Model output discussion 25th Jan onwards

[Jason M]

Some good posts in here this morning IMO

[nick sussex]

It's very much back to square one this morning apart from the UKMO which delays the energy from the PV over Siberia feeding its evil twin over in Canada.

 

The ECM loses the height rises near Svalbard and the GFS goes into a more December like zonal pattern. There is some positives coming out of the strat but you would never guess it by looking at the models today.

 

Overall the stalemate continues with troughing never likely to make much eastwards progress past the UK, unless the trop responds quickly to the signals from the strat than I'm afraid we can rule out anything wintry for the next two weeks.

 

We can just hope that there will be a quick response because the strat info is really not correlating with what we're seeing in the trop.

[Gibby]

Good morning. Here is the report on the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Thursday January 30th 2014 taken from Midsomer Norton and Radstock Weather Website at http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

 

All models show a quiet day today as the remains of the early week Low remain close to SE England. Through tonight and tomorrow a very active depression deepens over the Atlantic and spins it's way up towards N Scotland by Saturday with a series of active fronts crossing East and NE over the UK with spells of heavy rain as a result. Showers will follow, heavy, thundery and wintry over the hills and will affect mostly Southern and Western areas while some NE areas become drier. At the end of the weekend a new area of Low pressure begins to move up towards the SW with more heavy rain and strong winds developing by Monday morning. After a chilly day today temperatures will recover somewhat over the weekend.

 

GFS shows the remainder of it's run with incessant strong winds from between South and West and depression after depression moving across the Atlantic towards the NW of the UK with their attendant troughs crossing all areas, repeatedly bringing spells of rain and strong winds followed by showers throughout the period and with temperatures close to or above average at times.

 

The GFS Ensembles maintain a mild and unsettled view this morning with total Atlantic domination shown by all members throughout the period. From this one can expect plenty more rain events over the period with strong winds from between South and West and very little in the way of reliably dry weather lasting more than a day or so.

 

UKMO closes it's run with Low pressure out to the NW and West of the British Isles with SW winds pumping spells of rain and showers NE across the UK on Wednesday with further troughs looking poised to affect the UK later in the week.

 

GEM looks much the same with Low pressure out to the NW with frequent bands of rain spreading NE across all areas with some regularity. Winds will be strong at times too but being from the SW temperatures will hold well up to average and possibly above at times.

 

NAVGEM also shows Low pressure to the NW with secondary Low pressure areas moving frequently NE across the UK with spells of rain and showers in very average temperatures for early February.

 

ECM also shows very unsettled conditions with periods of rain across all areas at times as further Low pressure areas spin up towards the NW of Britain with temperatures close to the seasonal average and possibly above later.

 

The ECM 9 and 10 Day Mean Charts show the likelihood of very unsettled conditions persisting across the UK with a high chance of a deep Low pressure area to the NW of Britain likely to be in total control of our weather with attendant rain and showers continuing to affect all areas of Britain at times, probably still heaviest towards the South and West. The second trend is that it looks like with rising pressure over SE Europe the SW flow will become rather mild for early February.

 

http://www.wetterzentrale.de/pics/Reem2161.gif

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

 

The GFS Jet Stream Forecast continues to flow strongly West to East just to the South of the UK before the trend is then for the flow to tilt more SW to NE across the UK towards Scandinavia in Week 2.

 

In Summary today all models continue to show an unrelenting run of Atlantic domination as Low pressure after Low pressure is programmed to steam across the Atlantic towards NW Britain powered by a strong Jet flow close to Southern Britain next week. Later in the period pressure does show signs of rising towards the SE of Europe which would pump ever milder air NE over the UK with little relief from wind and rain as further Low pressure up to the NW steers further troughs NE across the UK. There is an almost zero chance of anything remotely cold showing up anywhere over the British Isles within the forecast period given the output this morning and that includes the ensembles. Environment Agencies and authorities looking for a dry spell will not like my report this morning as there seems little relief from events from the sky undoing any good that is being done at the surface in the flood stricken part of our County.

