Model output discussion pm 13/01/2016

[karlos1983]

I cant see much wrong with the 144 chart

I'll take that thank you very much

[warrenb]

Just now, northwestsnow said:

I guess its not good !!! Had a feeling ukmo 120 was beginning to move the atlantic in ..

I suspect the winky means quite the opposite.

[frosty ground]

4 minutes ago, Steve Murr said:

Im not posting the 144 ---- dont look dont look !!!!  

; )

Not sure what this post has added... unless it confusion

[SLEETY]

credibility of one model

4 minutes ago, Steve Murr said:

Im not posting the 144 ---- dont look dont look !!!!  

; )

channel low,maybe ?

[Snowman.]

Would love to see the difference graphs between the 12z and 6z in pressure.

Edited January 14, 2016 by SN0WM4N

[Djdazzle]

UKMO and GFS differences at short range are astonishing.

BIG ECM coming later . . .

[No Balls Like Snow Balls]

3 minutes ago, karlos1983 said:

I cant see much wrong with the 144 chart

I'll take that thank you very much

A very cold and snowy North Easterly in my un expert opinion 

[warrenb]

Just now, No Balls Like Snow Balls said:

A very cold and snowy North Easterly in my un expert opinion 

I would go with "Step into the freezer to warm up", totally still under very cold air.

[bobbydog]

"the GFS is poor" "not worth looking at"

well its only 'poor' if its wrong and we dont actually know that yet. its just showing a possible evolution from the interaction of the approaching tropical storm. it could be wrong (hopefully) but maybe we should wait and see before poking it with sticks...

[karlos1983]

What we really don't want to see tonight is a middle ground scenario from the ECM. It would be nice to see the evening out with 2 models agreeing at +72/+96. When is the last time we had that......

[SLEETY]

1 minute ago, No Balls Like Snow Balls said:

A very cold and snowy North Easterly in my un expert opinion 

after the channel low goes past i think,im no expert either

 

[northwestsnow]

While i like ukmo very much you can see by 144 the blocking highs to the north have virtually vanished and that PV is getting angry again.

Still, opportunities for some snow much as the meto update today suggests

[Singularity]

Unbelievable that GFS has somehow managed to push things NE even faster while UKMO has headed the other way again after the morning wobble!

I spent a bit of time staring at the GFS jet stream charts and wondering where the momentum to the NE is coming from. The main jet is angled just south of due east at +84 for example:

If anyone has the answer, I'm all ears - or should I say eyes!

 

If only we still got to see UKMO jet stream charts. I'd love to see what it makes of things at +72 and +96.

I must say, the expected Alex track, with that slight hook left, does look like a block-reinforcer to me, much as Sandy was in 2012 for example - though that was a more extreme hook left I know.

 

Oh and it's fascinating what UKMO comes up with with respect to that shortwave off the U.S. +96 to +144; the way it avoids merging with the main Atlantic trough and races east to undercut the remnants of that cut-off high. That sounds like the 'mobility at latitudes south of the UK' that Fergie mentioned yesterday with respect tot he parallel version of the model.

Also worth noting that the fact the cut-off wedge is fizzling out +120 to +144 despite the undercut is a sign of what looks like inevitable pressure from the rise in AO toward near neutral values in response to strat. forcing. If the lowering heights near the pole interact with the trough near Greenland as this and a number of other recent model runs have suggested going forward, then it will take something special to avoid a removal of the cold conditions for at least a time in the final week of the month. You never know though, even a weak wedge of cut-off high pressure can be enough to trigger trough disruption so another battle or two would be achievable with a bit of luck (or bad luck if you're not a disruptive snow fan).

 

Finally for the moment, one has to wonder where the frontal boundary is on Monday according to UKMO. Judging by the kink in the isobars the surface boundary is probably SW of the UK at noon, but being an occluding warm front the precip could extend far enough ahead of it (to the NE) to affect the SW corner at least. Basically there's just a chance that somewhere could see a bit of snow followed by the cold air reasserting which really would be a lucky scoop. Anyone feel like placing a bet? 

Edited January 14, 2016 by Singularity
additions are awesome

[warrenb]

Blocking highs don't need depth, it is all to do with position and orientation, the 144 ukmo has the high coming now from the north almost vertically, the trough over scandi holding it in place.

[igloo]

well the GFS has the worst possible outcome at the 168h mark with another euro slug forming which we had for the whole of december nasty.either way the UKMO has downgraded this mornings run with the breakdown not till mid week so a bit better at least

[Nick L]

11 minutes ago, Steve Murr said:

Im not posting the 144 ---- dont look dont look !!!!  

