Model Output Discussion - Autumn arrives

[mb018538]

7 minutes ago, bluearmy said:

Incidentally the ec46 was much Improved weeks 3/4 compared to previous output.

this obvs takes even more confidence away from what is already a low bar for weeks 3/4 

interestingly, up until the past day or so, the Meto 30 dayer had been fairly optimistic for early July which puzzled me somewhat. Now I note it has gone to where I would have expected it to be based on the past few runs of the 46. Will they now change their wording on the back of one run??  Presumably their own model had also flipped less settled - hence the change this week. Would be typical for them to now need to flip back again! 

35 right by the wash ??

methinks it may need a re calibration!

Early July has been flagged as an improvement for a while.

Global AAM should start to rise sharply as we head out of June and into July. This should hopefully give the mid Atlantic high a bit of a kick east towards the UK and hopefully settle things down. I note the met office forecast as you say has turned more unsettled which puzzles me somewhat. I’d expect an improvement from the end of June sometime in the first 7-10 days of July. One to watch.

[minus10]

Ecm with a low over north Biscay now for Monday...

[bluearmy]

it would seem that the 00z output has lessened the chances of the cut off upper low staying down there next week and not escaping ne as the upper trough headed south this weekend meets up with it.. there did seem to be a reasonable chance that the Atlantic ridge would push across rapidly over the weekend and avoid the two joining up. That would be my take from the overnight runs. Whether the 12z’s swing back at all on this will be notable. 

[Earthshine]

1 hour ago, Ben Sainsbury said:

Definitely right on the upper end of the models, ARPEGE reaches 33C maybe 34C, GFS not far off now either. Logically, the UKV is by far the highest resolution model we have, so in theory it should be best in forecasting min/max temperatures. The fact that the UKV has consistently been forecasting 34-36C too, to me assuming it produces the same values the day before then if we don't see temperatures of 34-36C then I think it will be a bit of a disaster from the UKV tbh.

Not really, models are never going to give exact temperatures especially in an extreme situations like this.  You would have to know the exact state of the atmosphere which of course we can't with current observation capabilities.  If we see 32°C for example that doesn't mean the model failed, it's just that the pattern was on such a knife edge that even a 10° change in wind direction (for example) could mean the difference between 32° and 36°C

Edited June 14, 2022 by Earthshine

[NO LONGER POSTING]

 

27 minutes ago, minus10 said:

Ecm with a low over north Biscay now for Monday...

Who was it that said you can't have a warm/hot easterly? 

[Earthshine]

35 minutes ago, mb018538 said:

Early July has been flagged as an improvement for a while.

Global AAM should start to rise sharply as we head out of June and into July. This should hopefully give the mid Atlantic high a bit of a kick east towards the UK and hopefully settle things down. I note the met office forecast as you say has turned more unsettled which puzzles me somewhat. I’d expect an improvement from the end of June sometime in the first 7-10 days of July. One to watch.

Yep and even next week isn't looking bad.  Pretty bog standard summer weather.

[SqueakheartLW]

Seems the models have more or less made this heat event a certainty but then again weren't we 3 days out from the predicted cold spell last Christmas then the models suddenly dropped the idea?

Friday

GFS 00z

The GFS is less bullish on getting the highest temps into the UK and on this particular run the range of temps is from 22.7C as a max from P27 through to 27.3C from P23 with the mean max sitting at 24.8C. Not really much of a hot day there if 24.8C is the expected maximum for Friday. A bit of a downgrade if that is to be believed. Better to see what the rest of today's runs come up with.

GEM 00z

GEM is far more keen to deliver heat on Friday with the range of temps from 26.6C as a max from the Op run through to 33.9C from P09 with the mean max sitting at 31.3C. Quite a bit higher than what the GFS thinks will happen on Friday.

Saturday

There have been a few runs that extend this heat into the Saturday as well. How many are doing it on the 00z's and how many members are doing it in each run.

GFS 00z

GFS 00z has 11 members keeping temps above 25.0C for Saturday although still not keen on the idea of any chance of 30C on either Friday or Saturday. The max temp is on P19 at 27.6C. The mean prediction for Saturday is a lot lower than this though at 21.3C and when you see what some of the members are doing you can see why the mean is so much lower. Some of the members are seeing a big crash in temps and 3 of them are coming in with maxes below 15C, P03 is the coldest at a measly 10.7C as a max for Saturday

GEM 00z

GEM 00z is more keen to remove this heat compared with GFS so a bit of a balancing act here. GEM more keen for higher temps on the Friday compared with GFS but then more keen to drop these temps into Saturday compared with the GFS too. Only 1 member seems very keen to have a hot Saturday too with a temp max of 32.4C. All the other members remove the heat quickly, some much quicker than others as can be seen with the slowest one P14 getting a max of 24.4C vs the quickest one the control run that only has a max of 12.0C

Beyond Saturday

As for beyond Saturday there are a whole range of outcomes as expected but in general 2 themes. Members that are more keen to keep the heat or warmth around for a while or even to the end of the run and those that once the heat is gone keep things on the cool side for the time of year. I have picked out 2 members from each run that clearly show this.

