Model Output Discussion - The Start Of Winter

[knocker]

All the models want to run a disturbance in the trough across the uk mid/end next week. At the moment, that looks pretty dangerous. Nearer the time it could be less so. The London ECM ens wind spikes later will be interesting re this.

With the week 2 Canadian vortex retreating to the far n of Canada/nw Greenland and the northern arm losing some strength as the uppers in Eastern Canada ease off in intensity, I wonder what the main driver will become in the n Atlantic basin? Will the Atlantic high just ease in ? Will the Siberian edge west? Will we end up with a fairly stagnant upper trough around nw Europe? the anomolys aren't currently large enough to show a strong likelihood as we progress through week 2. Assume that will change as we head through the next few days.

 

Yup. It's a bit like a chess match with everyone poised for the next, vital, move. This mornings GEFs not a big help.

Charts courtesy weatherbell

[IDO]

The charts in GEFS FI offer nothing and that takes us up to the last third of December. The mean uppers at D16 show a trend for milder than average rather than cold:

 

 

 

The PV looks to continue to indicate a movement towards Siberia so that would indicate the UK quadrant being slacker than Week 1, where the Canadian PV lobe is mobile and dragging the uppers along for the ride.

 

The disturbance for late next week looks like it's core is north of Scotland so for the south the story could be short wave developments of satellite lows or troughs bringing rainfall. Both ECM and GEM hint at the former on this run:

 

 

 

The GEFS 2m temps for London show a cool few days then a slow recovery to closer to average with a very low risk of snow:

 

 

ECM again has its D9-10 charts trying to tempt us into higher expectations but they have been wrong so many times that I cannot put any faith in them. It is a colder run from start to finish (uppers) on the ECM and that is due to higher amplification in the Conus; neither GEM or GFS have that intense of anomalous positive uppers or as far north:

 

 

Remaining average fare for anyone south of Birmingham at sea level, though hills and mountains  should get some flurries on Sunday and Monday before a warm sector quickly passes through Tuesday. The the storm then edges in afterwards...

Edited December 3, 2014 by i'm dreaming of...

[Frosty.]

I agree with PM..lots of polar maritimes to look forward to in the weeks ahead and always the chance of something more significantly wintry evolving out of this disturbed early winter pattern..at last some excitement after the boring, sluggish warm autumn.  

[nick sussex]

Overall wet,  very windy at times, temps close to average, occasionally colder, some snow to higher elevations in the north. That covers the next ten days.

 

The ECM day ten the best of the major models as that suggests low heights lifting away from the southern Greenland, from there taken at face value the troughing should weaken over the UK and some interest might develop later.

 

Not the most exciting of outputs from a cold perspective but I'm sure roofing companies will already be looking at where to take the family on holiday next year.

 

In these types of set ups the  secondary feature forming at the base of the main troughing is worrying as this has the propensity to bomb quickly and run ene into the UK.

 

The sooner we can get rid of this anticipated limpet trough the better.

 

Looking at the ensemble spreads a cluster of ECM ensembles take low pressure further se and build high pressure out of Siberia towards the Svalbard region at T240hrs, overall the mean supports the ECM operational run with limpet trough and displaced Azores high.

Edited December 3, 2014 by nick sussex

[TonyH]

I think that the next 5 days or so often dry not wet.

[johnholmes]

For the time being cold fans will have to make do with bursts of Polar Maritime air behind surface lows with the chance of a brief Arctic Maritime outburst to the rear of these lows. It could be pretty windy with one or more of these thanks to the strength of the upper flow over the Atlantic and the lows deepening quite markedly as they veer away north of the north of the country.. There are SLIGHT indications in the later outputs from 1 at least of the anomaly charts that the current pattern MAY change. But I would rate that as below 25% in the next 2 weeks.

latest ECMWF-GFS shows their idea which is not quite the same as NOAA showed last evening, both links below

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

Edited December 3, 2014 by johnholmes

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY DECEMBER 3RD 2014.

