Model Output Discussion - Autumn arrives

[Mizzle]

I have a couple of questions that hopefully the more knowledgeable members can answer for me.

When the models show 2m readings, are they taking into account local topography to a fine detail or just in broader geographic terms i.e. in a city like Southampton with both built up urban areas and a sea coast does the model average out the temperature across a broad area?

With that in mind, is it therefore possible local readings will go substantially (and potentially dangerously) higher than maxes shown? 

TIA  

[mb018538]

43 minutes ago, kold weather said:

Just fwiw I looked at France yesterday and the GFS expected temps at the same time

The GFS was a solid 2-3c too hot.

Might suggest the GFS is going too high for its forecasts, and it has been noted that it does have a bias to rise temps too much in very dry airflows over in the US, so that may well be an issue.

Interestingly the ECM was also too hot mind you.

It’s been noted that the gfs may be overdoing dryness in the ground. Soil moisture content is too low, so it shows it hotter than it should be. 
That said - the met office and bbc have both gone for 40c, and they wouldn’t do that for a laugh would they. It’s a very realistic possibility.

[Captain Shortwave]

12 minutes ago, MattStoke said:

Tiny bit slower. Not much in it.

UKV 6z up to midday Monday is a little bit hotter in the far south. Much the same elsewhere.

Enough I suspect to bump the temperatures up a little on Tuesday, also looking at the low resolution I suspect temperatures on Monday might be up a notch too. Both days had patches of 38c now.

It appears we have a ballpark figure of 36-40c on Monday and 37-41c on Tuesday. I would say this range will shrink over the coming runs but if cloud cover is a factor then maybe not.

Edited July 16, 2022 by Captain Shortwave

[Singularity]

11 minutes ago, Mizzle said:

I have a couple of questions that hopefully the more knowledgeable members can answer for me.

When the models show 2m readings, are they taking into account local topography to a fine detail or just in broader geographic terms i.e. in a city like Southampton with both built up urban areas and a sea coast does the model average out the temperature across a broad area?

With that in mind, is it therefore possible local readings will go substantially (and potentially dangerously) higher than maxes shown? 

TIA  

It depends on the model resolution, the highest ones such as UKV and AROME capture the finest detail with even small cities and valley formations being resolved to some extent, while GFS for is relatively course but can still resolve urban heat islands for large cities like London or Birmingham. ECM is a little higher res than GFS but I’d still use UKV when available.

[tight isobar]

Cobra meeting called due to impending heat .. let’s see where the 6z takes things this morning.. And watch out for stronger pulses of Azores going forward!!!

[MattStoke]

4 minutes ago, Captain Shortwave said:

Enough I suspect to bump the temperatures up a little on Tuesday, also looking at the low resolution I suspect temperatures on Monday might be up a notch too. Both days had patches of 38c now.

It appears we have a ballpark figure of 36-40c on Monday and 37-41c on Tuesday. I would say this range will shrink over the coming runs but if cloud cover is a factor then maybe not.

Monday should be into range of the Arome soon. Will be interesting.

No-one discussing the UKV overdoing temperatures based on how dry the air is despite it showing similar temperatures to the GFS.

[Cambrian]

The cold front coming in across southwestern parts at midday Tuesday looks to be our little saviour. The T850 20 degree isotherm has reached its most northerly extent, to the north of Scotland, just as the breakdown arrives in the southwest. If the breakdown was to be delayed by a day, the day by day increase of 2-3 degrees shown on the 0z ECM ensemble could well have given a mean of around 38 degrees for Wednesday in places in the east of the UK. These plots don’t even show the mid-afternoon peak, so the Wednesday maximum would have been comfortably and widely hitting 40 degrees, not just in a few spots, such is the advance of the heat over the next few days.

  

It has been fascinating, and indeed at times a bit scary, to have been part of a group of people who have watched this momentous weather event emerge for getting on a fortnight now. I hope that the next time the modelling thread is this busy, that it will be due to an equally well foreseen super-blizzard!

[mushymanrob]

30 minutes ago, Singularity said:

That chart shows pretty much the long-term average late July pattern for NW Europe hence the anomaly over the UK is very slight.

This is possible even with the positive  anomalies to the west, as they represent the stronger than usual Azores High rather than one displaced northward (hence no negative anomalies near Azores), while ones across the Arctic aren’t strong enough to suggest a -AO.

So, a standard westerly setup is suggested to me, mostly settled in the south, unsettled at times in the north.

I’m not sure how much I buy into it though, given the modelling difficulties I mentioned yesterday. Could be interpreted as ‘no clear signal’ from NOAA.

Yep..

Last line.... their own confidence rating for this chart is 4/5 which is high for the 8-14 dayer. Plus the evolution of this has been steady and consistent, suggesting to me anyway that it is a pretty clear signal.

Personally i hope its wrong and we get more heat! lol..  But as things stand it does look like pretty standard Summer fayre, which isnt bad.

[Ben Sainsbury]

ICON 6z going for localised 38C on Monday, and 39C on Tuesday which is a touch up on its 0z run as the clearance of heat is delayed an hour or two.

