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Model output discussion - winter proper underway

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!

Message added by Paul

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17 minutes ago, nick sussex said:

Very quiet in here which often happens when some snow is imminent for certain areas .

This slider low must surely go down in NW history as one of the  most microscopically analysed , with every jog south or north by a few miles met with panic or joy !

Putting aside this current saga which is drawing to a close we have seen some interesting trends over the last day on both the ECM and GFS trying to develop a ridge near Scandi towards day ten.

Looking at the De Bilt ensembles we’re beginning to see a small cluster developing some very cold conditions.

There are hints upstream that we could see a bit more amplitude developing after a relaxation of the positive PNA.

This would help as it will begin to pull back the PV and send a bit more energy se which you need to develop lower heights over Southern Europe to support any high.

It might be that we might need more than one attempt to get that Scandi high but perhaps it might arrive a bit sooner if the models are still slow at picking up the correct MJO signal . Singularity a few pages back made  an excellent post regarding that  and it does seem that the models forecasts were wrong and weakening the signal.

So after an initial suggestion that things might turn milder it’s possible we could see the mainly cold weather extended .

 

It was met with panic or joy because a snow event like this hasn't happened for 4 and a bit years, so everyone is more sensitive to every bit of movement haha.

Anyway look at these totals from the Euro 18z 

858275D4-20F2-4C75-A130-F8A629437F68.jpeg.626aa487607444b8c82d8d522e88d247.jpg

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5 minutes ago, Ross Andrew Hemphill said:

Quite a bit further North, thoughts? 

Yes it has been noted in the NW regional...all these hi-res models couldn't be 50-75 miles out at such a short lead time could they?!

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Not looked at the models much today, but there is a growing trend to develop heights to the NE longer term, with the azores high possibly joining hands with these in time... all attention later next week, signs we may see more pronounced azores high ridging through mid atlantic with a colder northerly feed through the latter part of the week, with the trough anchoring down into central europe which is key as this would allow heights to build to the north.

We may see a shortlived milder phase around the 18-22, a dry mild before we start having to then look to our east.

In the meantime, a predominantly cold outlook in the main for the north, a bit milder for a time in the south mid next week.

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22 minutes ago, Lynxus said:

I dont know Nick, (To be fair, you should know...? I recognise the name from a long ago.)

Years ago this place would of been unbearable (10 to 20 posts every few seconds ) , lucky now its all split out more than it used to be so I guess better in a way.

- More in topic..

What i find most impressive is how the last few days its gone from being a very much midland and north snow event to being a midland and south snow event.
Time is ticking by and soon we will know for sure!

In times like this I always take GFS and METO with a pinch of salt. They work well for westerlies but as soon as we get the 1/10 setup's they suck! 
They just dont have the data needed to make a good guess and I see this year after year after year... As soon as its east, north or south, They cant handle it.  Coming from the west? They will nail it.

If I was still in the UK I’d probably be in that panic or joy mood with this slider low !:D

Yes these snow events are rare and these set ups are difficult because normally if it’s just rain the stakes are low but because of the narrow margin for snow or rain any shift in track can make a huge difference .

 

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cold Pool over West Europe later this week again

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Edited by Dennis
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A quick look at last nights NOAA, GEFS and EPS anomalies, not forgetting previous runs, to see whether there are any indications of the forthcoming evolution. I need to keep the waffle short as I'm on my Tablet as my main website connection is still on the blink.

Overy the next 14 days there are some upstream changes perhaps indicative of the PNA going negative. An Aleutian trough develops with a stronger Alaskan ridge and more importantly a reorientation of the Canadian vortex lobe and associated troughs, one of which is aligned east south of Greenland. Quite importantly this affects the orientation and intensity of the Atlantic Ridge and with a strong upper flow still leaving the eastern seaboard a tendency for the flow over the Atlantic to become more zonal

Having said that the flow in the eastern Atlantic does abate somewhat and splits under the influence of the aforementioned Atlantic Ridge,  positive anomalies NW of Norway connected to the east European Ridge and the weakening  trough to the south East of the UK.

Ergo the changeable and quite cool weather could quite possible become more settled with Temps creeping up to be near average but more than likely a return to the proverbial north south split.

pna_cfsv2_32ens_2017120918.thumb.png.9d67ddabadbd97f0d3b8150de71d5384.pnggefs_z500a_5d_nh_41.thumb.png.57775702d2047259e6010e37a3225893.pngecm_eps_z500a_5d_nh_11.thumb.png.06b3a047188e8792c2ba971f7c1b5e40.png610day_03.thumb.gif.2db4461d74d39d4783aaa42b494382cc.gif814day_03.thumb.gif.df626a2642d4ab5ca25d77f09a2211a9.gifgefs_z500a_5d_nh_61.thumb.png.02c9648f64ae53e84778122917833c3a.pngpna_cfsv2_32ens_2017120918.thumb.png.9d67ddabadbd97f0d3b8150de71d5384.png

Edited by knocker
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Our positive trend of yesterday has hit the buffers this morning!

