Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[TonyH]

Can't see raging Sw flow either looking out

[john mac]

Quiet on here this morning, may be everyone's actually waiting for the ensembles to come out before jumping the gun for a change!!! Lol still snow chances to come through the week!!

[shaky]

At least its not one of tbose weeks where we get snow and then it gets washed away straightaway! ! Whatever falls will stick and stay in place till sunday with temps freezing at surface!

[Captain Shortwave]

Considering the changes at anything post 4/5 days at the minute i find it hard to see how you can gain confidence from charts at t144 , "it's not if its when " has to be the most misleading post of the year I'm afraid . Yes the models have picked up an apparent eastward movement following Fridays low but given its 5 days away I'm not worried just yet, remeber the models done this several days ago with regards to tue front , only to backtrack .

Particuarly given the MJO signal to keep things amplified , along with the split vortex , and yes another warming looking more and more likely , with decent wave one coming in from about day 6 onwards which will only put more pressure on the vortex , then given all this , also with Tamara's excellent posts over the last few days on where we'r going moving forward , raging southwesterlies don't really tie in too well at all to be honest and rather than allowing one run of the models to make my mind up I think il continue to sit quietly and try to look at the bigger picture with regards to background drivers, il be very surprised if these charts verify . They may of picked up on a push , but as they normally do they'll most likely be over reacting to a signal , only to fall back in line over the coming few days .

Where was the bit where I said raging south westerlies???

Next weekend still looks pretty cold still under a polar maritime influence so it will only be until next week when temperatures will start to properly rise as the usual variation of TM and PM airmasses starts to begin.

Feel free to look at the rest of the post again to find it.......

I said a return to a near normal westerly based pattern which is well supported by the models and ensembles. This also is backed up by the views from other forecasters including the metoffice. There is no model output this morning which shows the Russian ridge putting up a significant a fight to repel the westerlies coming in at the end of this week. 

Edited January 19, 2015 by Captain shortwave

[Jason M]

I think these SWesters will verify briefly.

That said, I suspect they will be very short lived. It's probably no bad thing that the current set up breaks down as the extension West of the Russian high is probably a road to nowhere anyway as it would just be gloom fest . The upper air profile to our southeast is not supportive of anything truly wintry and that's where we would be sourcing the air from.

Even now some of the GEFS are wanting to quickly amplify things post breakdown. There is always the risk that any zonal pattern will overstay it's welcome but that risk is lower now than after christmas. Personally I'd rather roll the dice again than lose 10 more days stuck under a badly aligned ridge.

Edited January 19, 2015 by Jason M

[Severe Siberian icy blast]

Where was the bit where I said raging south westerlies???

Feel free to look at the rest of the post again to find it.......

I said a return to a near normal westerly based pattern which is well supported by the models and ensembles. This also is backed up by the views from other forecasters including the metoffice. There is no model output this morning which shows the Russian ridge putting up a significant a fight to repel the westerlies coming in at the end of this week.

What the met have said or at least Ian himself on hear , is to be cautious of any quick return to the atlanitc , there's so many uncertainties going forward , and he said they expect to see a return to westerly mobility in the 10-15 day range , which sounds a resonable assessment , I'm not saying it won't happen , I'm saying we see time and time again the models pick up on something , only to drop it again , it was only 12 hours ago there was no real end in sight , now it's definately coming in 5 days ? Things will change again as they always do which is why I never take one run as an emotional rollercoaster like many do .

[mulzy]

ECM ensemble day 9 and day 10 charts...

 

 

 

Looks bog standard January synoptics for me.  Strong PV over Greenland and moderate Azores high = positive NAO.  Maybe the shallow troughing of Europe may help going forward but in my eyes these are poor charts and it could be a long way back to cold...

