Model Output Discussion

[ribster]

I can’t say I agree with the last statement, you know we really have seen a classic old fashion winter this year, very 60s or early 80s, and what in the main those winters produced was a real mixed bag, some cold and snow some milder interludes, and I think we really are seeing more of the same, despite model runs showing deep cold and plenty showing a return to milder weather, what we have had this year in the main, is something in between. This period coming up is a case in point, a mixed bag, no deep freeze but no real return to mild SWlys either. Unfortunately the model thread like the climate change threads has a tendency, if you pardon the pun to polarize itself, it’s far too often deep freeze or blowtorch, whereas in fact the UK climate, other than on rare occurrences is usually betwixt and between and that’s what the models suggest for this week coming up.

But WE, the cold has mostly won this winter, fact. There have been very few mild interludes, and where there have been it's only got to average if not a little below. My own stats bear this out - you have to go back a long way to have the number of ground and air frosts, falling and lying snow days that we have had this winter.

Edited February 21, 2010 by ribster

[andymusic]

Yes I agree a real mixed bag this week. I disagree with Robert in suggesting such widespread snowfall because like recent days its going to be relatively small areas of the UK that are perfectly positioned to see snowfall.

Based on the models I have a rough idea about this week!

Monday.

Snow on the N flank of the precip with the N limit probably around the Wash. Heavy rain in the SE.

http://expert.weathe...022212_2112.gif

Tues/Wed.

Band of rain turning to snow across the Midlands/N England during Tues/Wed. However I am far from certain how far N the precip will be. I feel the chance of this being modelled further S is possible.

http://www.meteociel...0-594.GIF?21-18

Fri.

Even more uncertain but based on the modelling in previous days of these LP systems then I feel the Midlands yet again look in the frame as LP exits around Norfolk area.

http://www.meteociel...20-21.GIF?21-18

So a real mixed bag ranging from snow to possible flooding. However despite these changing runs there is a clear pattern developing. As the +144/+168 charts enter +96 the models are backing away from milder SW,lys by tracking the LPs further S. As these enter the +48 timeframe the models are tracking these even further S. The UKMO is a good example because its a case of rinse and repeat. Due to the LP at +120 taking that track the colder N,lys that follow mean any other LP moving up from the SW brings another risk of snow.

So in summary no sign of a freeze but little sign of milder weather. More of the same I feel over the next 10 days. I will add that for those in N England/S Scotland I would be wary of any model output suggesting the precip reaching you due to the reasons above.

no idea how you came up with that lot above - I'm sure you've got a great handle on the weather but - the meto/beeb/GFS/ECM/UKMO/NAE and any other forecasting method can't even agree on where the low is gonna go tomorrow yet - so anything after that is gonna be impossible to figure out - surely

Edited February 21, 2010 by andymusic

[Brassmonkeylily]

Yes if we believed all the wonky GFS runs this winter then it could also have been a lot better, I don't know how many times mega easterly's have appeared, leading all of us (some more than others) up the garden path but the GFS has really pushed the boat out in this respect this year. Still good stuff but rather watered down, when all's said and done

Some pretty wild weather to come, with a mixed bag of rain, sleet and snow depending on location this week. In truth looking over all the runs on the main models, GFS, ECM, UKMO and GEM over the last few days this has always looked the odds on bet, I certainly never saw the possibility of a nationwide snow event and its always looked very unlikely to be one for the south in particular, as it stands it may not turn out to be much of one for the north either, but that is still up for grabs IMO.

You would think this thread should be called the "snow model thread" given that despite a really interesting period of weather that's coming up for the UK all that's being talked about is where it might snow. I have a feeling that next week's news coverage may feature the weather a fair amount; snow may be the least of many in the south's concern by next weekend. As for the 12z far evolution it may happen, but given the detail changes we are seeing at close range I feel it's a wild guess, although I would not be surprised to see our weather dominated by high pressure in some form or other.

great post.... totally agree that next week will be really interesting .. warnings are now piling in for heavy rain in the south ....

[TEITS]

no idea how you came up with that lot above - I'm sure you've got a great handle on the weather but - the meto/beeb/GFS/ECM/UKMO/NAE and any other forecasting method can't even agree on where the low is gonna go tomorrow yet - so anything after that is gonna be impossible to figure out - surely

Obviously details will change but I did say a rough idea.

