Model Output Discussion - Into Autumn 2019.

[shaky]

Icon 06z takes it much further south compared to 00z!!its appalling really in my opinion!!you would think in this day and age the technology available that we would have come to an agreement a day or so ago on where lorenzo is gona hit!! 

[Ukwoody]

9 minutes ago, shaky said:

Icon 06z takes it much further south compared to 00z!!its appalling really in my opinion!!you would think in this day and age the technology available that we would have come to an agreement a day or so ago on where lorenzo is gona hit!! 

Too many variables, thats the beauty of weather.  Trouble is we still dont really understand how a lot of the interactions affect one another enough.  If some of the most powerful computers on the planet cant agree then we have no hope! lol

[carinthian]

54 minutes ago, johnholmes said:

Assuming that the Fax chart for 12Z Friday turns out to be about right then Lorenzo, or rather its remains, is going to follow a pretty unusual track=NNE then ESE. I honestly cannot ever remember either in internet days or in my work period any major low doing that sort of track into the UK. Perhaps others can show something similar?

Baffling the team over here JH. They really do not know what to make of it all ! Throwing all sorts of predictions out of the window for the later part of the week. For us over here will it snow or not ? Interesting times !

C

[Man With Beard]

9 minutes ago, shaky said:

Icon 06z takes it much further south compared to 00z!!its appalling really in my opinion!!you would think in this day and age the technology available that we would have come to an agreement a day or so ago on where lorenzo is gona hit!! 

I've felt the models have had a pretty good year on the more extreme situations (esp. ECM) but this storm has caused more grief for the models than any other. Still, would be a major surprise if most of the UK had a major wind event now - I think it's a question of whether the west side of Ireland, perhaps outlying W Scottish islands, get F10-F12 conditions, or if these conditions stay west. I suppose there is the rain to consider, too. 

[johnholmes]

26 minutes ago, shaky said:

Icon 06z takes it much further south compared to 00z!!its appalling really in my opinion!!you would think in this day and age the technology available that we would have come to an agreement a day or so ago on where lorenzo is gona hit!! 

I think you misunderstand the enormous complexity of the problem. Hurricanes and tropical storms have yet to be successfully modelled once they get into the North Atlantic. You can be assured that intense work is going on within the major forecast centres to try and solve this. So far with only very limited success.

[shaky]

6 minutes ago, johnholmes said:

I think you misunderstand the enormous complexity of the problem. Hurricanes and tropical storms have yet to be successfully modelled once they get into the North Atlantic. You can be assured that intense work is going on within the major forecast centres to try and solve this. So far with only very limited success.

Totally understand where your coming from!!and to add to my post before the latest gfs 06z now takes lorenzo through the uk and undercuts the scandi high whereas on the 00z most of the energy was going north east!!its just madness!!

[mb018538]

There certainly seems to be an appetite for a pattern change into the middle of October:

Day 4 - deep Atlantic trough:



Day 15 - +ve heights close to or over the UK, Atlantic much quieter

[shaky]

Arpege finally undercuts and takes lorenzo through central ireland and then probably across southern england!!

[feb1991blizzard]

14 for me please - Genuine snow chances.

[booferking]

2 hours ago, johnholmes said:

I think you misunderstand the enormous complexity of the problem. Hurricanes and tropical storms have yet to be successfully modelled once they get into the North Atlantic. You can be assured that intense work is going on within the major forecast centres to try and solve this. So far with only very limited success.

Ireland is a good shout 2 in 2 years Debbie 61 seems its the bullseye for anything coming from azores homework done

Debbie (1961  https://en.wikipedia.org/wiki/Hurricane_Debbie_(1961)

Ophelia (2017 https://en.wikipedia.org/wiki/Hurricane_Ophelia_(2017)

Lorenzo (2019 to be continued?????????

Edited October 1, 2019 by booferking

[Kirkcaldy Weather]

On 20/09/2019 at 14:15, Kirkcaldy Weather said:

An interesting spell coming up over the next few weeks with a few things going on, I will start with the ensembles which show a tropical feature in the Atlantic during the first week of October with some bringing it our way and others moving it up toward Greenland / Iceland

   still some of the ensembles trying to bring in a northerly too    

Also looks like the MJO will head into phase 1 (currently phase 8         https://docs.wixstatic.com/ugd/31d9e0_3c062d439cb841d2eea3ea174256642b.pdf  https://docs.wixstatic.com/ugd/31d9e0_10ee87ce9b95595674142ec32136a6c6.pdf The majority of those charts suggest lower pressure to the west / north west possibly extending into the UK. Will be interesting to see how it pans out and if the models follow suit and lower the pressure especially to the north west where they seem keen to try and develop some blocking ATM. 

