Model Output Discussions 12z 01/09/2016

[knocker]

Excuse my ignorance but I'm a bit puzzled by the 'diving trough' terminology so would I be correct in assuming this is the upper low to the NW phasing in with the upper low that has been around to the SE for some time as the blocking HP drifts east and thus initiating height rises in mid Atlantic? And hey presto we have an Omega block.

And a chilly scenario. Best got out of the way now of course.

Edited September 30, 2016 by knocker

[Cloud 10]

Black hole anomaly season starting early this year.

 

Another chance for the OPI  (October pattern index) this year?

 

ECM day 8..

[Summer Sun]

'If only it was winter'

[bluearmy]

The  15 day ens means and  many gefs members are with the high lat  high anomolys 

certainly an absence of the vortex wanting to set up home to our northwest. Early in the season but quite a deep gulf of Alaska trough appearing. If we were a month further ahead then would be a fair bit busier on here. 

[damianslaw]

Models continue to show a very blocked scenario overall, with the atlantic really having trouble breaking through thanks to the very strong heights forecast to build to the east. A very plausible outcome is a diving trough scenario, or at least low heights to the SW, which in turn has to lead to height development to our NW - something the GFS and ECM are showing in the long range timeframe.

Ex tropical storm activity is a wild card, some of the models are suggesting ex storm Matthew being forced north up the eastern seaboard this in turn would aid warm air advection and help develop strong heights over Greenland.

Certainly very interesting model watching - far from the default westerly zonal train, especially so when we are now approaching the time of year when the Polar Vortex starts to really get its act together. Very different set up to the past 3 autumns I say..

 

[knocker]

Today

A band of showery rain moving east during the day, could be heavy in places in Wales and the Midlands. Temperatures no great shakes.

Not much significantly different this morning with the GFS within the reasonable time frame so a very brief summation.

Monday sees the start of the expected amplification with strong heights building to the east. This high pressure dominates the weather for the rest of the week, apart from the the far NW, bringing a light SE flow and some Autumnal diurnal temp variation. Cool nights and warm days.

By the weekend this pattern is beginning to change with the HP slipping east, a cut off upper low to the SE and a developing trough to the NW. This translates on the surface to the UK being temporarily in a col.

From hereon in there are a number of evolutionary scenarios all more or less depending on the development of the upper trough and thus the orientation of the surface low pressure so just one example. But this being quite complicated and over a week down the line I'm personally not inclined to get to wrapped up with the detail at this stage, or at least until there is some good model agreement

 

Edited October 1, 2016 by knocker

[mb018538]

The models are showing much more of an easterly component rather than a S/SE today, and it looks decidedly chilly by the weekend in the east! My weekend by the coast is looking cool!

[Matthew.]

ECM still painting a very chilly picture longer term:

[knocker]

Well the ecm take on next weekend and after is a cut off upper low and Mathew sauntering in from left field. I'm not placing any bets.

[bluearmy]

With strong upper ridge in nw Russia/ne  scandi and the Azores displaced wnw , we have a weakish meandering jet. the result continues to be the trough dropping south into Europe between them. being one for repeating patterns, this is intriguing and the NH profile in a fortnight continues to show an appetite for a lack of low heights on the Canadian/Greenland side. 

Be interesting to see how the strat profile develops through October.

[SMU]

21 minutes ago, bluearmy said:

With strong upper ridge in nw Russia/ne  scandi and the Azores displaced wnw , we have a weakish meandering jet. the result continues to be the trough dropping south into Europe between them. being one for repeating patterns, this is intriguing and the NH profile in a fortnight continues to show an appetite for a lack of low heights on the Canadian/Greenland side. 

Be interesting to see how the strat profile develops through October.

Yes interesting output today - almost dream winter synoptics on the ECM & more particular the UKMO with those long fetch easterlies-

waiting the important september QBO data !!!

[BLAST FROM THE PAST]

Fast forward 2- 3 months please....if only.  Couple of things of interest as noted in other posts.  The way the trough drops down, it is what happened in Feb 1986 and we know what happened there.  Difference here is that we'll get warmth and not cold.  So a picture of a deep LP sinking over UK with reload to warm weather being brought in from SE....could be a hell of a month

 

 

BFTP 

[Faronstream]

Slightly below average in the temperatures of 850hpa in long range 00Z run for most of europe, a big shift from the very warm upper air we have had in September, the average temperatures is returning at least for a couple of days

[blizzard81]

1 hour ago, bluearmy said:

With strong upper ridge in nw Russia/ne  scandi and the Azores displaced wnw , we have a weakish meandering jet. the result continues to be the trough dropping south into Europe between them. being one for repeating patterns, this is intriguing and the NH profile in a fortnight continues to show an appetite for a lack of low heights on the Canadian/Greenland side. 