 

NEXT UPDATE THURSDAY DECEMBER 4TH 08:00

 

THE CURRENT GENERAL SITUATION A ridge of High pressure lying across Central Britain will decline slowly as fronts lie across the SE of Britain and approach the NW tomorrow.

 

MODELS-2 WEEK HEADLINE After weakly changeable conditions in the next 5 days or so it will become more unsettled with wet and windy weather developing for all areas from the middle of next week.

 

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast shows an undulating flow likely for a few days with a plunge South of the flow for a time before with time it settles on a West to East flow across Southern England through Week 2 between High pressure to the South and Low to the North of the UK.

 

GFS OPERATIONAL The GFS operational this morning shows a gradual change to more unsettled and very changeable conditions taking over with spells of windy and rainy weather alternating with colder and clearer air with showers, some wintry in places as Low pressure troughs digs further South down across the UK. Later on in the period the High pressure to the South tilts the airflow to more of a WSW flow with further spells of rain at times for many with the worst rain in the North and West. It would become milder in the SW flow at times especially in the South.

 

THE GFS PARALLEL RUN The GFS Parallel run illustrates a very zonal pattern developing with Low pressure to the North bringing spells of wind and rain to all areas in temperatures close to average overall with some colder interludes next week with showers, some wintry before generally milder conditions develop later in the period.

 

THE GFS CONTROL The GFS control run also shows a more volatile and potentially stormy period a week from now as deep and vigorous Low pressure is allowed to make much larger inroads across the UK with gales and heavy rain followed by chilly aor with wintry showers at times. The trend later is for pressure systems to be less pronounced and with High pressure never far to the South the rain looks like it could become more biased towards the North and West later in a milder Westerly flow.

 

THE GEFS ENSEMBLES The GEFS Ensembles maintain a period of zonal Westerly winds over the next two weeks circulating around Low pressure to the North and High to the South. As some colder air interjects at first some rather cold and showery interludes develop though as the pattern flattens later with strong West or SW winds temperatures will recover to average or above with all too frequent periods of rain in the strong winds.

 

UKMO UKMO today shows the current period of rather cold and changeable weather persisting into next week with some overnight frost for a time. Then the trend next week looks like being towards winder and wetter conditions as deep Low pressure develops to the North of the UK later next week allowing temperatures to rise somewhat especially across the South.

 

THE FAX CHARTS The Fax Charts show a slow moving trough close to SE England over the coming few days with the ridge across Central UK declining. Occasional rain in the SE and troughs to the NW giving the same will move SE over all areas later in the weekend followed by a chilly NW flow with some showers for a time, wintry on hills.

 

GEM GEM shows a pattern which deteriorates conditions across the UK from the North later this weekend as Low pressure deepens in the Iceland area feeding the UK gales and heavy rain next week with spells of sunshine and showers in between. Temperatures look like alternating between average conditions or a little below in the showery spells to rather milder at times across the South as warm sectors rush through at times.

 

NAVGEM NAVGEM too shows strong to gale Westerly winds next week as Low pressure to the North of Scotland delivers very wet weather at times as troughs rush West to East across the UK followed by squally showers. Temperatures will generally be close to average made feel colder in the strength of the wind.

 

ECM ECM this morning shows a very wet and windy spell developing next week as the current weak troughs crossing SE in a chilly NW flow give way to much deeper fast changing weather type as intense Low pressure  lies close to North of Scotland bringing fast moving periods of rain and showers in near average temperatures and strong winds.

 

ECM ENSEMBLES This morning's Ensemble data illustrate a typical Winter pattern for the UK with Low pressure to the North of the UK and High pressure near the Azores giving rise to a strong Westerly flow across the UK with rain at times and average temperatures overall.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The theme has now become strong in support for the quiet and benign spell of late giving way to much more unsettled and windy spells of weather with rain bands and gales alternating with sunshine and showers for all areas. The pattern has flattened this morning making any colder polar maritime incursions of air less potent than was shown yesterday.