Starting again with the tropical feature which had been shown to develop in the Atlantic during the first week of October, which we all now know is Hurricane Lorenzo which became the easternmost CAT 5 ever recorded https://weather.com/safety/hurricane/news/2019-09-26-hurricane-lorenzo-category-4-rare-eastern-atlantic  https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2019/will-hurricane-lorenzo-affect-the-uk  and is now heading toward the Azores then toward the UK which I will get onto in a moment. Overall I think the ensembles done a good job with timing and positioning at this stage. There were also hints at a northerly across the UK which is on course to move in through tonight bringing some chilly air     MJO did indeed move into phase 1 and is still in phase 1  so I would say a continuation of the current pattern remains likely with lower pressure in the Atlantic extending into the UK at times. Going back to Lorenzo I mentioned a track towards the UK, models appear to have firmed up on the idea (although there could still be some changes in position as is always the case with hurricane paths) of Lorenzo skirting the west / northwest coast of Ireland then moving eastward across Ireland before moving SE through the Central part of the UK / England effectively becoming a sliding low which IMO is an uncommon occurrence especially at this time of year when low pressures would be expected to be moving directly west to east. Actually a good example of the effects that blocking high pressure can have (especially during winter)   

[Sunny76]

2 hours ago, booferking said:

Ireland is a good shout 2 in 2 years Debbie 61 seems its the bullseye for anything coming from azores homework done

Debbie (1961  https://en.wikipedia.org/wiki/Hurricane_Debbie_(1961)

Ophelia (2017 https://en.wikipedia.org/wiki/Hurricane_Ophelia_(2017)

Lorenzo (2019 to be continued?????????

Maybe a warm sunny spell will follow lorenzo. I would love a 4-5 day spell of 20-23c days just before the clocks go back. 

[johnholmes]

For anyone with an understanding of the skew-t diagram, the Camborne and Lwerick ascents clearly show how the UK is going from summer to mid autimn in 24 hours!

http://weather.uwyo.edu/upperair/sounding.html

[knocker]

18 minutes ago, johnholmes said:

For anyone with an understanding of the skew-t diagram, the Camborne and Lwerick ascents clearly show how the UK is going from summer to mid autimn in 24 hours!

http://weather.uwyo.edu/upperair/sounding.html

[MATTWOLVES 3]

Definite signs from the extended ECM ensembles of an improvement towards mid month.... Slp at this stage close to a 1020mb,with the mean temps around 5C. So perhaps some late bursts of sunny daytime conditions and cool misty evenings.... That would be some perfect sunsets and rises and a much needed rest for some of our waterlogged friends who are currently getting fed up with this non stop rain.... Bring it on I say. 

[Paul]

33 minutes ago, johnholmes said:

For anyone with an understanding of the skew-t diagram, the Camborne and Lwerick ascents clearly show how the UK is going from summer to mid autimn in 24 hours!

http://weather.uwyo.edu/upperair/sounding.html

And for anyone who'd like to learn, take a look at John's Skew-T guide in our shiny new learning area

 

 

[booferking]

Damaging.

Edited October 1, 2019 by booferking

[Mike Poole]

Now that the track of Lorenzo is firming up, here's a GIF of the ICON 12z take up to T90:

That change of direction as it presumably comes up against the block to the north north east and undercuts, it looks so odd, but most models are showing this.

[SMU]

Afternoon All-

Having 45 mins to kill while im relaxing I thought I would just pitch up a post of what Im looking for in a model which indicates a probable move from say Mild to a colder outlook- ( especially in winter )

This isn't a definitive process however after watching every model / model run for the last 15 or so years you get to see whats happening in some models & where they are going to follow another.

A text book one this week comes from UKMO V ICON.

I place UKMO at the top of the pile at the moment & this current evolution of the 'lorenzo' track its had nailed from pretty much 144 onwards -

However its the subsequent ridging & block formation west of Scandi thats been the difference for me again.

You may have seen me comment that the ECM has been way to progressively lately & it was following the ICON for its 'slower' progression, well the ICON has been to progressive V the UKMO-

Post Lorenzo UKMO always had decent residual heights to the North generating an 'undercutting theme' heres the 3 day ICON evolution leading to *07am Sunday* ( IE they are all the same timestamp )

You will note across 8 runs we see a ridge appear from nothing in the East to a full blown block. - If you watch the signs you can forecast model 'change'.

