Model Output Discussion - Mid Summer Onwards

[seb]

23 minutes ago, Daniel* said:

Can you actually support that? GFS has maxes barely double figures on Sunday in London mostly single figures across UK.. similarly ECM not much higher. 

also lows forecast Monday AM a widespread air frost… this night is clearly going to be a frosty one, with a cold air mass, very light winds and clear spells. I think we should return to this once it passes.

 

 

Of course we can return to this at some point on Monday

I've explained in a few of my subsequent posts why I don't believe the ECM Op raw figures for Monday morning (or indeed Sunday) - GFS sits comfortably several agrees above; more than half of the ECM members are above; high SSTs are not taken into consideration (along with several other factors) and the ECM more often than not puts nighttime minima several degrees lower than actuals, especially in autumn.

[Notty]

12 minutes ago, seb said:

Of course we can return to this at some point on Monday

I've explained in a few of my subsequent posts why I don't believe the ECM Op raw figures for Monday morning (or indeed Sunday) - GFS sits comfortably several agrees above; more than half of the ECM members are above; high SSTs are not taken into consideration (along with several other factors) and the ECM more often than not puts nighttime minima several degrees lower than actuals, especially in autumn.

Frankly I’m amazed that SSTs would not taken into consideration when most of the surface of the earth is covered by seas. Is it factually correct that the models don’t consider SSTs ?

[ANYWEATHER]

These charts will undoubtedly bring ground frost to many ,air frosts for some ,even in the south, away from most coastal locations. ......

[Paul]

1 hour ago, Notty said:

Frankly I’m amazed that SSTs would not taken into consideration when most of the surface of the earth is covered by seas. Is it factually correct that the models don’t consider SSTs ?

No, it's not. SST's are definitely part of the data within the models and absolutely would be taken into account. 

[danm]

 

[seb]

58 minutes ago, Notty said:

Frankly I’m amazed that SSTs would not taken into consideration when most of the surface of the earth is covered by seas. Is it factually correct that the models don’t consider SSTs ?

Someone shared a document with me in the summer but I can't find it now. It explained that the SST data used for the daily model runs is normalised data which comes from SST forecast rather than raw data. The current way of normalising the SST data, if I remember correctly, outputs values that are too low compared to actuals.

Don't quote me on it; maybe someone here has more details.

Having said that, just looking at the temp maps it would appear that both ECM and GFS simply do what they've always done and add a couple degrees for a very narrow strip along the immediate coast. To me that doesn't look like doing much with the fact the the SSTs around the UK are currently several degrees above where they should be.

[Paul]

There's more info in the links below on what the models ingest - the first link is GDAS which is what the GFS uses. It'll use bouy data and satellite data as the primary method of getting SST's. 

Global Data Assimilation System

WWW.NCEI.NOAA.GOV

---

The National Center for Environmental Prediction (NCEP) uses the Global Data Assimilation System (GDAS) to interpolate data from a variety of observing systems and instruments onto a three-dimensional grid...

A bit more here from the meto:

Marine Observations

WWW.METOFFICE.GOV.UK

---

The other half of surface observations. Marine observations concerns data collection out at sea.

 

[Mike Poole]

1 hour ago, Notty said:

Frankly I’m amazed that SSTs would not taken into consideration when most of the surface of the earth is covered by seas. Is it factually correct that the models don’t consider SSTs ?

No.

[Rain All Night]

A few of the attempts at next week's high as it enters the semi-reliable range are looking rather feeble...

I guess in the case of the ICON it's because it hasn't really formed the low over Portugal to prop the high up?

On a different note, we now have all of the monthly mean seasonal forecasts for October that were produced at the beginning of this month, which I have pasted below alongside those that were produced for October at the beginning of September, when there was a lot of interest in Atlantic trough activity and perhaps a weak signal for some northern blocking. The main change in the more recent forecasts is that a Scandi or NW Russia trough signal has appeared on all apart from the UKMO (GloSea). If our Scandi high forms, we will be entering the final third of the month when it does, from which distance it would have been difficult for the seasonal models to "see" it at the beginning of the month.

...

Edited October 10, 2023 by RainAllNight

[Lukesluckybunch]

no ECM coming out?

[summer blizzard]

7 hours ago, Addicks Fan 1981 said:

According to this our cooler interlude is brief before temperatures 🌡 rise again.  

Time-longitudes diagram - Extended range forecast

CHARTS.ECMWF.INT

---

This is a time/longitude diagram (Hovmoller diagram) of 500 hPa or 1000 hPa mean height anomaly (contours) and spread (shading). The mean anomalies are derived from the ECMWF extended...

 

Did not expect to say this because it normally is wrong but I think the Euro weeklies and Met Office are onto a winner. 

We are about to couple in just about the best position tropically for a +PNA/-AO pattern. 

Blocking to the north and east likely in the final third though we should beware..

- +PNA over warm SST's could just juice the jet

- Always a risk of west based -NAO response

- Blocking centered to north and east can always sag and we can still draw warm uppers.

 

Edited October 10, 2023 by summer blizzard

[Wiltshireweatherwatcher]

1 hour ago, Lukesluckybunch said:

no ECM coming out?

