Model Output Discussion 13/11/12 18Z onwards

[summer blizzard]

Very cold at the surface on the GFS18z..

I'm normally very skeptical however with events coming into the high resolution i am increasingly confident of some kind of cold setup be it high pressure on top, a northerly or an easterly.

[snow drift]

This is in the next 48 hours. Very strong winds for Ireland.Coupled with some heavy rain.Yellow warning for SW Scotland.

[Jupiters Winter]

Models very Unstable. I have not seen any consistency over the last few days with any model run. The ensembles are also juggling. I think maybe a few days wait longer to settle placement of the highs east or west.

[Liam J]

More wild swings on the 00z but still remaining very unsettled out to T192hrs as a series of low pressure systems cross the UK courtesy of the anchored trough which really will not give in. The Azores high migrates towards Iceland on the later stages of the GFS run with a pool of warm uppers - 10-12c! Again right in the last frame we have a teasing chart indicating a N/NE flow could be setting up thanks to a Scandinavian trough and heights over the N Atlantic towards Greenland. No deep cold making it to our shores on this run.

A good scatter each way towards the end of the month so still no forgone conclusion at all, still wide open. The control run thinking it's summer...

Edited November 17, 2012 by Liam J

[IDO]

The cooling theme continues, at a snails pace, for sure. The end of FI is now December 3rd and the 850s mean is now around -2.5c (London):

http://cdn.nwstatic.co.uk/ensimages/ens.20121117/00/t850London.png

The members uncertainty explains that and as the experts have said, once the cold setup is in the reliable this figure will show a lower mean (nearer -5c).

So we are heading for something cold if the status quo is maintained. I doubt even the pro weather forecasters would be confident after T184 as anything from cool to snowfest is on the cards, with varying degrees of certainty. The GEFS members highlight this (0z):

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384

Scandi Highs, Greenland Highs, Northerly, HP over the pole, Easterly, etc.

Its a waiting game, and compared to this time last year, a real puzzle.

[AWD]

Looking at the big 3 up to T144 & they all look very similar;

http://www.meteociel.fr/modeles/ukmo2.php?carte=1021&ech=144&nh=1&archive=0

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=144&code=code&mode=0&mode3h=0&runpara=0&carte=1

http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=1&type=0&archive=0

The main difference being the ECM has less of a trough over the UK & more in the way of heights over Europe.

The GFS then becomes more amplified, attempting to send a ridge towards Greenland at T192;

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

Whilst the ECM instead winds up a deep depression over southern Greenland keeping it flat to our west, but introducing heights over Scandinavia instead, something the GFS didn't do above;

http://www.meteociel.fr/modeles/ecmwf.php?ech=192&mode=1&map=1&archive=0

The GFS continues with its amplified pattern in the Atlantic, sending heights & WAA up over Iceland at T240;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=240&code=0&mode=0&carte=1

Introducing some colder air over the UK;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=240&code=0&mode=1&carte=1

ECM also starts building heights to our west, with heights tentatively looking like they are on their way to the Greenland/Iceland area at T240;

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=1&archive=0

Again with cold air starting to filter over the UK;

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=0&map=1&type=0&archive=0

and FWIW in deepest FI, the GFS sends strong heights over the Greenland area, splitting the PV and sending some very warm 850's up over Iceland;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=384&code=0&mode=0&carte=1

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=384&code=0&mode=1&carte=1

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121117/00/384/npst30.png

IMO, we have brought some colder weather forward on this mornings runs. Nothing too cold yet, but at T168 onwards we do have colder days forecast with frosty nights & amplification to the east & west of us.

We also have strong winds & heavy rain forecast Sunday into Monday;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121117/00/51/airpressure.png

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121117/00/57/ukwind.png

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121117/00/57/ukprec.png

Northern & western areas look to take the brunt of this as things stand.

All in all, very interesting model output of late, with no one weather type dominating for the foreseeable, and good potential as we enter winter proper.

[Gibby]

Good morning. Here is the morning look at the 00zs from GFS, UKMO, GEM and ECM for today Saturday November 17th 2012.

