Model Output Discussion - Mid Summer Onwards

[Addicks Fan 1981]

Just now, WYorksWeather said:

Yeah it is important to take the OP runs with a pinch of salt - as I've been pointing out over the past few days the operational runs have been close to the bottom of the ensemble packs lately. However, tonight it does seem that the 12z runs are mostly singing from the same hymn sheet (pending ECM), and so it does look like there'll be a period of cooler weather.

I also think given the tropical features at this time of year, anything beyond T+120 is iffy, and beyond T+168 is FI. Strictly for fun only.

Think that anything colder will be only for a short period of time before the winds back in a SW direction, this thread needs @Tamaraas things stand as the NWP shouldn't entirely be taken seriously. 

We need to look at other variables like the Hovmollers, AAM and the MJO as @Metwatchmentioned.  

[Metwatch]

You know winter is fast aproaching when it's fully dark outside and the ECM is barely half way through it's 12z run.

Another spell of high pressure modelled for this time next week, but a lot more seasonal and suitable for the time of year!

[Guest]

10 minutes ago, Addicks Fan 1981 said:

Think that anything colder will be only for a short period of time before the winds back in a SW direction, this thread needs @Tamaraas things stand as the NWP shouldn't entirely be taken seriously. 

We need to look at other variables like the Hovmollers, AAM and the MJO as @Metwatchmentioned.  

You and mushy and Tamara need to get a room

[Lukesluckybunch]

ECM again going for the scandi high later on...UKMO at 168 looked a little flat..ECM looks much better!

[WYorksWeather]

15 minutes ago, Addicks Fan 1981 said:

Think that anything colder will be only for a short period of time before the winds back in a SW direction, this thread needs @Tamaraas things stand as the NWP shouldn't entirely be taken seriously. 

We need to look at other variables like the Hovmollers, AAM and the MJO as @Metwatchmentioned.  

Not really qualified to talk RE: those outputs, but I will flag up the National Hurricane Center forecasts.

Yellow X in the Gulf of Mexico can probably be ignored - only 20% chance of formation and probably not likely to head our way.

However, the red X is likely to form in the next few days:

Quote

A low-latitude tropical wave located several hundred miles south-southwest of the Cabo Verde Islands continues to produce a large area of showers and thunderstorms. This activity has become a bit more concentrated this afternoon, and environmental conditions appear conducive for additional development of this system during the next several days. A tropical depression is likely to form in the next couple of days while it moves west-northwestward or northwestward across the eastern tropical Atlantic.

Formation chance through 48 hours...high...70 percent.

Formation chance through 7 days...high...80 percent.

As a general rule, we've been seeing a lot of these tropical storms / hurricanes tossed out to sea as they approach the U.S. East Coast, which normally then sends them extratropical and heading E or NE towards Europe, leading to direct or indirect effects on our prevailing weather patterns - the cause of our heatwave in September and then more recently Storm Agnes. I wouldn't rule out further effects from this one in a week or so if it does get tossed in our general direction.

Edited October 9, 2023 by WYorksWeather
Changed typo 'N or NE' to 'E or NE'.

[Kasim Awan]

EQBO & El Nino is a strong combination.

The recent mostly closely matching winters for this combo.

86/87 - cold
91/92 - mild with a decent January
09/10 - very cold
14/15 - decent for current years

It seems something about an EQBO / El Nino may increase the amount of blocking. I think this may be related to the fact that both these instances can increase pressure on the stratospheric polar vortex zonal flow. The zonal flow is more receptive to easterly input during El Nino years. Looking at this below, we can see that El Nino winters with at least one SSW are a lot colder than La Nina winters with atleast one SSW. 

This mechanism is backed up by (e.g., García-Herrera et al 2006; Garfinkel and Hartmann 2007; Cagnazzo and Manzini 2009; Fletcher and Kushner 2011; Butler and Polvani 2011). The easterly QBO simply raises the potential for stratospheric disturbances whilst helping to break up the zonal flow, of which the stratosphere will be highly receptive to due to the easterly wave trains being more ideally placed due to El Nino. So from an evidence based and scientific literature based perspective there are grounds to say this Winter may just be a lot more interesting than some are proclaiming. I don't usually shout about cold potential before a Winter season but this year I see a need to LEVEL out the bias here at the minute which seems to be strongly in the mild direction. I believe we are already seeing the effects of such juxtaposition in current model output.

The only caveat is, this record breakingly warm September, which is strongly linked to mild conditions. As a result, I think a near normal winter is likely this year. Something close to 2014/15 and 2020/21. Could be particularly snowy for northern hills. 

Image and references from.

https://www.climate.gov/news-features/blogs/enso/el-niño-and-stratospheric-polar-vortex

 

[Cheshire Freeze]

That is some European cold pool for October

[Metwatch]

1 minute ago, Cheshire Freeze said:

That is some European cold pool for October

Anomaly to go with that, up to 10C below average!

[Cheshire Freeze]

1 minute ago, Metwatch said:

Anomaly to go with that, up to 10C below average!

Verging on unprecedented really. Can't think of any Octobers in recent times where such an extensive cold pool has been modelled across into Europe like that.

