Model output discussion - 5th December 2016 - Into Winter we go

[nick sussex]

Thankfully no major drama this morning with the ECM broadly similar to last night although a bit further south with the initial high. The GFS 00hrs has moved towards it. I think we need to be looking to the ne east to deliver with the ridge extending north then toppling towards Scandi with some shortwave energy heading sw into Central Europe. NCEP expect an extended spell of cold across much of the USA so this would tie in with high pressure building south out of the Arctic there, troughing over the west Atlantic. High pressure near the UK , as is the way with these set ups it's where exactly the cold from the east gets funneled, whether that can directly hit.

Its hard to see milder conditions with the expected upstream pattern but I think the uncertainty today is more whether it's a cold and mainly dry scenario or one with the long forgotten S word included.

The slight irritation today is the UKMO output which at T 144hrs is more complicated but that's not supported by either the ECM or GFS. Let's hope we can avoid any drama there.

[SMU]

43 minutes ago, frosty ground said:

It means knockers version has more evidence to back up his claim than your version.

I don't see anything that shows cold air backing West. I do see what knocker says. I am not saying it won't happen that their is no evidence of it. No support from models.

The only reason knocker has more alleged evidence is because he wrote 1 paragraph which is pretty similar to what I wrote.

If you dont want to take my word for it based on the fact ive looked at every single UK easterly since 1879 & how they developed & where high pressures moved to then fine.

Or perhaps just reread Nick Fs post or BA s post.

theres all you need to know - all based on the ECM day 10.

[Man With Beard]

Like a cliff-hanger drama in here this week! 

My very simple take:

Still on for a "snow window" from 1st Jan-3rd Jan, with details to be decided. Models have generally performed very well on this (particularly ECM). Not looking drastically severe right now but of course little disturbances can cause big dramas at the last minute in such scenarios!

Then, odds favouring the "reload" 6th - 8th Jan, though UKMO looking uncertain so not quite in the bag. In terms of severity, again not looking particularly severe at least at first - perhaps comparable to this first northerly outbreak.

Many many options open after the 8th Jan - some "holy grail options" for cold but goodness me, so so many hurdles to cross first!

[northwestsnow]

Gfs6z looks an upgrade on the initial northerly with the colder uppers sweeping in much quicker than the 00z run..

[That ECM]

Nailed on snow in Bournemouth 

model excitement if nothing else.

[Brenda 'Bee' Lau]

And poof goes the snow on the 06z!

[northwestsnow]

Just now, Brenda 'Bee' Lau said:

And poof goes the snow on the 06z!

Thats odd as its colder than the 00z run for sun/mon..

[Luke Attwood]

2 minutes ago, northwestsnow said:

Gfs6z looks an upgrade on the initial northerly with the colder uppers sweeping in much quicker than the 00z run..

Agreed -10 850's almost reaching the south coast!

[Brenda 'Bee' Lau]

1 minute ago, northwestsnow said:

Thats odd as its colder than the 00z run for sun/mon..

Dew points are fairly high that's the issue.

[radiohead]

2 minutes ago, northwestsnow said:

Thats odd as its colder than the 00z run for sun/mon..

Dew Point temperature above freezing = rain.

[northwestsnow]

Just now, radiohead said:

Dew Point temperature above freezing = rain.

Yes must be a mild sector - west is best then!!

[karlos1983]

 

35 minutes ago, Banbury said:

Might please some

Yes very pleasing.... I'll leave it there or I might get a grammar lesson 

I have a feeling the ens will look better than yesterday's at mid day..

 

[A.J]

posting ppn charts at T96 and analysing then with a fine toothcombe...........that old chestnut.....lol

snow is hard enough to forecast at T24 let alone T96+!......see john holmes's fine post in the learner's area for snow forecasting and not get hung up on these ppn charts 

[numbnutts(uk)]

Just now, northwestsnow said:

Yes must be a mild sector - west is best then!!

still touch and go tho more cooling please

 

[Nick F]

8 minutes ago, Brenda 'Bee' Lau said:

And poof goes the snow on the 06z!

IMO has been and still looking a slim chance of snow falling away from hills of Wales, northern England and Scotland from that precip band along the cold front as it moves south, just don't think there's enough inertia in the surface flow to undercut sufficiently cold and dry air for snow to fall low down. If it moved through overnight, might be better chance at lower levels. Potential for snow to lower levels across N/E Scotland and perhaps NE England from the wintry showers following in the northerly Sunday night into Monday though.

