Model Output Discussion

[kold weather]

I'm the only one who thinks the 12Z is an upgrade! Perhaps a bit further south to keep colder air in place but in many ways this spell was becoming less interesting for those in Scotland due to the majority of the precipitation being further south. Just a different opinion on it but of course others will inevitably disagree. Outwith the lows is not really worth thinking about given the models continue to show this breakdown at the start of FI/end of high resolution but it hasn't really moved too much in the last few weeks to be honest.

LS

Yeah its an upgrade up there but even up in Scotland the 12z is marginal at times, still you guys should like the 12z more then 06z anyway.

Ensembles are still a mess with the evolution between 72-96hrs which makes a huge difference as to where the snow threat is, evolution is very far from clearcut thats for sure!

Remember in this evolution if your on the northern side of the low then your going to have every chance of snowfall, however we cannot afford to have a warm front come up before the main low otherwise as we see with the 12z GFS, everything becomes amazingly marginal.

Edited February 18, 2010 by kold weather

[January Snowstorm]

Yeah its an upgrade up there but even up in Scotland the 12z is marginal at times, still you guys should like the 12z more then 06z anyway.

Ensembles are still a mess with the evolution between 72-96hrs which makes a huge difference as to where the snow threat is, evolution is very far from clearcut thats for sure!

I see nothing marginal in Scotland & think this deep cold nearby will affect our weather more than you think. My call is widespread lying snow during the weekend for the North and West, which will of course thaw during daylight

[kent]

Too many LP systems around which have always been good at dragging milder air into the mix, and equally adept at keeping the real cold at bay. Hence a rather cold wet and dreary outlook, for us in the far south anyway. really needs a pattern change as TEITS suggests.

[kold weather]

JS, you'd be marginal where you are, but further north in Ireland might do ok if the 12z came off on Sunday. The intial front would almost certainly be a snow event thats for sure, its the events after that, the possible big daddy which would be marginal on Monday, take a look at the dew points:

http://www.wetterzentrale.de/pics/Rtavn9610.png

What would be in your favour would probably snow on the ground already, may just tip it the roght side of marginal...

Saturday could have some ok snowfall as well in Ireland, 2-5cms looks possible.

I'm looking forward to the field I have to walk across in Chichester to get to uni being a total flooded bog again...joy!

[January Snowstorm]

JS, you'd be marginal where you are, but further north in Ireland might do ok if the 12z came off on Sunday. The intial front would almost certainly be a snow event thats for sure, its the events after that, the possible big daddy which would be marginal on Monday, take a look at the dew points:

http://www.wetterzentrale.de/pics/Rtavn9610.png

What would be in your favour would probably snow on the ground already, may just tip it the roght side of marginal...

Saturday could have some ok snowfall as well in Ireland, 2-5cms looks possible.

I'm looking forward to the field I have to walk across in Chichester to get to uni being a total flooded bog again...joy!

Yes marginal for Cork alright, but we are well used to that word haha

Having said that pbly be our best chance of seeing snow this year and I am 500ft above sealevel which always helps

[MR EXTREMES]

I see nothing marginal in Scotland & think this deep cold nearby will affect our weather more than you think. My call is widespread lying snow during the weekend for the North and West, which will of course thaw during daylight

to be fair kold the uppers on the gfs run do look pretty good in scotland,

whethers thats what you ment it does become marginal towards the end of the run.

but before that yes indeed scotland and northern england could get something on and off but it does become marinal.

Too many LP systems around which have always been good at dragging milder air into the mix, and equally adept at keeping the real cold at bay. Hence a rather cold wet and dreary outlook, for us in the far south anyway. really needs a pattern change as TEITS suggests.

yep that about sums it up spot on post.

Edited February 18, 2010 by grab my graupel

[Hammer]

The interesting thing for me, take this example is Met Office today issued an advisory for Monday for much of the midlands southwards and wales based on their earlier run today.

It always interests me when Met Office are so quick to put an advisory in place, that then within hours, or you would think after this run, looks possibly a little unlikely.

However that is the point, to me, I would think they must have had reasonable confidence to put a advisory in place in the first place and so with that in mind, I am willing to think unless we get several more runs, that Monday is still an item to watch for a large part of the country.

As I would Saturday is.

