Model Output Discussion - mid Autumn

[WYorksWeather]

As it turns out I have do have enough time to do my usual comparison post. Looking first at the operation run position within the ensemble, GFS is close to its mean. ECM is in line with the ensemble up to around day 5 but then goes a fair bit milder.

 

At T+72, the low in the Bay of Biscay moves in on top of most of the UK, and joins with a major low extending out towards Greenland on both models.

 

At T+120, elements of the Greenland low get thrown our way. GFS scores a direct impact, but ECM has the worst of it aiming more towards the near continent. Regardless of the outcome though it looks very wet. The Scandinavian high leaves the low pressure with nowhere to go. We can't get the wind into a proper easterly as the high ridges down from Scandinavia, so the low has trouble exiting our vicinity, particularly so on the ECM.

 

At T+168, we again have deep low pressure set up and practically parked over the UK with nowhere to go. The Scandinavian high creates a bit of a battleground, Scotland probably turns quite cold with easterlies, but for England and Wales it is probably mild rain. Not pleasant though regardless of the temperature!

 

Same old mess at T+240 for the most part. GFS has some very deep low pressure systems to our north and south, which turns into an Atlantic deluge as the Scandinavian high disappears and one low pressure system after another barrels in. ECM gets some transient ridging going around day 8-9 but it doesn't really amount to much and then it's same old same old with yet more low pressure.

 

The GFS extended looks like this at T+384, and would you believe it, there's yet more low pressure sat over the UK.

ECM probably the warmer of the two options - looking at the next 10 days it seems to have quite a few days where the south gets into the mid teens, and some even the high teens (probably the odd spot 20C on the mildest days). But both look pretty horrendous if its usable dry weather you're looking for.

Might be a bit like July this, seems like this is a bit of weather we've just got to get through. Speaking personally I switch to being a coldie probably from around mid to late November when there starts to be a reasonable chance that colder than average temperatures might actually bring snow rather than cold rain.

 

 

[MATTWOLVES 3]

Tonight's ECM shows early promise! The build of heights around scandy could be more robust than some currently believe! And GFS is always gonna be overly optimistic on powering the Atlantic through. But worth a mention is a promising day 10 with some heights emerging around Greenland and developing PV being shunted further East..as my good man Mike Poole points out.

Firstly if you want to spend a Winter of being sent up the garden path several times a day...then follow the GFS 4 times a day and it's 14 day outlook....otherwise take a little more notice of the ECM and UKMO GEM models.

And finally do not become stressed over sypnotics that don't look good at this stage of the year...how often have we seen great sypnotics in November quickly crumble as we move into the start of Winter! 

Personally I feel this Winter shows much more promise than recent ones. 

To finish we have a couple more fine and settled days before things go downhill towards midweek...it could also feel cold at times with the airmass alternating and far from set in stone.

Winter will come and I'm hopeful snow will come into the forecast at some stage...im salvernating at the mouth in anticipation  

A sterling week ahead too you all.

[MattStoke]

3 hours ago, I remember Atlantic 252 said:

Horrid I'd say, but we all like different weather, 6 degrees and rain/gales is horrid to me, but maybe not others

Yep. Total waste in October.

[Met4Cast]

Now we’re talking! 

Huge WWB (westerly wind burst) now taking place over the Pacific. This should help drive the MJO and in turn lead to more positive AAM (El Nino) conditions.

Mid-long term should be a little more predictable as a result.

The recent (albeit brief) spike in AAM tendency associated with a previous smaller WWB is the reason I suspect for the Scandi high/cyclonic (UK) pattern we’re moving into now. 

It’ll be interesting to see how things develop in the tropics & sub tropics in the next week or two.

With the MJO likely moving into phase 8, assuming we see the above rise in AAM as a result we could be looking at an incredibly wet & unsettled November. 

All the while fighting against blocking to the NE.. vortex under pressure, anyone?

[damianslaw]

1 hour ago, Mike Poole said:

It may be that this scandi block might take more shifting than the models give credit for.  Mind you, the pattern at T240 on the ECM is not without interest either:

Heights building over Greenland, and the developing vortex far from where it would like to be.

Those wanting a white christmas, would be very happy if the word October was replaced by December.

