Model Output Discussion 01/09/17

[Froze were the Days]

1 hour ago, LRD said:

I've mentioned this before on here. It's the expanded tropical high pressure belt (Hadley Cell) that includes the Azores High. It's not only in winter we experience this either. It's pretty rare to have a poor summer in the SE of England now due to the expanded tropical high cells having enough influence in summer too - even in the most unsettled summers. Even in 2012 the SE had a nice warm August. The models don't seem to have a handle on quite how dominant southern heights are becoming/have become and I'm not sure why. I really worry about winters in this country now (that is the first 'winter is over... forever' post!)

Spot on!...first place I look when analysing at the models runs etc. can we get rid of those darn heights 1. over southern Europe/central Europe 2. Azores  - majority of the time they don't go anywhere.

[karlos1983]

Hmmm such confidence...

 

 

[Man With Beard]

1 hour ago, knocker said:

Then equally obviously one would have to be very, I repeat, very. optimistic about their ability to correctly forecast a -AO and -NAO post day five.despite the sudden obsession with them in the thread.

That is very true, too but will take a monumental shift to move it positive now

EC clusters very confused once again, the largest cluster looks better for cold than the op but doesn't mean much

[SMU]

2 hours ago, knocker said:

Then equally obviously one would have to be very, I repeat, very. optimistic about their ability to correctly forecast a -AO and -NAO post day five.despite the sudden obsession with them in the thread.

The models have beem very accurate over the last week - 10 days in predicting the -AO signature - even the NAO which has less volatility - not sure why your repeating yourself - 

Day 5 is only T120, yet the GFS plots have trended negative back from day 10-

All the AO does is release cold into mid lattitudes & the deeper negative it becomes so the more stationary the overall 2-4 standing waves become -

It doesnt guarantee cold for the UK - there is no global metric / teleconnection that is small scale enough for that - 

but you know all that- not sure why your being so pedantic- Theres always been an obsession with these 2 because when the UK has had long sustained cold events then these being negative go hand in hand-

Net weather members should make up their own metric - Call it the NWO

measuring pressure differential or Height differentials across Iceland / The azores / Norway & somewhere like France -

That would work the best for the UK

S

Edited November 15, 2017 by Steve Murr

[Mucka]

Knife edge but GFS has improved this morning, still the possibility of a snow event for the North if enough cold air is drawn in from the NE before the front moves in.

UKMO not quite as good

Edited November 15, 2017 by Mucka

[booferking]

Towel through in to early by many this block is looking mighty strong.

[Mucka]

4 minutes ago, booferking said:

Towel through in to early by many this block is looking mighty strong.

It's the trough to the SW that is the issue.

Still nice to see a cut off Greenland high modelled even if we still need the trough further South.

[Daniel*]

A relatively significant improvement versus 18Z now that’s what you call a Greenland high with John’s yellow colours appearing - Arctic high also stronger across the pole and the Azores high is displaced well away from Western Europe with troughing digging deeper southwards & southeastwards - lower heights S of us much more pleasing to see.

Edited November 15, 2017 by Daniel*

[Mucka]

GFS ensembles a small improvement over 18z with just a few decent runs among them, most notably (13,17,19) 

 

It would be nice for that signal to strengthen through today.

[SMU]

Indeed

the GFS isnt far off one almighty chart...

[knocker]

Today generally cloudy with the odd spot of drizzle in places in N. Ireland, Wales and England but in some places during the day the cloud will break giving sunny intervals and temps could reach 14C except possibly in the far north of England where it will be fresher and brighter. This will aslo be the case in Scotland where there has been a slight frost in places but later a rapidly developing low will track quickly north east to be NNW of Scotland 987mb by midnight with the front and strong winds already impacting the north west of Scotland/

The front tracks south east across the UK on Thursday as the low continues north east veering the wind NW over Scotland with showers, of snow on the high ground, allowing the high pressure to edge in further south. But by 12 Saturday the high pressure has quickly amplified and ridged strongly north west thus halting the progress of the low as it moves into western Norway (dumping a fair amount of snow in the progress) as it starts to change track south east and resulting in a cooler northerly airstream over the UK albeit quite light.

From this point things get a tad complicated with new upper trough tracking east from the eastern seaboard linking to the trough further south creating a complex surface low pressure area to the west which by 00 Tuesday has pushed fronts in from the south west which at that time are lying across central Britain accompanied by rain. But it's worth looking at the delineation between the cold and warm air here as it is possible that snow could be generated to the NE of the front.