GFS 00z

850hpa                                                    2m temp

P07 - (Cooler option) Once the "heat GFS style" which isn't really that much heat on the 00z is gone this run takes temps below 20C and then there we languish right until +384h with some very low temp maxes too on some of the days. Very much a summer is over member if this one comes off

P18 - (Warmer option) Although the temps on P18 do drop back for a short while it doesn't take long for temp maxes to get back over 20C again and there they remain until +384h. Better to have this member if you want summer to continue for a least the next 2 weeks or so.

GEM 00z

850hpa                                                    2m temp

P04 - (Cooler option) This one, really like P07 from the GFS removes the heat very quickly and once it does 20C maxes are history right out to +384h although this one is slightly less chilly than the GFS equivalent and does extend the heat into Saturday but we pay the price for it for that extra hot day it seems.

P17 - (Warmer option) This warmer option sees a temporary cool down after the heat before then bringing in another very warm to hot spell next week with maxes approaching 30C again. However unlike the GFS warm option this one eventually does cool down right at the end with maxes only just scraping over 20C at best.

[Ben Sainsbury]

6 minutes ago, Earthshine said:

Not really, models are never going to give exact temperatures especially in an extreme situations like this.  You would have to know the exact state of the atmosphere which of course we can't with current observation capabilities.  If we see 32°C for example that doesn't mean the model failed, it's just that the pattern was on such a knife edge that even a 10° change in wind direction (for example) could mean the difference between 32° and 36°C

You're not wrong and I do agree to some extent, but surely this logic should be applied to all of the models because they all begin their runs with the same observational data so should have somewhat similar errors (obviously I know the model physics differ slightly). But as I said in my previous comment, the UKV having the highest resolution means it should still perform slightly better regarding the peak max temps for this Friday (whether that be 32C or 36C), regardless of whether one of the variables is slightly off or not. Maybe saying it would be a 'disaster' is a bit far, but this brief hot blast will definitely give us a good insight into how we should perceive the models (& UKV in particular) going forward when we are expecting extreme heat.

[Methuselah]

1 minute ago, Ben Sainsbury said:

You're not wrong and I do agree to some extent, but surely this logic should be applied to all of the models because they all begin their runs with the same observational data so should have somewhat similar errors (obviously I know the model physics differ slightly). But as I said in my previous comment, the UKV having the highest resolution means it should still perform slightly better regarding the peak max temps for this Friday (whether that be 32C or 36C), regardless of whether one of the variables is slightly off or not. Maybe saying it would be a 'disaster' is a bit far, but this brief hot blast will definitely give us a good insight into how we should perceive the models (& UKV in particular) going forward when we are expecting extreme heat.

Personally, I never thought the pre-Christmas model output was as clearcut as some posters claimed and I said so at the time. But, then, I've long thought the notion of computer models 'giving and then snatching away our preferred weather' to be absurd: the weather (as in the latest data) controls the models; models do not control the weather?

[Cambrian]

0z ECM operational run showing the close interplay needed between the heat hanging on in the southeast on Saturday forcing a sharper temperature contrast and the subsequent intensity of the breakdown. 

Temperatures peaking on Friday afternoon, 28-30 degrees inland in the south and east of England. The heat being pushed southeast by Saturday 8am, just a few light showers drifting south over Wales and parts of northern England,
    

but the low over Biscay keeps on pumping up the heat into the southeast corner, the warmth holding on until the evening.

  
The showers have perked up considerably by the afternoon, but the band really gets going later in the day and into Sunday, 2-3 inches of rain in 24 hours for some places in the southwest by the middle of Sunday.

    

It looks like we could go from the main talk being about parasols this week to umbrellas by the weekend. Still a long way off for any precision regarding rainfall and this setup would need a lot of fine balancing to happen this way. Also the ECM often overdoes the precipitation totals and hopefully is on this occasion too, as with local topographical effects that wouldn’t be looking too good for parts of Devon, Cornwall and Somerset. 

Edited June 14, 2022 by Cambrian

[johnholmes]

Sticking my neck out for beyond the weekend with the 500 mb anomaly charts

Update on Tuesday 14 June

Ec in the process of shifting the marked trough, last 2 days, over uk into near continent with ridging following into much of uk on this output.

NOAA is not much different really, lost the last 2 days so not sure how it evolved from the Friday issue (flat w’ly) to the current, but both look reasonable ideas of the expected upper flow 6 days from now.

