Model Output Discussion 01/09/17

[Daniel*]

1 hour ago, blizzard81 said:

I wonder if this will  be reflected in the next ec46 update. Or will it continue to lead us up the northern heights garden path like it did last year. 

Same old every single year folk jumping to firm conclusions based on a single operational ect. Uncertainty is high a negative NAO still puts us in the ballpark - still pretty decent if I may add just nothing exceptional. I follow the 'professionals' who work for the met and going by recent tweets they seem more enthralled refer to tweet thread. 

[blizzard81]

The best way to explain  the model output at the moment can be summed up by glass half full or glass half empty. With the former in mind then there is no doubt that the outlook is very untypical of most November's we have become accustomed to over the last 25 years. With the latter in mind then you are looking for a late November 2010 which is probably a 1 in 100 year event. 

[blizzard81]

8 minutes ago, Daniel* said:

Same old every single year folk jumping to firm conclusions based on a single operational ect. Uncertainty is high a negative NAO still puts us in the ballpark - still pretty decent if I may add just nothing exceptional. I follow the 'professionals' who work for the met and going by recent tweets they seem more enthralled refer to tweet thread. 

I do apologise if my post offended you in any way. It certainly wasn't meant to. With regards to 'tweets', they just aren't my thing to be honest. 

[tight isobar]

9 minutes ago, Daniel* said:

Same old every single year folk jumping to firm conclusions based on a single operational ect. Uncertainty is high a negative NAO still puts us in the ballpark - still pretty decent if I may add just nothing exceptional. I follow the 'professionals' who work for the met and going by recent tweets they seem more enthralled refer to tweet thread. 

There is absolutley 'nothing' to be despondent about throughout output!

We are in early november and a whole array of option(if your looking for cold) are in front of you.

And with such northern-hemispherical state'and blocking solutions it hardly suprising the divergance...to a degree.

All looks very promising from a cold perspective...

Moreso later this month/early december!

[damianslaw]

Always important to look at the jetstream profile forecasts alongside the model forecasts, for an idea of likely conditions at the surface. Period 20-27 Nov a firmly southerly tracking jetstream. You only need a slight build of heights to the north with the jet riding underneath to produce preety cold wintry conditions at the surface in the UK, very cold uppers are not needed.

[tight isobar]

Just now, tight isobar said:

There is absolutley 'nothing' to be despondent about throughout output!

We are in early november and a whole array of options(if your looking for cold) are in front of you.

And with such northern-hemispherical state'and blocking solutions it hardly suprising the divergance...to a degree.

All looks very promising from a cold perspective...

Moreso later this month/early december!

 

[Nick F]

25 minutes ago, Polar Maritime said:

The GFS has consistently shown a N/W flow of types over the past few days. A better option tonight though.

 

 

Next weekend could be the fourth weekend running that we have a northerly, seems reasonable ensemble support and high res consistency for it too. Quite an usual feat in recent years ... though never really potent looking for now we have to rely on it as our coldest source at the moment until out east gets colder.

 

[phil nw.]

What we have is a changeable and often rather cold setup.The UK often on the polar side of a wavering and split jet.The models all continue to show a dis -organised pv right through their runs incl 12z gefs.

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384

It's not a classic northern blocking pattern but the amplification and mobility in the Atlantic is enough to filter polar air south so we see snow higher up and some night frosts.

Tis a little early in the season to expect anything too wintry  but certainly we have a more Autumnal chill to the weather this November.

 

Edited November 10, 2017 by phil nw.

[Man With Beard]

19 minutes ago, blizzard81 said:

Is this because the Atlantic breaks through?

Atlantic breaks through on some, others just see the ridge collapse. I suppose clusters 3 or 4 might result in a weak high towards Scandi, on reflection, and Euro heights mostly surpressed apart from cluster 1 - so hardly a mild-fest, either.

[feb1991blizzard]

2 minutes ago, damianslaw said:

Always important to look at the jetstream profile forecasts alongside the model forecasts, for an idea of likely conditions at the surface. Period 20-27 Nov a firmly southerly tracking jetstream. You only need a slight build of heights to the north with the jet riding underneath to produce preety cold wintry conditions at the surface in the UK, very cold uppers are not needed.

I have to disagree with some of the comments regarding uppers lately, someone even suggested -1c uppers could be good enough yesterday which I just cannot see, lets look at the synoptics.   

