Model Output Discussion 12z 18/10/2012

[ANYWEATHER]

A cold outlook, is for sure, looks like the models may bring us some stormy cold weather, pointless, looking out at too much detail but the "fun" Starts on Thursday in the North,Friday in the South!!!! Then we see some really cold weather plenty of hill and mountain snow!

Edited October 23, 2012 by ANYWEATHER

[lindy2017]

The weekend start cold with snow showers as far south as Yorkshire possible

High pressure trys the move in but it quickly gets shifted away in the next run

By 120h the high pressure at 96h quickly gets shifted back with low pressure taking over again

This cold air remains in place into next week with low pressure holding firm the North York Moors and high parts of Scotland should see a decent covering of snow by this time next week

Do you think south wales will get snow im approx 1350 ft above sea level

[Cloud 10]

A cold outlook, is for sure, looks like the models may bring us some stormy cold weather, pointless, looking out at too much detail but the "fun" Starts on Thursday in the North,Friday in the South!!!! Then we see some really cold weather plenty of hill and mountain snow!

Certainly a chilly/cold looking ensemble mean from the GFS at 10 days out.

The Scottish ski resort's gaffer seems to like it as well!

http://www.kumulos.c...terHappyman.png

Edited October 23, 2012 by Cloud 10

[stewfox]

evening All- minimal posting time currently- I hope to get something more meaty up later-

..

S

If I do your ironing will you get your thoughts out ?

[ITSY]

well well well GFS 18Z is very interesting. Surprised there's not a soul to be found on this thread!

[Met4Cast]

18z must have been smoking something with its drinks tonight

Crikey! In reality, at this time of year and after the initial cold shot later this week uppers aren't very good, but an impressive chart nonetheless and the trend towards keeping things cold continues too!

[AWD]

Some snowfall to modest levels in Scotland at T144

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=144&mode=0&carte=1

Remaining cold & unsettled with further snowfall possible on higher ground in the north

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=168&mode=0&carte=1

Unsettled still with the cold air starting to mix out by now, so mostly rain here

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=192&code=0&mode=1&carte=1

Another run showing a rather cool/cold period of weather coming up after the cold front clears the country within the next 48 hours.

[Isolated Frost]

Reload had so much potential, end product is this. Lots of snow I assure you to be had from this chart, especially in Scotland, N Ireland and NE England. The initial cold snap for Thursday-Saturday has been downgraded ever so slightly, but the charts after +96 had the reassuring smell of a meridional flow, dipping trough and stubborn block. Long stretch N/NE'ly. End the day on a high I guess.

Latest FAX not much different from the last one at +72, about the same as the ECM/UKMO solution, more conductive to snow shrs than the GFS. Night.

[Timmytour]

Does the GFS 18z offer the prospect of sleet and snow getting down as far as the M4 corridor for early next week?

[Stu_London]

possibly back edge snow on Tuesday.

timings need to be spot on however - 6 hours either way and chances fall. I wouldn't expect anything to settle away from elevated areas.

[EML Network]

If I were to pick a day next week where on THIS run there was the most potential for snowfall somewhere in the UK, I'd go for the early hours of Wednesday morning,

the dew points down the spine of the UK look marginal but on the right side of marginal and the humidity is quite high nationwide

based on this chart anyway ...

[Robbie Garrett]

Nothings changed compared the morning runs, interesting to say the least. Looks like the charts GP posted a few weeks back, have come to fruition in terms of a negative NAO and AO. It does look likely that the Azores is linking up with the Greenland high, providing some warmth to re-in-force the Greenland high. Which means that the Atlantic is likely to become blocked, with any low pressure probably going south of this block with a jetstream over Iberia into north Africa as we approach mid-November. Interesting that the CFS was showing this 3 weeks ago, now it's completely done a runner and is on it's own going for an Azores high over the UK..... whilst I have had faith and confidence in the CFS, I think it is struggling and is out there on it's own at the moment.

These 500hpa anomalies are doing it for me, this actually might be a lot better than November 2010,

NAO forecasted to remain negative, as well as the AO on the latest update.

Have a look at this chart, it's an anomaly and a pressure overlay at 500hPa. Interesting as to that warmer air temperatures over the blocks are likely to show they are being re-enforced by the tropics. An example is the one over the Azores/Greenland Region. Showing temperatures 30*C above normal at 500hPa. Be interesting to see if it remains with this idea into the mid range and then into the short range.

