive Weather Map and Radar | Weather Underground

[Zenarcher]

Weather master can I have the Link to the ECM charts above ^^

S

Missed this here it is http://www.wunderground.com/wundermap/?zoom=4&rad=0&wxsn=0&svr=0&cams=0&sat=0&riv=0&mm=1&mm.mdl=GFS&mm.type=SURPRE&mm.hour=0&mm.opa=100&mm.clk=0&hur=0&fire=0&tor=0&ndfd=0&pix=0&dir=0&ads=0&tfk=0&fodors=0&ski=0&ls=0&rad2=0

[shedhead]

Looks more North Easterly by Sunday @T162 on the 18Z and much colder than the 12Z and then back to a northerly on Monday@T192

Nothing milder about the 18Z

That is why I said 'trend', not individual runs.

[ITSY]

another variation on the overall theme - and another major model that would, at some point during the mid term, produce a snow event for most (transient and wet as that may be).

At this time of year the further it gets pushed back the better, every week gets a little closer to where we need to be for a decent event. Off to bed at last but hoping for more of the same in the upcoming days.

[Duane S.]

Nice to see the models firming up on a cold spell. One way or the other, that's nailed. It's what happens next that is anything but...

The ECM seems to point at a possible West based -NAO? Undesired but plausible.

I think it should be all eyes on the what's going on in the States over the next week or so. I suspect fairly wild trough activity over there will allow the models to deduce all sorts of subsequent downstream permatations and we will see the charts deliver blocking and reloads from heaven one day to a Euro high from hell the next!

[ZONE 51]

Good morning. Here's a look at the 00zs of GFS, UKMO and ECM for today Sunday October 21st 2012.

All models show slack winds over the UK at present between High pressure to the NW and Low pressure well to the SW. The light East or SE flow will draw rather warmer uppers across the UK for the next 48 hours or so, The quiet and rather humid atmosphere supports much fog and low cloud and this will dominate proceedings over the coming days. Apart from a little very light rain and drizzle many parts will stay dry and in any brighter spells and sunshine it will become rather warm.

GFS then shows the middle of the week very similar though a steady increase of an Easterly wind will lift the fog and low cloud above the hilltops and bring in drier if progressively colder air from the East, By the weekend things will be much colder everywhere with a cold NE flow over the UK with High pressure out to the NW and Low pressure over Southern France. Over next weekend High pressure slides South to the West of Britain backing winds off the the North with even chillier air flooding South. Many areas would be dry at this stage but some wintry showers could start turning up over Northern and Eastern parts of Scotland and NE England. Through FI the status quo is maintained for a few days with mostly dry and cold conditions with widespread night frost and fog patches for all. Then as Low pressure moves down from the North and another centre moves East to the South a very cold, unsettled and windy spell is shown with showers or longer spells of rain, sleet and snow occurring widely, with the snow down to quite low levels at times even in the South.

The GFS Ensembles show a sharp drop off in uppers on the 26th more or less guaranteed now with 100% support from the members. The operational and control are not without support at the lower end of the pack for the rest of the run with unsettled conditions developing in the still rather cold conditions at the end of the run. The average for the pack though does show more average conditions more likely later on.

The Jet Stream shows the current set up breaking up over the coming days with the main flow setting up North of the UK before steering SE over Britain in a week or so.

UKMO at midnight on Saturday shows an anticyclone South of Iceland and West of Scotland with a cold and increasingly cold and raw North or Northeast flow over all of Britain. It would likely be cold with plenty of cloud with some rain or sleet at times in the East and South-east.

ECM finally shows a less strong Northerly flow over Britain but still cold at the 144hr stage. The High slips South with a day or so of cold, dry and potentially foggy and frosty weather in the South. Apart from a few wintry showers in the NE at first a lot of dry weather would prevail. At the end of the weekend and start of the following week winds will increase from the West in Scotland as Low pressure moves SE to the North of Scotland. A band of rain will move SE followed by cold and strong NNW winds over all of the UK as the Low drifts slowly down the East coast of Britain. Cloud and rain would clear the SE followed by windy and cold conditions with showers or longer spells of rain and hill snow to all parts.

In Summary the screw has been turned slightly more towards cold this morning as the angle of attack from the North looks somewhat better with the bulk of High pressure staying further West out of Britain. All areas will see a quick transformation to cold conditions late this week with some Northern and eastern areas at risk of seeing there first snow of the season thereafter. It looks unlikely that much if any snow will be seen in the south and West with frost and cold rain the more likely prospect here. Nevertheless, the trend holds good for some interesting cold synoptics to be thrown at the UK repeatedly over the coming weeks.

Just got to repeat this for cold fans.

[mike Meehan]

I was quite surprised - the long range forecast by accuweather fo Capestang on 03.11.2012 is forecasting rain and snow, so I checked with Meteo Ciel and sure enough they showed cold weather coming down in this direction with a dollop over the Massif.

I checked accuweather further for Issoire which is on the Northern slope of the Massif and their forcast was for just less than 20cms of the white stuff in that date. Sure enough it is a long time ahead and there is many a twixt 'tween cup & lip but it will be interesting to see how this particular set up pans out in actual fact but at the moment it does appear that parts of Europe are going to get an early blast of winter - possibly.

