Model output discussion - heading into 2018

[Allseasons-Si]

The 18z icon has a parrot

@BLAST FROM THE PAST,so glad to here that your mum and dad are home for Christmas and i wish them and you all the best for the future

and the rest on NW,have a very merry christmas

 

[snowray]

A very happy Christmas to everyone, and a fabulous new year. Yes enjoy Christmas day and boxing day and then it could be time for a bit of fun in the snow for many of us around the country even in the far South-East this time.

 

[ACCOUNT DELETED]

13 minutes ago, andymusic said:

bit early for warnings for Wednesday just yet from meto - looks just fine and the welsh mountains will be pasted once again oh and the mild is being pushed back on each run and cold is being extended

Sleet showing already for the coast of South Wales on the GFS & Met Office forecast. Also the sea temperature has dropped from 10-8C in just a fortnight so that might help but no guarantees

[ukpaul]

10 minutes ago, andymusic said:

bit early for warnings for Wednesday just yet from meto - looks just fine and the welsh mountains will be pasted once again oh and the mild is being pushed back on each run and cold is being extended

The higher Welsh areas should but, apart from West Midlands and the Peak District the rest of us are currently given the chance of a few flurries and a smattering of lying snow with elevation. GFS snow totals last time were high but this time, 1 and 2cm are widespread on the ‘hauteur neige’ charts. That often translates into less than that.

[snowray]

8 minutes ago, ukpaul said:

The higher Welsh areas should but, apart from West Midlands and the Peak District the rest of us are currently given the chance of a few flurries and a smattering of lying snow with elevation. GFS snow totals last time were high but this time, 1 and 2cm are widespread on the ‘hauteur neige’ charts. That often translates into less than that.

Oh well, at least we have tickets for this event and no doubt some people will be disappointed but others will get a nice surprise. 18z looking better generally, out to T192.

Edited December 24, 2017 by snowray

[Catacol]

12 hours ago, Interitus said:

Increased zonality in the midlatitudes typically means higher AAM in this region - flatter jet, increased u-wind = higher AAM by definition, a wavy meridional jet has higher v-wind and lower AAM. This can be seen by comparing a chart of AO as a proxy for zonality, with charts of AAM and its tendency, broken down into 6 time periods - the constrast between midlatitude and subtropical AAM reflects the AO -

 

How you relate this to a GWO/GLAAM budget is up to you, but zonal midlatitudes means higher midlatitude AAM.

 

Of course. Loss of AAM in the tropics is transferred as a higher AAM budget in the extra tropics. It is the loss of tropical AAM that has effectively hamstrung the recent forecasts for more blocked conditions at higher latitude for January as we observe westerlies taking control through our sector of the Atlantic.

The GWO is an index of net AAM in the system - and the inverse relationship between AAM at tropical and extra tropical latitudes is reflected in its value. It has nothing to do with me as to how this is related - it is a calculation that states the condition of GLAAM. Analogue data would suggest that in a Nina base state GLAAM tends to fall.. and with it chances of high lat blocking reduce as winter progresses. Hence the general idea that in a Nina year cold will tend to be front loaded. What was interesting about this year was that GLAAM levels looked to be holding up, as favourable MJO amplitude working alongside a -AO.

We have now seen this reverse... and the only question worth answering in my mind is why. Finally, after literally weeks of waiting and a few texts directly to WDT, we have updates for key AAM drivers. Frictional torques have been negative the last couple of weeks and are only just beginning to trend faintly positive

while global mountain torque has tanked through the floor almost off the scale

 

I really wish this data had been available over the last 10 days or so rather than not updating as expected at WDT (since 6th Dec) as it would have allowed a much earlier "warning" sign to those looking for cold that a change around was in the air. However it all falls into line with what I posted yesterday: stalled tropical signal combined with negative torques helping to scrub westerlies from the tropics and allow the trades to fire up once again. Net result = +NAO regime as westerlies take hold in the north atlantic.

What would cause both torques to fall and the MJO to stall? I cant answer that right now. There's a lot of chicken and egg about all this. I'm hungry to know more... and I'll keep hunting.

[blizzard81]

Trend on today's later runs is for some slight amplification in the north Atlantic at day 7. Let's see if the Xmas day 00z runs can build on this. 

[lassie23]

59 minutes ago, Allseasons-si said:

The 18z icon has a parrot

@BLAST FROM THE PAST,so glad to here that your mum and dad are home for Christmas and i wish them and you all the best for the future

and the rest on NW,have a very merry christmas

 

looks angry too, seems to have its  eye on east anglia

[feb1991blizzard]

29 minutes ago, Catacol said:

 

while global mountain torque has tanked through the floor almost off the scale

 

 

.

along with E.asian (as you would expect) being very low, does this practically put pay to any chance of an over the top SSW in January?

.

Edited December 24, 2017 by feb1991blizzard

[SLEETY]

Merry Christmas from gfs .Europe goes in the freezer in fl Is this the new trend for the new year

[Snowman.]

2 minutes ago, SLEETY said:

Merry Christmas from gfs .Europe goes in the freezer in fl Is this the new trend for the new year

The control is also feeling festive tonight. 

Edited December 24, 2017 by SN0WM4N

[Frosty.]

6 minutes ago, SLEETY said:

Merry Christmas from gfs .Europe goes in the freezer in fl Is this the new trend for the new year

Indeed the 18z flirts with something Epic from the east / northeast not far into the new year..would love to see bitter cold marching westwards!

There is plenty of wintry interest for the week ahead with potentially some surprising amounts of snow in places and some sharp overnight frosts..winter is coming back after tomorrow!merry christmas

[Man With Beard]

The action will really kick off with the latest runner low now it's within range of the EURO4 - and it's taking the main fronts through the Midlands so it would seem. To turn to snow later I'd guess. However, 100 miles of difference in the track is nothing at this stage:

Merry Christmas all!!

[Ice Man 85]

18 minutes ago, SN0WM4N said:

The control is also feeling festive tonight. 

Is the mormon back on the wagon?

To all the coldies, mildies, and everyone in between, have a merry christmas!

[Ice Day]

Massively off topic, but I'm hoping the mods will forgive me as it's Christmas Eve. This a fantastic place for us weather geeks to swap theories and opinions and most of all learn. We have some fabulous posters, Steve Murr, Glacier Point, Tamara, Blue Army, Knocker, Nick Sussex plus dozens of others. We're lucky to have a place to get together and chat and the mods have their hands full every time there's cold in the offing. I would like to wish you all a very Merry Christmas and Happy New Year, maybe a year with less bickering and more respect for all on here!

[blizzard81]

4 minutes ago, Ice Day said:

Massively off topic, but I'm hoping the mods will forgive me as it's Christmas Eve. This a fantastic place for us weather geeks to swap theories and opinions and most of all learn. We have some fabulous posters, Steve Murr, Glacier Point, Tamara, Blue Army, Knocker, Nick Sussex plus dozens of others. We're lucky to have a place to get together and chat and the mods have their hands full every time there's cold in the offing. I would like to wish you all a very Merry Christmas and Happy New Year, maybe a year with less bickering and more respect for all on here!

Thank you Ice Day. A lovely message and let's hope this is remembered throughout the coming year. Merry Christmas to all. 

Edited December 25, 2017 by blizzard81

[geordiekev]

Merry Christmas All,  for anyone wanting to see snow falling check out the Aviemore ranges around midday. 

www.glencoemountain.co.uk/webcams/

 

 

Edited December 25, 2017 by geordiekev

[Britneyfan]

Happy Christmas everyone 

[West is Best]

58 minutes ago, SLEETY said:

Merry Christmas from gfs .Europe goes in the freezer in fl Is this the new trend for the new year

Indeed: loving the later evolution on the 18z! 

[stainesbloke]

Merry Christmas everyone! Another year of interesting analysis and discussion on here, hopefully plenty of interesting weather on the way 

[feb1991blizzard]

Unfortunately it hasn't been an interesting year of snowfall totals.

[bobbydog]

Merry christmas to everyone on netweather.  

twas the night before christmas and all thro' the home, not a model was stirring, not even the AROME....

have fun, be merry and may all your F.I.'s be white.... ❄☃️

[karlos1983]

Merry Christmas one and all, I’ll sign off with some cold Ens members 

Ignore the mild ones, ba hum bug ?

[Daniel*]

Merry Christmas all,

The best gift you can hope for is security of good health, family & prosperity not materliastic things that’s not what Christmas should be about. The models ought to have a swig of fizz.  

Some snow to look forward to this week, take a step away from the computer/devices!

[nick sussex]

No model ramblings for me this late just wanted to say a Merry Christmas to everyone here. 

And here’s to a happy and hopefully snowy New Year!