Edited January 19, 2015 by mulzy

[fergieweather]

What the met have said or at least Ian himself on hear , is to be cautious of any quick return to the atlanitc , there's so many uncertainties going forward , and he said they expect to see a return to westerly mobility in the 10-15 day range , which sounds a resonable assessment , I'm not saying it won't happen , I'm saying we see time and time again the models pick up on something , only to drop it again , it was only 12 hours ago there was no real end in sight , now it's definately coming in 5 days ? Things will change again as they always do which is why I never take one run as an emotional rollercoaster like many do .

Return to mobility is firmly expected through/post weekend. Transition period itself remains messy. I can only post non-current versions of certain analysis courtesy of UKMO agreement for explanatory/educational purposes, but previous DECIDER output for entropy shown here largely reflects latest version... example below from weekend shows clearly the lower confidence phase as we switch through blocking to mobility (note how MOGREPS was a tad earlier than EC at that stage), followed by good confidence/low entropy into period thereafter (i.e. little spread of lamb type, with flow diagnostics showing this as cyclonic westerly regime). Latest output v similar albeit a *bit* more uncertain into early Feb. So, we go with the mobile, westerly pattern as the primary likely broadscale outcome for trend period, with colder phases (v similar to much of winter thus far in many respects).

[IDO]

The ECM mean brings back the Atlantic a couple of days before the op:

 

 

 

There appears to be very little uncertainty within the models and I do not know why it would flip back. This cold spell just looks like a normal January spell and probably not a reaction to any strat warming or major pattern change, any heights were just wedges of surface highs, and I think we would expect more from even a minor SSW. The GEFS spread at D7 shows the ensembles are all in line:

 

 

 

 

 

 

 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY JANUARY 19TH 2015.

NEXT UPDATE TUESDAY JANUARY 20TH 2015 08:00

THE CURRENT GENERAL SITUATION A slack and cold airflow will persist today with a weakening occluded front approaching the West of the UK tonight and moving slowly East tomorrow, weakening further.

MODELS-2 WEEK HEADLINE Rather cold and unsettled with rain or snow in places. Frost at times. Perhaps becoming less cold with rain at times next week.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow flattening out over Europe later this week and beyond as the trough over the Med finally lifts out. We then have a more traditional Jet flow for the time of year just to the South of the UK and on across Germany in a more mobile Atlantic feed fuelled by Low pressure to the North of the UK.

GFS OPERATIONAL The GFS operational today shows a rather cold or cold eek this week with fronts moving in from the west and weakening and eventually collapsing as they move SE. Some rain, sleet or snow can be expected as they cross though amounts will generally be quite small. The process repeats at the end of the week before the milder Atlantic westerly winds break through briefly. Then further disrupting Low pressure moves SE over the UK with further rain and snow through the second week with temperatures generally maintained on the cold side of average for most.

THE GFS CONTROL The GFS control run is very similar in pattern with the cold weather generally ahnging on well into next week with this weeks disrupting troughs and Low pressure delivering occasional spells of rain or snow before a cold ridge at the weekend brings cold and frosty weather before the next batch of Low pressure slides SE next week with further rain and snow. The end of the run does show a more traditional Westerly flow setting in across the UK eventually.

THE GFS CLUSTERS The GFS Clusters today have sided with Low pressure lying to the North of the UK and NW Europe with rather chilly and unsettled Westerly airflow conditions by far the most likely position we will end up with in both 10 and 14 days with rain at times and hill snow in places.

UKMO UKMO this morning also shows troughs of Low pressure slipping SE across the UK midweek with a mix of rain and snow before a drier phase later in the week. Then the pattern repeats on Friday before milder atlantic winds look poised to cross most parts of the UK over the weekend with some rain at times across the North but still cold conditions for rather longer over the South.

THE FAX CHARTS The Fax Charts continue to illustrate a series of troughs edging slowly East across the UK with a mix of rain, sleet and snow for many at times. It also shows a repeating pattern of this towards the weekend.

GEM GEM today also keeps the theme of the other models in showing a week of disrupting troughs of Low pressure sliding away SE over and away from the UK with smoe rain and snow events for some as they go. It's trend does repeat the pattern at the end of the week but then goes the way of the other output in releasing milder Westerly winds to cross the UK from the Atlantic early next week following a ridge of High pressure over the weekend.

