Model Output Discussion - The Start Of Winter

[snowking]

Some rather underwhelming output overnight it has to be said with just some fleeting NWly outbreaks - pretty good for Northern and Western upland areas but a little frustrating for those a little further South I am sure.

However as Matt alluded to earlier with some promising activity continuing to showi up way above our heads, and this pretty well matching expected timing from a number of winter forecasts, I remain pretty optimistic in the face of the rather Scrooge like charts

SK

Edited December 10, 2014 by Polar Maritime
To remove LRF comments.

[Nick F]

So looks like average to above on the charts this morning. Not great output if it's cold and snow your after. Especially with the Azores moving into Southern Europe. This could move the temps into the above average category. Think until we see the ssw take effect we will just have to grin and bear it. In the words of frosty mild mush is making a comeback I'm afraid.

 

I can understand if you live down south, but some snow potential near your doorstep over the next few days surely? Particularly over northern hills.

 

For a change, I'm not looking too far ahead, as we've some cold weather across the north and we are resigned to the fact there's no pattern change until end of Dec at the earliest.

 

Besides the wintry showers today and tomorrow, which will fall increasingly as snow to lower levels as the cold air kicks in from the NW, we have a wave moving in by early Friday, with potential for some snow on the northern flank of the rain area Friday morning, particularly across northern EIRE, N. Ireland, north Wales and northern England.

 

 

moving on from that, NAE only as far as Friday 00z, GFS shows lowering 1000-850mb thicknesses and dew points from the north on the northern flank of the wave. Ideally need thickness below 129 gpdm and Dps 0C or below

 

 

GFS precip type charts:

 

Probably won't be any significant accumulations - but potential for lower elevations to wake up with some snow falling Friday morning in the areas I mentioned before the wave clears the precip away.

[SMU]

Christ has everyone been listening to david gray its like depression fm in here this morning.

We have to face facts that if we want cold then we need more high pressure on the scene.

The azores high has many guises, one is of course a ridge into europe however not being a 1 trick pony it doesnt take a huge amount of amplification to keep us pretty cold

More later

Dentist

[Gavin Hannah]

I think a bit of perspective is required here. ATM, (the GFS anyway) is showing some HP moving into europe in 2 weeks, just in time for Xmas. Until then, we are getting some very seasonable PM weather. And at 2 weeks timeframe, I wouldn't get to disheartened just yet.  I know we all want a white Xmas, but lets not get to carried away with what the models are showing for that period just now.

 

Even if the 'trend' remains constant over the next week or so, it looks to me that it could still remain quite mobile. It appears to me that the HP may struggle to get locked in leaving the possiblities open for it go north for the winter 

[Frosty.]

Speaking of depressions we have explosive cyclogenesis or weather bomb to use the dumbed down American version..the UK weather is certainly not boring this week, especially if you are being hammered by 40 feet high waves in northern scotland!!!

[Polar Maritime]

Yes Frosty, Lot's of interesting weather to come over the next few days with storms and snow possibility's falling further South into the Midlands tonight/tomorrow as Nick alludes to, With some parts across Scotland seeing some heavy falls above 150m with blizzard conditions. A seasonal cool and sometimes cold Pm flow continues in the Models for now at least, As you say certainly not boring for the UK in such an unstable flow, Very interesting indeed.

Edited December 10, 2014 by Polar Maritime

[carinthian]

Morning all, well I must be looking at the wrong charts. I cannot see any particular movement in the shorter term limit ( 144hrs ) with the main models towards a milder scenario. The Azores high is not showing movement into Europe. Beyond that with -in the now reasonable forecast period , a cold outlier seems more likely than a mild one. Note the rise in pressure over NE Canada and the emergence again of the Siberian High. Still encouraged by the holding of lower heights over Southern Europe which eventually can be your best bet to link into a more prolonged colder pattern prior to Christmas.