[LomondSnowstorm]

The interesting thing for me, take this example is Met Office today issued an advisory for Monday for much of the midlands southwards and wales based on their earlier run today.

It always interests me when Met Office are so quick to put an advisory in place, that then within hours, or you would think after this run, looks possibly a little unlikely.

However that is the point, to me, I would think they must have had reasonable confidence to put a advisory in place in the first place and so with that in mind, I am willing to think unless we get several more runs, that Monday is still an item to watch for a large part of the country.

As I would Saturday is.

Monday is, but whether it is for Manchester northwards or Midlands southwards remains to be seen

[kold weather]

to be fair kold the uppers on the gfs run do look pretty good in scotland,

whethers thats what you ment it does become marginal towards the end of the run.but before that yes indeed scotland and northern england could get something on and off but it does become marinal.

Just looked at the high resolution verison on the run, I've probably overstated the marginality of it, dew points are probably low enough as are other factors so snowfall seems quite likely in the north, actually would be a very big event for the north if that came off and the snow on the ground will probably help swing things the right side of marginal...

Amazing how such a puny little synoptic difference can shift the threat 300 miles further north and thats stil lreflected in the ensembles...BUT being a rather old dog at this game now, the 12z evolutions will be the correct ones I'm certain.

[Hammer]

Monday is, but whether it is for Manchester northwards or Midlands southwards remains to be seen

Sure, and not to bothered either way. The point I am making is that Met Office reacted quite early putting an advisory in place for Monday, yet after last set of model runs it seems perhaps like they may have reacted a little to soon or at least with the locations impacted.

Ok so the question probably not for this thread and maybe I should be asking Met Office. But what perhaps does have some relevance in this thread is that by them making an advisory, gives an indication they have at least some confidence in an outcome and that should at least mean we need to see some more modelling before we can write off or have increased confidence re an event as far off as Monday.

[David-kig]

just shows how marginal this event is!

[MR EXTREMES]

Just looked at the high resolution verison on the run, I've probably overstated the marginality of it, dew points are probably low enough as are other factors so snowfall seems quite likely in the north, actually would be a very big event for the north if that came off and the snow on the ground will probably help swing things the right side of marginal...

Amazing how such a puny little synoptic difference can shift the threat 300 miles further north and thats stil lreflected in the ensembles...BUT being a rather old dog at this game now, the 12z evolutions will be the correct ones I'm certain.

i agree if had been a few weeks ago maybe it would have been different.

so its going to be intresting how it pans out i think we both like to see a southerly shift im not certain it will .

but regardless of this i think your right it will be an amazing event before things turn even more marginal,

but thats only looking at the deeper outputs which im thinking will turn out to be correct.

but i hope were wrong:drinks:

[kev238]

The 12zs are less good than the 6z. However, still pretty good for some regions- I am not sure whether we need to be looking at the -5 isotherm or not religiously. Certainly- the gfs has shown something crossing the South on Saturday and then a very messy picture from Monday onwards.

My location (Nottingham)looks well placed as the output stands but the line is likely to shift North or South over the next few days!

[David-kig]

these low pressure systems need to stay further south to keep us in the cold air which seems at the moment unlikely. i dont think they will go as far north as the gfs is showing. midlands north looks the best bet further south. rain or sleet on the most part

[LomondSnowstorm]

Sure, and not to bothered either way. The point I am making is that Met Office reacted quite early putting an advisory in place for Monday, yet after last set of model runs it seems perhaps like they may have reacted a little to soon or at least with the locations impacted.

Ok so the question probably not for this thread and maybe I should be asking Met Office. But what perhaps does have some relevance in this thread is that by them making an advisory, gives an indication they have at least some confidence in an outcome and that should at least mean we need to see some more modelling before we can write off or have increased confidence re an event as far off as Monday.

I think perhaps that they do this more quickly when the precipitation shown is widespread and affecting major population centres - in this case Manchester, Birmingham, Leeds and the advisories do go as far south as Oxfordshire - rather than if it was progged to affect e.g. the northwest highlands, for obvious reasons, but I think the advisory status rather than early warning status shows how little confidence the Met has of this outcome as most people won't notice the advisory until it moves onto the stage of BBC forecast. Anyway, we shall see what the ECMWF shows, but the UKMO does back up the GFS quite nicely http://www.meteociel.fr/ukmo/run/UW96-21.GIF?18-18 http://91.121.94.83/modeles/gfs/run/gfs-0-96.png?12

In terms of the position of the low that is, not in the strength of the flow or intensity of the low, which in itself will affect things.