NAVGEM NAVGEM is rather less progressive in bringing in Atlantic Westerly winds at the end of it's output with pressure staying quite High towards the SE and SW winds blowing across the UK with attendant milder air for the North and West at least. A weakening toughs brings rain across the UK before the front bringing it weakens and slows across Southern Britain a week from now.

ECM ECM this morning too maintains a rather cold period this week as troughs of Low pressure run SE down across the UK midweek and again at the end of the week with a mix of rain, sleet and snow at times for some. Following the second push milder air affects the North over the weekend and this extends South to all areas under Westerly winds early next week with rain at times and nearer to average temperatures.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart is trending towards a flatter pattern as the trough to the East of the UK lifts out somewhat by 10 days time at the same time as moving further to the East. This allows a push of milder Westerly winds across the UK under Low pressure to the North and High to the SW with rain at times and nearer to average temperatures more likely though still cold enough for some wintry showers over Northern hills at times.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The main trend this morning is a firming up of the cold weather being released over next weekend with next week looking rather milder from all models with a return to westerly winds and rain at times for all.

MY THOUGHTS It seems this morning that the cold weather currently being experienced by the whole UK will release it's grip from the West come the weekend for the North and in the South too early next week. In the meantine it's the pattern as before with disrupting troughs of Low pressure sliding SE down over and away from the UK with outbreaks of rain and snow affecting many parts at times through the working part of this week. Amounts of wintry precipitation doesn't look likely to be particularly bothersome on a nationwide scale although no doubt a few locations will do OK out of these troughs as they slide through. Frosts of course will be prevalent where skies clear overnight but temperatures should exceed freezing point almost everywhere by day. Then we look towards the weekend and next week to see a ridge of High pressure give some frosty and cold weather for many especially the South while the North and West gradually see a feed of less cold SW winds develop with rain at times and this is shown by most output to work it's way down into Southern Britain too by next week with temperatures returning to closer to average and some rain at times for many. The problem is that this has a high percentage likelihood of happening as we have received little help from High pressure to the NE which is too far away to hold back the Atlantic push expected next weekend. Our old friend the Azores High is also much too prominent to the SW and could of done being more displaced towards a location further West than is programmed as it continues to feed repeated pushes of warm air around it's Northern flank towards the UK next weekend. A ridge from the Azores High at the weekend across the South of the UK cuts off the path of depressions and fronts from feeding SE and instead sending them NE towards Scandinavia instead and returning milder WSW winds across the UK. So in summary this morning it looks like we have another 4-6 days of cold weather with some snow opportunities in places and frost at night before the inevitable slip into a more traditional mix of Westerly winds and rain at times returns next week.

[Kentish Snowman in Yorks]

I think these SWesters will verify briefly.

That said, I suspect they will be very short lived. It's probably no bad thing that the current set up breaks down as the extension West of the Russian high is probably a road to nowhere anyway as it would just be gloom fest . The upper air profile to our southeast is not supportive of anything truly wintry and that's where we would be sourcing the air from.

Even now some of the GEFS are wanting to quickly amplify things post breakdown. There is always the risk that any zonal pattern will overstay it's welcome but that risk is lower now than after christmas. Personally I'd rather roll the dice again than lose 10 more days stuck under a badly aligned ridge.

Regarding the post breakdown amplification, I believe that is the scenario that Tamara has been going for in her recent posts.

A diving South of the jet bringing Westerlies across the UK for a short period and then a more favourable pattern developing after that.

Having looked at the charts for the weekend this morning, I think it is more likely than not we will be in some kind of Westerly influence by then but I am not convinced it will ever turn truly 'mild' before a re-amplification of the pattern and further shots of PM air bringing colder conditions particularly the further north you are.

We may then be influenced by something more substantial from the North / North East if pressure remains low in Europe and the Azores high remains displaced, particularly if that Russian high does not get blown away.