Charts starting to appear now.

[raz.org.rain]

7 hours ago, Addicks Fan 1981 said:

According to this our cooler interlude is brief before temperatures 🌡 rise again.  

Time-longitudes diagram - Extended range forecast

CHARTS.ECMWF.INT

---

This is a time/longitude diagram (Hovmoller diagram) of 500 hPa or 1000 hPa mean height anomaly (contours) and spread (shading). The mean anomalies are derived from the ECMWF extended...

 

Rising again?? Even I have to admit it's ridiculous now  

[summer blizzard]

GEM would be pretty fantastic if it were January. Atlantic is being pulverised. 

Days 8 and 10.

 

Edited October 10, 2023 by summer blizzard

[Kasim Awan]

Think we need to change the title of this thread. This is not a Summer chart.

Edited October 10, 2023 by Kasim Awan

[Cloud 10]

Huge change in the feel of the weather tomorrow,especially across Northern areas,highlighted by tonights Dp's compared with tomorrow afternoon's.

 

[MATTWOLVES 3]

25 minutes ago, Kasim Awan said:

Think we need to change the title of this thread. This is not a Summer chart.

 Change it to what? Cold sypnotic charts in Autumn thread

Seriously folks at long last after recent warm balmy days we are finally seeing a change! Heavy rain tomorrow will soon be followed by much colder conditions come the Weekend...infact ground frosts look increasingly likely,which could bring some lovely early morning scenery.

I think we are done now with a return of anything much warmer til next year,and I feel we could be shaping up for some early blasts of cold during the run up to Xmas.

I've already noticed a touch of tension on these pages just lately regarding how cold it will be and feel,with others quick to dismiss it! And far to much expectations from the met office to be nailing the longer term patterns down! Let's be honest they had a shocker this Summer! Don't expect them to get all the details correct this coming winter!

And just before I go Amazon prime day deals is now running and you can get a really good deal on handbags and towels, so get in there while you can cause I just know that this winter there will be many being thrown in anger on this thread before much longer,and many a towel waving surrender for good measure

I'm now in Winter mode and it should be fun...hey you lot let's all have fun and when times get a little stressful,let's try to remain  humane and good natured with one another.

A very good evening to you all and get ready for some much colder weather later this week.

Bring it on.

[sheikhy]

And ecm 12z still has the frosts from saturday night onward with the scandi high formation!!control has the high further west!!!

[WYorksWeather]

41 minutes ago, Kasim Awan said:

Think we need to change the title of this thread. This is not a Summer chart.

Ironically though, that's actually quite a mild pattern for the UK, with the +10C isotherm in - a long way above average if the ECM is right.

 

Some cooler weather to get through first though from Saturday through Monday:

  

[Rain All Night]

17 minutes ago, WYorksWeather said:

Ironically though, that's actually quite a mild pattern for the UK, with the +10C isotherm in - a long way above average if the ECM is right.

 

Some cooler weather to get through first though from Saturday through Monday:

  

These charts are always so cheering to see, that big bright glowing orb of joy...

But we're not best placed to benefit from this just yet, as you say...

[Derecho]

Quite a temperature gradient there from here to Scandi, if only it was winter!

I'm enjoying the settled October output at the moment after the end of this working week. Quite chilly this weekend but also refreshing

[Methuselah]

1 minute ago, RainAllNight said:

These charts are always so cheering to see, that big bright glowing orb of joy...

But we're not best placed to benefit from this just yet, as you say...

That's why I can't be bothered with them until January. Being close to the North Sea always means that what would once have been snow is now rain/sleet -- hardly the most enjoyable of weather-types? 

[Rain All Night]

28 minutes ago, Methuselah said:

That's why I can't be bothered with them until January. Being close to the North Sea always means that what would once have been snow is now rain/sleet -- hardly the most enjoyable of weather-types? 

There is one benefit of these "winter" synoptics though - especially the northerly for my location - that I'll gladly take at any time...

Edited October 10, 2023 by RainAllNight

[summer blizzard]

52 minutes ago, Derecho said:

Quite a temperature gradient there from here to Scandi, if only it was winter!

I'm enjoying the settled October output at the moment after the end of this working week. Quite chilly this weekend but also refreshing

Very similar to the GEM evolution but a day or two slower. We'd likely see the hight hold out since it's fairly far north and linked (no path over for the low) which would hopefully see the low attempt more of an undercut. 

[WYorksWeather]

GFS looks to be going in the same broad direction - a cooler than average spell, possibly even quite cold, for most of the UK for at least three days. After that though, it does favour a return to milder conditions. Chart is at T+240 which is probably FI, but the evolution to milder conditions starts around day 8.

Before that though, there are at least three days with strongly negative 850hPa anomalies across virtually the whole of the UK. Probably a further day or two for the northern half of the UK.

  

Surface temperatures may be somewhat modified by cloud, humidity and SSTs so are probably unlikely to be quite as cool as this output indicates, but nevertheless I think descriptions of this spell as 'near average' are likely to be wide of the mark. Raw output surface temperatures in the low double digits by day and low single figures by night as shown for much of the country are definitely below average, even if you bump them up by a degree or two to account for model bias.