LS

[conor123]

Well somewhere's gonna get a whiteout Monday, it's just unsure on where.

Still plenty of Borderline snow risks on the 12z runs though for selfish reasons the 06z was better.

[Higher Ground]

After all the fuss about the GFS and UKMO, the ECMWF takes the low further south at T+96!

[kold weather]

Yep you can depend on the ECM to mix things up, it shows the other solution which some of the ensembles are suggesting, seems like we relaly do have two camps...I'd still nail my mast to the GFS/UKMO solution BUT the ECM equally cannot be ignored either as it is the best model usually.

[MR EXTREMES]

Yep you can depend on the ECM to mix things up, it shows the other solution which some of the ensembles are suggesting, seems like we relaly do have two camps...I'd still nail my mast to the GFS/UKMO solution BUT the ECM equally cannot be ignored either as it is the best model usually.

if that ridge from the south on the ecm 120h was not there i think the low pressure system would be futher south still although look better for a little more of the country.

anyway messy is certainly word and i think all three main models have the systems moving in from the southwest.

looks like the alantic is streaming in low pressure after low pressure mind you did not surprise me to be honest.

[J10]

ECM is fascinating with several attempts at channel lows. IF the ECM verified some snow would be certain for many areas, how far north though would be very open to debate.

[cooling climate]

Yep you can depend on the ECM to mix things up, it shows the other solution which some of the ensembles are suggesting, seems like we relaly do have two camps...I'd still nail my mast to the GFS/UKMO solution BUT the ECM equally cannot be ignored either as it is the best model usually.

None of the models have a clue at the moment. They don't know what to do with the

vortices's and with these shallow lows moving around, I think its a case of nowcasting

for the next 48 to 72 hours.

Beyond this hopefully the models will start to show a much colder pattern setting up

with the block more east based and a continental airflow.

[conor123]

ECM is fascinating with several attempts at channel lows. IF the ECM verified some snow would be certain for many areas, how far north though would be very open to debate.

I'm thinking judging on past experiences that these lows will end up tracking further South in the end, at the moment we'd be looking at big snowfall events across Northern England, Northern Ireland, the higher ground of Wales & The Midlands with lower levels of Wales, Midlands, East Anglia and The West Country probably having snow to rain events though im guessing these low's will end up at least 100 miles further south than currently shown, probably more actually.

The fact the lows may take a very similar track one after another means that somewhere is going to get quite a substancial level of snow (whilst those to the south of it a flood risk).

Interesting times ahead.

Edited February 18, 2010 by conor123

[MP-R]

What on earth is all this!?

http://www.wetterzentrale.de/pics/Rtavn1261.png

Shortwave troughs all over the place!

I think I need to see the next model run before I believe anything of what is being shown. Also, the low for Monday has a central pressure of 975mb on this run, that has to be pretty rare for February.

Edited February 18, 2010 by Michael Prys-Roberts

[Mark Bayley]

Cold air hangs on in Northern England and Scotland till the end of the run on the ECM. Looks to be a fair few snow events (or rain events depending on your location!) From T120 onwards snow is confined to the Northern half of the UK with Northern England, Scotland and Ireland staying in the coldest air. Looks rain or a wintry mix further south. An interesting period coming up. Will all depend on the track of the lows (with who sees what). A risk of flooding further south?

We really need to lose this western based NAO. Hopfully transfer Eastwards a little with that annoying low getting lost!

[Nick F]

ECM is fascinating with several attempts at channel lows. IF the ECM verified some snow would be certain for many areas, how far north though would be very open to debate.

12z ECM shows heavy precipitation across southern counties Monday mainly south of the M4, T850s look a bit too warm though, with the -5C line across central areas and 0C line creeping across far south. These charts are for 06z Monday:

Obviously track of low and precip liable to change that far off, 12z ECM the most southerly solution for the low moving NE from Biscay, followed by GFS and UKMO with a much more northerly track.

Looks like a trough feature running east across southern UK on Sunday too ahead of this low, which may bring snow across S Wales, south central and eastern England. Lots going on over the coming days!