General Model Output Discussion

[Lewis]

FORGIVE ME PEOPLE

OMG OMG OMG OMG

http://91.121.94.83/modeles/gfs/run/gfs-2-162.png?18

STREAMER ALL THE WAY BACK TO --- WARSAW---- SOMEONE FIRE UP THE WARSAW RADAR...

S

very nice, way out in FI, but have you seen the dew points +1 to +2c, for some reason as the flow comes from across France the air becomes modified i don't know why it does not make sense, but that's what the gfs shows, for the above chart you posted.

Lewis

[PB22]

FORGIVE ME PEOPLE

OMG OMG OMG OMG

http://91.121.94.83/...fs-2-162.png?18

STREAMER ALL THE WAY BACK TO --- WARSAW---- SOMEONE FIRE UP THE WARSAW RADAR...

S

Here we are Steve: http://www.imgw.pl/wl/internet/zz/english/weather/radar/radar_en.html

Another stunning run, we run out of cold air eventually, but I think that would come as a relief to many people! In any case, as long as the flow is off the continent, then it will remain cold, i.e.

http://www.wzkarten.de/pics/Rtavn2401.html

http://www.wzkarten.de/pics/Rtavn24017.html

[Rob K]

Well it doesnt look like -10,s are covering the whole country to me, Scotland and East anglia are not under -10 air and same goes for -12,s, but hey we are splitting hairs here, its going to be very cold across the whole country with snow in many places.

SS2

As I said they were the 12Z runs when I posted them.

The 18Z still has -10s over almost the whole country...

http://www.wzkarten.de/pics/Rmgfs1472.gif

http://www.wzkarten.de/pics/Rmgfs1562.gif

[Ian Fergusson]

FORGIVE ME PEOPLE

OMG OMG OMG OMG

http://91.121.94.83/...fs-2-162.png?18

STREAMER ALL THE WAY BACK TO --- WARSAW---- SOMEONE FIRE UP THE WARSAW RADAR...

S

9th January 2010 might as well be 9 March 2011. It's miles away. So much shortwave detail to bother about on a day to day basis, let alone the goodness-knows-how-many-days-ahead blarf.

[Nick L]

Well it doesnt look like -10,s are covering the whole country to me, Scotland and East anglia are not under -10 air and same goes for -12,s, but hey we are splitting hairs here, its going to be very cold across the whole country with snow in many places.

SS2

Rob was referring to the 12z, which did indeed have -10 covering the country. The updated charts no longer show this.

[Frosty.]

I'm not impressed by the GFS 18z FI evolution which turns the winds into the south and then milder and unsettled later, typical of the gfs to have a raging FI NE'ly on the 12z and then a S'ly on the next run. At least next week's bitter cold is in the bag and snow will feature daily although if you look at the bbc precipitation charts you would be forgiven for thinking it will be a non event with just the odd splodge of white here and there and some days showing no ppn at all.

[nick sussex]

very nice, way out in FI, but have you seen the dew points +1 to +2c, for some reason as the flow comes from across France the air becomes modified i don't know why it does not make sense, but that's what the gfs shows, for the above chart you posted.

Lewis

It must be some sort of error there, it's impossible to have those dew points off that flow and with the previous synoptics.

Edited January 2, 2010 by nick sussex

[Rob K]

very nice, way out in FI, but have you seen the dew points +1 to +2c, for some reason as the flow comes from across France the air becomes modified i don't know why it does not make sense, but that's what the gfs shows, for the above chart you posted.

Lewis

The dewpoints are -1 to -2 at the time of the chart, not +1 to +2.

http://www.wzkarten.de/pics/Rmgfs1628.gif

[Lewis]

The dewpoints are -1 to -2 at the time of the chart, not +1 to +2.

http://www.wzkarten.de/pics/Rmgfs1628.gif

yeh just as it hits the coasts, go to the next chart on the run as it pushes N and you'll see what i mean.

Lewis

[bluearmy]

9th January 2010 might as well be 9 March 2011. It's miles away. So much shortwave detail to bother about on a day to day basis, let alone the goodness-knows-how-many-days-ahead blarf.

very true Ian but the trend is there for the euro trough to deepen sufficiently for it to squeeze up against the developing scandi height rise. whatever happens in the interim, this is a bigger part of the pattern than the shortwave behaviour in the flow before this point. in a pattern such as we have, your concerns are understandably much more short term and i dont envy you one bit.

[Rob K]

Rob was referring to the 12z, which did indeed have -10 covering the country. The updated charts no longer show this.

Well not far off! http://www.wzkarten.de/pics/Rtavn1502.png http://www.wzkarten.de/pics/Rtavn1562.png

yeh just as it hits the coasts, go to the next chart on the run as it pushes N and you'll see what i mean.

