Winter Model Output Discussion - 06Z 09/02/13 onwards

[Mucka]

For those that don't trust the GFS 06z.

Forget the exact synoptic it is throwing out. The pattern being backed West with more undercut and ridging toward Greenland has good support if you read between the lines.

It will show something different on its next run in FI but the only thing worth looking for beyond tomorrows rain or snow is for how far West we get the next low to slide, remember it was programmed to go over the top in most out until today. Also look for more energy to head under the block as it does.

ECM is not that dissimilar and now it also wants to force more and more energy under the block with the next system as does UKMO.

If this trend continues then we will see better agreement and more security in strong ridging toward Greenland thereafter.

It may be we don't get a Greenland high but we have a good chance a steep gradient and strong aligned SW/NE Atlantic ridge at least which with the likely synoptic at that time would still bring a good cold spell.

There will be big variations run to run but the trend is your friend and the trend this morning is toward cold.

The CFS is not worth our time IMO cold or mild.

Edited February 9, 2013 by Mucka

[johnholmes]

Sorry if this is off topic - not sure where else to post. As a real amateur just wondered what the Netweather forecasts ( 7 day/10 day) are based on - they seem to change so dramatically with each 6 hour whereas with the Metoffice forecast you can generally think that the next 24 hours is pretty much correct - for example hardly any snow for my region on the 4am run whereas by 10.00am snow everyday for almost the next 10 days.

I am still struggling with the models so rely on the forecast to know what is going on but I am just confused as to why such drastic changes occur on this particular forecast which are not showing on others.

Again sorry if off topic but would be grateful for your thoughts.

Essentially, with modifications from Net Wx Towers it uses GFS outputs so if GFS changes so does the model Net Wx forecast?

hope that explains things

[johnholmes]

how about after reading this giving it a try?

assessment of prob snow for sun-sat 9 feb.pdf

done in great haste so apologies if any technical errors!

Edited February 9, 2013 by johnholmes

[AWD]

how about after reading this giving it a try?

assessment of prob snow for sun-sat 9 feb.pdf

done in great haste so apologies if any technical errors!

Things have moved on over your lifetime hey John?

:p

[SnowBallz]

For those that don't trust the GFS 06z.

Forget the exact synoptic it is throwing out. The pattern being backed West with more undercut and ridging toward Greenland has good support if you read between the lines.

It will show something different on its next run in FI but the only thing worth looking for beyond tomorrows rain or snow is for how far West we get the next low to slide, remember it was programmed to go over the top in most out until today. Also look for more energy to head under the block as it does.

ECM is not that dissimilar and now it also wants to force more and more energy under the block with the next system as does UKMO.

If this trend continues then we will see better agreement and more security in strong ridging toward Greenland thereafter.

It may be we don't get a Greenland high but we have a good chance a steep gradient and strong aligned SW/NE Atlantic ridge at least which with the likely synoptic at that time would still bring a good cold spell.

There will be big variations run to run but the trend is your friend and the trend this morning is toward cold.

The CFS is not worth our time IMO cold or mild.

Disagree 100%.

I posted yesterday, that the CFS was the first model to advertise - with conviction - the broad blocked pattern that we're currently experiencing, and long before any other model. The detail is different - which is to be expected - but, importantly, it remained resolute as to a blocked pattern forming. The next model to pick up the pattern was BOM-ACCESS.

The CFS has been very consistent with regards to its prognosis for March. Now, as I posted about a while back, consistency isn't necessarily accuracy, but it certainly demands more than cursory dismissal. Usually, the CFS displays huge intra-run variance - as one would come to expect from a LR NWP model, but it's noticeable how this has very much been lacking, in favour of this consistent signal.

[Iceni]

Things have moved on over your lifetime hey John?

What they call a 'Nowcast' on here

[Tim Bland]

Whilst its quiet others I thought I'd mention that the met office further outlook; it's ramped up a gear this morning esp with the longer range into march. Now sounding more confident about colder weather and increased risk of "wintry precipitation"

What's people's views on the from coming in in Weds? Reading on twitter about how it will give the whole of the UK snow as it undercuts, I'm struggling to see this on the NWP models at the moment ? I can obviously see rain preceded by snow but can't see it undercutting ?

[Jax]

Disagree 100%.

I posted yesterday, that the CFS was the first model to advertise - with conviction - the broad blocked pattern that we're currently experiencing, and long before any other model. The detail is different - which is to be expected - but, importantly, it remained resolute as to a blocked pattern forming. The next model to pick up the pattern was BOM-ACCESS.

