Model output discussion - 16th Nov onwards

[Methuselah]

To me, the current model output is looking quite optimistic...Aren't many UK cold spells preceded by a spell of quiet anticyclonic nothingness? I'm thinking that, once HP has reached the UK, half the job is done?

[BlueHedgehog074]

To me, the current model output is looking quite optimistic...Aren't many UK cold spells preceded by a spell of quiet anticyclonic nothingness? I'm thinking that, once HP has reached the UK, half the job is done?

I guess so. It's just like on the GFS run, for example, the prospect of High Pressure ridging over the UK from the South-West could at least mean the possibilities for some cool days and some chilly nights with a risk of frost for places. What happens to the High Pressure after it reaches the UK (if that was to verify) could then have consequences of whether we get colder conditions or milder conditions. (I admit I would choose the latter). Edit: although even then, some kind of split could arise where one part of the UK sees milder conditions and another area sees colder conditions.

Edited November 26, 2015 by DiagonalRedLine

[nick sussex]

The models are making a real mess of the pattern over in the USA. This chaos has been going on for several days now with a lack of agreement as to what happens with that low pressure moving east across the US plains and whether it phases with low heights over eastern Canada.

 

You can see the big differences between the GFS and UKMO at T144hrs and this will impact any ridging in the north Atlantic. The GFS does have an interesting trend and we're back to the issue of trigger shortwaves or in this case the low which fills and heads towards Denmark.

 

We'd need to see this drop south further west and go under the high as that ridges ne, after being totally underwhelmed by this mornings outputs tonights GFS especially has woken me up, lets hope the ECM doesn't put me back to sleep!

Edited November 26, 2015 by nick sussex

[SnOwFeSt]

Hmm, heights being pushed ever higher into the Arctic, putting pressure on the vortex?

I have a feeling that there could be some very interesting model watching in about a weeks time.

[Hocus Pocus]

A settled but chilly spell developing on this afternoon's GFS as we move into December

Looks very nice if that was to verify, chilly settled and hopefully sunny would be right up my street. We don't need -10 uppers and heavy snow just some frosty days and nights will suffice after the miserable damp and grey weather we've had to endure. Edited November 26, 2015 by Hocus Pocus

[inghams85]

That chart synoptically is way better than today. The high is centred over England and lower heights are in the med. The high is 200-300 miles further north so had less distance to travel to establish northern blocking. You need to look at the detail....

i wonder how many "winter's over" posts this chart would spawn if it was today.

archivesnh-1962-11-26-0-0.png

(todays date in 1962...)

[Scott M]

Hey guys I have been looking on the model discussion for the best part of 2years. Well since that dreadful winter of 2013 from a cold point of view that is. I have not really had the courage to post as I have been trying to understand what is being said and what people have posted. Anyway I still have a lot to understand. Just wanted to say prob one of best weather forums going about that I have came across and to encourage use all to keep up the good descussions use are doing. Also could someone point me in the right direction on here so I can understand models better. Thanks Scott

[phil nw.]

Hey guys I have been looking on the model discussion for the best part of 2years. Well since that dreadful winter of 2013 from a cold point of view that is. I have not really had the courage to post as I have been trying to understand what is being said and what people have posted. Anyway I still have a lot to understand. Just wanted to say prob one of best weather forums going about that I have came across and to encourage use all to keep up the good descussions use are doing. Also could someone point me in the right direction on here so I can understand models better. Thanks Scott

Hi Scott,

Welcome to the forum.Have a look here

https://forum.netweather.tv/forum/69-learners-area/

there are plenty of threads about various aspects of weather charts etc. in that section.

I hope you find them usefull.Btw perhaps you could enter your location into your avatar .

edit.Ha PM beat me to it.

Edited November 26, 2015 by Polar Maritime
Got rid^

[Scott M]

Thanks guy much appreciated.

[bobbydog]

That chart synoptically is way better than today. The high is centred over England and lower heights are in the med. The high is 200-300 miles further north so had less distance to travel to establish northern blocking. You need to look at the detail....

but that high didnt develop into northern blocking. it hung around much like the latest GFS run is forecasting. it then flattened out later. the northern blocking popped up (seemingly from nowhere) at the end of december.

you need to look at the archive charts...