 

MY THOUGHTS All models now support a change to a much more mobile pattern of weather developing from early next week. The current benign spell of rather chilly weather with occasional rain will become a much more robust Westerly flow for all next week as Low pressure deepens markedly to the North with a strong West to East Jet Stream setting up home near Southern Britain. Troughs will rush Eastwards regularly, each bringing it's own mix of rain and gales followed by squally showers. As the pattern remains a Westerly based flow temperatures will be average at worst with only the showery interludes providing any chance of wintry precipitation and these only likely on the high hills and mountains of the North. There is some trend notably from GFS on High pressure to the South of the UK creeping a little closer to SE Britain later backing winds towards the SW which if happens would direct the worst of the continuing wind and rainfall towards the North and West and more importantly bring the chance of mild temperatures to all as the flow tilts more SW to NE. There looks little chance of any significant cold across the UK over the period of the output over the next 10-14 days and conditions shown this morning at the extremities of the run are hardly conducive to bringing any risk of cold in the period thereafter so the chances of anything cold and snowy wise for Christmas 2015 look rather forlorn at the moment though of course there is plenty of time for that to change at this range. Meanwhile it looks like we must all batten down the hatches for a rather different style of Wintry weather than we have seen recently over the upcoming period though I doubt it will set the world on fire by many unless it's gales and heavy rain that floats your boat.

 

[Cloud 10]

All the models want to run a disturbance in the trough across the uk mid/end next week. At the moment, that looks pretty dangerous. Nearer the time it could be less so. The London ECM ens wind spikes later will be interesting re this.

With the week 2 Canadian vortex retreating to the far n of Canada/nw Greenland and the northern arm losing some strength as the uppers in Eastern Canada ease off in intensity, I wonder what the main driver will become in the n Atlantic basin? Will the Atlantic high just ease in ? Will the Siberian edge west? Will we end up with a fairly stagnant upper trough around nw Europe? the anomolys aren't currently large enough to show a strong likelihood as we progress through week 2. Assume that will change as we head through the next few days.

 

A long way out to pin any detail down,but certainly some midweek mayhem if the ECM day 6/7 charts were to verify,which looks like an "everything but the kitchen sink" type scenario.

 

 

The ECM 00z ens.  continues with its below average theme right through its run with only short milder blips along the way.

 

[Iceaxecrampon]

00z

 

Incoming

 

T+141 Monday

 

 

T+168 Wednesday

 

 

 

Ireland chance of widespread altitudle ppn.

 

Should be interesting.

 

Meanwhile still on for Sunday the 7th December as trended over the last week - all good for Scotland.

 

 

Ian

[ItNeverSnowsInWindsor]

The GFSP this morning continues to show lots of cold Pm shots throughout the run, With Snow over Northern hills and maybe down to lower levels at times further South, And possible stormy conditions up North around the 9th. Quite a Wintry period coming up and a good start to the new season. Already last nights temps dropped colder than of all last Winter alone!

 

ECMWF also ends on a Wintry note with a cold N/W flow - 

ECM always ends on a wintry note. We still wait to see the cold charts enter the reliable timeframe.

[Gibby]

Meanwhile the 10 Day Mean Chart looks rather uninspiring still with a broadscale pattern of a long fetch Westerly across the Atlantic and the UK with Low presure to the North...spells plenty of rain and showers to my eyes with snow likely on the highest ground of Northern Britain at times after each cold front passes. I concede the operational would bring something rather better though.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

[mushymanrob]

 

However, I'm not too happy about the persistent Azores high and would be interested in others' thoughts on that. 

 

i agree, im not happy with its current position. id like to to drift eastwards and sit over northern france all winter! lol and theres currently as much chance of a mild evolution, as a cold one.

 

meanwhile we look to be entering a very unsettled period, with the return of rain and very strong winds by midweek next if the current outputs become reality.  the outlook is unsettled.