The upstream pattern doesn’t re-amplify and a lobe of the PV ne of Scandi  runs west re-invigorating the PV near Greenland .

The cold extension is looking  ropy this morning but we’ll have to wait to see what tonight brings.

There has been a pattern recently of flatter 00hrs runs and more amplified 12 hrs so let’s hope that continues.

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Just a quiet reminder that for those who want to post about their snow (or lack of in some cases), can you please use the regionals threads, the general winter chat threads or no snow club section please. A few posts have already been removed this morning.

Thankyou :)

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3 minutes ago, Steve Murr said:

Big forecast bust for the GFS here

high res hirlam & aperge spot on- !! Another 20-30 mile slide overnight brings heavy snow to london --

Yes quite a slide south..

Currently snowing v-heavy here 2 cms already!!!!

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11 minutes ago, Steve Murr said:

Big forecast bust for the GFS here

high res hirlam & aperge spot on- !! Another 20-30 mile slide overnight brings heavy snow to london --

The high res models and ecm have done well on the final evolution. Where gfs did well was sliding the system against a more defined wedge across the Atlantic as opposed to ecm which appeared to want to dive the system in an arc around the Atlantic high. Ecm got the final position of the longwave trough pretty well from last weekend  (apart from one op run)

this experience tells us that one model is never completely right but a blended view should take account of run to run consistency and weight ecm more strongly in this context 

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57 minutes ago, tight isobar said:

Yes quite a slide south..

Currently snowing v-heavy here 2 cms already!!!!

Great to see these upgrades for the south, shame that means downgrades for the north but nice to see the southward adjustments from the models this morning.:santa-emoji:I have a lot of friends and relatives in the south / southeast so good luck to them!:)

Edited by Frosty.
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Worst models out of the hi-res were the Icon and the NMM, I'm sure I saw the NMM have it way to the south at one point and the Icon consistently modelled it too far North, a lot had it slightly too far North a few daysout but Most models were pretty decent once it got within 24 hours I think, you cant expect them to be accurate to the nearest mile, 10-20 miles isn't that bad IMO, and theres no way you can get the snow-rain line 100% right because of varying local topography.

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Props to the Met Office, they have handled this situation really well. 

Indeed the high res models and the ECM pretty much got it bang on from 36-24 hours out and the corrections southward noted by experienced posters came to fruition. 

Great to see ice days modelled over the snowfields over the coming couple of days too. 

 

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2 minutes ago, JamesL said:

Props to the Met Office, they have handled this situation really well. 

Indeed the high res models and the ECM pretty much got it bang on from 36-24 hours out and the corrections southward noted by experienced posters came to fruition. 

Great to see ice days modelled over the snowfields over the coming couple of days too. 

 

Hats off to the ECM never in a million years would I believe I would be waking up here as far as the South side of the Thames to a covering of the white stuff. I'm like a kid at Christmas.

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24 minutes ago, Frosty. said:

Great to see these upgrades for the south, shame that means downgrades for the north but nice to see the southward adjustments from the models this morning.:santa-emoji:I have a lot of friends and relatives in the south / southeast so good luck to them!:)

A good few mile south correct.

Some mods had this badly incorrect.

And yes still snowing...

Around 4 cms now....

20171210_090101.jpg

Edited by tight isobar
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Can we please keep snow reports to the regionals. Thanks.

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4 minutes ago, Polar Maritime said:

Can we please keep snow reports to the regionals. Thanks.

Personally interested in any snow reports linked to model verification. 

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Just to show how fair, balanced and completely neutral I am with my posts...the Ecm 00z shows much milder conditions bathing the uk on days 8/9 :santa-emoji:

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There is talk of some milder weather on the way but by looking at the gfs cold never leaves the south east England..

IMG_0020.PNG

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1 minute ago, Luke Best said:

Personally interested in any snow reports linked to model verification. 

The regional threads are the best place for snow reports Luke.

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1 hour ago, Steve Murr said:

Big forecast bust for the GFS here

high res hirlam & aperge spot on- !! Another 20-30 mile slide overnight brings heavy snow to london --

Depends how far out you were looking. The ARPEGE was completely wrong at 48 hours on Friday, getting closer at 36 hours and only correct at 24 hours out. 

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