Edited December 29, 2016 by Nick F

[northwestsnow]

Cold tastic EC ens!! If there is any legs in them the meto mrf has to go colder surely!!!

[Man With Beard]

A little low in Iberia blocks heights from the south at T132 ... what impact will this have later on?

[Ali1977]

Looks like a better GFS coming up, Atlantic block stronger and better aligned!!

[northwestsnow]

Liking the look of 6z looks better to the west and plenty of energy under the block!! 

[Frank Trough]

7 minutes ago, ajpoolshark said:

posting ppn charts at T96 and analysing then with a fine toothcombe...........that old chestnut.....lol

snow is hard enough to forecast at T24 let alone T96+!......see john holmes's fine post in the learner's area for snow forecasting and not get hung up on these ppn charts 

It's pretty easy to forecast  snow for southern coastal counties in these scenarios: There won't be any, it will be rain.

Still worth keeping an eye on over the next few days for more inland areas. Cold and frosty will do me for now and we wait and see if the second phase will deliver anything more significantly wintry.

[Weathizard]

The differences at 120 are rather surprising. Can't post charts but thats a pretty significant change at just day 5.

[EML Network]

17 minutes ago, Luke Attwood said:

The way I see things developing is like this..we get the cold northerly around new years day probably lasting 2 or 3 days and with the threat of snow for some particularly in Scotland.as we approach midweek it turns milder with the high moving southeastward, a northwesterly wind.during the latter part of week we see a stronger ridge developing in the Atlantic initially pushing up to Greenland to allow another cold northerly to develop. What happens after this is crucial, we ideally want to see the high drift east then north, rather then east then south.I believe the latter will happen sadly which means the deep cold will escape us and Germany France and northern Spain may well see the bitter temperatures! So as I said where the high drifts later next week is crucial in terms of whether we see deep cold,or something just below average...I do hope I am wrong and we see the deep cold move westward towards us,we shall see. ☺

Very sensible post. 

 

I honestly can't understand why everyone is so upbeat this morning, either I'm reading the charts wrong, Or i've woken up miserable or I've woken up in an alternate universe. 

Gone are the charts that were showing a more sustained colder period and this morning we have woken to see a firming up on the ensemble cluster 06z Leicestershire ensembles

 

It's pretty certain that this weekend we start to get a temporary plunge of colder air, which clears away early next week , but it's becoming clear that next week things are going to warm up slightly although it will still be fairly chilly at the surface and then it's simply a case of rinse repeat, more or less the same pattern we have been stuck in ALL WINTER LONG !!

The only difference is that the high pressure systems aren't making as much in roads and are more or less stalling over the UK, this gives the illusion that the doors are opened to a northerly component or a Easterly component coming into play, when in truth and how many times already this winter have we seen this...the systems push off south and east and we get a temporary south westerly feed, before the pattern repeats. 

 

I don't claim to understand the background signals, I simply say what I see...and that's what I am seeing.

 

 And I'm really getting bored of it...Any chart that shows an omega block or Scandi High dragging in easterly's should only be worth enjoying as eye candy if it's post 168, get it to within a +144 chart and then it's worth having a better look at.

 

We've ALL been led up the garden path countless times, every winter only to be let down and end up chasing the cold again in FI. 

Things are much better positioned this winter, however, and I DO think we will get a cold spell of weather and that it's not too far away, just not next week !!

[karyo]

6 minutes ago, Man With Beard said:

A little low in Iberia blocks heights from the south at T132 ... what impact will this have later on?

Low pressure in Iberia is always good news for us as it can prevent our high from sinking.

[frosty ground]

23 minutes ago, Steve Murr said:

The only reason knocker has more alleged evidence is because he wrote 1 paragraph which is pretty similar to what I wrote.

If you dont want to take my word for it based on the fact ive looked at every single UK easterly since 1879 & how they developed & where high pressures moved to then fine.

Or perhaps just reread Nick Fs post or BA s post.

theres all you need to know - all based on the ECM day 10.

Don't take it personally Steve.

Knocker has access to more info than most of us due to his subscription to WB

Pattern matching is an awful method but clearly as has been mentioned there is evidence to support your claims. 

 

[Tim Bland]

Big change at relative short term from 00Z to 06z GFS.  Look west of Ireland, that little low (995mb)  has disappeared and now we have a high (1030) in its place!