[Paul]

Just a reminder that NOAA won't be running the GFS-P after today's 6z until Monday as they're doing work on the supercomputer which is currently running it.

[Summer Sun]

Snow amounts in north west Scotland start to mount up from Sunday its not often you see the beeb talking about 'quite a bit of snow in the north' at the 7 to 10 day range but they did last night so I'm confident the charts are onto something

 

Saturday sees a dusting at best

 

 

24 hours on to 19:00 Sunday and the amount of snow is increasing with 1 to 3 inches in places with a dusting for higher ground in northern England

 

 

24 hours on to Monday evening and the amounts are similar

 

 

Now we move onto Tuesday and the areas seeing snow in Scotland increases with Northern and the Republic of Ireland also seeing some snow

 

 

By 19:00 on the 10th and the snow is increasing for western Scotland with 7 inches in places the snow in Scotland starts to spread further east with some more for higher parts England and Wales

 

 

Another 24 hours on to December 11th and parts of western Scotland are getting close to 10 inches of snow Aviemore could have around 4 inches by this stage. Parts of higher ground in the south could also start and see a dusting

 

 

The final 24 hours takes us to December 12th again its western Scotland which has the most snow at around 10 inches in places and a few inches for the lakes and pennines

 

 

Parts of Scotland could see scenes like this next week

 

 

 

 

[joggs]

Well a slight worry re the progged deepening system mid nxt wk.The position will change right down to the wire so one to keep a eye on.Other than that,its how you were,after a few cold settled days with night frosts this wk turning cool/cold zonal from the west with nw incursions ableit short,behind the clearing fronts that will give wintry stuff at elavation,particulary n/nw the nxt 10 days or so.Cant really call beyond imo.Keep up the good work all.

[terrier]

Think with this 950mb low on the models we are certainly in for some intresting model watching in the days ahead. But think away from Scotland we will see some troublesome rainfall totals and with risk of storm damage not a great charts in the run upto xmas that's for sure.

[Polar Maritime]

ECM always ends on a wintry note. We still wait to see the cold charts enter the reliable timeframe.

I would have to disagree there reg the ECMWF. And cold charts do show with-in the reliable as per my post.

Edited December 3, 2014 by Polar Maritime

[snowking]

Beyond the obvious concerns for next week, this tweet from Matt Hugo is certainly worth a look:

https://twitter.com/matthugo81/status/540075794903859200

That's some pretty serious clustering for +360. Obviously as we do not have access to these clusters every day it's difficult to know if this is a new development or a trend, but encouraging to see.

It looks increasingly likely that the next response will have to be tropospherically led and this may be the first sign.

Also, big thanks to Matt to providing a glimpse at some otherwise unseen data

SK

[Hocus Pocus]

Beyond the obvious concerns for next week, this tweet from Matt Hugo is certainly worth a look:

https://twitter.com/matthugo81/status/540075794903859200

That's some pretty serious clustering for +360. Obviously as we do not have access to these clusters every day it's difficult to know if this is a new development or a trend, but encouraging to see.

It looks increasingly likely that the next response will have to be tropospherically led and this may be the first sign.

Also, big thanks to Matt to providing a glimpse at some otherwise unseen data

SK

Possible heights building towards Greenland from NE Canada perhaps around the 3rd week, or I'm I misinterpreting those charts?

[blizzard81]

Beyond the obvious concerns for next week, this tweet from Matt Hugo is certainly worth a look:

https://twitter.com/matthugo81/status/540075794903859200

That's some pretty serious clustering for +360. Obviously as we do not have access to these clusters every day it's difficult to know if this is a new development or a trend, but encouraging to see.

It looks increasingly likely that the next response will have to be tropospherically led and this may be the first sign.

Also, big thanks to Matt to providing a glimpse at some otherwise unseen data

SK

Thanks for posting that Snowking. It certainly ties in with post 10 day ensembles for De Bilt. No mild trend there. Lets hope that trend continues.