[Severe Siberian icy blast]

It's very much back to square one this morning apart from the UKMO which delays the energy from the PV over Siberia feeding its evil twin over in Canada. The ECM loses the height rises near Svalbard and the GFS goes into a more December like zonal pattern. There is some positives coming out of the strat but you would never guess it by looking at the models today. Overall the stalemate continues with troughing never likely to make much eastwards progress past the UK, unless the trop responds quickly to the signals from the strat than I'm afraid we can rule out anything wintry for the next two weeks. We can just hope that there will be a quick response because the strat info is really not correlating with what we're seeing in the trop.

Lol iv literally just asked the question in the strat thread. With strong wave 2 in the near time that looks like verifying for once things look by far the best they have all season. Il be extremely surprised if we dont see a flip in the output in the next 5 days or so. Its really the best news yet as far as the strats concerned. I recognise its frustrating for people all this strat talk an nothing happening but the current split we have is as a result of the strat activity and we just missed out but Europe has been freezing as a result. So I get the feeling we may well be about to see the retrograde number 3 tamara has mentioned. If we can get a decent split from the activity the past 3 wks then this one coming up may well be a final goodbye from the vortex once we get the next week out the way. That leaves a good 4/5 weeks opportunity of cold and snowy weather to make its presence shown.

[offerman]

The latest GFS still offering no respite for places such as Somerset next weekend...

But there are differences in the mode of delivery with apparently a little less progression...

18z (6am)

 

0z (six hours earlier)

 

 

Hi Timmy,

 

I live in Somerset and yes is been pretty soaking so far since about Start November really and quite windy at times to.

 

Thanks for your concern.

[Duane S.]

The D10 mean (from the bottom of the troposphere to the top of the stratosphere) zonal wind chart shoud give us great hope.

 

The ECM op run, for example, shows an incredible wholescale transfer of energy from Siberia to Greenland. No split, very unfavourable for us. Yes, possibly it is one viable option but also possibly the worst case scenario amongst many far better ones.

 

I'm of the mind that the trop models are going to be all over the place from raging zonal to perfect blocking in the coming days. ..

 

[Summer Sun]

Out to Feb 15th its the west and south west which continues to take the brunt of the rain with another 40mm to 80mm possible by next Friday (7th)

 

[Frosty.]

Round 2?

Yes it's round 2, the first round of persistent stormy weather lasted about 8 weeks, then we have had a bit of respite from the storm force winds in recent times with a few frosts and brighter days but not really any break from the rain, but the weather is going rapidly downhill tonight and tomorrow with the stormiest spell for a wee while with the flooding problems becoming even bigger and damaging wind gusts. Low pressure then becomes anchored to the northwest of the uk with more lows spawning along the PFJ for probably weeks to come.

[somersetsnow]

I know it's a bit of a daft question but can the models get it wrong? and has there been a time when they were churning out,say mild for the foreseeable future  and then complete opposite happens all of a sudden? I know it's a bit of a Pink and Fluffy question from Deepest Darkest Somerset but if you don't  ask, you will never know. Sorry if this is the wrong place to post.  Lurker and learner

[snowmadchrisuk]

Increasing chance of some Snow into the South West Friday night / Saturday morning , going by the latest few GFS runs, -5 850's with a pocket of 528 dam air over us and some heavy PPN . Be nice to see some Snow falling even if it only is brief 

 

 

 

 

[Iceni]

Yes, during January 1937 there was a lot of blocking to the east of the UK, and a huge cyclonic block to the west of the UK, and there was no trough disruption to allow the block to the east to influence the UK, until it finally came together for a few days at the end of the month.  February that year wasn't anything to write home about but it did have a good cold March to follow on.