Be interesting to see how the strat profile develops through October.

Indeed. I wonder if we are on the cusp of one of those very rare beasts over the last 20 years or so - A very cold November!

[Evening thunder]

6 hours ago, Matthew Wilson said:

ECM still painting a very chilly picture longer term:

These charts themselves aren't particularly cold really, more around average as the 500hpa Geopotential height does not correlate well with nearer surface (or 850hpa) temps 

 

Edited October 1, 2016 by Evening thunder

[Frosty.]

13 minutes ago, Evening thunder said:

These charts themselves aren't particularly cold really, more around average as the 500hpa Geopotential height does not correlate well with nearer surface (or 850hpa) temps 

 

It would feel cold, or at least cool in the wind and rain though, which is what I think Matthew meant.

[Dancerwithwings]

Agreed Frosty..Pretty similar to todays charts, uppers not on the cold side but giving below average temperatures, just ten degrees here today.

 

Edited October 1, 2016 by Dancerwithwings

[Evening thunder]

2 hours ago, Frosty. said:

It would feel cold, or at least cool in the wind and rain though, which is what I think Matthew meant.

Yes indeed, wasn't sure whether that was the case but thought I'd clarify at least for anyone reading, that didn't know that those charts are not nearly as cold as the 500hpa height looks.

Those charts would give mid-teens at least for some between rain bands (and mildish nights) especially with sea temps still that high, though of course feeling chilly compared to most weather recently, as you say.

Edited October 1, 2016 by Evening thunder

[knocker]

11 minutes ago, Evening thunder said:

Yes indeed, wasn't sure whether that was the case but thought I'd clarify at least for anyone reading, that didn't know that those charts are not nearly as cold as the 500hpa height looks.

Those charts would give mid-teens at least for some between rain bands (and mildish nights) especially with sea temps still that high, though of course feeling chilly compared to most weather recently, as you say.

I'm afraid I'm struggling to understand what you are getting at here. Essentially the 500mb height represents the temperature of the layer surface to 500mb. ( forget for this sake the variation caused by changes in surface pressure) so the lower the height the colder the air but I'm struggling to find the connection between this and the surface temp. Or the 850mb temp for that matter.

[Evening thunder]

18 minutes ago, knocker said:

I'm afraid I'm struggling to understand what you are getting at here. Essentially the 500mb height represents the temperature of the layer surface to 500mb. ( forget for this sake the variation caused by changes in surface pressure) so the lower the height the colder the air but I'm struggling to find the connection between this and the surface temp. Or the 850mb temp for that matter.

I think you have misinterpreted me as that was exactly my point. The original post I quoted suggested a 'very chilly picture' from charts showing low (blue) 500mb heights over us, I was pointing out that that doesn't necessarily mean cold weather at the surface, and indeed it doesn't with those charts.

[knocker]

3 minutes ago, Evening thunder said:

I think you have misinterpreted me as that was exactly my point. The original post I quoted suggested a 'very chilly picture' from charts showing low (blue) 500mb heights over us, I was pointing out that that doesn't necessarily mean cold weather at the surface, and indeed it doesn't with those charts.

Okay fine my apologies.

[knocker]

Interesting upper trough evolution on this evening's GFS

[Frosty.]

A much more pleasant, benign end to the Ecm 12z compared to the unsettled later stages of the 00z, there looks like being a lot of fine weather during the next 10 days plus across most of the uk, especially for the east and south.

Edited October 1, 2016 by Frosty.

[Matthew.]

1 minute ago, Frosty. said:

A much more pleasant, benign end to the Ecm 12z compared to the unsettled later stages of the 00z, there looks like being a lot of fine weather during the next 10 days plus further east and south.

Yes Frosty. Very different end of the run to earlier The pressure average for the 1/3 of October very impressive!

[Frosty.]

14 minutes ago, Matthew Wilson said:

Yes Frosty. Very different end of the run to earlier The pressure average for the 1/3 of October very impressive!

Agreed Matthew, hopefully the Ecm 12z will be nearer reality than the damp squib end of the 00z..

Edited October 1, 2016 by Frosty.