Model Output Discussion - Summer 2024

[LRD]

GFS still going for, what in winter, would be the perfect E'ly. However, any model that shows a scandi high more than 3 days away is about as trustworthy as a bloke with a striped jumper, mask and bag with 'swag' painted on it

GFS also persists with the retrogression signal followed by autumnal lows on a more S'ly track. An interesting run but it's at the cold end of the pack in FI

UKMO and ECM go for some kind of a drift from the East but nowhere near as pronounced as GFS. That similar disagreement between Euros and N American models has been there for a few runs now. Not crazy warm but very pleasant conditions to be had I'd have thought

[Scorcher]

Fantastic ECM and UKMO this morning for next week. GFS not so good in terms of the positioning of the high, but would still be warm to very warm for many from Wednesday onwards. 

Uppers are also much higher on the Euro runs this morning than the GFS. I think some may end up being surprised by how warm it gets next week.

[carinthian]

Morning all. Colder air now in place over Eastern Alps and as the models predicted snow currently falling at 2000m. Currently in the village it is rain at 1300m with temp of 3c and sleet at 1650m with a temp of 1c . During the next 24 hours colder air aloft will see the snow level drop but the question remains how much precipitation over the next 24 hours ? The different models show a wide range in amounts. The fine mesh model used over here now indicates less than forecast 48 hours ago. This as previously explained is how much moisture is generated by the Genoa Low now forming as shown on the latest fax chart can affect the exact location and amount of rainfall/snowfall. Current indications seem to send most of the energy southwards with a significant cold front into Italy. So during the next 24 hours there will be close scrutiny of how this develops to affect the weather in the Alpine countries. Will keep you updated.

C

Edited September 12, 2024 by carinthian

[johnholmes]

yes above about 5500ft for the Jungfrau region

 

ski for wengen 2024-5 first snow.doc

[Mcconnor8]

 Scorcher The GFS seems to be blowing up the Atlantic low quite a lot even by day 3, whereas no other models are doing that really, so think it should flip to similar to the UKMO/ECM output in the next few runs, not unusual for the GFS mind you.

To illustrate look at how much deeper the Atlantic low is on the GFS 6z compared to the ICON 6z at just 72 hours away.

Edited September 12, 2024 by Mcconnor8

[Don]

 LRD Although the GFS is at the cold end of the pack, it has more support from its ensembles than it did yesterday when it was an outlier.

[danm]

Superb runs again this morning. Just a bit of a shame that it's coming during the second half of September rather than the first half. If the UKMO/ECM set up occurred then we could have had one last heatwave. 

Next week is shaping up to be warm and sunny for many. The only fly in the ointment is the positioning of the high on the GFS, which would allow some cooler air to get mixed in. 

[Cambrian]

Over the next week or so, we quietly benefit from inheriting a generous share of the enduring Ural heights and warmth, here at day 0, on the 0z ECM mean heights and T850 anomalies, the process contributing to the block at last moving on. 

 

It’s a profound retrogression, during days 0-10, from Siberia to ultimately link up with heights over the Canadian Arctic, 

 

in a high latitude link-up of the end of season continental heat from Eurasia and North America, with the big gain in the eventual outcome at the Canadian end. 

The trigger for our involvement is already underway in the pushing up of heights from the southwest, that by day 2 not only unceremoniously shunts the trough to the north but sets up a 1030mb high too. 

 

It is this relatively modest development, that along with another more notable mini-plume of warmth from the southwest around day 5, 

 

that draws successive waves of heights our way from the east, consolidating the warmth and high pressure over Northern Europe at day 6, 

 

and culminates in the retrogression of the whole block by day 10.

Two other things happen along with this move, between day 0,

 

and day 10.

 

Firstly, the main polar trough gets becomes misaligned with the main mid latitude troughing, meaning any mid latitude troughs will become weaker compared with recent weeks; and secondly, the UK and Ireland go from trough magnet due to repeatedly landing under meridionally framed troughs, to a bit of an anticyclone magnet due to latitudinal retrogression and linking of heights. 

With the marked Eurasian cooling that we see through the run, it’s very fitting that this pattern change coincides with the run-up to the autumn equinox at day 10. It’s the last apology of a very mediocre summer. 