 C

[MattH]

Just to quickly add, of which I forgot to mention in the last post given I was primarily focusing on the medium and longer term, but as some have said within the short term and so far this December the UK has, overall, achieved some cold synoptics from a broader synoptic regime that, in theory, doesn't really promote much cold weather. This constant re-development of NW'lies and polar maritime airmasses has clearly produced snow, cold temperatures, frosts and ice since the start of December, especially away from the far south of England, but even down there frost has been in evidence, so yes not all doom and gloom, but I was primarily focusing on the medium and longer term which doesn't look like the opening 7 to 10 days of December. The overal evolution of the forecast charts suggests a continued +NAO pattern but it's the subtle differences of the location of the Azores high and areas of low pressure to the north that may well start to introduce more W or SW'lies rather than W or NW'lies which for the UK, at this time of year, can produce significantly different weather.

 

The 00Z GEM is just that, a little gem, it really does try hard within the longer term to produce something totally different (on many occasions) and the amplification that it shows just doesn't look like coming off at all. Clearly it would bring a far more settled, colder regime to the UK as high pressure builds over and to the NE as per the 240hr chart. I'll be reviewing the 00Z EC ENS, for work within the next hour or so and will comment on twitter if there is anything remotely similar, but I doubt it.

 

Plenty to play for, only 10th of December 'we' have done well so far, try and keep last winter in your thoughts and compare and contrast a year ago to present day and I still suggest that January could be a very interesting month indeed, if you like cold weather of course!

 

Cheers, Matt.

[Duane S.]

I'm with Steve, I cannot understand the doom and gloom this morning. Nothing has changed on the charts whatsoever apart perhaps from a shoring up of the predominantly westerly theme for the next 10 days or so. Atlantic ridging (of the type that COULD lead to HLB) in the medium term has not been realistically on the table at ANY point in the past 3 weeks. Nothing has changed nor was it likely to. The profile has been of waxing and waning moderate amplification and subsequent ridging of the Atlantic high, leading to PM blasts at best, the degree of which the only issue unresolved.

Away from the usual elevated areas and other than transient affairs, it is extremely difficult to see where the start of a decent cold spell is going to come from this side of Xmas.

The expected feedback following the OPI and SAI has been set back more than extinguished, watch the GEFS FI start to sniff out the seeds of change over the next week or so, the stratosphere warming is looking to exact some revenge on the polar vortex as we head into January. With that in mind it is highly likely cold incursions will happen down to the mid lats as we go through January but as always worst case scenario we will need to roll a lucky number on the dice, best case scenario we will need to not roll the unlucky number on the dice!

It remains this year and last are not even on the same sheet as each other.

[BlueHedgehog074]

Going to have to agree with what others have been saying this morning. The NOAA 8 to 14 Day 500mb Anomaly chart (issued 9th December) still not buying into anything particularly cold for the next week or so. The little bump in the 500mb flow to our South-West (green line) along with higher than average heights towards the Azores marking out ridging in that area, but with some kind of West to East Atlantic troughing likely. Essentially Low Pressure extending from around Southern Greenland towards the UK, but with the lowest heights likely to be concentrated to our North/North-West. As such, no signs really that the Azores high will significantly ridge Northwards towards Greenland. For now. Overall a Westerly Atlantic dominated outlook looking likely. So it does look as though the cold and snow fans may not quite get the tickets to board the Polar Express towards Snowy Paradise.

Doesn't neccesatily mean the cold and snow fans still won't see further wintry surprises however. Some models, like the GFS 00Z, continue to show further possible chilly Polar Maritime flows beyond this week which, if potent enough, could provide additional wintry treats for the coldies. I suppose obtaining occasional Polar Maritime flows is what you would expect at times from a Westerly drivern pattern. So pretty standard, I guess, for December.