On the other hand I am due to travel up that way on 09.11.2012 and if Issoire is going to get some 20cms at 500 to 600 metres altitude I wonder what it is going to be like on the top at 1125 metres. Time will tell.

[weather is fun]

Well gfs sticking to its guns this morning. Making this cold spell a none event really. Plus the gfs picked up on it first so cant be dismissed.Plus the ukmo has also gone along with the gfs pushing the cold out further east. Only real comfort this morning is the gem model. But does look like this cold spell might be a none starter before it even got going.

[Liam J]

As perhaps feared by many the 00z model runs have fallen more in line with the GFS runs from yesterday - Sending the colder air further eastwards and picking up on the shortwave activity developing around Greenland eroding the heights away. The northerly is still shown but further toned down & the longevity and potency are now under threat from this new trend.

ECM 00z rolling out

Edited October 22, 2012 by Liam J

[Nick F]

Well gfs sticking to its guns this morning. Making this cold spell a none event really. Plus the gfs picked up on it first so cant be dismissed.Plus the ukmo has also gone along with the gfs pushing the cold out further east. Only real comfort this morning is the gem model. But does look like this cold spell might be a none starter before it even got going.

Wouldn't say it's a non-event, though I guess it depends on what you expect out of it. We are likely to a see at least a 10 degree drop in day maxima values on Friday compared to today and tomorrow - when we could reach 18C in the south. Also there is a risk of some wintry showers Friday/weekend in the north and east, with snow over high ground, following the cold front sweeping south Thurs/Fri. Along with widespread overnight frosts.

Looking into the medium range, the jet axis looks to remain aligned NNW to SSE and perhaps eventually more NW-SE, so probably remaining below average temperature-wise over much of the UK, though generally unsettled - as shortwaves move down from the NW.

Edited October 22, 2012 by Nick F

[johnholmes]

quite how in mid/late October you can describe as Nick F has done, a drop in temperature of 8-10C in a briskish northerly as a non event is hard to undertand.

Just what were you expecting, a repeat of the snowfall many had in December 2010?

Edited October 22, 2012 by johnholmes

[Isolated Frost]

No mention of it? Last night's FAX at 120 was encouraging, to say the least.

[Chess01]

Maybe it's good that its toned down so we have a better chance in decemeber

[Frosty.]

If it's a non event, why are the bbc forecasters saying we are in for an arctic blast by fri/sat with snow showers for scotland and ne england by the weekend?

Get the thermals ready i heard the radio4 farming 5 day outlook a few hours ago saying by next weekend it will be very wintry, especially in the north.

[Gibby]

Good morning. Here's my take on the 00zs for the start of this new week Monday October 22nd 2012.

Incidentally, There will be no report this evening as I'm too busy doing un-weather related things. Should be back to normal tomorrow.

All models are fairly agreed on the sequence of events through the working week. A weak and light Easterly drift lies over the UK with a warm front draped over the UK fairly slow moving. From today until Wednesday the weather will be quite or totally cloudy with hill fog and drizzle quite widespread today. The drizzle will lessen with time but the cloud will probably stick and sit on higher ground with fog in places. By Wednesday an Easterly wind will freshen lifting the gloom and merk somewhat though large sunshine amounts are unlikely. By Thursday it will of become quite windy in the South and Northern areas will see a band of rain move South reaching Southern England by Friday. It will then become colder everywhere behind the rain band with some wintry showers developing around Northern and Eastern coasts by the weekend.

GFS then shows high pressure moving South just to the West of the UK with winds falling lighter and backing NW in the North. The weather will be fine but cold for many over the weekend with widespread night frost and fog patches. By the start of the new week more cloud and rain will move down from the North-west principally across Northern and Eastern areas with a return to cold weather with scattered wintry showers for the North and East by the end of Monday. Through all this time Southern and western areas would remain mostly dry with sunny intervals in rather chilly conditions. Through FI this morning the weather becomes generally unsettled and cold for a time as Low pressure sinks South over the UK with sleet and snow possible on all Northern high ground for a time with even the odd flake in the South. Late in the run pressure rises over Europe pushing the cold air back North and introducing Southern areas at least into something rather less settled and milder.

The GFS Ensembles show a cold spell starting from the 26th and lasting till the turn of the month when there is growing support for a return to milder and more unsettled conditions with rain at times.

The Jet Stream shows it to be currently blowing North just to the west of the UK. It strengthens markedly way North of the UK over the coming days before diving SE then south down the North Sea before disintegrating early next week.

UKMO for midnight on Sunday shows a High pressure just to the west of Ireland with a slack and cold Northerly flow over the UK. All areas will be cold with overnight frosts. Most places would be dry spare a few wintry showers near Eastern coasts.

ECM this morning shows High pressure west of Ireland too with a ridge extending East over Southern Britain delivering cold and dry, bright conditions with frost at night. The North sees freshening NW winds and rain moving in with some snow for the mountain tops. This sweeps South over all areas followed by a return to cold and bright weather with further wintry showers close to Eastern and Northern coasts. After a few frosty nights winds back Westerly as per GFS with a large and deep depression developing to the north of Scotland with rain, wind and milder air off the Atlantic looking likely to end the cold snap by the end of the run.