 

Typical, a block to the east doesen't guarantee cold for the UK, but neither does zonality guarantee mild, it is only its orientation that does:

 

http://www.wetterzentrale.de/pics/archive/ra/1984/Rrea00119840116.gif

http://www.wetterzentrale.de/pics/archive/ra/1984/Rrea00119840124.gif

 

That sort of zonality is a model watcher's dream, and among the best setups for the UK, and quite often including this month north Scotland have done OK, whereas anywhere south of Scotland at least this month has been just bile and a pile of pants.

 

 

Could someone please provide me with a recent example of a Scandi high which produced sustained cold - it was a Greenland hps which gave us December 2010 - right? Unless there's next to no jet stream and the polar vortex is over Alaska, I don't see the point of drooling over Siberian/Scandinavian highs.... they're rubbish, I thought so a week ago and this has confirmed my opinion of them.

 

Every single one of them has failed to deliver ever since I've had the time to take an interest in the chaotic system which is our weather. Greenland highs are a different matter.

 

And why do we imagine we can model weather 10 days in advance? We were supposed to be having our first bite of winter today according to the models 10 days ago.

[nick sussex]

I know it's a bit of a daft question but can the models get it wrong? and has there been a time when they were churning out,say mild for the foreseeable future  and then complete opposite happens all of a sudden? I know it's a bit of a Pink and Fluffy question from Deepest Darkest Somerset but if you don't  ask, you will never know. Sorry if this is the wrong place to post.  Lurker and learner

The models often get it wrong especially with colder patterns shown past T168hrs, in terms of mild suddenly switching well generally that normally only happens when theres a background signal that is poorly modelled at later timeframes and we see that generally with events higher up in the stratosphere. What happens in that instance if lets say you get a reversal of the normal west east flow in a layer of the strat this can send the models quickly to a colder solution.

 

At the moment if you're looking for colder weather our last hope before February ends is for events in the strat to deliver a quick change to the NH pattern.

[somersetsnow]

The models often get it wrong especially with colder patterns shown past T168hrs, in terms of mild suddenly switching well generally that normally only happens when theres a background signal that is poorly modelled at later timeframes and we see that generally with events higher up in the stratosphere. What happens in that instance if lets say you get a reversal of the normal west east flow in a layer of the strat this can send the models quickly to a colder solution.

 

At the moment if you're looking for colder weather our last hope before February ends is for events in the strat to deliver a quick change to the NH pattern.

Thank you for your answer. Know we won't get Cold,just one of those things i've wanted to know.

[swfc]

Pretty dire mo this morning so far and the gfs 6z is actually worse in fi!!!Really fear for the current areas suffering floods atm.Tbh just some dry bright weather would be welcome now on the run up to spring

[BLAST FROM THE PAST]

I know it's a bit of a daft question but can the models get it wrong? and has there been a time when they were churning out,say mild for the foreseeable future  and then complete opposite happens all of a sudden? I know it's a bit of a Pink and Fluffy question from Deepest Darkest Somerset but if you don't  ask, you will never know. Sorry if this is the wrong place to post.  Lurker and learner

They can and have been wrong, but unfortunately this winter its been the undercut and cold block backing west which has failed and failed.  The signals from all types at present, models, strat and us alternatives is 'as you were' and confidence in that is probably higher than in past due to advancements in all.  Get your sand bags ready, it aint going to be pretty for a week or so.  I am still erring on the side for a pressure rise to our southern quadrant down the line, but like the block to our E/NE it may not be influential enough.

 

regards

 

BFTP

Edited January 30, 2014 by BLAST FROM THE PAST

[Mucka]

Looks flat and zonal to our West to the end of time on the output this morning but then the models often show that once they have decided on breaking down a block and a pattern change - it is like default position or reset and then they settle down and begin to sniff the next pattern change.

That is a little abstract and not very scientific but then knowledge gained through experience is by its nature a difficult thing to quantify.