On Monday 12z Ive highlighted the first attempt at energy undercutting identified by the model.

We now over the last 36 hours in a model going from T174 > T120 been able to note a model trend & forecast a block to the North....

 

Hope this helps people why I post how I do & also why I posted the central European ENS swing to cold yesterday as the change was coming ....

 

Best

S

 

 

Edited October 1, 2019 by Steve Murr

[johnholmes]

21 minutes ago, Paul said:

And for anyone who'd like to learn, take a look at John's Skew-T guide in our shiny new learning area

 

 

Goodness me that was a few years ago. Thanks for that plug Paul. Do the illustrations still work I wonder-will have a look see.

Seems okay with a quick glance, very basic diagrams but back then all I had was a very basic Microsoft paint box!

[johnholmes]

13 minutes ago, Steve Murr said:

Afternoon All-

Having 45 mins to kill while im relaxing I thought I would just pitch up a post of what Im looking for in a model which indicates a probable move from say Mild to a colder outlook- ( especially in winter )

This isn't a definitive process however after watching every model / model run for the last 15 or so years you get to see whats happening in some models & where they are going to follow another.

A text book one this week comes from UKMO V ICON.

I place UKMO at the top of the pile at the moment & this current evolution of the 'lorenzo' track its had nailed from pretty much 144 onwards -

However its the subsequent ridging & block formation west of Scandi thats been the difference for me again.

You may have seen me comment that the ECM has been way to progressively lately & it was following the ICON for its 'slower' progression, well the ICON has been to progressive V the UKMO-

Post Lorenzo UKMO always had decent residual heights to the North generating an 'undercutting theme' heres the 3 day ICON evolution leading to *07am Sunday* ( IE they are all the same timestamp )

You will note across 8 runs we see a ridge appear from nothing in the East to a full blown block. - If you watch the signs you can forecast model 'change'.

On Monday 12z Ive highlighted the first attempt at energy undercutting identified by the model.

We now over the last 36 hours in a model going from T174 > T120 been able to note a model trend & forecast a block to the North....

 

Hope this helps people why I post how I do & also why I posted the central European ENS swing to cold yesterday as the change was coming ....

 

Best

S

 

 

Apologies about keeping the full post but it seems appropriate.

Interesting post Steve. The situation is not that different from an empirical rule used in UK Met LONG before computers arrived in trying, in winter, to predict when a Scandinavian high could develop. The charts you show are not too different from the ideas behind the empirical rule and the probability of the ridge then persisting for more than 48 hours.

Remember in the 50's and 60's only human forecasts were done so trying to predict beyond 24-48 hours was pretty unusual.

[knocker]

29 minutes ago, Mike Poole said:

Now that the track of Lorenzo is firming up, here's a GIF of the ICON 12z take up to T90:

That change of direction as it presumably comes up against the block to the north north east and undercuts, it looks so odd, but most models are showing this.

It actually loses it's fuel source as it leaves the main jet to the west and thus drifts SE and fills rapidly having undergone full transition

Edited October 1, 2019 by knocker

[SMU]

2 minutes ago, johnholmes said:

Apologies about keeping the full post but it seems appropriate.

Interesting post Steve. The situation is not that different from an empirical rule used in UK Met LONG before computers arrived in trying, in winter, to predict when a Scandinavian high could develop. The charts you show are not too different from the ideas behind the empirical rule and the probability of the ridge then persisting for more than 48 hours.

Remember in the 50's and 60's only human forecasts were done so trying to predict beyond 24-48 hours was pretty unusual.

Cheers John- 

So what method did they have - wasnt it based around coordinates of high pressure leading into developing a Scandi HP?

UKMO 96 sizing an Easterly up- 

[johnholmes]

5 minutes ago, Steve Murr said:

Cheers John- 

So what method did they have - wasnt it based around coordinates of high pressure leading into developing a Scandi HP?

UKMO 96 sizing an Easterly up- 

No but will try and copy the very basic map and explanation and see if I can post it.

 

On another topic, Lorenzo, this link is interesting, the Portugese forecast for the Azores area showing how they expect it to move over the top of them and on to Ireland?

https://www.weather-forecast.com/maps/Azores-Portugal

[JeffC]

42 minutes ago, knocker said:

It actually loses it's fuel source as it leaves the main jet to the west and thus drifts SE and fills rapidly having undergone full transition

it does seem to just fizzle but no doubt it will produce some potent gusts for many - I need to remember to tie my wheelie bin to its hook!