Edited October 23, 2012 by Robbie Garrett

[ZONE 51]

If we take a look at 2 thickness charts from GFS 18z we can see the cold air has plunged right down across Britain by friday evening,

850/1000hpa:

500/1000hpa:

(for those that don't know the 546dam line is to the southwest as shown on the next chart, 528dam is the line with light blue following it)

Looking through GFS 18z it's cold and wintry and not much less then that, a more potent cold spell could develop towards the end of the month with an indication of another not long after that.

Edited October 24, 2012 by ElectricSnowStorm

[summer blizzard]

If I were to pick a day next week where on THIS run there was the most potential for snowfall somewhere in the UK, I'd go for the early hours of Wednesday morning,

the dew points down the spine of the UK look marginal but on the right side of marginal and the humidity is quite high nationwide

based on this chart anyway ...

Flows all wrong for anything more than a few showers in NI and Western Scotland.

What interests me is the tight thermal gradient with the cold front on Monday combined with low thicknesses and cool surface air ahead. No snow to low levels but once to watch as low as 300m imo.

[SMU]

A big cross polar flow developing on the overnight ECM- great news from northern lattitude blocking again-

With it being slightly west based the only concern is we end up on the eastern side of the mean trough-

Otherwise all very positive signs this morning- with the above being the only risk of milder air ..

S

[snow drift]

http://www.meteociel...1-192.GIF?24-12

A big cross polar flow developing on the overnight ECM- great news from northern lattitude blocking again-

With it being slightly west based the only concern is we end up on the eastern side of the mean trough-

Otherwise all very positive signs this morning- with the above being the only risk of milder air ..

S

The blocking to our NW on previous runs has been shown to sink south. However it stays in place on this run. Looking at the charts T192 plus. Would this be correct? Trying to learn all the time.

Regards. SD

[Gibby]

Good morning world. Here is my view on the 00zs from GFS, UKMO and ECM.

All models show a slack but mild and chilly East or North-east flow currently over the UK. Over the next 24 hours this strengthens lifting the cloud and gloom somewhat from most places. In addiyion a cold front from the Arctic sinks South from the Arctic down over the UK reaching Southern England on Friday. A weakening band of cloud and rain will move South with it introducing substantially colder air but clear conditions to all but the far South by friday night. A frost will develop everywhere Friday night with a sunny and cold day on Saturday as a ridge of High pressure slips South across the UK in association with High pressure out to the West. A few innitial wintry showers in the far North and East on Saturday will dissipate as winds back North-Westerly later in the day. On Sunday cloud and rain will encroach from the NW as Low pressure begins to move SE towards the North of Scotland.

GFS brings a trough SE over Monday with some heavy rain likely for most followed by a change to colder and clearer conditions again later in the day. Frost will return in places sheltered from the wind on Monday night though further cloud and rain with hill snow moves SE overnight too in association with more Low pressure just to the North of the UK. Tuesday and Wednesday will see a cold and showery NW flow over Britain with a sunshine and shower mix with the showers heavy and wintry in places, especially in the North and West. In FI this morning the trend is for High pressure to slowly build to the South gradually cutting off the rather cold unstable air of the first few days of FI to Northern areas and eventually for all as winds turn SW bringing milder Atlantic winds to all areas to end the run.

The GFS Ensembles show a rather cold couple of weeks once the innitial really cold surge loosens its grip at the end of the weekend. A period of rather cold zonality looks the most likely outcom with rain at times with conditions cold enough for at least some snowfall on the Northern high ground at times and frost at night. The operational was a mild outlier at the end.

The Jet Stream continues to show a split flow with the Northern arm gradually tilting SE over the UK in the coming days and eventually meeting the southern arm near Spain in a week or so.

UKMO for midnight on Tuesday shows an unstable NW flow over the UK with a trough having recently cleared the South Coast carrying any remaining rain away with it. The weather elsewhere would likely be rather cold with broken cloud and scattered showers with snow possible on Northernmost hills and mountains though most places would likely stay dry.

ECM at the same time point shows a similar synopses as UKMO moving forward to develop an intense and deep Low pressure area near Scotland in the days that follow with an attendant area of rain, gales and temporarily milder conditions sweeping across all areas followed by rather cold conditions with strong winds and squally wintry showers behind it for the remainder of the run. Northern hills and mountains of Scotland could see some appreciable snowfall at times from this setup.