Just my two penneth worth anyway...

[BLAST FROM THE PAST]

Well it looks like, as others have said, that the cold spell will last to the weekend, front clearing Friday and a brief ridge followed by the Atlantic at D8. Then from the current NH profile it looks like the PV over Siberia will drain back to our NW (NE Canada). It looks a slow process and the mobility does not really promote any chance of HLB'ing. By around the 2nd Feb the PV is re-organised, control and op:

 

gensnh-0-1-348 (1).png gfsnh-0-384 (12).png

 

What happens after then may determine the Feb flow. Of course that is based on this run and it may change. Has about 50% support from the ensembles, so by far the largest cluster, but several more runs needed to see if it has spotted the next trend.

 

ECM and GEM also back to the Atlantic from around D8. All the models suggesting the Russian high is pushed back east after D8 so some sort of push west by that high now looks to have missed the boat.

 

So the main question is can some in the south get a spell of snow  this Wednesday? The London ensembles have been consistent around 40% for several runs, so there is still a chance for some in the south:

 

graphe6_0000_306_141___Londres (7).gif

 

(Note the op and control are the coldest runs Friday-Sunday with the majority bringing in the milder air on Sunday.)

 

According to the hi-res WRF the first front slows as it travels east and stalls by T50 and the second front catches it by T56:

 

nmmuk-1-56-0.png

 

So spine of the UK. Afterwards the satellite low gives the SE a chance of some snow:

 

nmmuk-2-61-0.png nmmuk-1-61-0.png

 

So promising 

Carol Kirkwood having none of it, total rain event for lowland UK.  Re the discussion or a return to weather from Atlantic to return over the weekend I think it will happen but also a return of HP building back later in Scandinavia as it axes and wanes BUT it won't be typical SW;ly flow as its the AZH nudgin in with LP to NNW BUT as Carol said...we won't be anywhere near tropical but no doubt for me a regime from the west to be more apparent.  An interesting feature pops up on the 00z but by then temps are too high.

 

 

Big change comes months end into Feb.  Anomalies for me showing the way ahead with AZH retrogressing and troughing moving down over us.  With having had the SSW [mini, full, half...whatever] I think this will be to do with a shifting of the PV.

 

BFTP   

Edited January 19, 2015 by BLAST FROM THE PAST

[Captain Shortwave]

What the met have said or at least Ian himself on hear , is to be cautious of any quick return to the atlanitc , there's so many uncertainties going forward , and he said they expect to see a return to westerly mobility in the 10-15 day range , which sounds a resonable assessment , I'm not saying it won't happen , I'm saying we see time and time again the models pick up on something , only to drop it again , it was only 12 hours ago there was no real end in sight , now it's definately coming in 5 days ? Things will change again as they always do which is why I never take one run as an emotional rollercoaster like many do .

Ultimately my take is based on the last 48 hours or so, plus experience that when the high sinks over to Russia, it doesn't usually come back. This is of course opposite to the surging Siberian highs we see which can lead to an easterly through the back door.

There is good agreement that a occluded front will push east on Friday which may give snow to some areas depending on how the front sheers and disrupts as it hits the cold air over the UK, ultimately all the models clear this front into the north sea with the Azores high ridging to some degree over the UK. At this point the jet can only run over the top and hence the next low will meet little or no resistance. From this point our next source of cold air will be more likely to come from the north or north west as low pressure pushes over the UK and into Europe.

Shown by the anomalies here

I would definitely favour a more mobile set up, but still scope for PM incursions to occur. As we head into February there are definitely signs of interesting develops as we head into February (possible SSW and the MJO coming into play again)

Ultimately for me the Russian highs only help now will be to allow more potent PM incursions and also its potential to put north towards the Arctic which of course would have its own implications, as opposed to seeing a prolonged easterly develop from it.

Edited January 19, 2015 by Captain shortwave

[Barking_Mad]

GFS charts show snow for much of West Yorkshire on Wednesday. BBC and Met Office show nothing but dark cloud on Wednesday. *shrugs*

[Hotspur62]

Good morning all.