Also, despite what I said earlier, the rest of this week does continue to hold promise for some of those into snowy weather to be given that ticket to ride that train to Snowy Paradise. Especially those in the Noryh. Today could bring an assortment of wintry showers to places. These being carried along in strong gale-force Westerly winds with the worst of the showers occurring towards Western and North-Western areas, and possibly falling as sleet and snow down to about 150 meters towards the North-West (this was, at least, according to the TV forecast today). Winds also possibly gusting upto 80 mph towards North-Westerm coasts, although anywhere could be at risk to seeing strong winds. So do take care if travelling in this weather. It will feel very cold too, particularly for those exposed to the very strong winds. The models then gradually show the stormy Low Pressure system to our North to transfer to our East in the next few days with further chilly and windy weather likely. Further wintry showers or longer spells of rain, sleet or hill snow will affect the UK, too. But things should then start settling down somewhat towards the weekend with fewer showers and the winds dying down. Perhaps also becoming a bit milder, especially to the South, as we start to lose the cold North-Westerly/Northerly winds later on this week.

[nick sussex]

It's at times like this that you need to find a few crumbs of comfort!

 

Thankfully the ECM has dropped last nights horror show and delivered something still underwhelming but not nearly as bad:

 

Last nights T240hrs:

 

 

Todays 00hrs run to T216hrs:

 

 

The centre of the Azores high further west and better pressure rises to the east.

 

 

[Frosty.]

So..the models are showing explosive cyclogenesis with huge coastal waves, blizzards across northern hills and yet some members are playing the last post..it's bemusing, baffling and outrageous!!

[fergieweather]

I don't get all this we will be returning to a westerly regime next week business..we are already in a westerly regime are we not? As for it turning generally milder, when the met office stop saying cold incursions then I will accept it but for now, there has been no downgrade..I mean, what is there to downgrade from? the south has had diddly squat cold weather as it is..so what's new?

UKMO do expect milder/less cold conditions to begin to prevail after this week, courtesy of broader warm sectors and less potent NW-N incursions between now and Christmas. As Matt suggested, no broadscale change expected for at least most of December.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY DECEMBER 10TH 2014.

NEXT UPDATE THURSDAY DECEMBER 11TH 20:00

THE CURRENT GENERAL SITUATION An intense depression lies to the East of Iceland with a severe gale Westerly flow across the North and a less strong flow across the South. A wave depression approaches Western Britain from the Atlantic later tomorrow.

MODELS-2 WEEK HEADLINE Remaining changeable with rain at times especially across the North and West. Temperatures generally close to or a little above average but a few colder periods over the North when showers could turn wintry.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast maintains the flow to the South of the UK for the next week blowing somewhat less strongly next week and easing slowly North to lie across the UK through week 2.

GFS OPERATIONAL The GFS operational this morning shows very little change in the overall pattern over the period of it's output this morning. Low pressure will continue crossing East to the North of Scotland bringing spells of rain alternating between spells of colder and more showery weather with snow on Northern hills. High pressure edges up closer to Southern Britain in week 2 with milder and less unsettled conditions for a time possible as a result more especially in the South.

THE GFS PARALLEL RUN The GFS Parallel run is very similar in Week 1 as the operational though in Week 2 it enhances further the trend towards mild and less wet conditions across the UK as High pressure takes up residence over Southern Europe steering mild and benign weather NE across the UK on the run up to Christmas with rain at times across the North and West.

THE GFS CONTROL The GFS control run also shows a similar pattern with it too replacing any cold injections with generally mild, less windy and occasionally wet conditions for a period of the second week before stronger and more deeply unsettled weather return towards the end of the run in strong Westerly winds.

THE GEFS ENSEMBLES The GEFS Ensembles are indicative that Low pressure to the North of the UK and High to the South and SW will be the dominant pattern over the whole period with occasional rain and showers over the UK with rather less cold weather overall as the incidence of tropical maritime air in association with Low pressure to the North increases across the UK.

UKMO UKMO today shows a flat but strong Westerly pattern across the UK at the start of next week between Low pressure to the East of Iceland and a strong Azores High pressure area remaining in situ. There will be spells of rain with some showery interludes with temperatures recovering to average values after the chilly weekend especially in the North.

THE FAX CHARTS The Fax Charts show a strong and unstable Westerly flow across the UK ahead of a wave depression crossing East into the UK later tomorrow. As this clears winds turn to a cold NNW flow very briefly before a complex series of warm fronts over the Atlantic bring back breezy, milder and sometimes wet weather early next week.

