Model output discussion-mid Autumn and beyond

[Paul]

A new thread as we move past the mid-point of Autumn..

This thread is for more general model discussion - eg without the specific focus on the hunt for cold weather, which can be found in the hunt for cold model thread. As ever, please keep it to the models in here.

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[Summer Sun]

Short term high pressure looks to be the main features sat to our west at times allowing a cooler breeze but still pleasant enough in any sunnshine

[knocker]

If nothing else the 0600 gfs highlights the precarious business of attempting to estimate the surface temp, armed with just the 850mb temp, in an anticyclone in Autumn, Or for that matter in any other scenario where the lapse rate in the boundary layer has been modified.for some reason

,

[Weather-history]

That is an intense area of high pressure, possibly some local pressure reading records maybe broken for October. 

[DiagonalRedLine]

Not much change from the GFS 12Z up to 120 hours (run still coming out):

To be expected since it’s the next 6 days. Good agreement, at least, in this timeframe for High Pressure to scare away the Atlantic Lows keeping the U.K. mostly dry and settled.  The odd rain band and a few odd showers likely to give Northern and North-Western parts of the UK some wet stuff at times.

A more widespread area of rain may affect the U.K. during Sunday as the models show a wave feature from a passing Low Pressure system to the North tracking Eastwards.

(Again using the 12Z GFS as an example):

But a good chance the rain band could fragment as it tracks South-Eastwards through the U.K. 

Certainly in sunnier, brighter spells, during the day, can imagine it would be very mild or warm at times during the next few days, especially towards the early weekend when the flow turns South-Westerly for wide areas of the U.K. And maybe beyond depending if High Pressure can maintain its control over, or close to the West of, the U.K. While nights are likely to be cool, especially during periods where the High is concentrated more towards Western U.K, is like Summer still doesn’t want to let Autumn win for good without wanting to dig its paws into it!

Using the 120 and 144 hour charts, the 12Z UKMO shows a similar story to the 12Z GFS:

(⬆️ Also, as posted above by Weather-history, where the High does look powerful)

Only difference is, the High Pressure system is a bit more suppressed and a little less rounded and pronounced than it is on the GFS at 144 hours. Still pretty much the same sort of theme. 

While it ain’t impossible for models to show disagreements within the 6 day range, looks to me overall a generally settled outlook, particularly for the South, with High Pressure being a strong ol’ thing, being the No. 1 favourite. 

[I remember Atlantic 252]

19 minutes ago, Weather-history said:

That is an intense area of high pressure, possibly some local pressure reading records maybe broken for October. 

dosen't look nice though for this location, screams rain/drizzle off the Cheshire Gap

[DiagonalRedLine]

Would have thought it would have stayed dry for your location if that UKMO chart came off considering how strong the surface and upper High is.

(But then, I’m not from Staffordshire so may be wrong).

[I remember Atlantic 252]

does depend on shape of high, exact wind direction, certainly won't be sunny, but need winds more WNW'ly or NNW'ly to avoid any drizzle

[DiagonalRedLine]

Fair enough. Probably won’t quite come off exactly like that. 

The 12Z ECMWF, though, very similar with its positioning of the Atlantic High Pressure for Monday. 

A 1045mb High - just like the UKMO!

(Albiet the High is a touch further West on the 12Z ECMWF than it is on the 12Z UKMO for that day).

[Hotspur62]

Looks like a fairly settled outlook which should enhance the autumn colours.The big question is how far West will the High move across the Atlantic which could leave the door open to some colder air to move down from the North.Atm looks like the real cold snap/spell will move to the East of the UK which if indeed it does happen isnt really a problem as it is far too early for snow to last in most of UK at this time of year.I have been on this planet for close on half a century and can only remember snow lasting for more than a couple of days in November and on both occasions the snow fell in last week of the month.What is of more importance is the general pattern in the NH and i think we are in a far better position at this time of year than we have been for a few years.

 

[knocker]

Quite interesting that the ecm this evening is following a path suggested by the EPS anomalies this morning of moving the upstream pattern east which briefly amplifies and realigns the pattern downstream before quickly flattening the high cell

 

[Rocheydub]

Was going to suggest that knocker, so glad you (a) posted it and (b) agree with me.