; )

More knowledgeable members would see this as tongue in cheek but it's hardly helpful to those learning is it?

[Snowman.]

2 minutes ago, bobbydog said:

"the GFS is poor" "not worth looking at"

well its only 'poor' if its wrong and we dont actually know that yet. its just showing a possible evolution from the interaction of the approaching tropical storm. it could be wrong (hopefully) but maybe we should wait and see before poking it with sticks...

It's poor because it's inconsistent and reminds me of a flapping fish.

[Geordiesnow]

I think the GFS is being far too progressive in bringing the Atlantic in, even yesterday's GFS was not so quick to bring the Atlantic in but I'm still on the side, the cold air will be shunted sometime during next week though however timing is still very much in the air. 

I said yesterday I would not be surprised if the cold air gets shunted out of the way quicker than we think but I do believe the GFS 12Z is too quick in doing this however with so much uncertainty you can't rule it out. 

Can't rule the UKMO out either, obviously its much better for coldies but Atlantic air is having ago on this run also but the cold air putting up more of a battle on this run so who knows. Hopefully the UKMO is right, would not mind a couple of frosty mornings and then a snowy breakdown.

[bluearmy]

I could be fussy re the T144/T120 UKMO and say I would like thicknesses to be a tad lower but given the surface cold in place, we would be looking at quite a snow event across the midlands for sure at day 5 as the occlusion moves ne and potentially bit further s day 6 as the wind swings off the continent. day 6 is tricky though 

[Hull snow]

So what is unknown 144 showing to me it's cold and snowy Steve murr want to explain ?

[northwestsnow]

Just now, bluearmy said:

I could be fussy re the T144/T120 UKMO and say I would like thicknesses to be a tad lower but given the surface cold in place, we would be looking at quite a snow event across the midlands for sure at day 5 as the occlusion moves ne and potentially bit further s day 6 as the wind swings off the continent. day 6 is tricky though 

Just thinking exactly that Blue-

http://www.wetterzentrale.de/pics/Rukm1201.html

That to me screams snow as the atlantic moves against the block ?

[Weather Wonder]

Without taking an in depth look at the latest output I think the gfs is more likely to be correct in modelling the tropical low than ukmo, I expect to see the ukmo backtrack slightly and most likely meet halfway with the gfs.

[Catacol]

1 minute ago, karlos1983 said:

I cant see much wrong with the 144 chart

I'll take that thank you very much

Ha - that is very much a stalemate chart. If anyone can work out what the weather will be over the uk from that, then they have my full respect.

It is from battleground charts like this that the UK can get its best falls of snow. But quite honestly the model divergence today is so huge that I wouldnt bother worrying about it. There are quite clearly background signals that the models cannot get a handle on. I have to assume that an increasingly distressed trop vortex superimposed over significant AAM and placed alongside a record breaking ENSO signature has caused algorithm meltdown in the models. I'm not sure (unless corrected) that we have an analogue year that quite matches what is going on at the moment though GP did say 1983 was the closest match, and that was for a Scandy trough working alongside blocking to the N and W. 

Who knows what the end result will be, but in a winter of extremes so far I wonder what the odds might be that the current switch to a colder pattern may also bring something extreme. I keep looking at the cold gathering over NE Scandy and into Russia and wondering whether we must just end up dragging it towards the UK as heights build to our north. One thing is for sure - the overall pattern remains strongly amplified so any suggestion of an extended return to flat westerlies over the atlantic looks to be off target. We have cold air embedding today across all parts, and a pretty strong signal for at least 3 - 4 days of cold nights and cold days. This is exactly the base from which to work if snow is what you want, and we all know the cold air will be slow to move. Patience required for precipitation, but provided the HP is far enough north then precipitation will arrive from west or east eventually. Any relaxing of the cold under this regime looks likely to be short lived.

[Glacier Point]

Op GFS has just shifted in a massive 600m in its 500 hPa geopotential height over Kara Sea at day 7 between 06z and 12z runs. It also now has the North Atlantic a seething pool of meridional flow where once there was a unified deep upper low....

 

Atlantic hurricanes in January, this is just bonkers.

Edited January 14, 2016 by Glacier Point

[Catacol]

1 minute ago, Glacier Point said:

Op GFS has just shifted in a massive 600m in its 500 hPa geopotential height over Kara Sea at day 7 between 06z and 12z runs. It also now has the North Atlantic a seething pool of meridional flow where once there was a unified deep upper low....

Hehe - torpedo on impact.... NAO flip? :-)