Model Output Discussion

[nick sussex]

Please could you let me know where to access these NAE charts, so I can access them and see previous and later charts?

Many Thanks, TS.

Here you go.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=201002201200&VAR=prty&HH=6&ARCHIV=0&PANEL=0&ZOOM=0

Edited February 20, 2010 by nick sussex

[MR EXTREMES]

Am I missing something??

The way your going on, your taking one gfs run as gospel lmao!

well take a little time to filter through 3 days or more of posts and then come back and tell me why ive stated my opion which i might add are as valued as any.

ive said cold snowy the futher north you are until mid week when things look as though there going to becaome more average with wet and windy spells of weather.

and thats been the trend for the last few days or more but its looking like a slow evolution.

Edited February 20, 2010 by badboy657

[andymusic]

According to the NAE the 12Z GFS is wrong at +48. This makes the rest of the run pointless IMO.

Sunday/Monday looks very good especially for the Midlands.

http://expert.weathe...022212_2012.gif

the annoying thing is - the NAE got today's snow over wales wrong and the GFS was right with no snow

I hope the NAE is right this time and not the GFS - the meto have no warnings out - so mmmmmmmmmmmm!

[TEITS]

thats a very confusing chart infact that would give snow on the southcoast but i for one think thats not a good chart for us id ignore that other than futher north.

The PPN the NAE is showing for today isn't what it seems. This may look like widespread snow but its actually indicating scattered wintry showers.

Edited February 20, 2010 by THE EYE IN THE SKY

[Harsh Climate]

the annoying thing is - the NAE got today's snow over wales wrong and the GFS was right with no snow

I hope the NAE is right this time and not the GFS - the meto have no warnings out - so mmmmmmmmmmmm!

I dont really rate the NAE, I prefer to flick between ukmo and gfs precipitation using own disgretion

[snowking]

the annoying thing is - the NAE got today's snow over wales wrong and the GFS was right with no snow

I hope the NAE is right this time and not the GFS - the meto have no warnings out - so mmmmmmmmmmmm!

Yep agreed

Whilst i suspect met office warnings were largely removed on the proviso that the 6z NAE had effectively removed the snow risk for monday, it only serves to highlight the volatile nature of the models at present, and I don't think we can particularly say with any certainty which model has something nailed even at the 48 hour time frame.

As I said over on the SW thread just now, 24 hours at a push looks to be the current range of interest with any certainty, such is the marginality involved

SK

[TEITS]

the annoying thing is - the NAE got today's snow over wales wrong and the GFS was right with no snow

I hope the NAE is right this time and not the GFS - the meto have no warnings out - so mmmmmmmmmmmm!

Sorry as I just said in my previous post the NAE wasn't wrong. If you had clicked on the precip accumlations you would of noted 0. The reason for the pinks is suggesting scattered light wintry showers and if you check the radar thats exactly what we have.

When viewing the NAE you really need to check the precip accumlations. During Thurs the NAE was suggesting around 9mm of precip and I recieved 7cm of snow which is about right taking into account the snow ratio.

[Cheese Rice]

I agree.. I think this long cold spell is finally coming to an end. I can't wait for some milder conditions, even if it is just average!

Based on one run? The last lot of runs have been snowy so I can't really see anything mild in the near future even if the GFS for this run has flipped to a different idea.

[andymusic]

Gonna need a few more runs before I'm convinced

[kent]

Going by the increasingly likelyhood of milder conditions on our doorstep so to speak its just as well snow isnt forecast here, it probably would have melted by the next day.

[Mole]

UK meto Model 12 h run not keen on any spring like weather.Looks like the gfs has gone off on one of its odd runs again.

,

[Severe Siberian icy blast]

Just a word of caution ,

The models are changing from run to run significantly , so just like last night when the 18z came out we knew changes would take place , we can be sure that the new ones will also , 100miles makes a lot of difference to our weather and we know that anythin past tommorrows weather its set to change , it happened mid wk regarding the wet snow on wed just 12hrs before , so things can change very quickly, to sum up. . .

Next wk is full of potential, not saying all will see significant snow , im saying these evolutions have delivered in the past , and once low pressure gets a track you oftern find due to currents in the ocean etc that other fronts follow the same trend, the beauty of the human input is we have the power of reason to help reason things out and look at things objectively , which any meterologist will take into consideration before giving a forecast ,

I really cant see the lows making there way up the country and into scotland , the channel lows never do that and the northern limit is usually the midlands/sheffield/stoke .

Time will tell.

[TEITS]

Gonna need a few more runs before I'm convinced

Based on the UKMO/NAE I feel Wales is going to miss Mondays possible snow event.

Looking at the surface pressure charts at +48 and I reckon the exit point of the LP will be roughly around Norfolk/Suffolk. This means only extreme SE parts of Wales, SW midlands to the Wash will see snowfall as the NAE suggests. This is actually very similiar to the snowfall on Thurs because the LP is going to take a similiar track.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/20/basis12/ukuk/prty/10022212_2012.gif

However this could change!

[andymusic]

New warnings from the meto - confirms the GFS is no good on this run - monday's warnings are back on for a small part of wales and the midlands

[LomondSnowstorm]

That is a rubbish GFS, with rain for all of the UK on Wednesday! UKMO looks nicer, with snow potential extending from northern England across to northern Ireland and into southern Scotland probably http://www.meteociel.fr/ukmo/run/UW96-21.GIF?20-17. Even looks better further south by +144 http://www.meteociel.fr/ukmo/run/UW144-21.GIF?20-17 .