In Summary the most likely outcome from this morning's output is that cold weather will arrive on Friday with a frost for a couple of nights at the start of the weekend. thereafter, Low pressure sinking down from Northern latitudes bring an increasingly windy and wet spell across all areas from the start of next week. With the air inherently rather cold there will be some snow at times though this restricted to the hills of North Wales Northwards. Winds will be strong and blustery too at times, accentuating the somewhat lower than average temperatures at the surface. Once establishes this pattern looks like persisting for some time as ECM at 240hrs still shows strong High pressure over Greenland.

[Liam J]

A very mobile cold zonal pattern emerging into next week & towards FI with some very deep depressions making it into to the outputs thanks to an increasing jet stream and steep thermal gradient over the North Atlantic. The UK remaining on the cold side with average to below average temps for many of us, especially in the north - snowfall likely over the highest ground but for most it will be cold rain accompanied by strong to gale force winds making it feel very miserable with the ever shortening days at this time of year.

Also of note is the trend to keep strong heights over Greenland.

Edited October 24, 2012 by Liam J

[legritter]

Looking at todays data/ charts i can only say at this stage that ,the Devil will show its true face next week .we have so much cold air further north and given the time of year ,warm sea temp , plenty of low pressure around etc im convinced that over the next 10days or so some very interesting weather could pop up . we will im sure see big upgrades AND Downgrades on a daily scale ,and thats twice a day . im very interested in a mayor low moving south next week ,get this low moving south or south east down the north sea but not to far east and later next week could be fun . it sounds a bit like hope forecasting but with current modell output we could have many outcomes ,so expect the weather to become a Quick change Artist . and for new learners and posters etc ,dont forget the met office fax charts ,and take time to look skywards , look at mother nature as cloud scapes change with different types of air mass .anyhow GFS rolling out soon , and met office update later this morning .i think tonights forum could be near a full house ,

[bluearmy]

http://www.meteociel...1-192.GIF?24-12

A big cross polar flow developing on the overnight ECM- great news from northern lattitude blocking again-

With it being slightly west based the only concern is we end up on the eastern side of the mean trough-

Otherwise all very positive signs this morning- with the above being the only risk of milder air ..

S

at this stage of the autumn, does it really matter that its west based -NAO ? as you say, the fact that the models still want to keep the HLB going is the main positive sign.

[BornFromTheVoid]

The current strong -ve NAO (re-inforced by a strong +ve dipole pattern across the Arctic) which is set to bring our cold spell on Friday, looks set to gradually ease and shift westward, with the upper trough becoming more centred over Ireland, rather than Scandi where it is now. Both the ECM and GFS agree on this.

................GFS out to t192................................. ECM t168

The falling Reyjavic SLP shows this quite well too

This trend continues into the medium term as can be seen on the 8-10 day 500hPa height anomaly charts, with the upper ridge drifting into Canada and Western Greenland, with a deep trough setting up camp across the British Isles.

So after the weekend, the trend is currently for progressively milder (though still quite chilly) northerly reloads before the low pressure takes hold.

[swfc]

From an untrained eyes perspective its looking like pretty normal autumn weather to me?temp below average temps then unsettled and slightly milder.pv moving to its normal hunting ground and the northern blocking loosing its grip.i got wsucked into the hype over the last week or so,so thats one think ive learnt if nothing else.still interesting times and onwards and upwards whatever the weather does.uto!!!!!

[latitude]

From an untrained eyes perspective its looking like pretty normal autumn weather to me?temp below average temps then unsettled and slightly milder.pv moving to its normal hunting ground and the northern blocking loosing its grip.i got wsucked into the hype over the last week or so,so thats one think ive learnt if nothing else.still interesting times and onwards and upwards whatever the weather does.uto!!!!!

Can you back that up with some charts?

[snow drift]

From an untrained eyes perspective its looking like pretty normal autumn weather to me?temp below average temps then unsettled and slightly milder.pv moving to its normal hunting ground and the northern blocking loosing its grip.i got wsucked into the hype over the last week or so,so thats one think ive learnt if nothing else.still interesting times and onwards and upwards whatever the weather does.uto!!!!!

This is not normal for 3rd week in October.

[Methuselah]

This is (hopefully) the GFS06Z for T+384. FI obviously, but still appears to show a poorly organized PV?

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121024;time=06;ext=384;file=h850t850eu;sess=65e3da1a51d046e06cb29a85513d9a06;