[LRD]

STILL the GFS persists with the E'ly idea.

If (when) the E'ly ends up not happening (or, at least, not happening in the way GFS has been showing for a few runs now) remember this episode when the winter comes round. If a model shows a similar scenario in Dec, Jan or Feb, don't be fooled!

But, if you like cold weather, imagine this if it was Dec or Jan 

Edited September 12, 2024 by LRD

[Mcconnor8]

 LRD I'm not buying this GFS idea when no other models are showing it and it is diverging majorly from them very early in the run by day 3, expect it to backtrack either today or tomorrow with how it is treating the rapid intensification of the Atlantic low

[Mcconnor8]

Only 5 days away on the ICON 

[Mcconnor8]

Still major differences between the GFS and UKMO at just day 3!!! GFS way deeper with the low in the Atlantic, surely one of the models will have to give way soon.

[northwestsnow]

UKMO looks a beauty 

looks warm and settled..

I like to see charts like this in Autumn ..

Edited September 12, 2024 by northwestsnow

[Methuselah]

 northwestsnow

Yes, please! 

[damianslaw]

 northwestsnow A long draw easterly flow deep from the recesses of russia, can hear the cold lovers out there saying if only it was December - February.

Alas this is turning into a very interesting September synoptic wise.. suggesting the atmosphere might not be in its normal atlantic westerly base state.. 

Clear skies may still result in cool nights by this stage in the year countering the warm maxes to some degree.

Edited September 12, 2024 by damianslaw

[carinthian]

This is the latest rainfall model projection from now until Monday. Extreme rainfall for Austria . Flood warnings just issued for valleys and avalanche warning for higher elevations. Its all happening now. Currently heavy snow now falling at 1000m and above.

C

[WYorksWeather]

 damianslaw Looking at next week's charts I think it's probably a no when it comes to anything particularly cool by night. Largely due to warm 850hPa temperatures, the fact that we're still before the equinox so nights aren't that long yet, and the strength of the high at 500mb. It's really more of a 'late summer' type high rather than an autumnal high.

If we look at Monday to Friday next week, suggestion is daytime temperatures at least in high teens pretty widely early on. Wednesday and Thursday look particularly warm with low to mid 20s for the CET region.

For lows, Monday morning to Friday morning, we have lows generally about average earlier in the week for most areas (except Scotland where it is still quite cool on Monday). From Wednesday onwards it then becomes really quite mild for the time of year for the CET region anyway, less so in Scotland.

I've ignored GFS' tendency to underestimate daily maxima here and assumed this will be counterbalanced by overestimating minima. I don't think the CET will absolutely rocket up with these temperatures,  but I'd expect returns of perhaps 16-17C or so daily which will slowly nudge it back upwards.

[Scorcher]

 damianslaw High pressure in September by no means guarantees cool nights. The air mass looks rather warm next week so I imagine temps will stay in low double figures for many of us overnight.

[I remember Atlantic 252]

doesn't look great for my location, screams north sea misty low cloud, that can take some shifting, so could I be looking at cool days with strong breeze and very little sun

[Frigid]

 Mcconnor8 EC 12z has gone for the easterly, looks like quite a long fetch one. Man if only this was in winter..

Still, it's way in fl so I expect a few more variations. GFS liking the idea of retrogression later in the month. 

 

 

[Greyhound81]

 WYorksWeather 

2 hours ago, WYorksWeather said:

If we look at Monday to Friday next week, suggestion is daytime temperatures at least in high teens pretty widely early on. Wednesday and Thursday look particularly warm with low to mid 20s for the CET region.

Are Saturday and Sunday likely to be warm as well?

Edited September 12, 2024 by Greyhound81

[Scorcher]

Very frustrating to see the ECM going the way of the GFS later next week and weakening the high- but not that surprising given prolonged UK highs seem to be fast becoming a thing of the past.

 

[Andy Bown]

 Scorcher I can foresee it becoming quite wet and potentially thundery in the South again by this time next week! 

[Kentspur]

 Frigid The developing/ weak La Nina effect?

[MoonlightShadow]

 Scorcher I look at the charts for weekend after next and the UK being sandwiched by two areas of higher pressure with a rather wary eye, it all seems so familiar.