model discussion Model output discussion 11th July onwards

[damianslaw]

26 minutes ago, sheikhy said:

Very very dry and mild runs all the way to the end for my part of the world!!!!dont mind mild as long as there no rain!!!

Mmm not sure about the dry.. plenty of weather fronts thrown in the mix and dank moist SW flow. Lots of low cloud and drizzle could be the order of the day.. very unappealing.. and a kick in the teeth given it's the last week before clocks go back and half term week. Miserable! Need to store today's sunshine.. make the most of it as we won't see many if any like it for the rest of October, well at least here in the NW!

Edited October 21, 2021 by damianslaw

[sheikhy]

24 minutes ago, damianslaw said:

Mmm not sure about the dry.. plenty of weather fronts thrown in the mix and dank moist SW flow. Lots of low cloud and drizzle could be the order of the day.. very unappealing.. and a kick in the teeth given it's the last week before clocks go back and half term week. Miserable! Need to store today's sunshine.. make the most of it as we won't see many if any like it for the rest of October, well at least here in the NW!

Midlands eastern england very dry but for wales its a different matter!!of course i would love colder weather and lets hope we get there soon!!

[tight isobar]

Ok- just a quick 1.. if it’s an - opening to a mid cold November you require.. then these evolutionarys are worth watching!.. by then there is more than Ample cold for feed and tap.. and the pv is being imprisoned to Russian geographical!.. with if near the money , an obvious open gate for some eye watering waa =Blocking . Further if we indeed reach this plausible out.. the Eurasia side- including Eastern Europe.. would start the cold spilling process quite rapidly. And the Pacific side would be likely on flatline > block reinforcing... my hunch.. mid November,.  And we could certainly be in a winter pocket of note:... as per we’ll watch evolutionary on this ..@starting point.

[Methuselah]

The GFS 06Z at T+384 looks like some cold air might at long last get into northern Europe. A scintilla of hope?

     

Edited October 21, 2021 by Ed Stone

[damianslaw]

49 minutes ago, tight isobar said:

Ok- just a quick 1.. if it’s an - opening to a mid cold November you require.. then these evolutionarys are worth watching!.. by then there is more than Ample cold for feed and tap.. and the pv is being imprisoned to Russian geographical!.. with if near the money , an obvious open gate for some eye watering waa =Blocking . Further if we indeed reach this plausible out.. the Eurasia side- including Eastern Europe.. would start the cold spilling process quite rapidly. And the Pacific side would be likely on flatline > block reinforcing... my hunch.. mid November,.  And we could certainly be in a winter pocket of note:... as per we’ll watch evolutionary on this ..@starting point.

The key is getting the trough further east into Scandi.. the models are heading in this direction. Indeed there is evidence now this is where the eventual direction of travel is.. with a northerly more amplified flow.. knock on implications upstream will have domino effect I.em deepening aleutian low/trough creating more amplification over USA and as you say resulting in warm air advection west Greenland, enabling the azores high to build northwards.. classic text book meridional flow.. until then it's a watch and wait.

[mb018538]

1 hour ago, sheikhy said:

Midlands eastern england very dry but for wales its a different matter!!of course i would love colder weather and lets hope we get there soon!!

West Wales, NW England and NW Scotland still really suffering on the 00z ECM run. As you say though @sheikhy, much of central and Eastern England potentially seeing very little rainfall over the next 10 days now.

[Ali1977]

Not much in the way of PV in the GEFS FI charts, Nov still holdings lots of that word “potential” I reckon. 

 

 

Edited October 21, 2021 by Ali1977

[Frosty.]

Looking at the GEFS 6z, there’s no real change since yesterday, it’s a broadly unsettled and mild outlook but the mean suggests that the last days of October are indicated to become more settled across the far s / se with light winds inducing an increasing risk of overnight / early morning fog whereas the nw / n stay unsettled with strong winds…and then it gradually turns more unsettled again nationwide?…also there’s a stronger chance of arctic incursions, especially further north during early November!? …anyway, just my thoughts, take them or leave them!    ? 