The CFS has been very consistent with regards to its prognosis for March. Now, as I posted about a while back, consistency isn't necessarily accuracy, but it certainly demands more than cursory dismissal. Usually, the CFS displays huge intra-run variance - as one would come to expect from a LR NWP model, but it's noticeable how this has very much been lacking, in favour of this consistent signal.

Have to agree (that you disagree), all models need to be taken into consideration, they all have good and bad points, but it is seeing patterns and discerning the data from the noise that matters.

Be interesting to see the later run output(s) when compared to current runs.

[Mucka]

Disagree 100%.

I posted yesterday, that the CFS was the first model to advertise - with conviction - the broad blocked pattern that we're currently experiencing, and long before any other model. The detail is different - which is to be expected - but, importantly, it remained resolute as to a blocked pattern forming. The next model to pick up the pattern was BOM-ACCESS.

The CFS has been very consistent with regards to its prognosis for March. Now, as I posted about a while back, consistency isn't necessarily accuracy, but it certainly demands more than cursory dismissal. Usually, the CFS displays huge intra-run variance - as one would come to expect from a LR NWP model, but it's noticeable how this has very much been lacking, in favour of this consistent signal.

So you don't really disagree 100% do you? Unless you are saying it is consistent and reliable but you seem to be saying the opposite.

I get your point though that it is worth taking more note of if it consistently showing the same high anomalies but since it often deviates broadly with much higher res models by day 8 and we have pressure anomaly charts I personally don't find it much use for forecasting pattern changes.

I have no idea how March will pan out, though I said Feb and March would be Easterly dominated and the coldest months compared with their average of the winter/spring but I also thought december would see more blocking to the West and NW in my winter forecast, I am talking about the second half of Feb.

Edited February 9, 2013 by Mucka

[IanM]

I was going to walk the dogs this afternoon, but seem to be spending my time deleting posts and tidying up the posts that comment on the deleted posts.

If someone posts something odd/off topic/in huge font/abusive/not model related, could we try to resist commenting in the thread please? I will be grateful, my dogs will thank you and this thread will steer back towards what it is designed to be.

Thanks

Ian, Buddy and Pepper

[nick sussex]

Whilst its quiet others I thought I'd mention that the met office further outlook; it's ramped up a gear this morning esp with the longer range into march. Now sounding more confident about colder weather and increased risk of "wintry precipitation"

What's people's views on the from coming in in Weds? Reading on twitter about how it will give the whole of the UK snow as it undercuts, I'm struggling to see this on the NWP models at the moment ? I can obviously see rain preceded by snow but can't see it undercutting ?

Judging by the UKMO update they're not buying even the chance of the GFS 06hrs trend, the UKMO 00hrs was very flat and they seem to be thinking more along those lines.

To get an all snow event you'd need to see something like the GFS 06hrs run with more amplification at the key timeframe. Of course the latest UKMO may be more amplified when it comes out, we'll know shortly.

[cooling climate]

The latest NAE's run is out and looks promising for the many eastern and southeastern

parts of the country for tomorrow and monday.

Not at all surprised by what the 06Z is showing as I mentioned a couple of days ago

to expect trough disruption and a continued easterly flow but uncertain as to how

cold the uppers would be.Heights becoming established over Greenland was always on

the cards with the downwelling of the second phase of the SSW but that it would occur

later in the month which the 06z run is showing.

Pretty good longer term outlook from the Meto as well today.

[Mucka]

Judging by the UKMO update they're not buying even the chance of the GFS 06hrs trend, the UKMO 00hrs was very flat and they seem to be thinking more along those lines.

To get an all snow event you'd need to see something like the GFS 06hrs run with more amplification at the key timeframe. Of course the latest UKMO may be more amplified when it comes out, we'll know shortly.

UKMO looks flat at first glance but there is a lot of trough disruption on that 144 chart and pressure tot he North is better than it looks with all those blues.

I'm hoping the 12z will look pretty good.

NAE

Given that little circle of rain over NW England is over my house that could be fairly accurate.

Edited February 9, 2013 by Mucka

[snowking]

Incidentally, strong ENS support for the GFS 6z solution from the GEFS suite:

Only issue presently, as BA pointed out, is that no signs necessarily of a significant trough coming through scandinavia to give us a decent shot of cold into the 850mb level, though even 3-4 below will give us a decent shot of some marginal snow events from time to time:

The signal has been coming/going a little on various suites in the last few days for this in the mid range (and funnily enough in line with Fred/Roger's thoughts), but I am personally most encouraged by the growing signal towards day 10 from the ECM EPS mean:

That is a very strong anomaly for a day 10 mean consisting of 51 individual runs!

