Model Output Discussion

[reef]

A new thread here, please continue.

Remember this thread is for discussing the models. Current condition reports, general chat, regional discussion and anything else all have other threads.

Thanks.

Old thread:

[MR EXTREMES]

well this mornings outputs no different than the last 4 days or so still a slow evolution towards more sleet rain type as we head into mid week except scotland.

it also need to be noted that the met o removed the advisory for southcoast as i said they would lastnight,

infact they removed it quick sharp,

so that tells me a more north track of this system but not much futher north perhapes only 100miles.

the other advisory is for futher north still this is inline with models trends pushing the more marginal weather futher north and yes its slow this could also have a margin of error 100 miles in either direction.

to put this simply its a case of now casting,

im still convinced after wed/thursday this will be the theme rather wet and unsettled for most of the uk except scotland around average or slightly below.

[MAF]

from the previous thread... i think it needs to be seen here too :o

This comment skews the reality and needs clarifying (this does have a model thread relevance, mods!):

The NAE (and UKMO-GM) output ingested into our graphics is modified at BBC Weather Centre by the UKMO Duty Forecaster before it goes on-air or to the web. These modifications, in turn, are based on (often major) tweaks made at UKMO Ops Centre by the Chief Forecaster and subsequently discussed in conference briefings held through the day / night. Moreover, those of us working regionally can make further tweaks to some elements (e.g., changing MOS temperatures to better reflect actual OBS, etc.). Thus, the raw NAE fields you might see on some websites do NOT always correspond to BBC graphical representation, because it will lack the additional 'human' tweaking of forecasters - some of which can result in quite critical changes. Clearly, to run TV graphics on just the raw NAE ingest would be quick, yes, but hardly offering the best stab at accuracy.

and without the human factor than all the regional forecasts would be pretty much the same as their immediate neighbours.

[MR EXTREMES]

after looking at every model there is certainly a trend for northern england and scotland holding onto the wintry stuff right up until fi.

very intresting how much the cold is trying to hold but mildlands north look good for the next couple of days but hard to pinpoint.

but met office warnings look pretty good so no lamp post watching looks like radar watch for some :o

[Paul T]

The ensambles for quite a few central and southern areas have mean 2m temps consistantly below 5oC, and between 23rd and 25th these are around 2oC consistantly. (check out wiltshire for example)

This doesnt tie in with what the charts are saying, looking at the charts i would say a wet and windy week with cool rain is on the cards for most of England, but the ensambles are hinting at a slightly colder view.

[SnOwFeSt]

Looking so marginal for next week here in leeds. Really are on the cusp of either getting a dumping of snow vs. a dumping of sleet on Wednesday. Lets hope the models have the low pressure tracking slightly further south as we near the time. At the moment, I'd say anywhere Newcastle northwards will be the right side of marginal...

But it will probably all change - some very complex synoptics for the models to deal with at the moment!

[Frosty.]

so no lamp post watching looks like radar watch for some

Well our lamp post is broken so it's definately radar watch. It's going to be a wintry week for all central and northern britain with heavy snow at times and arctic air pushing south into northern scotland with snow showers up there and severe frosts.

Edited February 21, 2010 by Frosty039

[TEITS]

Quiet a bit of disagreement in the ensembles for my location within +144 with this ranging from 0C to -10C.

http://charts.netweather.tv/ensimages/ens.20100221/06/t850Cambridgeshire.png

This becomes less so further N which suggests the track of these LPs this week is far from certain and that includes tomorrows LP.

[Weathizard]

Ensembles for my area are strange indeed, 2m temp is quite low at around 0 on some runs (GFS Control & Operational), but the GFS mean is just hovering above 5 throughout.

[andymusic]

Quiet a bit of disagreement in the ensembles for my location within +144 with this ranging from 0C to -10C.

http://charts.netwea...bridgeshire.png

This becomes less so further N which suggests the track of these LPs this week is far from certain and that includes tomorrows LP.

I think 24 - 36 hours ahead is plenty to look at and even that far ahead is open to change and now casting

[bluearmy]

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

no surprise that the foot of snow in the southeast on the 26th ecm op is an outlier

[Terminal Moraine]

I wouldn't say it's definite but there is good agreement between the GFS 06z and the Met' Office for the northern extent of the precipitation tomorrow. GFS shows it just getting into Derbyshire before moving away to the east and this ties in with the updated Met' Office advisory which includes Notts and Leicestershire but excludes Derbyshire and Staffordshire.

This is a shift southward of about 100 miles on the GFS model although the Met' have stuck with their prediction for the last 24 hours or so.

All eyes on the 12z later on today to see if the theme continues.