[Frosty.]

Who said there was nothing cold in the reliable timeframe? The Gfs 06z op run shows generally cold and very unsettled weather for the next week or so with gales / severe gales, wintry showers, night frosts, heavy rain and even sleet and snow in the north at times with max temps of 5c 41f in the south and closer to freezing across northern hills with short bursts of very cold weather sweeping across the north, especially scotland and the only borderline mild day is next tuesday as a warm front sector pushes east but is swiftly followed by another surge of polar maritmes with wintry showers. I have been waiting for these type of charts since october and finally they are here.

Mild mush, you are the weakest link..GOODBYE

[TonyH]

Snow amounts in north west Scotland start to mount up from Sunday its not often you see the beeb talking about 'quite a bit of snow in the north' at the 7 to 10 day range but they did last night so I'm confident the charts are onto something

 

Saturday sees a dusting at best

 

 

24 hours on to 19:00 Sunday and the amount of snow is increasing with 1 to 3 inches in places with a dusting for higher ground in northern England

 

 

24 hours on to Monday evening and the amounts are similar

 

 

Now we move onto Tuesday and the areas seeing snow in Scotland increases with Northern and the Republic of Ireland also seeing some snow

 

 

By 19:00 on the 10th and the snow is increasing for western Scotland with 7 inches in places the snow in Scotland starts to spread further east with some more for higher parts England and Wales

 

 

Another 24 hours on to December 11th and parts of western Scotland are getting close to 10 inches of snow Aviemore could have around 4 inches by this stage. Parts of higher ground in the south could also start and see a dusting

 

 

The final 24 hours takes us to December 12th again its western Scotland which has the most snow at around 10 inches in places and a few inches for the lakes and pennines

 

 

Parts of Scotland could see scenes like this next week

 

A foot in places there SS

[bluearmy]

Strangely there is no sign of any mean upper response to that surface cluster. presumably it would turn out to be a fairly mobile feature though at this range it seems odd to see such a large cluster on something which turns out to be mobile.??

The back end of the ECM extended ens shows the main part of the vortex the other side of the NH (Far East of Siberia extending into the Aleutian area) with a small Canadian segment just nw of Greenland. As I posted earlier, of that verifies to any eat extent, I would expect to see something this side of the NH taking control. That could vary from a displaced Azores ridge over us to the Siberian one extending into scandi and beyond. it could also leave us stuck in a weak mean trough between an Atlantic ridge and west Russian one. whatever transpires, it could stick around without too much of a northern arm to move it on.

[legritter]

Its certainly good to see some very interesting charts and Data today ,ok no deep freezer being forecasted but next week looking very disturbed possibly stormy for a good few of us .Also in the far outlook high pressure possibly occuring over north east canada west greenland area ,im not suggesting a block but if we can get the main trough over scandy and a lessening of any hights to our south and south west we could be looking at a synoptic situation that us Coldies would relish . Model watching as just gone up a gear today ,Brilliant forum ,And a big thanks to the knowlegable for their contributions ,bring it on we have Some meat on the bones ,  

[IDO]

Rather uninspiring 06z run with nothing like the ECM clustering: 

 

Much in line with GFS output in FI for the last few runs. The CFS MJO does not now want to take us into an amplified phase 6-7 which is not a good trend:

 

 

Suggesting a rerun of phase 3-4 (upcoming pattern). The UKMO also hinting in todays 30 day update of "average temps" & "North/South divide": http://www.metoffice.gov.uk/public/weather/forecast

 

I expect the ECM ensemble suite this morning is lemming like, following the over amplified op, another tendency it likes to show.

 

There looks little hope of cold from the east as the Dutch ensembles show: 

 

So a Scandi trough looks the only way to cold in the next 2-3 weeks but more than likely just a slacker westerly flow as the beaten up PV meanders aimlessly towards Siberia. 

 

GFS still looking at a nasty LP system later next week: