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Model Output Discussion - cold spell to end Autumn


Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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Just now, karlos1983 said:

Cracking set!

You won’t get snow from an easterly though northwest :oops:just kidding 

ensembles done, that’s my bedtime lol

Haha you might be suprised to hear my favourite wind direction is easterly- produces the goods here more often than not!!

Either way those Ens are brill-lets hope they look the same in the morning :)

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You know what - I havent seen 1 hopecast on here. People have put all their points of view across in a pretty good mannor- infact its been pretty good debate. The only post that sticks out a mile

Still coming slowly off a cautious fence Long term total global atmospheric angular momentum trends can tell you a lot about pattern changes due to the effects the rises and falls in global wind-

Afternoon All - A frantic few days on here with pages & pages of posts flying through in a matter of hours- I think we have 2 main discussion points at the moment-  1) The short to

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WOW -

Not a huge amount of scatter there in the extended range cracking set IMO many going cold and sustained cold possibly even colder onwards mid month, this would fit with an easterly. 

F82D609C-844B-431C-AB58-9018EA77D672.thumb.gif.6063e29ce5390d9af538a332b93074f2.gif:)

 

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17 minutes ago, fat chad said:

It's what makes this forum so great. If you can detach yourself from the dramatics and toy trowing when it usually doesn't go to plan, then you can enjoy an educated thread... 

Agree with everything you say except educated lol 

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2 minutes ago, MKN said:

If the trend remains consistant snowfall from any slider will be confined for the Scottish highlands.

Not sure-depends on which model you believe - doesn't look like there is clarity just yet and i'm not sure there is a trend, all 3 seem a bit different - hopefully the 0z runs will correct south, we can but hope..

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I've been rooting about, so I can compare the current fax with the last time a NW-based slider (as opposed to a channel low type slider) produced snow rather than rain here:

Now:

20171205_2248.PPVO89.thumb.png.2f96de8bff3c07c0d33e7e8f604964ce.png

 

Then:

5a2734c7de8f1_20130118SNOW.thumb.png.f724be51694cea8994cfae86aa999862.png

There needs to be an awful lot more south-westward correction to get to the 18th Jan scenario where there is no spoiler mild sector. In particular, check out the direction of the isobars ahead of the fronts. That's what I'm talking about.

 

Consequently, I'm currently focusing on Friday night's "hidden" trough, which is at least closer to becoming a reality:

 

Trough Only Hope.png

Edited by The Enforcer
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14 minutes ago, MKN said:

If the trend remains consistant snowfall from any slider will be confined for the Scottish highlands.

The irony of this post is that its not completely out of the envelope that you could get absolutely buried on sunday, indeed some recent runs have illustrated this.

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1 hour ago, Ed Stone said:

Looks promising...BUT not as promising as previous runs have done and is also 48 hours' later:

h850t850eu.png

Is that T384 ? That must have taken quite a bit of searching :hi:

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12 minutes ago, northwestsnow said:

Not sure-depends on which model you believe - doesn't look like there is clarity just yet and i'm not sure there is a trend, all 3 seem a bit different - hopefully the 0z runs will correct south, we can but hope..

None of the models show snowfall restricted to the Highlands so there is no ‘not sure-depends’. GFS has been a bit like a yo-yo north and south adjustments, I’d firmly say if you’re north of Birmingham you’re in the safe zone. Nor is the low trending further north the EC op took it further north, the EC ENS mean had it a sizeable shift further south. I’m almost certain we’re more likely to see a southern adjustment in the ECM 00z. 

3B1ABC9A-D0E0-4C7F-BA87-C855DE632DB5.thumb.jpeg.fc756277f3d176cafa3d46ba51388791.jpeg

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2 minutes ago, feb1991blizzard said:

The irony of this post is that its not completely out of the envelope that you could get absolutely buried on sunday, indeed some recent runs have illustrated this.

Maybe in the GEFS but I have seen nothing of the sort minimum I’ve seen is parts of Northern England get a pasting.

