Model Output Discussion - Mid Summer Onwards

[Metwatch]

1 hour ago, MattStoke said:

1st October 2011 (Current hottest  UK October day on record).

vs

ECM projection for next Saturday.

Extremely impressive airmass for October if it were to come off and if we are to assume it did happen then personally it would be very difficult to beat 2011. We might get close to some of the date records set during the incredible early October heatwave of 1921.

Approaching mid October, at solar noon the angle of sun is only 30 degrees above the horizon, and daylength is at a measly 11 hours. If low cloud or fog becomes a feature that would also suppress temperatures. October 2011 had perfect timing, with the heat starting end of September so stronger sun, soil moisture likely lower, and better mixing of the airmass lower down so no inversion.

It would be very interesting from a statistical pov, if it did come off to see what temperatures would be reached at the surface regardless!

Edited September 30, 2023 by Metwatch

[MattStoke]

4 minutes ago, Man With Beard said:

I'll raise you. 20C uppers upon closer inspection.

Raw actual maxes 25C on both Saturday and Sunday - can we still add on the summer "usual" 2C in October to get to 27C?

 

Not sure how we reached 29.9°C on 1st October 2011 under a less warm airmass than that projected by the ECM for next weekend.

[Don]

12 minutes ago, Man With Beard said:

Raw actual maxes 25C on both Saturday and Sunday - can we still add on the summer "usual" 2C in October to get to 27C?

With the right conditions, definitely!

[ANYWEATHER]

38 minutes ago, ANYWEATHER said:

Gfs ,not really interested in next week's warm up...and by day ten we are all plunged into the fridge, snow on northern hills , and there is a super storm in the Bay of Biscay...interesting if nothing else. ...

Ecms output is utter rubbish!  Total extreme ! Why would anyone believe this rubbish!  Ecm will climb down tommorow towards gfs ....☺

[Mike Poole]

27 minutes ago, MattStoke said:

Not sure how we reached 29.9°C on 1st October 2011 under a less warm airmass than that projected by the ECM for next weekend.

From memory, that spell was very clear and had been for some days, so there was some building of temperatures day on day.  High in a very good position, with dry air from the continent, here 27/9/11 and 1/10/11:

Edited September 30, 2023 by Mike Poole

[damianslaw]

GFS holding firm with the trough breaking through next weekend, ECM has pushed it further east with less of a southerly, more of a south westerly. Will this trend continue, with little warmth away from the far SE and a much more watered down affair. Interesting to see both eventually show same evolution longer term, heights to the NW, cooler NW possible northerly. 

[Methuselah]

6 minutes ago, ANYWEATHER said:

Ecms output is utter rubbish!  Total extreme ! Why would anyone believe this rubbish!  Ecm will climb down tommorow towards gfs ....☺

As if you'd know! 

[Mark wheeler]

10 minutes ago, ANYWEATHER said:

Ecms output is utter rubbish!  Total extreme ! Why would anyone believe this rubbish!  Ecm will climb down tommorow towards gfs ....☺

Saving this post 

[MP-R]

SW flow vs SE flow will make a big difference wrt max temperature. Goes without saying cloud as well. Not much use having such high uppers if it’s a cloudy southwesterly. Although, it’s also possible that with such high uppers weight actually end up with a relatively sunny southwesterly!

[MattStoke]

Impressive ECM mean as well.

[Metwatch]

51 minutes ago, MattStoke said:

Not sure how we reached 29.9°C on 1st October 2011 under a less warm airmass than that projected by the ECM for next weekend.

As I expected, the soundings confirm what I said above, there is a sort of mini inversion on the ECM one on the right modelled for next weekend, compared to 2011 with no inversion (red line the temperature)

[Mike Poole]

10 minutes ago, MattStoke said:

Impressive ECM mean as well.

Yes, and like yesterday’s 12z ensembles, the postage stamps look pretty consistent at T168.  The ultimate destination into week 2 is uncertain, but on ECM products a significant warm spell next weekend looks very likely.  Need GFS singing from the same hymn sheet before calling it, but my guess is GFS is being over progressive with advancing the low.

[legion_quest]

I think people are choosing the ECM because many want that to be the outcome. 

Though granted I want to believe the GFS because I want some cold! 

Hopecasting all round!

 

Edited September 30, 2023 by legion_quest

[alexisj9]

2 minutes ago, legion_quest said:

I think people are choosing the ECM because many want that to be the outcome. 

