Model Output Discussion - cold spell to end Autumn

[Man With Beard]

15 minutes ago, Yarmy said:

No, the numbers are in the legend:

ECM 0.924

UKMO 0.905

JMA 0.903

GFS 0.892

CMC (=GEM) 0.890

 

Well if the JMA is doing that well then it's worth looking at it:

Looks like it's attempting a split through Greenland up to the North Pole again at D8.

[Chesil View]

16 minutes ago, karlos1983 said:

This would be the exception rather than the rule though Nick. Pretty exceptional Synoptics are bringing this. In general winter, cold eastern US =  usually a strong jet heading straight for the uk. In all my years on here, this is the most incredible November into December and probably the new year model watching I’ve witnessed.

one question, when the hell am I going to get any sleep ?

Actually Karlos that is not really correct it depends as now on the amplitude of the pattern. If the cold air coming out of the states is pushed north over the western Atlantic by a mid Atlantic ridge then it is warmed and fed north as WAA in to the polar regions reinforcing the attacks on the polar vortex and helping to sustain a cold pattern here. It happened inquite a few of the 70,s and 80,s snowy winters .  

Edited December 6, 2017 by Broadmayne blizzard

[snowking]

Despite what any models show in terms of track in the next few days, history with these situations suggests we won't really know until until the day itself just how far north/south this will end up - I've seen many situations over the years where the radar returns end up showing the precipitation moving in being 30-50 miles further north or south of where it was projected to be, so if your area is forecast rain or forecast to miss out altogether, I wouldn't worry just yet. We'll be chasing this all the way down to T+0

[nick sussex]

BREAKING NEWS!!!

The UKMO and GEM discounted from the NOAA US forecast,  outlier solutions this in the run up to the UK slider. A blend of the GFS/ECM solutions preferred.

 

 

[Midlands Ice Age]

9 minutes ago, Man With Beard said:

Well if the JMA is doing that well then it's worth looking at it:

Looks like it's attempting a split through Greenland up to the North Pole again at D8.

Wow...

 Do not think I have ever seen the largest chunk of the PV sat over the MIdlands before.

Welcome sir,  you are very welcome!

I think I will die a happy man if this happens

Midlands Ice Age

[snowice]

2 minutes ago, nick sussex said:

BREAKING NEWS!!!

The UKMO and GEM discounted from the NOAA US forecast,  outlier solutions this in the run up to the UK slider. A blend of the GFS/ECM solutions preferred.

 

 

A good blend?

[Allseasons-Si]

So a look at all the models at 96 hrs and there is lot of agreement on the track of this slider low,the gfs op and control slightly further SW

[Summer Sun]

ECM might be a bit marginal for parts of the south on Sunday for snow

Bitter up to Saturday

Getting colder again Monday in the south

[karlos1983]

12 minutes ago, Broadmayne blizzard said:

Actually Karlos that is not really correct it depends as now on the amplitude of the pattern. If the cold air coming out of the states is pushed north over the western Atlantic by a mid Atlantic ridge then it is warmed and fed north as WAA in to the polar regions reinforcing the attacks on the polar vortex and helping to sustain a cold pattern here. It happened inquite a few of the 70,s and 80,s snowy winters .  

Hmmm 70’s and 80’s winters do tend to be a thing of the past, but we will send this thread well OT, best we don’t go there lol, plus i only arrived in 83 ☹️.

certainly in recent years, east coast cold and strong PV (again usual winter) equals strong jet.

[Summer Sun]

Arpege also going for rain in the south

Edited December 6, 2017 by Summer Sun

[Man With Beard]

It will be worth banging on for the next few days how MARGINAL the snow area will be. Little things like intensity of precipitation will make an accurate forecast of snow impossible until the T6, unless you have a bit of elevation, or if the snow band affects the northern powerhouse. 

[nick sussex]

1 minute ago, Britneyfan said:

Huh

They prefer the ECM and GFS blended for the upstream pattern in the USA which is better because the UKMO and GEM aren't as good for the UK slider low.

Theres also the issue of pressure rises near Iceland which NOAA wouldn't cover but the UKMO because it runs a deep low into the PV sends more energy eastwards and the second possible slider is too far east.