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1 minute ago, Daniel* said:

None of the models show snowfall restricted to the Highlands so there is no ‘not sure-depends’. GFS has been a bit like a yo-yo north and south adjustments, I’d firmly say if you’re north of Birmingham you’re in the safe zone. Nor is the low trending further north the EC op took it further north, the EC ENS mean had it a sizeable shift further south. I’m almost certain we’re more likely to see a southern adjustment in the ECM 00z. 

3B1ABC9A-D0E0-4C7F-BA87-C855DE632DB5.thumb.jpeg.fc756277f3d176cafa3d46ba51388791.jpeg

Hope your right - i suspect we will see a southward shift but not by much- its fascinating viewing- looks like parts of the north west might get some decent snow showers late thur into Fri morning.. shower distribution is impossible to call at this range but i'd say Peak district will get 5- 10 cm..

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42 minutes ago, beefy201 said:

Agree with everything you say except educated lol 

There is some really learned folk in here...  You just have to filter though the hype.... If you hang around often enough, you will see who they are.

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3 hours ago, I remember Atlantic 252 said:

'97 was good here, angle of attack was from SW, much better angle for snow

archives-1997-12-16-0-0.pngarchives-1997-12-17-12-0.png

And '96, in fact London had a white Christmas that year, didn't produce much snow though, more flurries if I remember right, Trafalgar square at New Years was bitter.:cold:

archives-1996-12-25-0-0.png

archives-1996-12-31-0-0.png

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1 minute ago, feb1991blizzard said:

prectypeuktopo.png

Contradictory to your point regarding there being an envelope for just snow falling for the Highlands? That is what I was getting at, indeed there is widespread risk of snowfall even south of the M4 there is a low risk if we see any southern corrections from tonight’s output. Mmm! 

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3 hours ago, I remember Atlantic 252 said:

'97 was good here, angle of attack was from SW, much better angle for snow

archives-1997-12-16-0-0.pngarchives-1997-12-17-12-0.png

The 18 Jan 2013 had such a good approach, fronts coming in from the south-west, even though the Low had originated from the north-west. What that and your examples have in common, is that the High concedes ground by moving eastwards rather than southwards, so it can influence the wind direction. Low res models at T+120 have been continually over-estimating snowfall amounts on every NW slider scenario since then, because at that range they are under-estimating the impact the mild sector has on dew points. The draw from the cold continent in our examples keeps the dew points down and if this was being projected now then the snow totals would be more realistic.

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3 minutes ago, Daniel* said:

Contradictory to your point regarding there being an envelope for just snow falling for the Highlands? That is what I was getting at, indeed there is widespread risk of snowfall even south of the M4 there is a low risk if we see any southern corrections from tonight’s output. Mmm! 

but the last few gfs runs have been fairly consistent, it would take a much bigger swing to only get snow for highlands than it woul for east midlands to get belted.

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19 minutes ago, feb1991blizzard said:

prectypeuktopo.png

Stop the clock. That chart essentially represents the snowfall spread of all the NW sliders since Jan 2013 and from the first ECM op run last week that touted a NW slider, if you had asked me to draw a line demarcating the southern extent of snow over the UK, I would have put it almost exactly in a line from Liverpool to the Thames estuary.

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4 minutes ago, The Enforcer said:

The 18 Jan 2013 had such a good approach, fronts coming in from the south-west, even though the Low had originated from the north-west. What that and your examples have in common, is that the High concedes ground by moving eastwards rather than southwards, so it can influence the wind direction. Low res models at T+120 have been continually over-estimating snowfall amounts on every NW slider scenario since then, because at that range they are under-estimating the impact the mild sector has on dew points. The draw from the cold continent in our examples keeps the dew points down and if this was being projected now then the snow totals would be more realistic.

