Model Output Discussion - 30th November onwards

[Frosty.]

Mosts intriguing and they of course will know better than us, is that my surface feature behind his head too? Also, just to clarify, it is also that feature which is driving the amplification and/or lack of it, Frosty?

Well from what darren shows, it looks like a direct hit Northerly blast to me with the atlantic high further west, much better than the ukmo 12z @ T+144 with the coldest uppers just brushing down the east coast of the uk.

[gottolovethisweather]

Hats off to GFS if its called this right its never been keen to prolong this cold by much more than 2 or 3 days, the same can be said for GEM as well

 

Yes, from a verification point of view it would be good as yes, sometimes the GFS does GET THINGS RIGHT. However, I'm not certain 95% of us would HOPE that it's correct. I trust that's what you were hinting at, Gavin.   Might end up cool and HP dominated anyway I guess, so if not snowy something seasonal. Whatever, I'm attempting to second-guess Mother Nature and it's time I had that drink.

[Joe Levy]

I think that some excellent posts have been made on this forum over the last few days explaining the effects of the upstream pattern on our weather. I know that I wouldn't be able to understand the importance of shortwaves and lows exiting the Eastern Seaboard without them explaining it, so in amongst all of this ramping and ranting that belongs elsewhere, those who look at the broader picture certainly deserve a round of applause 

[UV-RAY]

Right, I have just analysed the UKMO T+120 and T+144 charts to see what all the fuss is about. There is no need to get into a big personal argument about it chaps because by the time the next UKMO runs again, no doubt that there will be further changes - so in effect you will never know what the UKMO T+168 would show!

My take on it ? Well look at the T+120 and we see the offending low off the eastern seaboard:

UN120-21.GIF

Which way does it go by the next frame T+144. Well by my look 75% of the jetstream energy goes over the block with the resultant 25% going under.

UN144-21.GIF

That would tend to suggest that no undercutting would occur and the block would travel east before flattening. But we all know that in another 12 hours the charts may look completely different as they try to get to grips with what actually is going to happen and therefore we can't rule out the 25% option anyway.

The voice of reason and common sense prevails but no matter how many times you repeat this the same old, same old will continue with the next model output. It does show though that your better reading the the posts that aren't trying to point score or try and discreetly wind up others. Good analysis Ed and also from one or two others here. Edited November 30, 2013 by Sceptical Inquirer

[Mucka]

GFS ensembles showing a split between a 1 day flirt and a proper cold snap. Only one traitorous member in its suite is going for the sort of eye candy ECM has thrown recently.

 

Forget the mean after the 7th as we are almost certainly in sub -5 850's or +0 for the 8th and perhaps 9th. One or the other.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=254&y=86

 

Cherry picked purely to provoke. 

 

Edited November 30, 2013 by Mucka

[Frosty.]

The voice of reason and common sense prevails but no matter how many times you repeat this the same old, same old will continue with the next model output. It does show though that your better reading the the posts that aren't trying to point score or try and discreetly wind up others. Good analysis Ed and also from one or two others here.

Exactly and there is a zero tolerance policy against all the sniping going on, paul will be angry

[gottolovethisweather]

Right, I have just analysed the UKMO T+120 and T+144 charts to see what all the fuss is about. There is no need to get into a big personal argument about it chaps because by the time the next UKMO runs again, no doubt that there will be further changes - so in effect you will never know what the UKMO T+168 would show!

 

My take on it ? Well look at the T+120 and we see the offending low off the eastern seaboard:

 

UN120-21.GIF

 

Which way does it go by the next frame T+144. Well by my look 75% of the jetstream energy goes over the block with the resultant 25% going under. 

 

UN144-21.GIF

 

That would tend to suggest that no undercutting would occur and the block would travel east before flattening. But we all know that in another 12 hours the charts may look completely different as they try to get to grips with what actually is going to happen and therefore we can't rule out the 25% option anyway.

 

The voice of reason. Thanks, that's the first time I've heard mention of my surface feature for near on 100 posts, other than my own. I'm glad you've confirm I'm reading the charts correctly and that I did have had something worthy of chuntering on about.

 

Thank you again Chio.

Edited November 30, 2013 by gottolovethisweather

[radiohead]

12Z GFS ENS are roughly split on the 7th between cold and milder options. The op was with the milder group. Also looking at pressure, at midday on the 6th the op has higher pressure over northern England than all 20 of the ENS members and the control.

[pip22]

TBH I can see windstorms will be more likely feature than snow this December especially if the mild SWs involved. I wouldn't mind we have a major storm over Christmas.   The weather in the next couple of weeks is going to be changeable and mobile, much like last late October. I cannot rule out a cold snap or two. I could be wrong though.

Edited November 30, 2013 by pip22

[terrier]

Well from what darren shows, it looks like a direct hit Northerly blast to me with the atlantic high further west, much better than the ukmo 12z @ T+144 with the coldest uppers just brushing down the east coast of the uk.

But exeter have just tweeted that mogreps is only showing a 1 day cold spell now frosty. So i would expect downgrades now.

[Summer Sun]

Towards the end of GEM's run the Atlantic high is approaching but first the delayed northerly arrives

 

Edited November 30, 2013 by Summer Sun

[gottolovethisweather]

I think that some excellent posts have been made on this forum over the last few days explaining the effects of the upstream pattern on our weather. I know that I wouldn't be able to understand the importance of shortwaves and lows exiting the Eastern Seaboard without them explaining it, so in amongst all of this ramping and ranting that belongs elsewhere, those who look at the broader picture certainly deserve a round of applause 

 

Hear hear Joe, better to be educated by the masses in here as it all about our passion for the weather after all.  Indeed, I want to shout out to those whom have helped me over the years too, it is much appreciated. Like Joe, I have learnt a lot over the last few days as well. I have been on here a lot lately haven't I, must be a chance of something wintry turning up, or maybe the wait will be extended.