This battle between the warmer Atlantic and the cooler air to the north west continues over the next couple of days as the UK becomes the coal face of the two energy flows, one the NW around Greenland and the other from the south west, (shades of the anomalies) and if nothing else the detail of this weather wise would be interesting. Of course that is bound to change in the interim

The point vis the anomalies can be seen on this morning's GEFS

Edited November 15, 2017 by knocker

[LRD]

2 hours ago, Mucka said:

It's the trough to the SW that is the issue.

Still nice to see a cut off Greenland high modelled even if we still need the trough further South.

What a chart that would be - without those poxy French/Spanish heights

[Tracy Flick]

GFS 192h control and EC 192h are very much on the same page.

 

[snowbunting]

6 minutes ago, LRD said:

What a chart that would be - without those poxy French/Spanish heights

I just get a feeling those heights are being overplayed by the models. Why would the models underplay a Greenie High and overplay a Euro high? Other than struggling with la nina influences. Perhaps the 0z run of gfs has cottoned onto this and is making that nly outbreak creep ever southwards? What I have noticed is a disjointed atlantic influence and a split polar vortex. Time will tell. These next few runs are going to be very interesting. 

[Man With Beard]

The ECM is outrageously complex this morning with all manner of small troughs jumping the Atlantic and running into a trough to our NE - cold air does work its way south but it's painfully slow, probably snow over the northern hills by T216. Again it's so close to getting cold all the way from the Arctic to the UK but cut off at the final hurdle. Rather cold and wet by the end of next week I expect from this one. Still room for a change!

Edited November 15, 2017 by Man With Beard

[knocker]

The ecm is quite similar to the gfs up to Tuesday 00 but the delineation between the cold and warm air is further north and over the next couple of days the warmer air is over the UK as a complex area of low pressure moves east bringing sporadic rain to all.. But by Thursday 00 this away the east and the surface wind has veered northerly dragging colder air south. All of this is subject to change of course but certainly not without interest from a meteorological perspective.

[That ECM]

"Shannon's whojamaflip" is in full evidence and has been for many days. This clearly is a complicated set up and as stated before small changes have big impacts. The nh profile with various blocks setting up is of much interest. For many a year we have seen "big purple blob" another of my technical terms sat above us and a constant flow of predominantly westerly winds. Will we get what most want? Who knows but more chance in this type of nh profile than we have seen for a few years. 

[khodds]

Haven’t we been here before, where the models drop something only for it to be picked up a few days later...?! Sure we have! 

[bluearmy]

Ec op looks to be a sypnotic outlier against the mean and spreads later on in the run 

 

[mountain shadow]

4 minutes ago, bluearmy said:

Ec op looks to be a sypnotic outlier against the mean and spreads later on in the run 

 

Is it colder or milder than the mean?

[Nick F]

Models making the synoptic evolution past t+144 rather complicated as they try to handle a split jet stream over the N Atlantic going around the block next week and how much energy goes into the southern arm and how much into the northern arm.

Impressive Greenland block and cold air trying it's hardest to push south across the UK early next week, areas of low pressure spinning up from the SW beneath the block preventing the cold air getting all the way south in a confident manner, though the 00z EC det. does briefly at day 10 - albeit can't trust that would come off at that range.

Ultimately, I think the high latitude blocking will be situated too far north for all the UK to tap into the cold air to the north, however, could be some interesting battleground snow events playing out across Scotland next week?

[Summer Sun]

UKMO at t168 wet and relatively mild with a southwesterly flow

[bluearmy]

47 minutes ago, mountain shadow said:

Is it colder or milder than the mean?

Ec op is too cold and too troughy

the extended eps now with several runs showing w European high height anomoly. it got the low euro heights wrong - what odds it has this right!!

Edited November 15, 2017 by bluearmy

[Summer Sun]

The mean continues it's upward trend

Yesterday 00z

Today 00z

Taking the 24th as an example it has gone from around -2 to +3 in the space of 24hours

[frosty ground]

9 minutes ago, Summer Sun said:

The mean continues it's upward trend

Yesterday 00z

Today 00z

Taking the 24th as an example it has gone from around -2 to +3 in the space of 24hours

What are the ones further North Showring?