These are the best battleground type scenarios, projected to turn to rain in midlands and never did, very active weather systems - continuous huge flakes for hours.

archivesnh-1994-2-14-12-0.png

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After the initial northerly, for me it looks like a perfect set up for heavy snowfall somewhere in the UK. The question is where ?  The current fax chart for sunday is unlikely to be the actual fax chart. It will revise itself, with the mild air further south westwards. I've seen this happen many times before when very cold air has taken hold of the UK which it will have done in advance of the slider. Looking forward to an exciting weekends weather watching and beyond.  Indeed if it corrects itself far enough south west then the Scottish Highland's maybe one of the only place in the UK not to get some snow. Up there it may then just be very cold and frosty with the odd flurry !  Synoptics upgrades seem likely to be shown by the models as they try to get a handle on the developing situation.

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16 minutes ago, JBMWeatherForever said:

The current fax chart for sunday is unlikely to be the actual fax chart. It will revise itself, with the mild air further south westwards. I've seen this happen many times before when very cold air has taken hold of the UK which it will have done in advance of the slider. Indeed if it corrects itself far enough south west then the Scottish Highland's maybe one of the only place in the UK not to get some snow. Up there it may then just be very cold and frosty with the odd flurry !  Synoptics upgrades seem likely to be shown by the models as they try to get a handle on the developing situation.

Your aspirations are similar to mine. Here's what needs to change:

Hopecast.thumb.png.890ea631f14ebd38d12357b367637232.png

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6 hours ago, Djdazzle said:

I love Steve Murr’s posts, analysis etc, but to be fair even when he does get excited, 9 times out of 10 things still go wrong for coldies.

 

 

 

ukm2.2017121212.168.lant.troplant.prp.fcst.gentracker.png

 

I think you confuse excited with exciting....

Its exciting watching the models & running through the different permutations however Im only excited when there is deep cold from the east @T48 ..

So pretty much 2009/2010 & 2013 with regards to the weather - other occasions are when the SE gets in cold air then the winds slacken off generating a local cold pool- Anyway enough about me... 

9/10 - thats how often the exciting charts dont verify... - but dont shoot the messenger... maybe those 39k likes were imaginary...

This week has been exciting & I believe the GFS has performed well especially now as we see the ECM trending both the uppers downwards over the 48-72 area & corrected the slider South today-

Will it snow in the SE - the slider would have to elongate further to steer away the milder SW onshore flow - or become so shallow theres no mixing- so probably 60/40 against... but still a maybe - The key here is theres no undecut from the continent & that being absent we are always suceptable to the milder SW flow ahead of the fronts...

lets see what the 00zs bring-

* Look for GFS maintaining -10c 850s

* Look for the peak 850s to be lower in the temp warm up ( circa -3 )

* Secondary slider a distinct possibility 

* FI heights pushing up towards greenland again...

best all

s

Edited by Steve Murr
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1 hour ago, The Enforcer said:

Stop the clock. That chart essentially represents the snowfall spread of all the NW sliders since Jan 2013 and from the first ECM op run last week that touted a NW slider, if you had asked me to draw a line demarcating the southern extent of snow over the UK, I would have put it almost exactly in a line from Liverpool to the Thames estuary.

Yes because usually thats how far the inshore flow pushes the milder air ahead of the front -

no blocking usually means no snow in these zones...

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Well going through all these Posts ' i am no better than wiser to be honest ' Obviously some (most are rampers? is it gong to snow in my back garden or even in the front garden ) When you see a chart full of surprise then you are all on it like Sonic ' Then you see a chart like a wet fart you are all like ? WTF going to rain in my front and back garden ' This is only the first week of winter to be honest and there are some Dummy Throwing in here at most days .

Why and i say why look at Computer models ? Stick to Fax Charts ' why ' ? Because it is Human input and not a silly Computer sending Back and Forth to a Shatellite .

It will get cold this week obviously ' Now don't start me on Next week .

Shock to all of you ' it's going to get very very very cold with lots of Snow ' how do i know ?

i am a BIPOLAR BEAR X I SMELL THE COLD .

LISTEN AND LEARN THE GOOD WAY .

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