 

 

Edited October 21, 2021 by jon snow

[damianslaw]

2 minutes ago, jon snow said:

Looking at the GEFS 6z, there’s no real change since yesterday, it’s a broadly unsettled and mild outlook but the last days of October are indicated to become more settled across the far s / se with light winds inducing an increasing risk of overnight / early morning fog whereas the nw / n stay unsettled with strong winds…and then it gradually turns more unsettled again nationwide?…also there’s a stronger chance of arctic incursions, especially further north during early November!? …anyway, just my thoughts, take them or leave them!    ? 

 

 

Mild Halloween weekend. Cold Bonfire Night weekend. Become used to both being mild. Will be good to see one colder than normal.

[Frosty.]

19 minutes ago, damianslaw said:

Mild Halloween weekend. Cold Bonfire Night weekend. Become used to both being mild. Will be good to see one colder than normal.

Agreed, and as far as early November is concerned it would be wonderful if some of those GEFS 6z members were right, I would love a cold crisp bonfire night …the kind we seemed to get more often when I was a boy!   

[carinthian]

22 hours ago, carinthian said:

24 hours on and the GFS continues to raise hopes of a return to a more amplified set up as we enter the first week of November. So some glee of comfort for those looking for a colder slot into the British Isles. Longer term model shows some drift and split in the Polar Vortex away from Arctic Northern Russia which may have the effect of developing a break off Lobe ideally positioned to entice colder conditions into NW Europe particularly. 

C

Good news from the GFS model. Continuing to show a transformation to colder conditions from the North heading towards NW Europe for the beginning of November. Yes, and the snow models now picking up an area of snow between Iceland and Norway.. Lets hope this trend continues into the more reliable time span but looking better going forward.

C

Edited October 21, 2021 by carinthian

[Eagle Eye]

Today's update is more hope for me

Looking like originally I may have been right at the start to a point. Still that high to the West is worrying me but to a lesser degree than yesterday. 

Xander 

Edited October 21, 2021 by Eagle Eye

[Ali1977]

Quite a nice way to start November Snow showers maybe getting into the hills of Northern England with those temps.

Edited October 21, 2021 by Ali1977

[blizzard81]

Anybody fancy the first scandi high chase of the season? 

[Cambrian]

Like others have commented, in the current setup, the degree of warm air advection from Canada into Western Greenland is largely determining the likelihood of the cold trough being located over the UK and Ireland and the longevity of its stay.

This is so cleanly diagnostic for the 12z GFS operational run, using the T850 anomaly chart, the following if-then-else rule can be applied - If there is a continuous “bridge” of warm uppers directly linking the coast of North Labrador with the west coast of Greenland, then the trend is for colder than average uppers over us, else the trend is for average or milder uppers over us.

For example, 

24h - bridge broken, trend milder….then mild or close to average for the next three or four days 

120h - bridge still broken, trend still milder….

no complete bridge until 180h, trend colder

Bridge at a peak at 264h as is the upper cold 

Bridge remains there though and pretty much cold here through to the end, e.g. at 366h, so a sustained chilly spell during the second half of the run.

This current acute synchrony is no doubt a consequence of the broad U shape and persistent wavelength of the trough. I guess it wouldn’t always be such a direct relationship.

 

(This is my 100th post on this brilliant forum and I’d like to say thank you for all the interaction and knowledge. I look out for the regular posts from so many great contributors. The main point is though, 100 posts ago, I didn’t know about the importance of WAA on shaping the jetstream, or for that matter, the typical conformations of the jetstream needed for amplification or cyclogenesis., or the significance of the hemispheric wave number for the longer term patterns. The forum provides a fantastically interactive way to learn about a fascinating subject, in very good company. Have a great end to the week.)

[damianslaw]

27 minutes ago, Cambrian said:

Like others have commented, in the current setup, the degree of warm air advection from Canada into Western Greenland is largely determining the likelihood of the cold trough being located over the UK and Ireland and the longevity of its stay.

This is so cleanly diagnostic for the 12z GFS operational run, using the T850 anomaly chart, the following if-then-else rule can be applied - If there is a continuous “bridge” of warm uppers directly linking the coast of North Labrador with the west coast of Greenland, then the trend is for colder than average uppers over us, else the trend is for average or milder uppers over us.