[andymusic]

Well - we await the 12z models to put us out of our misery - at least possibly for tomorrow - but even they might not nail it 100%!

[MR EXTREMES]

i will tell you what although i dont toally agree,

but its looking awsome for a fair swathe of the uk for snow,

intresting news headlines if the meto are right i dont see why they wont be.

i go slight back on what ive been saying i think the evolution is slower towards mild for midlands north you lucky sods lol.

[R.P. McMurphy]

i will tell you what although i dont toally agree,

but its looking awsome for a fair swathe of the uk for snow,

intresting news headlines if the meto are right i dont see why they wont be.

i go slight back on what ive been saying i think the evolution is slower towards mild for midlands north you lucky sods lol.

I agree, next week is looking great for snow midlands northwards, but the fact remains, it also looks extremely dangerous. Possible flooding in the south, very heavy snow for the North. A week that could cripple Great Britain. All eyes on the 12Z to see the current trend as we get closer to the reliable time frame. A word of caution should be noted, if this weather is a severe as shown, take care of the elderly etc.

[MKN]

I agree, next week is looking great for snow midlands northwards, but the fact remains, it also looks extremely dangerous. Possible flooding in the south, very heavy snow for the North. A week that could cripple Great Britain. All eyes on the 12Z to see the current trend as we get closer to the reliable time frame. A word of caution should be noted, if this weather is a severe as shown, take care of the elderly etc.

Flooding in the south maybe snow causing disruption...not that likely. I dont see snow being a problem for most areas apart from during the snowfall itself. If the last few days are anything to go by the roads are clear of snow almost immediately after the sun comes up.

[andymusic]

Flooding in the south maybe snow causing disruption...not that likely. I dont see snow being a problem for most areas apart from during the snowfall itself. If the last few days are anything to go by the roads are clear of snow almost immediately after the sun comes up.

It'll all be to do with when the snow falls, how long it falls for (ie. if an area gets a stalling front) and if it continues to be cloudy afterwards to prevent the sun's attack on the snow and keep the low temps

Edited February 21, 2010 by andymusic

[R.P. McMurphy]

It'll all be to do with when the snow falls, how long it falls for (ie. if an area gets a stalling front) and if it continues to be cloudy afterwards to prevent the sun's attack on the snow and keep the low temps

And looking at the latest cloud cover charts, were in for at least 3 - 4 days of cloud, with limited sun.

[Cheese Rice]

I'm expecting the next GFS run to put the low further south, so probably snow for Northern England but this time not the Midlands.

I didn't realise how dull and wet it will be in the far south, the BBC 5 day forecast for London sums it up really http://news.bbc.co.uk/weather/forecast/8/ probably the worst 5 day forecast I have ever seen.

[MKN]

I'm expecting the next GFS run to put the low further south, so probably snow for Northern England but this time not the Midlands.

I didn't realise how dull and wet it will be in the far south, the BBC 5 day forecast for London sums it up really http://news.bbc.co.uk/weather/forecast/8/ probably the worst 5 day forecast I have ever seen.

Low further south but snow further north ? hmmm

[cooling climate]

I'm expecting the next GFS run to put the low further south, so probably snow for Northern England but this time not the Midlands.

I didn't realise how dull and wet it will be in the far south, the BBC 5 day forecast for London sums it up really http://news.bbc.co.u...her/forecast/8/ probably the worst 5 day forecast I have ever seen.

As I said yesterday evening I would not be surprised to see it run along the channel.

I just hope that if it does take a more southerly track the uppers are cold enough to

support snow. As for further out into the middle of next week its not even worth a guess at the moment.

Edited February 21, 2010 by cooling climate

[Harsh Climate]

For us in Northern England the GEM 00z is a peach.

We want wed/thu/fri low(s) to track something like this:

http://www.wetterzentrale.de/pics/Rgem961.gif

http://www.wetterzentrale.de/pics/Rgem1081.gif

http://www.wetterzentrale.de/pics/Rgem1321.gif

Allways right side of the 528 dam line and just on the northern side of heavy precipitation..

[Supercell]

That is quite a colossal shift southwards of the PPN band in such a short space of time. And we're not too far away from T0 now. More in line with this morning's NAE model (or even moreso).

[Harsh Climate]

lmao the plot thickens, even areas like birmingham who were promised a dumping tommorow (bbc/met office) could be bone dry! looks good for the rest of the run

http://www.wetterzentrale.de/pics/Rtavn244.png

[Eugene]

Much better 12z already, instead of having tommorow's front stall 10 miles south of here and not give anything but cause overcast muck which would ruin Tuesdays event, we now have it much further south allowing clear skies to move in from the North tommorow night

Yes and instead has overcast muck for you on wednesday