In the medium term however the UKMO does re-amplify the upstream pattern so not all bad news from it.

[northwestsnow]

2 minutes ago, Man With Beard said:

It will be worth banging on for the next few days how MARGINAL the snow area will be. Little things like intensity of precipitation will make an accurate forecast of snow impossible until the T6, unless you have a bit of elevation, or if the snow band affects the northern powerhouse. 

TBH i dont think we will know the exact track of the low until friday.

[karlos1983]

1 minute ago, northwestsnow said:

TBH i dont think we will know the exact track of the low until friday.

Im not sure about that. We will see the low sliding or not on Saturday, so will be worth checking back to previous runs.

obviously the track might move north or south by 50 Miles or so on approach, but the envelope won’t be very big by the time we get to Saturday morning.

Generally I think this will be resolved by Friday 12z latest. 

[Met4Cast]

Interestingly the NetWx-MR takes it way, wayyy South into the S Midlands, SE England and Central Southern England

I'll be banking that one, sorry for those up Norf

 

[shaky]

Can anyone post anymore of those snow charts but the ensemble ones from the ecm!!get a better idea of where this slider will most probably slide!!

[in the vale]

YR.NO for my location (NE Wales) has just updated following the 12z, and it shows not a snowflake for the next 10 days. I thought YR was usually just a straigh take from ECM, but am I mistaken, given the 12z output I have just looked through?

[Frosty.]

Well the Ecm 12z is choc full of wintry potential, we have an arctic blast incoming and following the initial very cold surge, a cold cyclonic pattern with plenty of snow opportunities as well as night frosts and ice, messy charts but as I said before, a cold mess beats the hell out of a mushy mild one..tomorrow the cold will be chasing the mild mush away south eastwards and the way I see the 12z output, mild definitely won't be a word to describe our weather from this friday and all through next week but the word sliders will be..indeed, no sign of mild returning for a good long while hopefully..well coldies, we have been so very patient during the last few years enduring too much mild gunk but it looks like that patience is about to be rewarded for the first of hopefully many times this winter!  

[snowking]

5 minutes ago, shaky said:

Can anyone post anymore of those snow charts but the ensemble ones from the ecm!!get a better idea of where this slider will most probably slide!!

Again a trawl through the individual EPS members looks pretty similar to the 0z, with the median position for snow still being primarily Wales into the Midlands (and some of Lancs/Yorks too) - some then take this across towards EA/Lincs, others run this slightly further SE into London, Surrey, Sussex and Kent.

That is very much a median - some have it much further North/South, but for me from the EPS at least the mean position still places the bulk of any snowfall between the M4 and the M62

Edited December 6, 2017 by snowking

[Paul_1978]

20 minutes ago, Midlands Ice Age said:

Wow...

 Do not think I have ever seen the largest chunk of the PV sat over the MIdlands before.

Welcome sir,  you are very welcome!

I think I will die a happy man if this happens

Midlands Ice Age

In practical terms what would this give?

[feb1991blizzard]

3 minutes ago, in the vale said:

YR.NO for my location (NE Wales) has just updated following the 12z, and it shows not a snowflake for the next 10 days. I thought YR was usually just a straigh take from ECM, but am I mistaken, given the 12z output I have just looked through?

You get hammered with the showers and then hammered on the sunday again on ECM - around 10 inches of lying snow by this time sunday.

[SMU]

37 minutes ago, snowice said:

A good blend?

Nescafe....

[The Enforcer]

First episode of Troughwatch of the season - focusing on Friday 00z:

T+60:

T+48:

T+36:

Analysis: The overnight trough pushing south over inland areas has survived 3 fax charts, two more to go.

 

[in the vale]

1 minute ago, feb1991blizzard said:

You get hammered with the showers and then hammered on the sunday again on ECM - around 10 inches of lying snow by this time sunday.

That's what I read from the charts but yr.no shows nothing. Odd.

[feb1991blizzard]

1 minute ago, in the vale said:

That's what I read from the charts but yr.no shows nothing. Odd.

Out of a 50 member suite, every single one gives you some sort of snow, the vast majority give you a moderate to heavy fall and some a severe fall.