 

The only model we get to see past day 10 is GFS and unfortunately that just happens to be the model that is most progressive so we can't take too much from the fact the operational output is flat zonal at T384. Its ensembles are of better use for picking out possible pattern changes but unfortunately there is no signal there for a more amplified pattern to develop either.

Still, with my first paragraph in mind I expect to see this change over the course of the next day or two's output and it won't be a signal that creeps in at 384h it will be more like 264h if anything develops.

I think ECM may be the same this evening or it may just show some more amplification to our West, the beginnings of an Atlantic ridge.

I do expect the pattern to become more amplified in around 9/10 days time in the Atlantic and the models to slowly pick up on this over the next day or two as the PV begins to move East with a possible trough setting up in Scandinavia eventually (deep FI 10 days +) so we could potentially be looking at height rises toward Greenland before we get to mid February.

This will be the last chance for Winter proper and of course I am hope-casting somewhat. If I was looking for mild in those sort of ranges I could find a case for a blowtorch Southwesterly setting up - it would be a similar synoptic at first but with a ridge toppling over the UK and into Europe with the jet aligned SW/NE over the top. 

 

Point being another pattern change is more probable than what the raw output currently shows even though that may not be a significant wintry spell - even so we are doomed to more winds and rain for foreseeable I'm afraid.

[Mucka]

Same here in Birmingham - thought the models were predicting rain so a nice surprise. 

 

No snow forecast on the Euro4 certainly. Here is the 06z output.

 

[Barking_Mad]

Snow forecast at low levels on Saturday.

 

 

Edited January 30, 2014 by Barking_Mad

[Newberryone]

Looks like these very tightly packed isobars could impact hard on our shores overnight Friday into Saturday. 

Just my look too that I'll be cycling to work during the small hours  

 

Wish me luck!

 

[snowflakey]

 

Looks like the jet wants to dive south

[snowmadchrisuk]

Snow Signal for the SW continuing to grow for Saturday morning , Euro 4 High res has it showing up now as well ...... Wonder what the Meto think

 

[SnowBallz]

I know it's a bit of a daft question but can the models get it wrong? and has there been a time when they were churning out,say mild for the foreseeable future  and then complete opposite happens all of a sudden? I know it's a bit of a Pink and Fluffy question from Deepest Darkest Somerset but if you don't  ask, you will never know. Sorry if this is the wrong place to post.  Lurker and learner

 

Hi,

 

Firstly, it's not a daft question at all - it's a perfectly reasonable one to ask.  The broad answer is 'yes', NWP does indeed get things wrong; indeed, sometimes very wrong.  NWP models - especially those that are stochastic in origin - are highly sensitive and susceptible to variance, the degree to which will depend largely on the integrity of the initialisation data (the 200m odd daily readings that feed into them)  If there are ghost areas of data - and this does happen, albeit not often - then you will often see a fairly dramatic consequential effect.  To counteract that, many variables are parameterised during assimilation and, where required, smoothed-out through applied algorithms (winsoring, outlier factoring)  This essentially 'cleanses' the data, pre-processing; not a perfect option by any means, but nevertheless it calms erroneous signals.

 

You may have heard about the ensemble approach?  This is where small degrees of variance is intentionally introduced to the initialisation data, in order to grow forecast depth.  You can then analyse that depth to ascertain degrees of confidence in the operational forecast.  The ensemble approach has probably been the biggest forward step over the last few years, and that's only really been possible with acceleration of supercomputing power; it takes an incredibly long time to generate forecasts, so you need a LOT of computing power to produce one, let alone an ensemble suite.

 

In terms of model skill (ie: how accurate are they?) there's been a fairly linear growth, as more powerful supercomputing becomes available. In real terms, the 96hrs forecast is - today - as accurate as the 24hr one, 30 years ago; so, a four-fold increase in skill.  Further advancement of skill comes from better understanding of atmospheric science and modelling and translating the effects back the models.  This is a continual area of research, and where - for example - there's been an up-tick in understanding of the stratospheric~tropospheric relationship.  In addition, ever greater data density (so, more observations / sensors) will only ever be of help to models that rely so heavily on data.