Lewis

Seems reasonable to me - the deep cold uppers are nearly exhausted by then http://www.wzkarten.de/pics/Rmgfs1652.gif

[Optimus Prime]

Seems reasonable to me - the deep cold uppers are nearly exhausted by then http://www.wzkarten.de/pics/Rmgfs1652.gif

You would expect that - go through the January 63 charts and you will see how quickly the 850s went from -10c to -4c or -5c. The pattern resets itself and so the cold balance is readdressed.

That's exactly what the models are showing.

[SMU]

http://91.121.94.83/modeles/gens/run/gens-0-1-132.png?12

This is the control run ( STUNNING BTW)

the ensembles at around 120 tonight have interestingly corrected to more of a direct easterly component.....

S

[cooling climate]

yeh just as it hits the coasts, go to the next chart on the run as it pushes N and you'll see what i mean.

Lewis

Dew points do not rise above 0c out to t180.

Great, Great run and I think we can bin the lower res output as I am sure that will show a mild outlier

amonst its ensembles.

[Bristawl Si]

9th January 2010 might as well be 9 March 2011. It's miles away. So much shortwave detail to bother about on a day to day basis, let alone the goodness-knows-how-many-days-ahead blarf.

Thanks Ian, for a dose of realism.

We've seen 'dream' charts on numerous occasions over the years. We all know, especially the more learned contributors on this forum, that detail in these cold situations change day after day. Some of the ramping on here in recent days has been way over the top IMO and surprisingly it's often come from the more respected members.

Edited January 2, 2010 by Bristle boy

[Guest North Sea Snow Convection]

very true Ian but the trend is there for the euro trough to deepen sufficiently for it to squeeze up against the developing scandi height rise. whatever happens in the interim, this is a bigger part of the pattern than the shortwave behaviour in the flow before this point. in a pattern such as we have, your concerns are understandably much more short term and i dont envy you one bit.

I think the issue is that the euro trough is actually too close to south eastern most parts of england. The present trend is to squeeze the euro trough northward towards the south east corner and push the north easterly flow northwards in line with the scandi block moving further north and west again. Like the pre xmas spell it could be areas to the north and west of London as well as swathes of the central belt and of course the most favoured parts of eastern and north eastern england. Snow could find its way quite a way arcing south westwards towards the west country and parts of central southern england too.

Edited January 2, 2010 by North Sea Snow Convection

[Cecil Hogmanay Melchett]

It must be some sort of error there, it's impossible to have those dew points off that flow and with the previous synoptics.

I concur Nick,

Those air temps progged on 18z for sunday next week just look plain wrong to me.It's FI though so probably irelevant.

What a memorable spell of weather we have before us.The really colder stuff being dragged down from Norway is just about to spread across the UK.

[reef]

Pretty amazing synoptics compared to the dross we've had to endure for much of the last 20 years. Whats even more pleasing is that they are occuring when the sun is weakest during the second half of Dec / first half of January which has traditionally put in a rather poor showing in recent years, with Atlantic often firing up.

Certainly no sign of any mild in the reliable timeframe and quite possibly a sub-zero first half of the month. The easterly forming at T+120 is interesting as like many easterlies we've had in the last few years, it involves a high pressure being sucked up into Scandinavia rather than the other way round. It seems its more appropriate to look west rather than east for our cold spells at the moment.

As other have said, its pointless looking for small features on the GFS as it simply wont pick them up. The main reason is that it just doesnt have the resolution, but even models with a very high resolution struggle to pick up these features even as little as 24 hours out.

[nick sussex]

I think the issue is that the euro trough is actually too close to south eastern most parts of england. The present trend is to squeeze the euro trough northward towards the south east corner and push the north easterly flow northwards in line with the scandi block moving further north and west again. Like the pre xmas spell it could be areas to the north and west of London as well as swathes of the central belt and of course the most favoured parts of eastern and north eastern england. Snow could find its way quite a way arcing south westwards towards the west country and parts of central southern england too.

Looking at the gfs 18hrs run, the main low centre starts off initially over se France and slowly transfers ne wards slowly filling, its not like the low is centred over Belgium, there looks to be a good 48hr window with lots of instability. Theres still a few days yet before we can see more accurately the flow and what the euro low will do but for the timebeing it all looks fine to me.

[VillagePlank]

Why do I think it will, mainly be dry ... relative humidity is the answer. A reasonable, if not academic explanation of exactly what this is, is here

So, grossly, and with a very wide paintbrush, the RH indicates the likelyhood of rain based clouds. Now, we are expecting such things to form over the North Sea and to settle in over Eastern and Northern Coasts. My guess would be >85% means precipitation at height, and we need more RH to get to over sea-level (height = orographic forcing)

Here's the RH chart, from the 18z, for the next week(ish)

It never gets above 70% - and to increase 70% to 85% requires a lot of energy - and the jet-stream is 300 miles south - so where is the energy, or insolation (cloud cover looks extensive) going to come from?