0z GEM and GFS suites still keen on a negative NAO/AO combination:

SK

[Tim Bland]

Into tommorow night central southern areas look like getting the heaviest precip / snow accumulations with over 10cm

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=42&ARCHIV=0&ZOOM=0&PERIOD=&WMO=

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=weas&HH=45&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

[-uksnow-]

Ok just before the 12z comes out, here is my interpretation for anyone not sure what to look for (if they are looking for cold that is) -

As shown by the 06z this coming wednesday is the key time period, we are looking for a clean separation of energy from the negatively tilted low out west

Seen here for wednesday evening:

And now for 24hrs later

Clean break away with a ridge of high pressure building vertically behind it, allowing for heights to build of Russia/Scandinavia

Rolled on 24 hours again to Friday @ 7pm

An easterly of sort, not a strong one but the block is there and now energy is heading underneath it

Sunday 1am - Block is retrogressing towards Greenland

Right - lets see if the 12z can carry this on!

-eded-

[johnholmes]

life videos from New York

http://www.earthcam.com/usa/newyork/timessquare/?cam=streaming&cam_type=streaming

[Supercell 89]

The models still showing a South-West correction for tomorrow's event, looking good for Central Southern parts of England for some heavy snow late on Sunday into Monday.

Looking further ahead, could have another slider low during Wednesday so some interesting times ahead. Also even though the GFS has been pretty poor at times this winter it still does pick up pattern changes quicker than the other models, so the 06z may be onto something here, i seem to recall it showing something similar a couple of days back so it could be picking up with a new trend. Fingers Crossed

[Cheshire Freeze]

The models still showing a South-West correction for tomorrow's event, looking good for Central Southern parts of England for some heavy snow late on Sunday into Monday.

Looking further ahead, could have another slider low during Wednesday so some interesting times ahead. Also even though the GFS has been pretty poor at times this winter it still does pick up pattern changes quicker than the other models, so the 06z may be onto something here, i seem to recall it showing something similar a couple of days back so it could be picking up with a new trend. Fingers Crossed

No sw adjustment on 12z GFS. If anything the precipitation is pushed further NE and intensified over S Yorkshire area. Cheshire/Derbyshire S and W shows rain due to higher uppers/dews.

Alex Deakin has tweeted someone from NW thread to say cold and wet tomorrow with snow on hills. So for those further S I really wouldn't be getting hopes up.

Edited February 9, 2013 by CreweCold

[Tim Bland]

No sw adjustment on 12z GFS. If anything the precipitation is pushed further NE and intensified over S Yorkshire area. Cheshire/Derbyshire S and W shows rain due to higher uppers/dews

Yes but the ukmo has pushed it SW and almost no precip ever reaches Kent. http://www.meteociel.fr/modeles/ukmo2.php?nh=0&carte=1594&ech=6&archive=0

Various meto sources on twitter saying its giving them a real headache trying to pin down tommorow !

[bradymk]

John, doesn`t look bad in N.Y, i thought press said they had 3ft of snow??

Back to us the links from Tim don`t tie in with M.O warning area so who should we believe. It seems these types of setups change so fast that its just going to be a nowcast T.B.H

Boston was the 3ft, New york City has got off lightly compared to areas to the north of them. NAE 12z shows more widespread snow tomorrow night. Crucial period coming up on GFS, will it follow 6z or a completely different outcome once again?

[Cheshire Freeze]

John, doesn`t look bad in N.Y, i thought press said they had 3ft of snow??

Back to us the links from Tim don`t tie in with M.O warning area so who should we believe. It seems these types of setups change so fast that its just going to be a nowcast T.B.H

Indeed, forecasting nightmare. If the system deepens more than expected the precipitation will intensify and push further NE.

[Tamara]

There are incremental changes westwards so far on the 12z's across both GFS and UKMO for both the low tomorrow and also the early mid week period with the Scandinavian High pressure out to t60 to t72. These early changes become cumulative like a rolling snowball over time, and will affect the evolution down the line when we get to the latter part of the week and the atlantic low, and what happens with it. On that basis worth staying open minded, irrespective of what this evenings models show in the medium to longer range

This to me at t72 looks better than for the t96 period suggested (for the same time) yesterday

And in turn this shows more inclination to trough disruption than this morning, whatever the UKMO goes onto show at t120. Baby steps and all that

Edited February 9, 2013 by Tamara Road

[Tim Bland]

Yep hence the bit about NW thread and about areas south of it not getting hopes up. Would have thought it fairly obvious what/where I was referring to!

Point is most models have the cold air boundary in a line from kent northwestwards. Areas such as NW and Ireland are in the milder air hence more marginal

[Methuselah]

And, the models are saying what?