For example, 

24h - bridge broken, trend milder….then mild or close to average for the next three or four days 

120h - bridge still broken, trend still milder….

no complete bridge until 180h, trend colder

Bridge at a peak at 264h as is the upper cold 

Bridge remains there though and pretty much cold here through to the end, e.g. at 366h, so a sustained chilly spell during the second half of the run.

This current acute synchrony is no doubt a consequence of the broad U shape and persistent wavelength of the trough. I guess it wouldn’t always be such a direct relationship.

 

(This is my 100th post on this brilliant forum and I’d like to say thank you for all the interaction and knowledge. I look out for the regular posts from so many great contributors. The main point is though, 100 posts ago, I didn’t know about the importance of WAA on shaping the jetstream, or for that matter, the typical conformations of the jetstream needed for amplification or cyclogenesis., or the significance of the hemispheric wave number for the longer term patterns. The forum provides a fantastically interactive way to learn about a fascinating subject, in very good company. Have a great end to the week.)

Warm air advection in the vicinity of West Greenland and Labrador is something I'm always looking out for.. a link up as you say often results in a colder trough digging in from the NW here and airstream predominantly between west and north. You need to look at upstream developments over east Pacific as well.. aleutian low, west Canada high, deep central north Canada trough which send warm air advection into saud region on eastern flank. Aleutian low is critical.. aleutuan high usually means the opposite. These are wavelengths for November to March.. models are showing an eventual cold trough scenario as we enter November.

[sebastiaan1973]

Is this the right topic? EC46 shows in the second half high pressure at the Atlantic and early december in NW-Europe. http://ECMWF | Charts

[bluearmy]

30 minutes ago, sebastiaan1973 said:

Is this the right topic? EC46 shows in the second half high pressure at the Atlantic and early december in NW-Europe. http://ECMWF | Charts

Interesting because it reflects other forecasts for end nov/early dec …..looks seasonal ……

[Ali1977]

44 minutes ago, sebastiaan1973 said:

Is this the right topic? EC46 shows in the second half high pressure at the Atlantic and early december in NW-Europe. http://ECMWF | Charts

I’d take those charts, a few arctic blasts likely beyond mid Nov which will be quite potent by then, and that last set up would also be very cold (hard frosts) but not necessarily BFTE territory - move the HP several hundred miles North then Bingo.

[Frosty.]

564 dam on Nov 1st! …but probably too wet & windy to truly appreciate it..having said that, the early daffodils won’t mind!!! ?  

 

Edited October 22, 2021 by jon snow

[I remember Atlantic 252]

6 minutes ago, jon snow said:

564 dam on Nov 1st! …but probably too wet & windy to truly appreciate it! ?  

 

18Z GFS had the odd 20 degrees on 1st! but not on latest one

[Methuselah]

Lots of cold-rain potential in today's GFS 00Z run. But, thankfully, there's some warm rain thrown in:

    

    

    

And, at the temps suggested by the ensembles, any precip will be of the 'wet' variety. Yuck!:

   

[knocker]

13 hours ago, Cambrian said:

 

(This is my 100th post on this brilliant forum and I’d like to say thank you for all the interaction and knowledge. I look out for the regular posts from so many great contributors. The main point is though, 100 posts ago, I didn’t know about the importance of WAA on shaping the jetstream, or for that matter, the typical conformations of the jetstream needed for amplification or cyclogenesis., or the significance of the hemispheric wave number for the longer term patterns. The forum provides a fantastically interactive way to learn about a fascinating subject, in very good company. Have a great end to the week.)

If you are interested in the jet stream I would humbly suggest a recent, very readable book, by Tim Woollings, called 'Jet Stream'

Edited October 22, 2021 by knocker

[MP-R]

On 22/10/2021 at 08:03, jon snow said:

564 dam on Nov 1st! …but probably too wet & windy to truly appreciate it..having said that, the early daffodils won’t mind!!! ?  

 

Funnily enough I did notice a pink magnolia with coloured flowers on it nearby. That can’t be normal!

Could be some notably mild nights again next week.

[damianslaw]

1 hour ago, Ed Stone said:

Lots of cold-rain potential in today's GFS 00Z run. But, thankfully, there's some warm rain thrown in:

    

    

    

And, at the temps suggested by the ensembles, any precip will be of the 'wet' variety. Yuck!:

   

Long way off bit the GFS late timeframe shows a very southerly positioned jet.