Alas most likely will bring cold rain.

The models are continuing to show a southerly tracking jet, with heights to some extent to the north. 

Outcome, possibly alot of rain and temps not far off average. 

[Frigid]

P12 really gets us in the freezer next week..

All JJF, but a fair few ens do go for another cold spell after the mild tick up. Been a while since we've seen a cool end to October. 

[RJBingham]

 

[SLEETY]

Poor performance from the models again, why do they struggle with these set-ups, the Easterly looks on track again this morning after all of them were against it,especially the UKMO, it's been miles our the last few days regarding the Easterly 

[Anthony Burden]

Morning all,ECM not keen on the Scandinavian block while GFS continues to show it influencing the UK all be it a short time.This northeast block could be very interesting for cold periods over this coming winter as the met office mentioned in their long range forecast.

[sheikhy]

Ukmo cold scandi high again!!gfs moves to ukmo as well!ecm just seems to struggle to slide the low into the continent and leaves it parked over england for days on end!now that would be worrying!!

Edited October 16, 2023 by sheikhy

[BlueHedgehog074]

A little fun tease regarding the 00Z GEM, but it manages to drag a little patch of -5*C 850 hPa temperatures over the London area during early Sunday morning via the Easterly/North-Easterly flow. The Eastern spot of Kent and the Eastern tip of Scotland also gets in on the -5*C 850 hPa temperature action. 

Edited October 16, 2023 by DiagonalRedLine

[minus10]

Yes a disturbed weather pattern from wednesday onwards..

...its like Autumn has come crashing in ...frost last night with temp around freezing and now after couple more days of relative calm..its the wet and strong winds between mainly  south and east directions ....

 

[MattH]

28 minutes ago, sheikhy said:

Ukmo cold scandi high again!!gfs moves to ukmo as well!ecm just seems to struggle to slide the low into the continent and leaves it parked over england for days on end!now that would be worrying!!

Very difficult synoptics through the week ahead, especially regarding the position for frontal features and resultant large rainfall totals and which areas at greatest risk. The block to the NE certainly a key feature in determining the position and orientation of frontal systems as they move up into the UK from the SW. Primary areas seem to be well highlighted at the moment, with E and SE Scotland for real concern for a significant weather event later in the week from rainfall totals.

With regard to the colder ingress through the forthcoming weekend it does seem more likely than not, clearly this is October of course and not January, but it should still lower temperatures and create quite a cold/raw feel with the E'ly wind into the weekend. The 00Z EC seems to be messing about too much with the low over England and Wales, not clearing it quickly enough and the deterministic frontal position highlights this well, over E England on Sat. It isn't without support, mind, but as things stand especially for more central and northern areas, at least, temperatures should fall away again this coming weekend.

Cheers, Matt.

Edited October 16, 2023 by MattH

[Downburst]

A wet period incoming as these lows wash around for a while, plenty of wet soggy leaves to engage with over next 7 days for most. Very typical of course for mid October.

[johnholmes]

Not looked in detail at the usual charts since Thursday last week so today

Monday 16 October

First NOAA 6-15 chart

The large +ve values in the east Pacific of the last few days continues with a –ve value beneath this; so we have slight contour ridging where normally there is a trough and a small trough beneath this ridge, into a general weterly flow over N America into the distorted pattern south of Greenland into western Europe, with a marked ridge off western Norway towards Greenland, with a +be anomaly of around 180+ DM. Again this has been showing for several days. The overall pattern across the Atlantic and into much of western Europe is westerly, with a change to a more S’ly over the UK and far NW France/Scandinavia. The 8-14 loses most of the +ve heights along with much of the ridging.

For the ECMWF output for 22-26 October (much the same period as NOAA 6-10) the 500 flow starts with an very similar one to NOAA. It becomes less distorted over time but remains first N of West and then more westerly by 26 th. The 850 temps are generally showing around + 5 C with some warm up towards the end as the +5 C moves into the SE of England.

Overall the two suggest somewhat less cold air slowly developing as the trough slowly warms out slightly. The settled dry spell initially probably becoming less settled with time.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

[Northwest NI]

We are being treated to Storm Babet on Tuesday/Wednesday then.

