Model Output Discussion - Mid Summer Onwards

[northwestsnow]

EC has temps below average by day 9

[alexisj9]

16 minutes ago, Mcconnor8 said:

Interestingly the GEM ensembles have almost no interest in the heat extension solution, so have to say it may be the GFS going a bit wild given the UKMO and ECM operational runs also have a breakdown early next week. 

GFS is probably making more of the second cut off low, than the others as per, but I guess we'll see.

[damianslaw]

General consensus between UKMO, GFS and ECM until Sunday, when we see divergence. Far enough out to say its too early to comment on how long the very warm/hot spell will last. It would be exceptional for such sustained heat to last upwards of a week in September. The atlantic does seem in a lull though,but we need to keep an eye on tropical storm development.

The synoptics are almost a carbon copy of the hot spell in June, cut off low to the SW.. high pressure to the north, jet far to the north.

ECM and UKMO suggesting heights will advect west and a much cooler NW/N flow will develop thereafter.

GFS just keeps the status quo.. looks a bit too static. 

 

[sheikhy]

19 minutes ago, northwestsnow said:

EC has temps below average by day 9

Gona feel like december after this week!!

[northwestsnow]

9 minutes ago, sheikhy said:

Gona feel like december after this week!!

I'm on  nights Tues- Fri this week not looking forward to sleeping through the day to be honest.

Of course det could be an outlier for the cool down,  let's see..

[Don]

40 minutes ago, damianslaw said:

The atlantic does seem in a lull though,but we need to keep an eye on tropical storm development.

The tropics helped get us into this mess, now they can try and get us out again! 

[alexisj9]

12 minutes ago, Don said:

The tropics helped get us into this mess, now they can try and get us out again! 

They'll keep us where we are if the GFS is right lol, rather unlikely though, I hope at any rate.

[Scorcher]

57 minutes ago, northwestsnow said:

EC has temps below average by day 9

By day 9. Looks like a worst case scenario to me.

[Rain All Night]

Monday 11th September: to cold front or not to cold front? Every opinion we have... (aren't we lucky to have so many at our fingertips?)

(alternative view of the ECM op - Z500 contours and T850 shading - alongside the two experimental machine learning models being published by the ECMWF)

Edited September 4, 2023 by RainAllNight

[Addicks Fan 1981]

1 hour ago, Mcconnor8 said:

Interestingly the GEM ensembles have almost no interest in the heat extension solution, so have to say it may be the GFS going a bit wild given the UKMO and ECM operational runs also have a breakdown early next week. 

Think we need to trust the mean charts and clusters on this, operational charts need to be observed with sheer caution in my books.    

[Addicks Fan 1981]

11 minutes ago, Scorcher said:

By day 9. Looks like a worst case scenario to me.

Have said this to another poster that the particular chart the poster was referring to was probably in the smallest cluster.  We need to wait until @Man With Beardcomes online or @Mike Pooleto tell us on whatever is more likely ahead.   

[Captain Shortwave]

The ECM operational looks a little extreme in developing that low and the slow eastwards track.

ECM ens suggest a quick return to drier conditions, interestingly good support to redevelop the southerly at day 6/7 before low pressure wins out.

     

 

Looks more like a blip and even the operational would return to fairer conditions after day 10.

[Rain All Night]

4 minutes ago, Captain Shortwave said:

The ECM operational looks a little extreme in developing that low and the slow eastwards track.

ECM ens suggest a quick return to drier conditions, interestingly good support to redevelop the southerly at day 6/7 before low pressure wins out.

     

 

Looks more like a blip and even the operational would return to fairer conditions after day 10.

What you say is also illustrated by the ECM ensemble daily box-and-whisker plots for the central south coast, which show that there are ways for an early-week cold front not to be the end of the party:

Edited September 4, 2023 by RainAllNight

[Addicks Fan 1981]

31 minutes ago, RainAllNight said:

What you say is also illustrated by the ECM ensemble daily box-and-whisker plots for the central south coast, which show that there are ways for an early-week cold front not to be the end of the party:

We need Tams online to see where we are in the GSDM budget on this.    

[Kirkcaldy Weather]

On 01/09/2023 at 19:58, Kirkcaldy Weather said:

Nailing a Rossby Wave Break Event from 330 plus hours out I'll take that everyday

Ps this CFS+GFS combo I've incorporated has become an absolute dream so props to both these models too

Anyone wanting to learn dynamics to watch in association with cut off lows you'll struggle to get a cleaner example 

 

We get a great insight to the conditions present as above average temps set in through the UK, France and Scandinavia with equally huge cold anomalous temperatures in Spain dropping through Northwest / North Africa

I'm focusing on 2 areas especially 

• Severe Flood Threat >>> Spain
• Rare 594 dam tongue extends into Southern UK through France into the low countries 

 

Not far away from a full negatively tilted trough which are common Severe weather scenarios in America. There's mega shear and likely enough of a pivot to give a genuine tornado threat especially on the Eastern + Southeastern quadrant which interestingly is a common feature of tropical cyclones.

The most severe conditions will begin overnight Saturday and persist all day Sunday, there is likely to be a zone where a strong region of a Jet streak sets up with current data suggesting this area near to MADRID in a high flood zone 

 

The ludicrous PWAT continues to hone in around Madrid 

 

Here's where I expect the FLASH FLOOD KINEMATICS TO BE MAXIMISING 

 

Add in the Swathe of damage on the Eastern - Southeast quadrant with maximising dynamic supercellular development is also a prominent concern 

 

PLEASE INFORM ANYONE YOU KNOW THAT LIVE IN SPAIN PARTICULARLY THE ZONES WITHIN MY POST

THIS IS ONE OF THE MOST HIGH END SETUPS FOR SIGNIFICANT IMAPCTS YOU CAN GET, NO SCAREMONGERING I AM HOPEFULLY GIVING HELPFUL INFO WHICH COULD BE LIFE SAVING, THANKS

OK let's start with a look into the dynamics involved with the pattern evolutions over multiple European countries.