GEM GEM in the short term shows the pattern of the majority of the output with regard to milder Westerly winds next week alternating with colder and chillier spells with showers before it drags Low pressure down the North Sea and into SE Europe allowing pressure to build across Scandinavia which then extends a cold ridge back across the UK delivering drier and cold weather with overnight frosts and fog as a result following a cold and showery period of weather later next week with wintry showers across the East and SE as this process takes place.

NAVGEM NAVGEM this morning shows windy weather continuing for the whole of the run with further Low pressure areas crossing a point to the North of Scotland at various occasions over the week, each bringing a spell of rain and followed by clearer and colder weather with sunshine and showers, wintry on the hills.

ECM ECM this morning shows a Westerly pattern maintained through it's duration this morning. After the cold blip for all this weekend milder air will flood east over Britain from the end of the weekend with some rain at times and any colder showery conditions only affecting the North on occasion before all reas see a reduction in rainfall and wind strength late in the period as High pressure to the SW edges ever closer towards SW Britain.

ECM ENSEMBLES This morning's Ensemble data has remained almost identical for days now making the chances of any major changes very remote indeed as confidence remains high that in 10 days time the UK will still be in the pattern of Low pressure to the North and High to the SW leaving the UK in an unstable Westerly flow with average temperatures and rain at times for all.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS Not any major shift in trend this morning with little or no sign of any major changes in the Westerly pattern other than the incidence of milder periods increasing with less in the way of polar maritime air affecting anywhere other than the far North of Britain later.

MY THOUGHTS It really looks like desperate times for those looking for any cold weather of note over lowland Britain anytime in the run up to Christmas with a locked pattern of High to the SW and Low to the far North unable to drag anything cold South meaningfully over the next few weeks. Instead we look to be increasingly fed maritime Westerly winds and a lot of cloud and occasional rainfall more especially across the North and West. There doesn't look to be any dramatic amounts of rain anywhere away from the far NW and indeed it may become drier across the South with time as that Azores High exerts even more influence towards Southern Britain later as the Jet flow edges back North somewhat later. With no building blocks at the needed locations to break us out of this pattern I'm afraid it looks very unlikely that any Christmas card scenes will greet any of us over lowland Britain over Christmas this year and the seek for cold goes on and looks as far away as ever at the term of all the output I've seen today taking us towards the end of the first third of Winter 2014. However, bear in mind my comments are borne on what is shown today and with Christmas still two weeks away there is time for change.

NOTE: I am unable to compile a report tomorrow morning due to work commitments but may post one on the 12z ones in the evening just for a change.

Edited December 10, 2014 by Gibby

[cyclonic happiness]

So..the models are showing explosive cyclogenesis with huge coastal waves, blizzards across northern hills and yet some members are playing the last post..it's bemusing, baffling and outrageous!!

I think it's just disappointing for us southerners, we were all so excited about the prospects of some of the white stuff, but it's been downgraded to nothing yet again.

 

Storms are all very well, but if you live slap bang in the middle of the country, you very rarely get anything interesting in winter.

 

The Strat' threat is making some positive rumblings though, and I can't help but thinking we 'at least we're not on the mild, zonal train' as it stands, just about on the right side of cold zonality still.

 

I'm sure it will change for the better soon :-) 

[No Balls Like Snow Balls]

The latest predicted ECM Temp anom for January issued yesterday.

It certainly does look like becoming milder next week, but possibly only for a brief period!

Edited December 10, 2014 by No Balls Like Snow Balls

[johnholmes]

nothing has changed in 24 hours, several sensible posts above this and from folk well respected on here-chill out, sorry about the pun; there has never been any real threat of deep cold especially of the long lasting type, the post I made yesterday and that by Vorticity gave detailed explanations of why there is nothing in the current 2 week outlook to suggest any marked change in the current pattern. Interesting the post from Fergie re UK met, but remember it is not quite the outlook they were suggesting to him 24-48 hours ago, unless I have misread his posts.To me there is no sign of anything other than short term deep cold or mild in the run up to Christmas. The upper pattern is well established and predicted by the anoamly charts. Forget the name, anomaly, just look at the contour flow being predicted by the main 500mb anomaly charts. No deep cold and no real mild suggested on any of the the 3. What happens at 3 weeks and beyond I never pretend to be able to make a realistic post about. Settle down to what some call 'wash and rinse' weather for the 14+ days to come. Maybe within that time frame the overall wave length may start to change, Until it does no marked change in surface weather can occur.