[damianslaw]

Only slight variations on the same theme from the models at present - resulting in significant levels of consistency and compatibility. The dominant feature for the future is a strongly building ridge of high pressure anchoring itself over and just to the west of the UK, but not far enough north to escape the vagaries of the atlantic completely. Alas, frontal activity looks like invading northern parts over the weekend, bringing a dose of rain but weakening in power as it moves SE, thus the dry settled theme will be maintained over southern and south west parts for the reliable.

Into next week, heights don't look like going anywhere fast, only the core re orientating on a more N-S axis as opposed to W-E axis, this though is crucial is allowing trough activity to dig down through scandi on its eastern flank, combined with some Warm Air Advection on its western flank, hence not surprised thereafter to see the models showing heights migrating towards Greenland perhaps aided by a shallow low/trough development in the vicinity of Iceland.

As we approach late October in an average year, we should expect the atlantic to ramp up a gear, but not this year - whether this an omen for the winter season remains to be seen, if we were a month on from where we are, then I would certainly be sitting up if you are looking for greater chance of colder conditions gaining the upper hand, alas too early to speculate, but its still notable, it what has been a year largely dominated by abnormal synoptics with the atlantic largely sound asleep.

[knocker]

The Eps anomaly this evening is continuing the theme from the det run. There appears to be a suggestion here, supported to some extent by NOAA of a quite quick pattern change upstream with knock on effects downstream

[knocker]

There is quite a bit of fluidity of the pattern next week according to the ecm det run this morning. Initially the high pressure is amplified just to the west of the UK with the cold trough sinking south into Europe to the east. But the subsequent 'reload' amplifies the high further west thus the trough is also further west giving wet, windy and quite cool conditions on Friday. Of course minor adjustments to this scenario would make quite adifference

[Ross90]

Being a bit of a noob when it comes to models does anyone want to hazard a guess what the first week in Nov looks like for Central Scotland? Being an events steward isn't much fun if it's raining all night. 

[mb018538]

2 hours ago, Ross90 said:

Being a bit of a noob when it comes to models does anyone want to hazard a guess what the first week in Nov looks like for Central Scotland? Being an events steward isn't much fun if it's raining all night. 

Too far away to be really certain at the moment I’m afraid! Ensembles are generally trending to below average, with higher pressure to the north, so I’d be fairly confident in it being chilly or cold. Whether that means quiet frosty weather or cold wind and rain is anyone’s guess at this range!

[Frosty.]

Next week looks really pleasant on the Gfs 12z with high pressure in charge and predominantly fine conditions with temps in the low to mid teens celsius with some chilly nights.☺

[knocker]

The first 'reload' and amp,ification of the high cell next week and then the second We won't worry about the third -too far away

[Frosty.]

The GEFS 12z mean indicates a lovely spell of mid / late autumn anticyclonic weather next week too..perfect for those autumn colours with sunny spells and light winds and some cool / crisp nights / early morning's.☺

[bluearmy]

Eps look to be headed where the ec46 week three/four was going on it’s recent output. New run due out soon. If it’s consistent then the Scandinavian trough retrogrades wsw and envelops w Europe as the W Russian heights spread west over the top 

[blizzard81]

51 minutes ago, bluearmy said:

Eps look to be headed where the ec46 week three/four was going on it’s recent output. New run due out soon. If it’s consistent then the Scandinavian trough retrogrades wsw and envelops w Europe as the W Russian heights spread west over the top 

That also seems to fit perfectly with the extended 15 to 30 day meto forecast for heights to rise to the north of the UK. 

[SMU]

18z making some nice corrections to the UKMO with more vertical ridging into the pole helping the pattern sharpen up

18z V 12z

 

[knocker]

Continuing on, very briefly, from the short range, The movement of the upstream  pattern east, including the vortex/trough which disrupts, obviously impacts downstream. and the wind continues to veer over the UK as the cold trough plunges into Europe to the east. Need to see what the ecm makes of this.

[bluearmy]

Back end of the gfs is broadly in line with the updated ec 46 for week 3. A wintry look about the set up (though no proper coldie excitement re the date) - anyway, Europe seem likely to have a cold November, especially to our east under blocking.  This is a consistent theme. December coming into view and as it does so, ec46 looks like the Atlantic will be trying to push ne into n Europe against that euro blocking. too far away to draw any conclusions ..........