Think of an analogy like putting a stopper in a bath, keeping the tap running, eventually with time this causes the water to fold / break over the  

Essentially we're getting a double RWB event each event has different characteristics with our current setup taking on a classic TRT [Trough>>Ridge>>Trough] look, however a single RWB event doing double breaking is pretty rare especially the conditions which have occurred thus far plus the rare setup yet to unfold, more on this shortly.

Multiple very important developing situations to watch here, I'll start with the evolutions following the Spanish wave breaking low. Interesting here as we draw our focus to Franklin 

Note there will be a merger taking place 

My big question is will this be a warm core which would maintain the tropical status of Franklin

This looks the most probable as Franklin's core is the dominant one and that's giving a legit TC meandering near to Portugal 2023 weather bingo card continues to deliver 

Now 95L ie developments involving Lee a worrying early trend He will have full scope across the MDR with an accompanying CCKW which will aid cyclogenisis. 

Currently I'm expectant to have Lee, Margot and the aforementioned Franklin all active come this weekend

We'll see how this trend evolves but definitely a worrying scenario which depends on 2 high pressure zones 

• One moving down from Canada
• Another west of Franklin / within the Atlantic

A Sandy style path is definitely within reason

The dynamical evolutions we see appearing were always coming you've got to factor us seeing a stagnating MJO for a month + via phases 8&1, I highlighted the next cycle getting on the go into week 1 of September... lo and behold the amplified tendency activated in the here and now

Joining all that action above is the upstream of the TRT scenario which leads to a Tropical Cyclone in this area via the Ionian Sea -- Mediterranean 

I have multiple zones I'm worried for substantial flood situations 

Iceland

Norway

Greece

Trends continue emerging with the gradual progression of the less amplified setup as September gets into the weeks 3-4 which I'd mentioned as my expectations

 

 

[TheOgre]

Bleedin’ hell this is probably the best run I’ve ever seen. It’s probably too good to be true though surely

Hot all the way out to 20 September:

Edited September 4, 2023 by TheOgre

[near northampton]

4 hours ago, SilverWolf said:

Can well believe that! Been hedgecutting all day in Tetbury, not that far from Staverton as the crow flies, and it was the hottest day I’ve worked since late June by a long way.. not scientific, but the models showing highest temps today and for a few days after at least may well be spot on. I was not expecting to be quite as hot as it was today having read this thread and seen some forecasts the last few days… 

I live 2 miles from the airport, if the wind direction is correct we should see a foehn effect off  leckhampton hill and another high temperature, maybe 32c 

[Captain Shortwave]

The pub run is essentially a little warmer than the 12z on every single day in the shorter term.

Sunday's chart now starting to show a bit more amplification like the ECM, though in this instance the GFS is close to pulling the 20c isotherm back over parts of the UK. Temperatures into the low 30s up to and including Monday.

   

 

Whilst we talk about the warmth, this type of set up looks more conductive for thunderstorms as we engage the low west of Portugal that should increase instability.

 

[Don]

49 minutes ago, TheOgre said:

Bleedin’ hell this is probably the best run I’ve ever seen. It’s probably too good to be true though surely

Hot all the way out to 20 September:

I sure as hell hope so lol.

The ECM longer term potentially looks to settle down after a blip but less warm/hot.

[Addicks Fan 1981]

1 minute ago, Captain Shortwave said:

The pub run is essentially a little warmer than the 12z on every single day in the shorter term.

Sunday's chart now starting to show a bit more amplification like the ECM, though in this instance the GFS is close to pulling the 20c isotherm back over parts of the UK. Temperatures into the low 30s up to and including Monday.

   

 

Whilst we talk about the warmth, this type of set up looks more conductive for thunderstorms as we engage the low west of Portugal that should increase instability.

 

Thank you @Captain Shortwavefor your rational perception on what is coming up, this September does have potential to be possibly record breaking if AAM remains positive.   

[Don]

Just now, Addicks Fan 1981 said:

Thank you @Captain Shortwavefor your rational perception on what is coming up, this September does have potential to be possibly record breaking if AAM remains positive.   

Certainly a realistic possibility, yes.

[damianslaw]

26 minutes ago, Addicks Fan 1981 said:

Thank you @Captain Shortwavefor your rational perception on what is coming up, this September does have potential to be possibly record breaking if AAM remains positive.   

Not clued up on AAM, where can we view AAM forecasts... 

Seems to be a carbon copy of the June heatwave set up, this. However, perhaps no significant thundery breakdown this time around. 

[Addicks Fan 1981]

11 minutes ago, damianslaw said:

Not clued up on AAM, where can we view AAM forecasts... 

Seems to be a carbon copy of the June heatwave set up, this. However, perhaps no significant thundery breakdown this time around. 

@MattHand @Tamarawill explain next time they are online.    

[near northampton]

21 minutes ago, Addicks Fan 1981 said:

@MattHand @Tamarawill explain next time they are online.    

You have stated that AAM will remain positive and when questioned why you have assured us that 2 other occasional albeit educated members will give us an explanation for your statement? 

[Metwatch]

Another feature of this September could be how dry it is.

GFS currently a more exceptional example, but the chance is there for one of the driest this century for sure. September 2014, 2009, and 2003 are the driest ones this century. Circled in blue are the England & Wales rainfall for those respective months.

Edited September 4, 2023 by Metwatch