For some frosts at times, for some even some snow at times and it looks good for the Scottish ski resorts at the moment for those planning on a Christmas in that area.

below the usual links and my summary of them

 

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

 

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

 

500mb summary Wed 10 Dec 2014

Both are much as they were yesterday, v similar w of the uk and not too different uk area and east, slight differences persist in how the treat the trough but over a similar idea is kept to the last 2-3 runs and is not too dissimilar to noaa 6-10 last couple

Essentially strong atlantic flow about west from trough off e coast n America into marked trough e of uk with 500 flow over uk somewhere around west, bit n bit s on day to day, expect deep lows at times and air mostly Pm

Edited December 10, 2014 by johnholmes

[Frosty.]

Agreed, expect moderate to large temperature variations from day to day depending on weather types..wet and windy=milder..showery= colder. I agree totally with the Experts on here, even though the colder incursions next week look less intense, it should still be cold enough at times for wintry showers and for overnight frosts and icy patches.

[IDO]

So..the models are showing explosive cyclogenesis with huge coastal waves, blizzards across northern hills and yet some members are playing the last post..it's bemusing, baffling and outrageous!!

 

Yes a cooler regime for the next 4-5 days, but mainly north of Birmingham for anything wintry. 7c with  just a breeze and lovely sunshine down my way. Might get down to 5c on Saturday. Zero chance of snow or frost. You hardy types in the north are use to a bit of seasonal stuff and fingers crossed there are no coastal floods. The CET remains at -0.4c so nothing exceptional down in the Midlands>south.

 

As for changes, of course changes can happen, but looking at the GEFS mean, out to D16 we still have a supercharged Asian/Pacific jet, a Greeny PV lobe, an Azores High with the jet only having one place to go on exiting the US, be it split or not, that is riding over the Azores straight through the UK:

 

 

 

Once the upstream jet slackens we will get the possibility of a meridional wave pattern and then we have a chance for the Azores to ridge to Greenland or Scandi. At the moment there is no slack in the UK segment as all heights are in the US and Russia. The only variable is the proportion of TM to PM flow and that is difficult to predict till closer to the date. The UKMO update for the next 30 days is a carbon copy of that type of setup.

[carinthian]

Agreed, expect moderate to large temperature variations from day to day depending on weather types..wet and windy=milder..showery= colder. I agree totally with the Experts on here, even though the colder incursions next week look less intense, it should still be cold enough at times for wintry showers and for overnight frosts and icy patches.

Yep karl  and the UKMO do not mention above average temperatures for the rest of this month, slightly below or average.

 C

[MR EXTREMES]

The most likely scenario would be little movement of the Azores high or movement over the uk or over the South of the uk in other words settled under clear sky's frosty fog possible feature later runs.

But near term very lively normal December weather.

Still confident on better winter chart further on through the next week or so.

[iamgazza]

Still confident on better winter chart further on through the next week or so.

 

Based on the current output, that shouldn't be to tricky lol.

[Gael_Force]

The latest predicted ECM Temp anom for January issued yesterday.

B4ax_lFIIAAiP-K.png

It certainly does look like becoming milder next week, but possibly only for a brief period!

 

Can  you credit/provide the source for the image, please.

[No Balls Like Snow Balls]

Can  you credit/provide the source for the image, please.

https://twitter.com/WSI_EuroEnergy

[frosty ground]

GFS 06z Run is rather Wintry after day 10.......... A repeat of the pattern we are currently in now.

http://www.wetterzentrale.de/pics/Rtavn2401.gif
http://www.wetterzentrale.de/pics/Rtavn2881.gif
http://www.wetterzentrale.de/pics/Rtavn3361.gif