The output can be split into 2 weeks this morning with Week 1 seeing similar conditions by all the models throughout. The current cold front across the UK will move on SE through the day clearing the SE tonight, Patchy rainfall along it will clear away East later to leave a day of sunshine and showers. There will be very few showers away from the NW where they will be wintry. Tonight will become clear and cold with a frost as a ridge of High pressure is shown to cross from the West. Tomorrow will see the ridge move across the UK with a fine and sunny day for most. However an increase of SW winds and clouds move into the West Sunday night and spread eastwards to all areas over Monday with rain following to all but the far SE through the day. The rest of the week sees deepeningly unsettled weather as Low pressures become progressively close to and eventually over the UK with showers or longer spells of rain in temperatures that will fall from rather mild levels early in the week to near normal values by the end.

GFS then begins week 2 with further changeable conditions as further Low pressure areas cross gently East with some brighter, drier interludes in between with some snow showers likely over Northern hills. Through FI Low pressure slides SE down over the UK into Europe with pressure building to the North and West. It would become rather cold and still unsettled in the South with rain or sleet at times and a chill East wind. The North and West would slowly become drier and brighter but cold as a ridge moves slowly down over these areas from the NW. The SE continues to hang on to cloudy and raw conditions with occasional rain for a while. Late in FI the high to the North recedes West back into the Atlantic allowing a weak Northerly to advance South over the UK with the main thrust of it directed at Europe.

The GFS Ensembles show a gentle cooling of conditions over the coming two weeks. A reduction in rainfall amounts is indicated in Week 2 as the Atlantic train is blocked. The operational was on the cold side of the pack for a time late in the run with the 850 mean for the run ending near -2C or slightly more below zero at the end

The Jet Stream shows a trough in the pattern near to the UK in a week's time as Low pressure moves deeper over the UK. It's position is lying around the 50N latitude line South of the UK before moving further North over Europe at that time point..

UKMO for midnight on Friday shows a deep depression South of Iceland with an unstable Southerly flow over the UK with troughs out to the SW. There would be cloudy skies with rain or showers scattered about in temperatures close to normal.

GEM today shows a flatter pattern at 144hrs with mild SW winds and weaker troughs moving East bringing rain to most. Later on a deep Low crosses the North giving a windy and wet spell before a cold Northerly digs in bringing a potentially wintry blast South by day 10.

ECM shows a Low pressure trough stretching South from a depression Noth of Britain crossing the UK at 144hrs with rain at times. A broadly similar outcome to GFS develops then as High pressure ridges across the UK although the axis of high pressure is further SE than GFS allowing a UK based high pressure to develop with drier and potentially frosty weather developing. By the end of the run it begins to pull back in the Atlantic with cloudier conditions toppling down over the UK with a cold Northerly likely in the days that follow.

In Summary there is still a change on the way in week 2 of this morning's output. Week 1 will be a mild and wet affair for many with rain or showers the order of all weekdays next week with strong winds at times in relatively mild conditions. In Week 2 things become more complicated as High pressure is shown to be building down over the UK from the North. The position of any formed High will be paramount to what conditions are like at the surface relative to any Low pressure areas to the SE but it looks like things will turn at least somewhat colder with the emphasis shifting from wind and rain to the chance of frost and fog later. There is also a chance of a cold Northerly hinted at by some models with the chance of snow showers occurring for some. As is usual in such synoptics northern and Eastern areas would be most prone to this should it verify

[Gibby]

Thanks Guys for the continued support. I don't get much time during the day's to join your debates but I do read all your posts. Certainly a pattern change on the way after next week's rainfest but the jury's still out on how it will affect us in the UK.

[phil nw.]

Yes as Gibby says next week looks unsettled with rain at times in a quite a strong rather mild flow from mainly south of west.

All the models agree to this setup with the approaching trough taking several days moving across the uk from the west.

GFS at T120 hrs is typical of the next few days..

That european block preventing any real eastward progression of low pressure.