 

First things first, the later outlook. All three models have a return to mild next weekend so whilst this may not be the case we should be open about it (edit, see Emotional Rollercoaster's post above which I've just seen: quite right). These are the respective T144 charts, so not exactly FI and note unanimity between GFS and UKMO, and almost identical ECM:

 

UKMO

 

GFS

 

ECM

 

 

Secondly, we've been hearing about westward progression of this low for some days now. Here's an example of how the upper air temps have moved significantly east: identical ECM charts from yesterday's 12z to the overnight 0z:

 

Yesterday

 

Today

 

 

So, for this coming week. I've never seen such a stand-off before between the BBC / Met Office (with whom I agree) and some on here / GFS / Steve. It shows how borderline this coming event is. The BBC forecasters are currently going for wintry mix, mainly sleet and rain for southern Britain whilst Steve's snow map and the GFS snow type charts are showing significant snowfall. What to make of this?

 

The reason I side with the current Exeter thinking on this remains the frontal attack line. Because the fronts are progressing west to east there is little or no extreme undercut. The first front would therefore most likely both fizzle out and drizzle out. By this time, without undercut, the 850 hPa temps and dew points are rising so that the second front pushes through, again straight west to east, as rain. The frontal attack west to east shows up on the latest Fax charts:

 

 

 

What we would have wanted to see is the centre of the low forced west, pulling the front into a 90 degree axis straddling from 270 to 90 degrees. This is the best snow scenario for southern Britain as exemplified in a channel low: the front pushes in hits the cold, easterly driven, air ahead leading to an easterly or north-easterly flow and huge undercut. The current set up is completely different with the frontal attack line axis almost running from 0 to 180 degrees as the fronts themselves push through from west to east. See below:

 

 

 

The best hope actually probably resides with the kink, which leads to an undercut, which you can see here on yesterday's fax chart and which Steve has occasionally mentioned. We await to see if this is still showing in today's update. I fear, to be frank, that it won't and that this is chasing phantoms, but there we go:

 

 

I'm not trying to be party pooper. The GFS still shows widespread snow. I think this is questionable and at the moment for the reasons above I think it's falling the wet side of the fence. I earnestly hope that's completely wrong.

This is exactly how I feel and mentioned that yesterday afternoon. This seems to be backed up by IF with return to zonality(coolish) by Saturday being the favourite. Howver,I don't think it will be especially mild, just slightly above average temps and then we may have a strat warming which appears to be commencing that could make the start of Feb interesting. However, nothing 100% yet(never is tbh with UK weather) and hope SM is right and for once Met Office is wrong(you have to say they have been consistently good this winter and big thanks to IF for his fantastic assessments so far this winter)

[winterof79]

Interesting further out in to Feb is this bad boy comes off that is toasty.

Meanwhile back at the ranch,a snowy week for some begins

 

100% better than last winter.

Edited January 19, 2015 by winterof79

[mushymanrob]

hmm.... well from a personal pov im quite happy with this, and the prospect of something mild for february is possible IF the azores high has a slight eastward shift.

looking like the chances of a deep freeze via a scandinavian high evolution is less likely this morning, but its not totally out the window. going off the above ecm charts, a ridge building between expected troughs might lead to something cold.

 

whilst the gfs...

 

demonstrates a possible route to a cold evolution , only on this run (00z) it doesnt materialise.

the next 2 weeks are imho the pivotal point in winter, if theres going to be a reasonable cold spell, it has to manifest within this timezone , or at least have the 'building blocks' in place. if however in two weeks time the atlantic zonal is established id suggest (based on experience) that a decent cold spell is unlikely. (but not impossible).

personally, id prefer a bartlett driven february but thats unlikely too.

the noaa 8-14 dayer suggests an upper flow from the northwest, so a cool mix of tm/pm air similar to early jan. so no deep freeze nor mild bartlett is likely IF this chart verifies' just average - ish winter weather.