1. convective showrers Easterly - you need the uppers low (around -6 at the very worst) preferably -8c to create any convection

2. Lee Easterly, unless theres low uppers it will just be the last back edge snow on high ground for half an hour as the trough clears SE.

3. Northerly, we are seeing and have done recently that -5c isn't good enough at all.

 

The only synoptical set up where -1c would be good enough is a slider-undercutter scenario but not now, it would have to be a push from the atlantic coming up against a very cold block with very cold surface conditions after a right ol dumping followed by lots of radiation for a few days during mid winter, and even then -1c would screem freezing rain to me even in those circumstances.

 

The facts are that even the few flatliners on recent GEFS suites have flatlined at -7c at best, the vast majority well above -5c with the average around -3c at best

[MP-R]

7 minutes ago, feb1991blizzard said:

I have to disagree with some of the comments regarding uppers lately, someone even suggested -1c uppers could be good enough yesterday which I just cannot see, lets look at the synoptics.   

1. convective showrers Easterly - you need the uppers low (around -6 at the very worst) preferably -8c to create any convection

2. Lee Easterly, unless theres low uppers it will just be the last back edge snow on high ground for half an hour as the trough clears SE.

3. Northerly, we are seeing and have done recently that -5c isn't good enough at all.

 

The only synoptical set up where -1c would be good enough is a slider-undercutter scenario but not now, it would have to be a push from the atlantic coming up against a very cold block with very cold surface conditions after a right ol dumping followed by lots of radiation for a few days during mid winter, and even then -1c would screem freezing rain to me even in those circumstances.

 

The facts are that even the few flatliners on recent GEFS suites have flatlined at -7c at best, the vast majority well above -5c with the average around -3c at best

But cold and wintry doesn't necessarily mean snow. What you say is correct re snowfall but last winter's cold was predominantly surface based with sometimes quite positive uppers.

It's something that bugs me a lot is when people say said month wasn't cold or the winter was rubbish for cold... when they actually mean snow. Last winter case in point!

[Man With Beard]

@feb1991blizzard it was me who mentioned -1C uppers but under the very conditions you mentioned (I referred to snow fields), which of course we don't have. 

I think at the moment - without a cold continent - we might possibly get snow from an easterly at -5C uppers at nighttime if winds are brisk and the sea-track is short.

But an easterly will cool very quickly from now on, so the real issue will be if the easterly could be sustained for three days or more. If it happened

Overall - realistically I think it's a 20% chance of snow for the south and 40% for the north based on what we've seen from the models in the past two days.

[blizzard81]

Just now, MP-R said:

But cold and wintry doesn't necessarily mean snow. What you say is correct re snowfall but last winter's cold was predominantly surface based with sometimes quite positive uppers.

It's something that bugs me a lot is when people say said month wasn't cold or the winter was rubbish for cold... when they actually mean snow. Last winter case in point!

Most of the forum members base the success of the winter on how much snowfall they experience. A cold rainy/sleety day or dry cold day  just doesn't cut the mustard for most coldies, myself included. 

[feb1991blizzard]

7 minutes ago, MP-R said:

But cold and wintry doesn't necessarily mean snow. What you say is correct re snowfall but last winter's cold was predominantly surface based with sometimes quite positive uppers.

It's something that bugs me a lot is when people say said month wasn't cold or the winter was rubbish for cold... when they actually mean snow. Last winter case in point!

Last winter was way above average temps.

[Daniel*]

32 minutes ago, blizzard81 said:

I do apologise if my post offended you in any way. It certainly wasn't meant to. With regards to 'tweets', they just aren't my thing to be honest. 

I apologise for the aggressive tone just having a scan through GFS 18z things are far from normal incredible last frame just to exemplify, it's stark how the pretty 'strong' stratospheric vortex is seemingly disconnected with tropospheric vortex from what I'm looking at, how long this persists for I do not know, but we must capitalise on it never mind it being too soon waiting till December may not suffice!..

 

Edited November 10, 2017 by Daniel*

[Froze were the Days]

13 minutes ago, feb1991blizzard said:

Last winter was way above average temps.

January last winter in the south/south east was slightly chillier than normal due to quite regular ground/air frosts but December and particularly February were mild.