As a result towards next weekend we start to see the general area of low pressure around the UK grind to a halt.

The models then show different resolutions from T168hrs.

GFS continues with the cyclonic and unsettled theme over the uk whereas the ECM favours a pressure build across the country with the trough warming out.

Looking further on for detail seems pointless until we see where are going with the changes from around next weekend.

[bluearmy]

I think today is when some will begin to 'smell the coffee'.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Trending ever colder.

Which anomoly is highest in 16 days ? North Atlantic/greeny or aleutian/kamchatkan?

Not seen that degree of confidence in that feature at 16 days range since nov 2010 naefs output.

Assuming the 12z is consistent, the NOAA cpc charts, being automated on a saturday, will just reflect the naefs run and maybe JH will be on tomorrow to post that he has the three charts showing the same upper pattern for three days and White smoke will billow from chimneys across the country!

Edited November 17, 2012 by bluearmy

[Gray-Wolf]

Am I really seeing a widespread melt event forecast for Greenland on Dec 1st (0z's)? This seems to be followed by it flowing out over Iceland (Föhn effect) as 10c uppers followed by a warm Northerly into NW Scotland? I've seen some odd FI's but that's surely odd?

[chris55]

I think today is when some will begin to 'smell the coffee'.

http://www.knmi.nl/e...agse/index.html

Trending ever colder.

Which anomoly is highest in 16 days ? North Atlantic/greeny or aleutian/kamchatkan?

Not seen that degree of confidence in that feature at 16 days range since nov 2010 naefs output.

Assuming the 12z is consistent, the NOAA cpc charts, being automated on a saturday, will just reflect the naefs run and maybe JH will be on tomorrow to post that he has the three charts showing the same upper pattern for three days and White smoke will billow from chimneys across the country!

Yes Nick, NAEFS still showing some strong and very interesting anomalies as we head towards the end of November and into December. Possibilities of the jet slipping over the top and underneath the block, helping to draw cold out of the Arctic as well as supporting the block

[Liam J]

Am I really seeing a widespread melt event forecast for Greenland on Dec 1st (0z's)? This seems to be followed by it flowing out over Iceland (Föhn effect) as 10c uppers followed by a warm Northerly into NW Scotland? I've seen some odd FI's but that's surely odd?

Yep the Azores high migrated north towards Greenland & Iceland with a pool of 12c T850's on the 00z GFS op run, I wouldn't worry about it for the moment as more wild synoptics are bound to crop up in the FI realms, until the models can get a good handle on the emerging pattern change..... Shorts & T shirt weather in Iceland!

Certainly one set of FI charts that don't occur very often, if at all!

Edited November 17, 2012 by Liam J

[chionomaniac]

Am I really seeing a widespread melt event forecast for Greenland on Dec 1st (0z's)? This seems to be followed by it flowing out over Iceland (Föhn effect) as 10c uppers followed by a warm Northerly into NW Scotland? I've seen some odd FI's but that's surely odd?

I have to agree with you, there, GW. I have seen some strange FI's but that is almost a 20ºC difference in 850 temps due to a Fohn effect!

[phil nw.]

I think today is when some will begin to 'smell the coffee'.

http://www.knmi.nl/e...agse/index.html

Trending ever colder.

Which anomoly is highest in 16 days ? North Atlantic/greeny or aleutian/kamchatkan?

Not seen that degree of confidence in that feature at 16 days range since nov 2010 naefs output.

Assuming the 12z is consistent, the NOAA cpc charts, being automated on a saturday, will just reflect the naefs run and maybe JH will be on tomorrow to post that he has the three charts showing the same upper pattern for three days and White smoke will billow from chimneys across the country!

Yes those anoms. are being modelled consistently Nick.Have you viewed the 850`s though? nothing really cold That may come later when/if the pattern sharpens.

The heights could do with being further north as at first i guess we could get too much Atlantic air in the mix.

Edited November 17, 2012 by phil n.warks.