[Lukesluckybunch]

1 minute ago, Cheshire Freeze said:

Verging on unprecedented really. Can't think of any Octobers in recent times where such an extensive cold pool has been modelled across into Europe like that.

could be a trend ..from the ECM perhaps setting up for somthing very cold end of month?

[Rain All Night]

The ECM certainly seems to be the most serious about this omega Scandi high business.

Edited October 9, 2023 by RainAllNight

[Frigid]

12 minutes ago, Lukesluckybunch said:

could be a trend ..from the ECM perhaps setting up for somthing very cold end of month?

Meteo-France did go for a blocked November in its recent update.. If it were to happen with all that cold to the east, a significant cold spell in November could be a possibility . 

[sheikhy]

Ecm with that big scandi high and potential easterly!!gfs the same!!!good  to see early on!!

[MattStoke]

Just now, sheikhy said:

Ecm with that big scandi high and potential easterly!!gfs the same!!!good  to see early on!!

A waste at this time of year.

[jamesthemonkeh]

4 minutes ago, Frigid said:

Meteo-France did go for a blocked November in its recent update.. If it were to happen with all that cold to the east, a significant cold spell in November could be a possibility . 

Which site do you get these from please?

[Lukesluckybunch]

9 minutes ago, Frigid said:

Meteo-France did go for a blocked November in its recent update.. If it were to happen with all that cold to the east, a significant cold spell in November could be a possibility . 

wow that is a lot of blocking around scandi..stretching across to greenland..lets see what happens!

[Cheshire Freeze]

5 minutes ago, MattStoke said:

A waste at this time of year.

Given the abnormal warmth we've had recently, I think many of us will take it.

Given the potential size of the cold pool, -6 to-8 uppers would be sufficient for some to see snow, even in October. Plus further to that it' be nice just to have the frosts and a generally cold feeling run up to Halloween and bonfire night.

[Frigid]

3 minutes ago, jamesthemonkeh said:

Which site do you get these from please?

Found them in the Winter's thread, credit to @Uncertainty 

[seb]

1 hour ago, WYorksWeather said:

Yeah it is important to take the OP runs with a pinch of salt - as I've been pointing out over the past few days the operational runs have been close to the bottom of the ensemble packs lately. However, tonight it does seem that the 12z runs are mostly singing from the same hymn sheet (pending ECM), and so it does look like there'll be a period of cooler weather.

I also think given the tropical features at this time of year, anything beyond T+120 is iffy, and beyond T+168 is FI. Strictly for fun only.

Cooler yes but nothing to suggest something cold and also not for long. 
Blended output for my location literally has 12 days of temps between 12 and 17 degrees. That’s far from cold and still mainly above October average.

Edited October 9, 2023 by seb

[sundog]

7 minutes ago, Cheshire Freeze said:

Given the abnormal warmth we've had recently, I think many of us will take it.

Given the potential size of the cold pool, -6 to-8 uppers would be sufficient for some to see snow, even in October. Plus further to that it' be nice just to have the frosts and a generally cold feeling run up to Halloween and bonfire night.

Agreed  I'd take anything thats going at this stage.  Beggers can't be choosers for coldies these days. Cold weather adds a lovely ambience to late October/ early Nov  imo.

[sheikhy]

17 minutes ago, MattStoke said:

A waste at this time of year.

Kinda agree but i would rather see that than blazing southwesterlies lol!!!!its better than nothing!!!!!im sure you would agree we have plenty of autumn and winters where we dont see charts like this what so ever!!!!hopefully it stirs things higher up for november december time!!!

[Lukesluckybunch]

2 minutes ago, sheikhy said:

Kinda agree but i would rather see that than blazing southwesterlies lol!!!!its better than nothing!!!!!im sure you would agree we have plenty of autumn and winters where we dont see charts like this what so ever!!!!hopefully it stirs things higher up for november december time!!!

the ECM mean is improvemt also..perhaps suggesting more of a southeasterly rather then easterly feed..if the high over scandi was a bit further north would be ideal!

[Uncertainty]

Quite remarkable that the big 3 are all going for a major +SCAND. Would be a pretty big fail now if it doesn’t come off…

 

GFS

GEM

Ec op

 

EC mean

 

Will it be transient? If it sticks around for 2 weeks or more then we could get a vortex disruption in December. This pattern is excellent for vertical wave flux into the strat. Judah will like it. We had something similar in late Autumn 2018 and did get an ssw following it but the Atlantic profile was anti-tripole and the wqbo was there so the cold never came. 
 

Anyway I’m getting ahead of myself. An interesting pattern nonetheless once Friday’s nasty rainband is squeezed out…

 

Edited October 9, 2023 by Uncertainty

[Mike Poole]

ECM mean strongly in support of the Scandi high option, T240:

1030 hPa on a mean chart is telling.

Yes, it’s that time of year folks, when I (and no doubt many others) stop posting the Europe view on Meteociel charts in favour of the NH view - from now on we need to see what the polar vortex is doing!

And in the troposphere, it is looking weak, with plenty of blocking continuing to show, the scandi feature clearly showing on the operationals at T240:

Different story up top on the same timescale, as I noted in the strat thread, so a disconnect between the two vortexes from the start.  

[Daniel*]

Cold frosty nights and relatively cold by day also on ECM 12z it would be a huge flip.