Little sign on either of anything but a rather cool flow for all areas, nw-se in terms of any rain/showers, possibly veering ne/sw as the flow edges/moves east with time transferring the upper low to east of the meridian. The 8-14 NOAA does show this. So a coolish spell for all from Sunday/Monday looks the most likely. No sign of any ‘plumes’ being possible on these charts

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

[sheikhy]

Thank god latest icon keeps wet weather towards the south east and london for saturday!!if it aint gona be hot and dry i really dont want humid and wet so that band of rain can do one and stay south of me!give me northerly wind but dry and sunny all day long!!

[Paul]

I've split out the posts from this morning into a fresh thread as the other one was getting a bit long  

[StormChaseUK]

The 06z introduces hotter temps into NW France compared to 00z run  (from 31c to 37c in places) this hopefully might prolong the Saturday warmth a bit more.

[Liam Burge]

1 hour ago, Cambrian said:

0z ECM operational run showing the close interplay needed between the heat hanging on in the southeast on Saturday forcing a sharper temperature contrast and the subsequent intensity of the breakdown. 

Temperatures peaking on Friday afternoon, 28-30 degrees inland in the south and east of England. The heat being pushed southeast by Saturday 8am, just a few light showers drifting south over Wales and parts of northern England,
    

but the low over Biscay keeps on pumping up the heat into the southeast corner, the warmth holding on until the evening.

  
The showers have perked up considerably by the afternoon, but the band really gets going later in the day and into Sunday, 2-3 inches of rain in 24 hours for some places in the southwest by the middle of Sunday.

    

It looks like we could go from the main talk being about parasols this week to umbrellas by the weekend. Still a long way off for any precision regarding rainfall and this setup would need a lot of fine balancing to happen this way. Also the ECM often overdoes the precipitation totals and hopefully is on this occasion too, as with local topographical effects that wouldn’t be looking too good for parts of Devon, Cornwall and Somerset. 

Bring on the rain and thunderstorms!!

[sheikhy]

Not as wet saturday on gfs 06z but brings in rain sunday night!no where near the deluge of ecm though!!

[MattStoke]

Noticing a slightly stronger push of the 20’C isotherm into southern areas on recent model runs. Some of which coincidence this with the warmest part of the day on Friday  

[sheikhy]

Gfs only has 28 to 30 degrees friday!safe to say ukv has lost the plot!!dunno what it  is playing at to be fair!!!considering its a high reso model and highly regarded dont think it gona do itself any favours!!!needs to go back the drawing board lol!

[Captain Shortwave]

8 minutes ago, sheikhy said:

Gfs only has 28 to 30 degrees friday!safe to say ukv has lost the plot!!dunno what it  is playing at to be fair!!!considering its a high reso model and highly regarded dont think it gona do itself any favours!!!needs to go back the drawing board lol!

Actually that is the most widespread spread of 30c for quite a few runs on Friday from the GFS. In fact looking at hi resolution there is a 32c for London.

 

 

Saturday has to be one of the delicate evolutions I have seen. Cold pooling moving down the developing Atlantic ridge and interacting with the low west of France/Spain. The boundary and subsequent rain will be hard to pin down for several runs yet. Temperatures into the low 40s across parts of NW France. Not far away if the boundary shifts 50-100 miles northwards.

Edited June 14, 2022 by Captain Shortwave

[mb018538]

14 minutes ago, Captain Shortwave said:

Actually that is the most widespread spread of 30c for quite a few runs on Friday from the GFS. In fact looking at hi resolution there is a 32c for London.

 

 

Saturday has to be one of the delicate evolutions I have seen. Cold pooling moving down the developing Atlantic ridge and interacting with the low west of France/Spain. The boundary and subsequent rain will be hard to pin down for several runs yet. Temperatures into the low 40s across parts of NW France. Not far away if the boundary shifts 50-100 miles northwards.

Yep - the one thing that i think will prevent the 35c temps from happening is the wind. Gusting 25-30mph will mix the air too much. Usually need it still for the higher temps to build.

[Paul]

3 hours ago, bluearmy said:

35 right by the wash ??

methinks it may need a re calibration!

It has the highest thicknesses in that area and we may need to extend the scale at some point if this sort of thing continues!

[swilliam]

That is some Northerly following the hot plume. GFS even has snow for the highlands

[SqueakheartLW]

11 minutes ago, swilliam said:

That is some Northerly following the hot plume. GFS even has snow for the highlands

As predicted that GFS Op run is one of the coldest outliers at that time

[Ben Sainsbury]

ARPEGE 6z will likely be an improvement for maximum temperatures on Friday too compared to the 0z run. 0z run had widespread low 30s, peaking at 34. 6z run has 850s at least 2 degrees warmer across the SW early on Friday, so maybe seeing 35C on this run? Unfortunately cannot see past T72.

[Troubleatmill]

Still so much scatter from Friday lunch time that anything after that is a 'look what happens if' scenario. Further south this split happens Saturday 

Using Preston as its central in the UK so clearly not showing any 20+ 850s 

Edited June 14, 2022 by Beano
Explan