Latest fax charts +48/+60.

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

http://www.meteociel.fr/ukmo/fax/fax60s.gif

So an occluded front moving N which means rain turning to snow. Very difficult to say where this will turn to snow but my intial guess ia around Wales/Midlands although S Wales/S Midlands may see sleet/rain.

[LomondSnowstorm]

The ECM at 96 hours is crazy - the low is further southwest than 72 hours! http://www.meteociel...CM1-96.GIF?21-0

This southgrading of everything is getting very annoying for me but surely it has to end at some point!

http://www.meteogrou..._thgt850_72.png

What use is the low this far south with uppers like these?

edit: Ironically at +120 the low is further north than the UKMO http://www.meteociel...M1-120.GIF?21-0

http://www.meteociel...20-21.GIF?21-18

Of course by this stage the uppers are no longer conduicive to snow because no cold uppers have been moving down the west side of a low to our east. If it had it would be very snowy for northern England and Scotland

Edited February 21, 2010 by LomondSnowstorm

[weather eater]

But WE, the cold has mostly won this winter, fact. There have been very few mild interludes, and where there have been it's only got to average if not a little below. My own stats bear this out - you have to go back a long way to have the number of ground and air frosts, falling and lying snow days that we have had this winter.

You miss-understand me ribster, I'm not for a second suggesting that we have not had a cold winter, certainly the most frosts and snowfalls I have seen for a very long time, However all of the model projections that good few got very excited about, 1947 et al, failed to come off and we got cold and snow but not long lasting deep cold and large deep falls of snow at least nothing like those I witnessed in say 79 or 81/82 or even for the brief but very cold period in 87. In other words at times the models predicted mega cold and snow, and although what we got was great, it was still a watered down version of what was shown. With this spell coming up we have seen hints of much milder and hints of much colder temperatures, what we will get is classic British Isles, somewhere in between. I’ve been watching the models and reading this forum for about 5 years, the one thing that has struck me is how easy it is to get sucked into seeing more on model projections than UK weather patterns are likely to deliver 95% of the time, now not getting sucked in to the frenzy that this thread sometimes resembles may not be an exciting or especially optimistic way to view the models but it is an objective and sensible way, and despite being as big a cold and snow lover as anybody on net weather you don’t see me making posts littered with wallbash emoticons I just manage my expectations.

Just to clarify what I mean by the cold, here we saw about 2 or 3 nights with low temps in the minus teens and good few between -5 and -10, obviously some places recorded more, Scotland especially, but I live within about 25 miles of where the lowest temps of I think -17 were recorded. That was about a two week spell, the canals froze over and the reservoir, however outside that spell we have seen nothing so dramatic, so nothing more than some of the winters I witnessed in the 60s late 70s and early 80s.

On the current model front not a great deal of difference between the ECM and the GFS at 96hrs, ECM has the low a little further east. Also at 120hrs not wildly different, ECM has a tighter center for the low and a bit further south.

[MR EXTREMES]

yeah - in france

i know the 528 dam line dont mean everything but i noticed where it was on the fax charts pretty far north really.

[MP-R]

The ECM at 96 hours is crazy - the low is further southwest than 72 hours! http://www.meteociel...CM1-96.GIF?21-0

And notice how the centre of the low is 900mb! :lol:

[MKN]

And notice how the centre of the low is 900mb! :wacko:

975mb**

[andymusic]

ECM - continues the cold theme into march for all

[weather eater]

Interesting ECM rolling out, however trusting any output past about 72hrs is a bit of waste of time really, but i suppose it does demonstrate another possible evolution.

[andymusic]

Interesting ECM rolling out, however trusting any output past about 72hrs is a bit of waste of time really, but i suppose it does demonstrate another possible evolution.

agreed - 12 - 24 hours seems more like it with tomorrow's front

[cooling climate]

You miss-understand me ribster, I'm not for a second suggesting that we have not had a cold winter, certainly the most frosts and snowfalls I have seen for a very long time, However all of the model projections that good few got very excited about, 1947 et al, failed to come off and we got cold and snow but not long lasting deep cold and large deep falls of snow at least nothing like those I witnessed in say 79 or 81/82 or even for the brief but very cold period in 87. In other words at times the models predicted mega cold and snow, and although what we got was great, it was still a watered down version of what was shown. With this spell coming up we have seen hints of much milder and hints of much colder temperatures, what we will get is classic British Isles, somewhere in between. I've been watching the models and reading this forum for about 5 years, the one thing that has struck me is how easy it is to get sucked into seeing more on model projections than UK weather patterns are likely to deliver 95% of the time, now not getting sucked in to the frenzy that this thread sometimes resembles may not be an exciting or especially optimistic way to view the models but it is an objective and sensible way, and despite being as big a cold and snow lover as anybody on net weather you don't see me making posts littered with wallbash emoticons I just manage my expectations.