Though granted I want to believe the GFS because I want some cold! 

Hopecasting all round!

 

Logic and seasonal forcings dictate that the GFS is more likely, however logic has gone out of the window re weather this year, so I guess we need more runs. They'll probably move towards eachother giving some sort of middle ground.

[Scorcher]

1 hour ago, Metwatch said:

Extremely impressive airmass for October if it were to come off and if we are to assume it did happen then personally it would be very difficult to beat 2011. We might get close to some of the date records set during the incredible early October heatwave of 1921.

Approaching mid October, at solar noon the angle of sun is only 30 degrees above the horizon, and daylength is at a measly 11 hours. If low cloud or fog becomes a feature that would also suppress temperatures. October 2011 had perfect timing, with the heat starting end of September so stronger sun, soil moisture likely lower, and better mixing of the airmass lower down so no inversion.

It would be very interesting from a statistical pov, if it did come off to see what temperatures would be reached at the surface regardless!

The solar angle isn't much of a barrier as many believe- yes it will restrict temps compared to a month ago, but get a hot enough air mass and the temps will still soar.

For example somewhere like Los Angeles has a December all-time record of 33C despite a similar midday sun angle (around 30 degrees above the horizon) to the UK in October and shorter days. I get the geography is very different and continental, but the low sun was no barrier to temps going that high.

[Metwatch]

15 minutes ago, Scorcher said:

The solar angle isn't much of a barrier as many believe- yes it will restrict temps compared to a month ago, but get a hot enough air mass and the temps will still soar.

For example somewhere like Los Angeles has a December all-time record of 33C despite a similar midday sun angle (around 30 degrees above the horizon) to the UK in October and shorter days. I get the geography is very different and continental, but the low sun was no barrier to temps going that high.

I would say wind direction is most important factor when we get a very warm airmass while the sun isn't that high. I think when the sun angle is around 30 degrees, (L.A is about 33-34 during December) for most low lying places in the NH, the ceiling is mid-high 20s, but that can easily be much lower with different surface wind direction or poor mixing of the airmass. Take June 2019 as a great example for the UK.

The average high for L.A is quite a few degrees higher in Dec than the UK during October.

Edited September 30, 2023 by Metwatch

[Scorcher]

4 minutes ago, Metwatch said:

The average high for L.A is quite a few degrees higher in Dec than the UK during October.

I know that but that's not the point I was making- I was simply making the point that a low sun angle of under 35 degrees can still support temps above 30C.

I'm not expecting temps to get that high here, even if we get an ECM type setup.

The LA sun angle is 32 degrees at midday on December 30th. 90F was recorded there on that date in 1980. 

[Mark wheeler]

Interesting . A few going below 0 later on.

[Notty]

3 hours ago, MattStoke said:

Not sure how we reached 29.9°C on 1st October 2011 under a less warm airmass than that projected by the ECM for next weekend.

I was there in Gloucester. It was unbelievable. My wife’s birthday. Really warm in the early evening even though it was dark and October. Unforgettable.

[Mark wheeler]

Well, well , well the GFS 18z has had a look at the ECM and said  , ok mate I think you may be on to something here .

[Don]

11 minutes ago, Mark wheeler said:

Well, well , well the GFS 18z has had a look at the ECM and said  , ok mate I think you may be on to something here .

Never ever ignore exceptionally warm charts these days!

[Metwatch]

21 minutes ago, Mark wheeler said:

Well, well , well the GFS 18z has had a look at the ECM and said  , ok mate I think you may be on to something here .

Would probably see a 25C somewhere, a degree away from the date record on the 8th!

[Don]

11 minutes ago, Metwatch said:

Would probably see a 25C somewhere, a degree away from the date record on the 8th!

26C recorded on the 8th October 1995?

[Metwatch]

1 minute ago, Don said:

26C recorded on the 8th October 1995?

https://www.torro.org.uk/extremes/date-records/max-temp

26.1C 1921, 25.6C 1995.

[Addicks Fan 1981]

For those in denial of anything warm or settled I have found something from Tropical Tidbits Eps fast which keeps us rooted in settled weather for quite a while.   

 

EPS Model – 500mb Height Anomaly for Northern Hemisphere | Tropical Tidbits

WWW.TROPICALTIDBITS.COM

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EPS model forecast of 500mb Height Anomaly for Northern Hemisphere

Wish mushy was back on this thread as his posts are of upmost help and he says it like it is.