[nick sussex]

Sadly the ECM has taken its bat and ball home and refuses to play!

 

The ECM and UKMO are similar upstream at T144hrs, the former turns into the Freddie Kruger cold lovers nightmare thereafter, the UKMO would likely have joined it if it went further.

 

The GEM is the best of tonights outputs in terms of cold, the GFS would be next as it at least would bring some cooler conditions however the issue is the disagreements upstream between the GFS/GEM versus the ECM/UKMO horror combo.

 

Unfortunately the GEM has a known bias for being over amplified and isn't one to put much trust in, the JMA has a different version of events.

 

Until the upstream pattern is agreed on then hard to say which solution is the correct one, as a coldie of course I hope the GEM somehow comes out on top but at this time I think the odds are probably more with the ECM/UKMO.

 

I fear the worst but will refrain from much toy throwing until tomorrow!

 

Looking at the NCEP forecasters maps, that's blended because of the uncertainty but at least phases that low with low heights over ne Canada. The State forecasts expect low pressure to deepen near the Great Lakes which is not what the ECM or UKMO do, the low is expected to head more ne and phase with a chunk of the PV and you'll see the ECM takes this east as a separate feature. You may wonder why I'm droning on so much about the pattern in the USA, basically tonight for coldies any hopes of being saved from the tedium dished out by the ECM relies on the upstream pattern of at worst the GFS but preferably the GEM which at this point would be akin to finding gold reserves in your back garden!

Edited November 26, 2015 by nick sussex

[SMU]

5 words describe the ECM tonight -

Flatter than a witches T*T

[nick sussex]

5 words describe the ECM tonight -

Flatter than a witches T*T

Agreed its dreadful stuff, I needed the smelling salts after watching that ECM run!

[Ali1977]

5 words describe the ECM tonight -

Flatter than a witches T*T

Just a glitch, another 4-5 days before ECM starts smelling the coffee.

[Liam J]

Tonight's ECM is going with what it's been showing for some time now and remains very consistent, not sure why it was such a shock tonight? And Ian mentioned this morning that Glosea was hinting at a pattern change around the 20th December (I think without checking back)... The ECM we get to view only goes out to day 10 so that potential pattern change is well out of reach of the ECM.  

[phil nw.]

Yes unusual to see the GFS more amplified.ECM doesn't favour ridging around the UK in week 2 on this evenings operational.

Looking at the gefs pressure graph there is a definite trend there for something further on.

 

whether this develops into a Euro or Scandi. high we will need to see more consistency from the models.

The spread and means for day 10 from gefs though do raise some interest

 

 

in the meantime the coming week looks very unsettled as the Atlantic jet powers up across the uk-the T72hrs fax and the NH Jet pattern for T96hrs and T144hrs tell the story.

 

wind and rain look like featuring widely in the coming week with hill snow at times further north as we see transient colder air from the north west.

Perhaps a UK high would be welcome after that lot,maybe with a bit of night frost and some calmer conditions.

 

[Frosty.]

Nice end to the Ecm 12z with high pressure building from the south with the southern half of the UK becoming more settled, this is also what the met office mentioned today with an increasingly fine spell beyond next week with overnight frosts possible.

Edited November 26, 2015 by Frosty.

[fergieweather]

Agreed its dreadful stuff, I needed the smelling salts after watching that ECM run!

Bear in mind:

- the evolution currently favoured is temporary phase of anticyclonic dominance into early Dec; then back to some zonality; then more mixed outcome signalled later Dec (as per GloSea5)

- thus GFS 12z unsurprising and fits broad expectation other than uncertainty re scope of height build

- EC-ENS still awaited and will take us out to T+360 for better look incl via clusters

- EC Monthly update later this evening too, may be instructive along with today's (awaited) GloSea5 ENS.

[Methuselah]

Nice end to the Ecm 12z with high pressure building from the south with the southern half of the UK becoming more settled, this is also what the met office mentioned today with an increasingly fine spell beyond next week with overnight frosts.

Fine, but with an increasing likelihood of persistent freezing fog?

[Frosty.]

Fine, but with an increasing likelihood of persistent freezing fog?