Just to clarify what I mean by the cold, here we saw about 2 or 3 nights with low temps in the minus teens and good few between -5 and -10, obviously some places recorded more, Scotland especially, but I live within about 25 miles of where the lowest temps of I think -17 were recorded. That was about a two week spell, the canals froze over and the reservoir, however outside that spell we have seen nothing so dramatic, so nothing more than some of the winters I witnessed in the 60s late 70s and early 80s.

On the current model front not a great deal of difference between the ECM and the GFS at 96hrs, ECM has the low a little further east. Also at 120hrs not wildly different, ECM has a tighter center for the low and a bit further south.

I agree with 90% of this for to compare the winter with winters in the 60s, 70s and 80s tells us how

different this winter was compared to the last 20 or so.

The thing is the UK has seen far colder spells of weather than we have experienced this winter (850s etc)

and with nothing like the northern blocking (-AO and NAO) that we have seen this winter and so when the

models came out with them dream synoptics it was imo realistic to believe that they would come off.

I know when I look back at this winter and especially this month I will think that we truly missed out on

a country wide deep freeze (850s of -14c to -16c ).

Just seen the ECM 12z and is that the fabled northeasterly coming into view on the t240 chart

I wonder lol.

Edited February 21, 2010 by cooling climate

[Ben_Cambs]

ECM - continues the cold theme into march for all

Yes, Im suprised nobody has commented on ECM! Looks like again GFS is on its own and has no support from the other models, looks like a very eventful week weatherwise with a full bag of different weather. But Im going to take everything past T+48 with a pinch of salt due to the uncertainty!

[weather eater]

I agree with 90% of this for to compare the winter with winters in the 60s, 70s and 80s tells us how

different this winter was compared to the last 20 or so.

The thing is the UK has seen far colder spells of weather than we have experienced this winter (850s etc)

and with nothing like the northern blocking (-AO and NAO) that we have seen this winter and so when the

models came out with them dream synoptics it was imo realistic to believe that they would come off.

I know when I look back at this winter and especially this month I will think that we truly missed out on

a country wide deep freeze (850s of -14c to -16c ).

Just seen the ECM 12z and is that the fabled northeasterly coming into view on the t240 chart

I wonder lol.

It’s nice that we agree CC; I am indeed not a mild winter fan, just the same as you. I think if we had these models in the 60s they would be projecting mega freeze ups then as well, but most of the time that’s not what we got and they would be wrong. That’s why I don’t trust the models when they predict mega freeze ups, it’s not about (as it is for some) about being blinded to the possibilities of sustained really cold weather hitting the UK just because of the recent run of really very mild winters. It’s about realising that synoptics projected for 144hrs plus will change, if they look as good as they are going to get at that 144hr mark then the only likely way for them to change is for the worse. And really I have waited in vain all winter for the pretty good at 144hr pattern to upgrade to something truly special, so far as I say in vain. Who knows maybe that ECM t240hr chart will come good, it’s another reason why I don’t get down about model runs, as who really knows what’s round the corner, GP maybe, he's been pretty good this year, but not infallible as I'm sure he is more than aware. I have a deal of admiration for the way he posts, all business and never gets drawn into arguments, maybe because he appears so knowledgeable nobody is brave enough to pick a fight, I wish I was that good.

[Milhouse]

Lovely GFS in FI. Nobody can deny that would be a great start to Spring. Warm days and cool nights. Hopefully the models will keep the idea of high pressure moving east over the UK in around 8- 10 days time.

[snowray]

yeah - in france

These Channel low type features are of course notoriously hard to pin pont, I have lost count now of the number of times in past Winters that they (MO and other models) have got it all wrong even at this time frame and the whole lot has ended up just clipping the Isle of White when the PPN had been shown as far North as the Mildlands in the early Morning forecast.