 

There's a few graphs here to show how accurate the forecast are; the final one depicting the linear growth in skill, over the last 30 years.

 

Hope that helps?

 

SB

[snowflakey]

Quite uninteresting 850 GEFS this morning with low confidence and nothing to extreme temp wise.

 

 

[Tamara]

Returning to my stratospheric/tropospheric cake analogy of fairly recently, the very simplistic way to look at the state of the NWP currently is represented as the continual shake-up of energies that are going on within the layers above our troposphere and as a reaction to the mid levels of the stratosphere recently returning to very cold levels. This reaction is the one to follow the recent split in the vortex and why we see the programmed re-organisation and reinforcement of energy back across the pole and why the Canadian vortex is dining out further on a late winter extra meal. As if it hasn't been spoiled enough...

 

As sequential warming and wave activities continue with some quite impressive wave 2 activity programmed (as detailed and discussed on the other thread) then we should surely anticipate the flushing of these cold mid level anomalies to the surface and this is bound to energise the jet stream across the atlantic in line with all the deeply cold air stateside and keep the atlantic pattern recalcitrant and uncoperative to our wishes for the foresseable, in line with the entrenched upper trough.

 

It is no surprise to see the current models intensifying the westerly pattern once more and why the charts on offer in the models atm are even more unenchanting and charmless. It is on this basis that with all the renewed energy of westerlies pushed into the troposphere, for the reasons given, that it isn't hard to see the model and ensemble suggestions to sink the Russian High SE into Europe with the jet stream going across the top of it.

 

Thats most of the negative stuff out of the way...well mostly anyway.

 

Is the sinking of the Russian High necesarily a bad thing though in the longer term?  As said in recent days, other background factors (dare I use that term again ) are more favourable with the Azores High repressed, amplification sitting upstream but the atlantic sector pattern in our locale sitting on this interminable log jam with nowhere west or east to go as the upper trough to the NW rules the show. 

 

The flushing of cold westerly zonal wind anomalies into the troposphere in tandem with wave 2 activity occuring could well represent the chance for the Canadian votex to be relocated finally across to Siberia in the longer term, and the flat strong jet process and sceuro ridge is simply a further unpalatable transition to this as that burst of energy crosses the pole. With the vortex ejected eastwards by the wave activity, then the upstream amplification can get to work, dramatically improve the atlantic pattern and cold air be pushed south. All of these possibilities though are still of course some way off in time.

 

A little tongue in cheek of course here  - but I think perhaps a little reverse psychology in the last few days from some of us might start to work *eventually*as very latest stratospheric data starts to look more hopeful once again. However, and a large *however* caveat here - we need to see consistency in this for a while and, notwithstanding my speculation above (albeit hopefully laced with a tentative splash of logic) we also need to be cautious about any tropospheric reaction speeds to all this. Hence in my own opinion don't expect too many changes for the foreseeable future in terms of the Canadian blob especially while all this energy transport is going on from one side of the pole to another, as detailed in recent days.

 

Maybe the latest signals offer a way out in the longer term - the question remains how long will it take, and as stated the other day, is it enough yet to do the job and arrive before the days have drawn out too much

 

We certainly best expect nothing in the next 10 to 15 days or so anyway - so we are looking to be at least at mid February by this time. In the meantime its 'as you were' for both us and those ducks

Edited January 30, 2014 by Tamara תָּמָר

[Severe Siberian icy blast]

jetstream.png

 

Looks like the jet wants to dive south

To me this is key to where we go next week to 10 days. I expect wave 2 activity next week will show it's hand more in the trop response. Jet diving south. Big scandi high to force westwards and the mighty canadian vortex weaken . Easy right?!!