[blizzard81]

18 minutes ago, Daniel* said:

I apologise for the aggressive tone just having a scan through GFS 18z things are far from normal incredible last frame just to exemplify, it's stark how the pretty 'strong' stratospheric vortex is seemingly disconnected with tropospheric vortex from what I'm looking at, how long this persists for I do not know, but we must capitalise on it never mind it being too soon waiting till December may not suffice!..

 

We need to strike while the iron is hot so to speak

[damianslaw]

As someone posted above, with reference to cold and wintry, I wasn't necessarily implying copious snowfall, I was meaning in terms of cold surface conditions sometimes significantly cold - under a ridge in winter you can easily see sub-freezing maxima especially where fog develops and you don't need -10 uppers for that. Yes expecting snowfall from -5 upper northerlies and easterlies at this time of year is quite a tall order in a showery airstream, but throw in a trough or frontal feature and evaporative cooling takes hold.. 

Warm fronts moving into cold surface air with uppers barely below 0 degrees in winter can deliver copious snowfalls... Its all about the synoptics, the strength of wind, flow of wind, intensity and duration of precipitation - these are the factors that need to be looked at when speculating snowfall, local topography, shelter, relief, proximity to water bodies including the sea, urban heat island etc etc all come into play.

[Cheshire Freeze]

1 hour ago, bluearmy said:

The ec 46 bottomed out at -2 aswell although it trundled slowly back to neutral around Dec 13th. 

Nick, I don't think it should come as any surprise that the extended ensembles are sniffing a move away from a -AO. The long range seasonals have mostly been suggesting a +AO/NAO winter for a significant period of time...including December.

[blizzard81]

I think the gfs 18z control run is just about the best we can hope for now. I would be cockahoop if that run came off. 

[MP-R]

33 minutes ago, blizzard81 said:

Most of the forum members base the success of the winter on how much snowfall they experience. A cold rainy/sleety day or dry cold day  just doesn't cut the mustard for most coldies, myself included. 

Some do, some don't. Some appreciate all aspects of cold weather, myself included.

30 minutes ago, feb1991blizzard said:

Last winter was way above average temps.

Not drastically so here. Had plenty of frosty weather in January and December started and ended cold.

[blizzard81]

This morning's runs will be very telling and will go quite a long way to deciphering where we go towards months end. 

[geordiekev]

I just hope that the council's aren't caught back footed as is often the case with any early falls, living at the 250m mark I have witnessed a few damaging wet blizzards which were tricky to forecast due to being early in the season and the uppers alone non conducive. Below was 12th Dec 15, gave 6 inches of wet snow in a couple of hours,  was treachourous, but had my first ever snow day from work.  Here's hoping for my second. 

It certainly looks like an interesting end to the autumn but worried as last year was promising too with lack of zonality,  similar vortex and had already had first snowfall on 9th Nov.

It's good to be back in the hunt though and can almost smell the wears of winter. 

[Hocus Pocus]

1 hour ago, CreweCold said:

Nick, I don't think it should come as any surprise that the extended ensembles are sniffing a move away from a -AO. The long range seasonals have mostly been suggesting a +AO/NAO winter for a significant period of time...including December.

They’ve hardly covered themselves with glory over the years though, I’m not suggesting that they are wrong now but all long range modelling is pretty poor really. 

[ScottishSnowStorm]

Need to stop worrying about short term deep cold and snow and look toward the later end of the month and see how the pattern progresses but there has been trends in the models that should the pattern remain for greenland then things may look more positive. 

First model the GEM 12z and this is looking good and blocked at the end with an easterly flow 

Now the 850 temps are showing all cold air taken from canada over to siberia which if pattern persists would put us in a really good position 

Next is the extended JMA 12z which also shows us inside of an easterly flow 

And again as seen from the 850 temps wants to steal the cold canadian air into siberia 

Now extended GFS 18z shows the same with pressure charts having us under an easterly influence 

It wont let me upload this pic but we all know how it ended 

And again 850 temps taking all cold out of canada to siberia 

The only stick in the ointment is the ECM 12z that has went pretty messy and is at odds with the others over western canada and would be questionable how good an easterly influence we would be under 

And as well with 850 temps differs from others and would be questionable how much of the cold air would transfer 

So from what i see in the short term there will be nothing spectacular but it has never shown that we would ever see anything like that but should the patterns and trends continue in the models the end of the month is looking far more promising and if we keep hieghts around greenland and the 850 trends continue could verge on the spectacular if the siberian cold moves in our direction