[Stormchaser17]

First look from the WRF to Monday's max temperatures, GFS 00z-based. Highest values seems to be in inland E England, but widespread hot temperatures between day and nighttime, heat islands are pretty defined, and London seems to definitely remain warm.

Never expected to see these colors over the UK when I created the scale.

  

[hotsummer]

There’s been a few flutterings of it, but heat from next weekend on 00Z not only arriving but staying for the entire last week of July - 30c plus (and into mid 30s) for 8 days! Could you imagine if that even came off? it would be quite remarkable.

A possibility given heat so close by - just an example in FI lol (27/7/22).

20c line right near, 15c well in. 564dam almost positioning itself as its own Hadrian’s wall. 

Jetststream pushed further north than now and early next week!

Edited July 16, 2022 by hotsummer

[MattStoke]

1 minute ago, hotsummer said:

There’s been a few flutterings of it, but heat from next weekend on 00Z not only arriving but staying for the entire last week of July - 30c plus and into mid 30s for 8 days! Could you imagine if that even came off? it would be quite remarkable.

A possibility given heat so close by - just an example in FI lol (27/7/22).

20c line right near, 15c well in. 564dam almost positioning itself as its own Hadrian’s wall. 

Jetststream pushed further north than now and early next week!

Certainly can’t be dismissed. Nothing can completely dismissed in weather forecasting. Even something ludicrous like a GFS ensemble showing 40’C+ in 3 weeks time. Can you imagine how ridiculous that would be though?

[Liam Burge]

Will be interesting to see how the models evolve with the breakdown of the heat come Tuesday/Wednesday. UKV has some wicked thunderstorms developing.

[Biggin]

13 hours ago, tight isobar said:

London ones 

So chance of rain on Wednesday a slight cool down  then an inkling of return to warm temps a few days later  ?

[kold weather]

Whilst not as extreme as next week, tomorrow is generally looking pretty hot now, having been upgraded over the last few days as the plume has become slightly more progressive over time.

GFS 06z for example giving a localised 33c in London which would make it briefly the hottest day of the year. 

[MattStoke]

Back edge of the pool of hot air is further west so far on the GFS 6z

[kold weather]

Here is a chart I'm not sure I ever thought I'd see, now within 60hrs away:

[Mark Smithy]

2 hours ago, Ed Stone said:

I wonder if the GEFS 00Z ensemble's operational run may be onto something?

    

That's extraordinary! Has there ever been such a persistent outlier operational in FI? 

[The Tall Weatherman]

Looks like the next update on the 6z GFS is going to be a scorcher.

[Mark Smithy]

1 hour ago, kold weather said:

Whats impressive is that Sunday looks like its almost as hot as last Tuesday was, yet its being absolutely shadowed by what is to come afterwards.

Anyways I'm watching the W.France temp profile today to see which model has a current better grip on the profile. ECM has temps broadly around 24-25 around Nantes for example by 09z, the GFS around 27-28c. Current temperature in the region is around 21-22c at 07z.

That's a really good idea to check model accuracy, albeit clearly there are some differences with the UK plume event.

Can you keep us posted on this KW? Particularly interested in temps at, say, 12z, 15z and 18z for comparisons.

p.s. And I assume by 'z' you are on the exact same zulu time as France i.e. not one hour out?

[Liam Burge]

 

Not sure if anyone has posted this yet or not as I am not 100% sure when this was declared.

However, a Level 4 (National Emergency) has been declared and a COBRA meeting is gonna be taking place today about the heat conditions. I don't think a Level 4 has ever been issued before, but please correct me if I am wrong.

[Stormyking]

Hello Everyone

Glad to say I can get involved with the models properly again after a long long absence, it really is looking a really exceptional event coming up and is gonna be very interesting tracking. No real change on the GFS 06z with 40'c+ still showing  in some central and eastern parts Monday and becoming more widespread come Tuesday. Certainly now growing in confidence of this actually happening, potentially dangerous heat.

[MattStoke]

6 minutes ago, The Tall Weatherman said:

Looks like the next update on the 6z GFS is going to be a scorcher.

Slightly hotter each day than the 0z for some areas.

[kold weather]

4 minutes ago, Mark Smithy said:

That's a really good idea to check model accuracy, albeit clearly there are some differences with the UK plume event.

Can you keep us posted on this KW? Particularly interested in temps at, say, 12z, 15z and 18z for comparisons.

p.s. And I assume by 'z' you are on the exact same zulu time as France i.e. not one hour out?

Yeah, it will probably be more useful tomorrow as the NW France should be starting to get into the peak airflow as the high withdraws eastwards.

06z biggest difference is the area of 38-40c is much larger, reaching right the way down into the SE this time as the plume takes longer to get displaced and we keep the southerly airflow intact for a little longer.

[chrisbell-nottheweatherman]

31 minutes ago, hotsummer said:

There’s been a few flutterings of it, but heat from next weekend on 00Z not only arriving but staying for the entire last week of July - 30c plus (and into mid 30s) for 8 days! Could you imagine if that even came off? it would be quite remarkable.

A possibility given heat so close by - just an example in FI lol (27/7/22).

20c line right near, 15c well in. 564dam almost positioning itself as its own Hadrian’s wall. 

Jetststream pushed further north than now and early next week!

That's almost as scary as this Monday and Tuesday!