In Summary the cold spell has been scaled back to some degree this morning. It now looks like the innitial surge of cold is going to be pulled away to the east of the UK with the UK close to High pressure just off our Western coasts. Nevertheless, there will be some cold and dry surface air for all with sharp overnight frosts, though snow looks far less likely for areas away from the high ground a little inland from Northern and Eastern coasts. What's more both GFS and ECM look like developing a deep Low to the North with winds backing West with Westerly winds and milder air entrained over Britain although GFS does engage cold Northerly winds behind it on its operational but is not supported by its ensembles. more likely is a return to more traditional late Autumn fayre of rain at times, heaviest in the North and west with a return of average temperatures in rather windy conditions for most, all in association of Low pressure anchored to the North of Britain.

[carinthian]

quite how in mid/late October you can describe as Nick F has done, a drop in temperature of 8-10C in a briskish northerly as a non event is hard to undertand.

Just what were you expecting, a repeat of the snowfall many had in December 2010?

This mornings TV forecast a significant drop in temperature over much of Europe by weekend with (unusually cold air for the time of year ) pushing south and replacing the very mild stagnant sitting over Europe and the Southern UK by Friday . Some of the posts here begger belief this morning. Anyway, I am confident of blizzards here by the end of the weekend ( Austrian Alps !)

c

[latitude]

Well gfs sticking to its guns this morning. Making this cold spell a none event really. Plus the gfs picked up on it first so cant be dismissed.Plus the ukmo has also gone along with the gfs pushing the cold out further east. Only real comfort this morning is the gem model. But does look like this cold spell might be a none starter before it even got going.

Well I tend to disagree, if your comparing last nights GFS 18z to this morning its actually further West from T84 onwards.

[Liam J]

Large temperature gradients being progged over the North Atlantic which would fuel cyclogenisis spawning some intense low pressure systems.

Edited October 22, 2012 by Liam J

[UV-RAY]

There's no denying after the initial cold plunge this weekend the outlook looks disappointing compared to what was on offer a few days ago, I suppose it was on the cards really as more often than not these cold plunges tend to end up more to our East. Still quite a drop in temps for all of us come the end of the week which I would say is significant, obviously some others don't .

[Kiwi]

This mornings TV forecast a significant drop in temperature over much of Europe by weekend with (unusually cold air for the time of year ) pushing south and replacing the very mild stagnant sitting over Europe and the Southern UK by Friday . Some of the posts here begger belief this morning. Anyway, I am confident of blizzards here by the end of the weekend ( Austrian Alps !)

c

Yes, a real change on the cards. I'm sure that some need to take a step back rather than taking every GFS run as gospel. I've been away over the weekend, come back and looked at the various models GFS, ECM, fax etc and am more than happy with prospects....given the mild muck we usually face at this time of year.

Also looking forward to the blizzards over the weekend....in the Austrian Alps, on account of skiing over Christmas in Russbach...just up the road from Abtenau. Given your local knowledge Carinthian does this sort of northerly flow give good precipitation amounts over this part of the Alps?

[Methuselah]

Beware of cherry-picked charts, everyone...posting only cold options creates false optimism?

[Alex]

As John said i'm not sure why ppl are so dissapointed, an 8-10c drop in temperature is noticeable. Snowfall is rare for a reason in October and the seas are still relatively warm. If it was December or January then yes the -5c uppers that will be evident as per the ECM run this morning and would probably bring a very cold stint of weather.

My take on the weather beyond October doesn't bode well for cold lovers, the stratosphere is looking likely to stay average/below average and this will help aid a Stronger PV during November.

[Frosty.]

Still quite a drop in temps for all of us come the end of the week which I would say is significant, obviously some others don't .

Yes it's very significant, southern england being 17c today and tomorrow but nearer 7c by fri/sat is a substantial drop and even more when you add on the windchill factor which will make that 7c max feel closer to freezing point. Even if we miss the main cold core, it's still 5 weeks to winter by next saturday..I think the models are still showing a big change to a wintry outlook and the op runs are not to be taken literally, there is still time for adjustments further northwest with the high and further northeast with the scandi trough.

[liam300]

Large temperature gradients being progged over the North Atlantic which would fuel cyclogenisis spawning some intense low pressure systems.

Why is this so different in comparison to the other models?

[shedhead]

As perhaps feared by many the 00z model runs have fallen more in line with the GFS runs from yesterday - Sending the colder air further eastwards and picking up on the shortwave activity developing around Greenland eroding the heights away. The northerly is still shown but further toned down & the longevity and potency are now under threat from this new trend.

ECM 00z rolling out

You are of course correct, but perhaps not surprisingly few want to listen. GFS does continue it's trend towards a less cold evolution, ECM and UKMO appear to be picking it up and slowly moving in that direction, but are clearly still going for somewhat colder conditions for now. More runs needed, but I will be surprised to see GFS swinging back towards the Euros from here on in.