[Catacol]

15 hours ago, Met4Cast said:

With the MJO likely moving into phase 8, assuming we see the above rise in AAM as a result we could be looking at an incredibly wet & unsettled November. 

All the while fighting against blocking to the NE.. vortex under pressure, anyone?

Yes. And things moving in the right direction broadly for those hoping for a winter with snowy interest:

- General trend in AAM is upwards, suggesting perhaps an eventual synergy between pacific ocean and atmospheric response by the time real winter begins

- MJO engaging positively. If we are to see wave breaks and a meridional jet buckling under pressure we need to see an active MJO. The last 3 NINA years produced a fairly active MJO and with NINO in firm control I would expect an even more robust MJO this winter season. Its periodicity will be key. Next 6/7/8 cycle maybe early December and then again late January. Opens up pacific driven blocking in mid Dec and early Feb....though this is guesswork based on averages rather than exact prediction.

- There is a really quite pronounced high pressure signal emerging around the Urals and slightly west. Should potentially help with some early wave 1 forcing on the strat though I say that with huge caution. Comical really making estimates on vortex development and trop led pressure on the strat this early.

Overall, with these features plus eQBO and some positive seasonal modelling last week I'd give the mid October rating a 7/10 for coldies with eyes fixed ahead. And a wet November, possibly quite stormy November, was a fairly obvious call given the Nino background. This  anomaly chart for the start of November screams 2 things to me: Rain for the UK and Strat Stress.

[Rain All Night]

The GEM ensemble this morning was keen for a trough near us to get trapped beneath an incoming ridge connecting to lingering northern heights at the very end of the month; the other two (ECM 0z and GFS 6z shown here) weren't overtly showing this but you can see that they could be seen as offering some support for the idea through their mean 500mb height contours:

Edit - Just realised that yesterday morning's EC46 was up for a bit of this too:

Edited October 16, 2023 by RainAllNight

[Mike Poole]

1 hour ago, Catacol said:

- There is a really quite pronounced high pressure signal emerging around the Urals and slightly west. Should potentially help with some early wave 1 forcing on the strat though I say that with huge caution. Comical really making estimates on vortex development and trop led pressure on the strat this early.

I’m not sure comical exactly!  SSWs are possible in early winter.  The last December SSW was in 2001, and even then it was right at the end of the month.  Does the fact we haven’t had one since, a) merely reflect that they are rare, or b) that they are no longer possible due to climate change?  I don’t think the answer to this is known, and a far bigger dataset would be required given a SSW only occurs about 6/10 years.  

I would be very interested to see how winter pans out with an early SSW, could be quite different to recent years.  

[Daniel*]

Hi Seb, you were saying?

 

 

England has also seen its lowest October temperature in 20 years (2003).

The CET for yesterday's date was the lowest in 30 years (1993). So this snap has been a bit more than little below average. 

Edited October 16, 2023 by Daniel*

[Met4Cast]

If it were 6-10 weeks later in the year and MOGREPS-G was signalling this the forum would be in meltdown. 

Some stunning mid-winter synoptics there for heavy significant snowfall, unfortunately the air isn’t cold enough so plenty of chilly/cold rain seems the most likely outcome. 

Perhaps a few early wintry flakes across Europe however. 

[Rain All Night]

Quite a spread of ways to get disappointing weather at T+168h:

[Metwatch]

Looks like we will manage to pull in a chilly easterly for this weekend, with some low pressure systems just to our east separating us between the milder and the much colder airmass. Though not lasting too long as the Scandi high is more round rather than elongated with a W - E orientation, and it moves away eastwards by early next week. A classic "if only it was winter" set up, and other numerous times in recent years.

Is anyone up for a snow chase into Central, northern Germany / Poland? May be a decent fall of snow for some elevated areas this weekend if anyone is eager to see the white stuff in October!

Edited October 16, 2023 by Metwatch

[jamesthemonkeh]

CFSv2 pointing at higher than normal pressure to our north-east into November.

Will be interesting to see whether we do get a blocked scenario, or a more unsettled one - of which there is plenty of theory as mentioned by others over the last day.

[sheikhy]

Ecm goes full on scandi high at 120 hours and a direct hit of colder air!!it has finally caved in at only 5 days out!!!