 

[mushymanrob]

 

 

So, for this coming week. I've never seen such a stand-off before between the BBC / Met Office (with whom I agree) and some on here / GFS / Steve. It shows how borderline this coming event is. The BBC forecasters are currently going for wintry mix, mainly sleet and rain for southern Britain whilst Steve's snow map and the GFS snow type charts are showing significant snowfall. What to make of this?

 

 

hi west... (richard isnt it?)

given that the predictive charts are notoriously unreliable, maybe the met o / bbc are more likely to be accurate?

[frosty ground]

the noaa 8-14 dayer suggests an upper flow from the northwest, so a cool mix of tm/pm air similar to early jan. so no deep freeze nor mild bartlett is likely IF this chart verifies' just average - ish winter weather.

 

Pretty much how this cold spell started as well, while these charts are useful for a general theme they do not pick up features that can greatly;y effect our weather..... 

Looking at the ECM Mean, I believe only one day do the 850's get above 0 and the GEFS have a pretty constant north westerly theme to them.... distinctly average. 

i would say in 15 days time we will be late the beginning of another cold outbreak like the one we are in now. By the time this breaks down another will be on the charts.

hi west... (richard isnt it?)

given that the predictive charts are notoriously unreliable, maybe the met o / bbc are more likely to be accurate?

No doubt about it the Human forecasters will have a better handle on events tomorrow/Wednesday

[Frosty.]

My take on the week ahead is we have 3 bands of wintry ppn pushing east, the first is on tuesdsy, the second on Wednesday and the third is on Friday, 3 chances of snow, I think that's not bad considering the mostly dross we have endured so far this winter! there will probably be a lot of wet snow on hills in central and northern uk but even southern UK could have wet snow, especially on hills and frosty, icy nights all through this week.

[seaside 60]

I must admit that sometimes I do wonder.

For the last two days we have been looking at possible cold weather extending and becoming more established via most models.
Today the models change, whilst believing and understanding Ian F,s expert input in here, even the MO cannot always be right.

I have understood and learnt many different aspects and inputs from the more professional people on here,  in which my understanding has greatly increased since being here.

The bottom line is I have learnt that each model has the last few hours readings put in, this can in times of extra chaos in the atmosphere, can  well change today's output and more especially the next few days.

I expect that by the end of this week the outputs may well be totally different, because the starting data is likely to run a different course, mainly due to conditions changing across different parts of the world.

[Man With Beard]

I often champion the resilience of the Scandi High compared to model output, but the question is not whether it will fight westwards with time (happens more often than not) but whether it will correct westwards enough to be any use to us. Due to a minor upper trough over Norway at T72, I cannot now see it coming back far enough - in the short term (see below):

However, now it has appeared once, it may have another stab a bit later down the line - as is sometimes the case (February 2005 springs to mind) - but we're talking a couple of weeks down the line now.

 

Back to the present, a slight westwards correction on 06Z, whatever happens on the edges, the Midlands does not look like a good place to be driving around on Wednesday:

Edited January 19, 2015 by rjbw

[liam300]

Interesting further out in to Feb is this bad boy comes off that is toasty.

Meanwhile back at the ranch,a snowy week for some begins

 

100% better than last winter.

 

 

 

 

 

Why would that be?

Northern part still got snow, where as southern areas still had rain.

Edited January 19, 2015 by liam300

[bluearmy]

Why would that be?

Northern part still got snow, where as southern areas still had rain.

Was only really the Scottish mountains last winter

[Timmytour]

hi west... (richard isnt it?)

given that the predictive charts are notoriously unreliable, maybe the met o / bbc are more likely to be accurate?

To be fair Mushy, i think he did say he agrees with the met solution.

Very tricky for them because, not only is the track not pinned down, and there's a fine line between it being snow or rain/sleet, but the accumulations if it's rain would not be worthy of any sort of warning, while if it's snow it may well be worth warning for some disruption. Very tricky for them imo