Edited November 30, 2013 by gottolovethisweather

[Frosty.]

Darren's forecast not ran with the 12z data though is it?

I don't know, only the guys at the met office can tell you what they use in terms of newest data.

[Jayces]

But exeter have just tweeted that mogreps is only showing a 1 day cold spell now frosty. So i would expect downgrades now.

 

Correct me if I'm wrong but wasn't the tweet from #Essexweather who are I believe an independent weather forecast company and nothing to do with the Met Office? As far as I am aware they pay to have access to the MO-GREPS model but aren't Met Office employees? So their opinion is just another one like the many here as to what may or may not happen?

 

Apologies if this is OT mods but the thread is filled with enough confusing conflicting opinions as it is that we don't need any incorrect statements as well. Oh and further apologies if I am actually wrong and #essexweather are a Met Office branch.

 

What I think there should be more of in this thread are posts like the one earlier that explained the 25% / 75% options on the low pressure (I believe most people call them short-waves incorrectly?) as posting charts with diagrams of what needs to go where and things we should look out for is a lot easier to understand then describing what needs to happen.

[TEITS]

Just a quickie.

 

I have been following the models lately and to be honest the output does not excite me from a cold perspective. Appears to me snowfall will not be widespread because by the time the cold N,ly flow is established it moves away E. Obviously favoured places in Scotland are the exception.

 

Beyond and I see HP becoming centred just to the S of the UK. So whilst the S should remain dry, settled, cold at night, the far NW could become milder and more unsettled although this depends on how far S the HP is. What I do not see is any prolonged cold spell from the N or E at the moment.

 

Just add that my view of the UKMO +144 is its a poor chart. Very little chance of the cold being prolonged from +168 onwards.

[I remember Atlantic 252]

Expecting a backtrack on the ECMWF 12Z, just not convinced and GFS is the main model

 

Still expecting a big backtrack on ECMWF 12Z, still fear GFS has this one right, no northerly next weekend

 

UKMO a bit better with a toppler

[Joe Levy]

At 72 hours and so far the ECM is behaving itself, but stay alert and stay patient as we know things could change in either direction at any moment! Such pretty colours with such evil tendencies, a sort of nightmarish meteorological rainbow...

[IDO]

Correct me if I'm wrong but wasn't the tweet from #Essexweather who are I believe an independent weather forecast company and nothing to do with the Met Office? As far as I am aware they pay to have access to the MO-GREPS model but aren't Met Office employees? So their opinion is just another one like the many here as to what may or may not happen?

We have to grab every titbit we can from these "higher-res models", as they are not public. They aid us in trying to understand which model may be right or not when we have a divergence.CFS Daily may be closer to the likely outcome:T138: T156: Edited November 30, 2013 by i'm dreaming of...

[Spah1]

@fergieweather: Hopefully in-out of cold snap late next week pretty speedily, as @metoffice always suspected. No 3-month gig as progged by Express 'experts'

[Cecil Hogmanay Melchett]

Unfortuantely it is starting to look like a blink and you'll miss it affair...That low is just too pwerful which is a real shame.

Edited November 30, 2013 by happy days

[gottolovethisweather]

At 72 hours and so far the ECM is behaving itself, but stay alert and stay patient as we know things could change in either direction at any moment! Such pretty colours with such evil tendencies, a sort of nightmarish meteorological rainbow...

 

I sound like a old record which keeps skipping but watch the surface feature over the Eastern seaboard of the US guys n gals, for developments further down the line.

Edited November 30, 2013 by gottolovethisweather

[Mucka]

My last word on the now infamous UKMO 144 chart. Those saying prolonged cold looks unlikely I basically agree with and as far as the initial disruption of the low and energy distribution Chino won't be far from mark but the low is spilt 3 ways not two and that is important because some of that energy (75%?) that is sent over the block is going to slide SE on its Eastern flank. The high will not be pushed East as quickly as some people suggest IMO because a) the forcing low that prevented ridging into Greenland and pushed the pattern East at 120h has now disrupted and not only that a slider on the Eastern flank would also help prevent it being pushed East. So what is forcing the high East?

 

There is a better argument to say the high would sink and that is likely IMO but it would be a fairly slow sink and if the slider developed into NW Europe that could bring about the possibility of WAA being forced NE later because the high would be propped up, imagine a low to the SE of the UK on that 144 chart and tell me it would look poor because if and it is a big IF that shortwave was a nice slider and deepened over NW Europe that is not far from the chart you would be looking at if saw a 168 except with the ridge sunk slightly SE but with no forcing low to seal its doom.

 

 

ECM 96h already better than GFS.

Edited November 30, 2013 by Mucka

[Cheshire Freeze]

Differences to the GFS at 96 hrs. If it sticks to its 0z idea at 120 hrs then I'm backing the ECM and its extra resolution all the way. As BA pointed out, it's been fairly steady on the progression for quite a few runs now.

Edited November 30, 2013 by CreweCold

[cooling climate]

The ECM does not seem to be backing down on the more amplified

pattern at t96 although the t120 chart will be more telling.

[ChartViewer]

Differences to the GFS at 96 hrs. If it sticks to its 0z idea at 120 hrs then I'm backing the ECM and its extra resolution all the way.

Unless that extra resolution recently upgraded I believe, is taking it down the garden path...Lets hope not!

 

Maybe not!

 

Edited November 30, 2013 by ChartViewer