For sure the North Sea will modify this value upwards - but will it be enough? Will it get to the magic figure? Yes, in places it will, but those places will be sporadic and ill-defined. I am sure those who get lucky will get a good dumping.

I am not saying no one will get snow, I just read the models as a very dry airmass, and that the North Sea simply isn't up to the job of saturating the air mass enough.

Of course, I defer to those who have seen these situations before; perhaps the North Sea is up to the job - but I can't help feeling that this is a matter for watch the radar on the day, and a lot of people are going to watch snow showers, when their own location is absolutely primed for snow, going elsewhere.

Edited January 2, 2010 by VillagePlank

[Guest North Sea Snow Convection]

Absolutely, for the bulk of the UK it is of course a very very cold outlook, and I don't agree with the view that this is going to be a very dry spell. There is almost undoubtably going to be significant snow in various areas of the UK

I just think as an antidote to the perceived south east snow deluge hype, that parts of the south east are not in line for the snow that some may seem to believe. And that is intended from a totally IMBY free perspective

Edited January 2, 2010 by North Sea Snow Convection

[Optimus Prime]

but I can't help feeling that this is a matter for watch the radar on the day,

Isn't that what we've all been trying to tell you?

[SMU]

9th January 2010 might as well be 9 March 2011. It's miles away. So much shortwave detail to bother about on a day to day basis, let alone the goodness-knows-how-many-days-ahead blarf.

Not being funny my friend- But whats the point of that post?- Like we dont know the detail will change- What value is that Adding-

This is about discussing the models & what they actually show- not discussing what they dont show-

Maybe an educated post of what could go wrong--

nah I guess not eh.....

Perhaps you would care to reference this-

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

Which is infact the ensemble data for the model that the UK MET use in conjunction with their own model-the fact that for London the mean doesnt get about 2/3c for 10 days

Or how about the panel map from the 18z- at T114

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=114

850's

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=0&ech=114

& a little further at 150

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=150

Or how about from top down-

http://www.hpc.ncep.noaa.gov/cpc/cpc_NHEM_f120wbg.gif

http://www.meteogroup.co.uk/meteo/ecmwf/Europe/2010010212/Europe_2010010212_thgt850_144.png

Ensemble Mean- is very consistent as well-

Infact Why do a fax chart for 120--- So much shortwave detail will change?........

Instead of telling me what to post or when or whenever to get excited- how about adding some value...

BTW the SW thread is here -

S

[VillagePlank]

Isn't that what we've all been trying to tell you?

Well, no. If you've read my posts it is easy to allude to the notion that my analysis of the models is a very dry one, and that snow will be very sporadic. It is my reading of this thread that widespread snow is a given. I do not think that is so, although I think snow will happen for the lucky few.

That I mention the radar is for those lucky few. I do not feel that this is a widespread snow event. Indeed, I've said so, in either a technical, or otherwise fashion for a few days now. Nothing has changed to modify my view ... yet.

[Ian Fergusson]

Not being funny my friend- But whats the point of that post?- Like we dont know the detail will change- What value is that Adding-

This is about discussing the models & what they actually show- not discussing what they dont show-

Maybe an educated post of what could go wrong--

nah I guess not eh.....

Perhaps you would care to reference this-

http://www.meteogrou...e_forecast.html

Which is infact the ensemble data for the model that the UK MET use in conjunction with their own model-the fact that for London the mean doesnt get about 2/3c for 10 days

Or how about the panel map from the 18z- at T114

http://www.meteociel...&mode=1&ech=114

850's

http://www.meteociel...&mode=0&ech=114

& a little further at 150

http://www.meteociel...&mode=1&ech=150

Or how about from top down-

http://www.hpc.ncep....HEM_f120wbg.gif

http://www.meteogrou...thgt850_144.png

Ensemble Mean- is very consistent as well-

Infact Why do a fax chart for 120--- So much shortwave detail will change?........

Instead of telling me what to post or when or whenever to get excited- how about adding some value...

BTW the SW thread is here -

http://forum.netweat...ell-discussion/

S

Errrr.... and chill (pardon the seasonally-relevant pun).

Who is doubting the prolonged cold spell? Who is doubting the consensus reflected by ensembles? No-one.

Doubting the snow threat, day-to-day; region-to-region, is another matter, and that's what I alluded to.

I'm well accustomed to the SW thread - thanks nonetheless for the helpful link.

Edited January 2, 2010 by Ian Fergusson