So hard to say what will happen, with model disagreement like this http://91.121.94.83/modeles/gfs/run/gfs-0-96.png?12 .

LS

[TEITS]

New warnings from the meto - confirms the GFS is no good on this run - monday's warnings are back on for a small part of wales and the midlands

Bang on cue from my post.

However I really cannot stress enough how much a slight change in track can make the difference. I would strongly recommend only following the NAE for tomorrow/Monday. This model for the +48 timeframe has been remarkably accurate so far.

[Ian Fergusson]

New warnings from the meto - confirms the GFS is no good on this run - monday's warnings are back on for a small part of wales and the midlands

You'll note a broader swathe included in the advisory based on the UKMO's 12z assessment. This run called for the spread of frontal PPN overnight Sunday-Monday to be slower and the NW extent is lessened - hence the advisory re-issued. In broad terms, not a dissimilar areal focus to the events of last Thurs albeit (modified) NAE fields for 09-12z Monday are eager for somewhat more SE extention in terms of the discrimination between rain and wintry PPN; e.g., into a fair part of East Anglia, Northants, N. Oxon, etc.

Edited February 20, 2010 by Ian Fergusson

[snowmadchrisuk]

You'll note a broader swathe included in the advisory based on the UKMO's 12z assessment. This run called for the spread of frontal PPN overnight Sunday-Monday to be slower and the NW extent is lessened - hence the advisory re-issued. In broad terms, not a dissimilar areal focus to the events of last Thurs albeit (modified) NAE fields for 09-12z Monday are eager for somewhat more SE extention in terms of the discrimination between rain and wintry PPN; e.g., into a fair part of East Anglia, Northants, N. Oxon, etc.

If the Low goes any further South though we could miss out on Precipitation all together away from the South Coast . There also looks like for most areas it may only be light precipitation .

[Thundery wintry showers]

UKMO disagrees strongly with GFS continuing the theme of low pressure and milder air making only very slow inroads from the south and repeated snow events for the Midlands and north- so unless ECMWF backs GFS I will suggest that GFS has, indeed, been over-progressive in this particular run.

[andymusic]

You'll note a broader swathe included in the advisory based on the UKMO's 12z assessment. This run called for the spread of frontal PPN overnight Sunday-Monday to be slower and the NW extent is lessened - hence the advisory re-issued. In broad terms, not a dissimilar areal focus to the events of last Thurs albeit (modified) NAE fields for 09-12z Monday are eager for somewhat more SE extention in terms of the discrimination between rain and wintry PPN; e.g., into a fair part of East Anglia, Northants, N. Oxon, etc.

Hi Ian,

I suppose the front could move further north too between now and Monday??????????

[TEITS]

If the Low goes any further South though we could miss out on Precipitation all together away from the South Coast . There also looks like for most areas it may only be light precipitation .

Always the risk because at the moment I would put the N limit around Lincs. However if the LP exits around Essex rather than Norfolk our locations would miss out.

I don't agree about light precip. Look at the +48 accumlations and you will see between 10-15mm. I have taken tomorrow into account I hasten to add.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/20/basis12/ukuk/rsum/10022212_2012.gif

Latest +48 fax chart.

http://www.meteociel.fr/ukmo/fax/fax48s.gif

Edited February 20, 2010 by THE EYE IN THE SKY

[snowmadchrisuk]

Always the risk because at the moment I would put the N limit around Lincs. However if the LP exits around Essex rather than Norfolk our locations would miss out.

I don't agree about light precip. Look at the +48 accumlations and you will see between 10-15mm. I have taken tomorrow into account I hasten to add.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/20/basis12/ukuk/rsum/10022212_2012.gif

Latest +48 fax chart.

http://www.meteociel.fr/ukmo/fax/fax48s.gif

To eb honest I only based my light precipitation on the latest GFS run , Havent had a chance to look at the others yet but am about to now . What do you think the chances are for Tuesday ?

[Frosty.]

I don't see how this gfs run can be anywhere near right because it would make a mockery of the met o update 5 hours ago. This is a problem the gfs has with it's 4 runs a day which are nearly always very different but not at T+96 / T+120 hours but if it's right I will eat my hat, if I had one.

[kev238]

Yeah- follow the NAE-- you need to look at the accumulated precipiation and precipitation fields to make an accurate judgement of what the model is showing. I found it exceptionally good for the snowfall on Thursday.

You need to look beyond the shadings and think about the amounts on offer. For example light pink means less than 1mm of precipitation over a 6 hour period.

I do think that TEITS is correct- snowfall in similar areas-- though my suspicion will be that things might trend slightly further South with time rather than Northwards. This would not suit my location at all (Nottingham) but it is what I think will happen and normally does happen with these types of low pressures.

Also using the NAE model 850s in the area of snowfall are between -1 and -3; which shows that being below -5 is not the be all and end all.

[TEITS]

Just to confuse you even more here is the GEM.

Monday LP is much further S.

http://91.121.94.83/modeles/gem/run/gem-0-48.png

Next LP tracks further S than the other models suggest.

http://91.121.94.83/modeles/gem/run/gem-0-102.png

Next LP is even further S!

http://91.121.94.83/modeles/gem/run/gem-0-144.png

Conclusion is its a waste of time sitting here looking at these models.