[IDO]

COLDEST WINTER IN 100 YEARS ON WAY

A severe bout of cold weather looks to be heading Britain's way

Saturday November 17,2012

By Nathan Rao

Have your say(12)

BRITAIN will grind to a halt within weeks as the most savage freeze for a century begins.

Temperatures will fall as low as minus 20C in rural areas, forecasters warned last night, while heavy snow and “potentially dangerous†blizzards will close roads and cripple rail networks.

James Madden, forecaster for Exacta Weather, said: “We are looking at some of the coldest and snowiest conditions in at least 100 years. This is most likely to occur in the December to January period with the potential for widespread major snowfall across the country.

“Parts of the North, Scotland and eastern

England

are likely to experience a run of well below average temperatures, which will include some potentially dangerous blizzard conditions at times.â€

He warned the South faces a bout of “unusually heavy snowfall†in December.

Its gotta be true now.

[bluearmy]

Yes those anoms. are being modelled consistently Nick.Have you viewed the 850`s though? nothing really cold That may come later when/if the pattern sharpens.

The heights could do with being further north as at first i guess we could get too much Atlantic air in the mix.

i agree with all of that phil. i'm not for one minute proposing a repeat of dec 2010 (at the moment). the background pattern is headed in that general direction and it would only take a trigger shortwave to make things very interesting.

[karlos1983]

I'll get my snow shovel out now shall I..........

COLDEST WINTER IN 100 YEARS ON WAY

A severe bout of cold weather looks to be heading Britain's way

Saturday November 17,2012

By Nathan Rao

Have your say(12)

BRITAIN will grind to a halt within weeks as the most savage freeze for a century begins.

Temperatures will fall as low as minus 20C in rural areas, forecasters warned last night, while heavy snow and “potentially dangerous†blizzards will close roads and cripple rail networks.

James Madden, forecaster for Exacta Weather, said: “We are looking at some of the coldest and snowiest conditions in at least 100 years. This is most likely to occur in the December to January period with the potential for widespread major snowfall across the country.

“Parts of the North, Scotland and eastern

England

are likely to experience a run of well below average temperatures, which will include some potentially dangerous blizzard conditions at times.â€

He warned the South faces a bout of “unusually heavy snowfall†in December.

Its gotta be true now.

[legritter]

Modells still pointing to a pressure change .But oh what a wait . things could get interesting regards any high pressure past next weekend but at this range its a case of a few more runs yet .but for coldies its still game on .cheers.

[chris55]

Yes those NAEFS charts just give us a potential idea of the broad pattern, the details are where the fun is but obviously at range that's not something we can look at. Having a strong high anomaly to the West/North West is a much better place to be than having a strong Low anomaly there as we head into winter!

[ronan]

Been following the model thread religiously for the last month and have learned allot from all of you do thank you. Something is brewing and I don't think it it will be to long before we can get more of an idea if what way things are going to go. I look forward to hearing everyone's thoughts over the next couple of weeks. Some of you put so much time and effort into your posts!

[phil nw.]

i agree with all of that phil. i'm not for one minute proposing a repeat of dec 2010 (at the moment). the background pattern is headed in that general direction and it would only take a trigger shortwave to make things very interesting.

Yes it`s all conjecture at this stage i know but there`s likely to be just as much chance of shortwaves heading over the top in such a split flow.

The Naef`s mean hts show a lot of blue around the poles so i feel the signals of solid northern blocking-at this stage-are not strong enough to get us to the next stage,

Of course as we know this could change with further wave breaking.

[Frosty.]

The Ecm 00z ensemble mean shows a gradual change in pattern during the next 10 days from wet, windy and milder throughout next week to higher pressure building from the east and south which eventually kills off the unsettled weather completely with a colder blocked pattern towards the end of the month with widespread frosts and fog which could be of the freezing variety by the end of the month.

[Liam J]

A very unsettled 6z run so far, typical autumn synoptics with wind and rain being the main players during the course of the coming week as the Atlantic roars into life. Some exciting weather at last

[Cloud 10]

The 06z throws some strong heights up over Svalbard in FI,just another option on the table!