Let's get the fine spell first pete before worrying about freezing fog. It does look to me as though it will settle down beyond the next 7-10 days or so but we have a very unsettled spell in the meantime with a succession of atlantic lows zipping across the UK on a very powerful jet stream.

Edited November 26, 2015 by Frosty.

[Singularity]

The GFS 12z det. shows a frontal boundary pushing south Sun-Mon, only to stall across the south by noon Monday and wiggle back north during Mon-Tue. Then it comes back south again Tue-Wed, finally clearing east during Thursday morning. That's about 4 days being affected by the same boundary between airmasses. We best hope it does move around that much, else somewhere could be in for a serious drenching. Even waving about like it does on that run, it still deposits substantial amounts - widely exceeding 100 mm across western parts with 30-70 mm for central parts. Mountainous terrain receives between 150 and 200 mm. In light of which a stalled out boundary that doesn't move about much would probably throw down 100-150 mm widely with near 200 mm for western reaches and over 300 mm on high terrain.

 

In that respect it's a good thing to see the models in agreement on developing LP to the west on Tuesday as that's what lifts the boundary back north for a time. But of course that brings another severe weather threat in the form of strong winds. GFS doesn't really go for it but ECM's 12z det. looks nasty for NW Scotland next Wednesday.

 

 

Longer term, there's a big contrast between GFS and ECM as has already been discussed by others on here. GFS has the vortex highly stretched by +240 and it only becomes more ragged during the following 6 days, with all sorts of wacky pressure patterns developing as a result. The state of the trop. vortex by +384 is just bonkers, and more like I'd expect to see after a SSW, as opposed to when there's a fairly potent strat. vortex (regardless of that modest wave activity):

 

 

 

 - which rather takes away its credibility in my eyes!

 

ECM's 12z det. looks ominously close to organising the trop. vortex as of +240, though it's not entirely conclusive - but when is it ever at such range? 

Whatever the root cause, clearly the models are handling the chaotic tropical signals in different ways at the moment. It's a shame that ECM's trend toward an Arctic High has not been continued, though we need the 00z before that can be entirely accepted (after all, there are those who like to compare 00z with 00z and 12z with 12z, for reasons that I've yet to fathom).

 

 

Worth noting that GEFS continue to be dragged kicking and screaming toward a more El Nino type AAM cycle, and if this trend continues the output will probably change in significant ways once again:

 

 

It makes me wonder if ECM is simply ahead of the game and has the AAM cycle largely in phases 5/6, which is in line with the El Nino basic state and goes a long way to explaining the exceptionally strong high pressure belt across the U.S; it's the classic strong El Nino pattern cranked up to the max - and something which was well predicted by most of the long-range models several months in advance, as you'd expect given the strength of El Nino's influence there. Of course the true test is whether such conditions manage to persist for a large part of the month - there are those in the U.S. who wouldn't be surprised to see changes brought on by the unprecedented combination of forcing variables in place this year.

[mountain shadow]

With glosea gem GFS showing changes I'll out the ECM as a dodgy witches boob

The GLOSEA was potentially showing colder weather 20 odd days from now, the ECM only goes out 10.

[cold snap]

ECM is outlier tonight has little support ,maybe something more akin to GFS going forward

http://projects.knmi.nl/exp/pluim/Data/pluim_06260_0_12_60.png

[Newberryone]

Let's get the fine spell first pete before worrying about freezing fog. It does look to me as though it will settle down beyond the next 7-10 days or so but we have a very unsettled spell in the meantime with a succession of atlantic lows zipping across the UK on a very powerful jet stream.

Sorry Carl, but I fear there's little if any room for optimism from a cold weather perspective from viewing the latest Ecm, especially when I read the initial reaction and hence sheer despair felt by both Nick S and Steve M. At this juncture I would be careful what I wish for with regards to getting the "so-called" fine spell first, for that unsightly looking high could quite possibly become a stationary feature anchored to our south with frost, if any, that wouldn't be worth talking about. Of course the hope would be for the orientation of the high to eventually shift to a more favourable position in terms of cold. Roll on mid-late Dec eh!!   

[Ali1977]

ECM is outlier tonight has little support ,maybe something more akin to GFS going forward

http://projects.knmi.nl/exp/pluim/Data/pluim_06260_0_12_60.png

Definitely cooling trend looking at those ensembles later down the line