If baffles me that with all this massive computer power they still can't model these features acurately even within 24 hrs. Probably will end up even further South, and no good to us down here because temps will be way too marginal.

Edited February 21, 2010 by snowray

[andymusic]

These Channel low type features are of course notoriously hard to pin pont, I have lost count now of the number of times in past Winters that they (MO and other models) have got it all wrong even at this time frame and the whole lot has ended up just clipping the Isle of While when the PPN had been shown as far North as the Mildlands in the early Morning forecast.

If baffles me that with all this massive computer power they still can't model these features acurately even within 24 hrs. Probably will end up even further South, and no good to us down here because temps will be way too marginal.

And they've gone the other way too - famous one last year in february - caught everyone out - piles of snow - shouldn't have even made it here

[lukemc]

Lovely GFS in FI. Nobody can deny that would be a great start to Spring. Warm days and cool nights. Hopefully the models will keep the idea of high pressure moving east over the UK in around 8- 10 days time.

Would that GFS FI be a similar outcome to late March 2009 or February 2008? With settled weather with warmish days but still with the possibility of frosts at night? I think many would welcome such settled weather with all the cold and snowfall that we have had this winter even among the cold and snow lovers on here!

Yes I got quite a bit of snow this morning most of it has melted now but how is it looking for further snowfall for me later this week? (I am from Liverpool of course) - we have had a few good snow events this winter but it would be nice to get a lot of snow in a single event to rival records in winters in the past for single snowfalls if the ECM came of could I see quite a bit of snowfall this week? Surley their is the potential for a February 1996 style event for the North looking at current models - I would be delighted with that - anyway talking of February 1996, how long did that event last and what where the depth was it like a true snowstorm in sense of what was recently experienced on the East Cost of the USA with heavy drifting and blowing snow?

Luke

[john mac]

And they've gone the other way too - famous one last year in february - caught everyone out - piles of snow - shouldn't have even made it here

Hope this is the case mate, we,ve had very little snow here this winter, i think pretty much all of this weeks weather will come down to nowcasting, i have very little confidence in the models at all at the moment.

[I remember Atlantic 252]

Lovely GFS in FI. Nobody can deny that would be a great start to Spring. Warm days and cool nights. Hopefully the models will keep the idea of high pressure moving east over the UK in around 8- 10 days time.

yes I think that will be a growing trend for high pressure to move in around 4th March, both models showing it, would be a decent start to spring. Will come as a relief as well after all the rain, the bbc 5 day for parts of the SE ive never seen it that bad

[MP-R]

Oh no! GFS FI showing the Azores High - already! Let's hope this changes as we have a lot of Atlantic catching up to do before the Azores High is welcome in...say May/June.

In the here and now however, this is an interesting branching off from the original low in the Atlantic for tomorrow:

http://www.wetterzentrale.de/pics/Rtavn241.html

[snowray]

And they've gone the other way too - famous one last year in february - caught everyone out - piles of snow - shouldn't have even made it here

Yes your quite right of course, they can go the other way and end up further North. Although in my experience they tend to go South more, maybe 70/30.

Hope this is the case mate, we,ve had very little snow here this winter, i think pretty much all of this weeks weather will come down to nowcasting, i have very little confidence in the models at all at the moment.

Very little snow here as well, since 10th Jan had one heavy shower that gave me an over night covering of .05cm, and a dusting on another morning.

[Cheese Rice]

Fingers crossed evryone that we get a nice suprise from GFS18z i cant handle anymore rain, lets hope the is slightly furthur south and east ( for my location at least)

I wouldn't be surprised if it further south on the next runs tbh, possibly just clipping Kent. Hopefully the GFS will come more inline with the UKMO/ECM, if it doesn't then another run for the bin.

[Duane S.]

Yes your quite right of course, they can go the other way and end up further North. Although in my experience they tend to go South more, maybe 70/30.

I'd agree with that. A more southerly track is looking more likely than not I would say.

A lot will depend on how deep the trough gets. If it is a fairly deep one then it will likely be win win for those in the North as not only will it track on a more Northerly latitude but will by defination also provide more PPN. A fairly simplistic way of evaluating it though.