Model Output Discussion - mid Autumn

[Derecho]

One thing about the model output recently is that it hasn't been a typical Atlantic driven pattern across Europe by any means. Yes it has been very unsettled and wet here but these lows have been tracking further south then usual allowing for some colder then average temperatures across northern Europe recently (especially Scandinavia).

The blocked pattern is emphasised by the temperature anomalies on the chart above for the next week, much warmer then average tropics and Arctic, colder then average temperatures in between over quite a few land areas.

Given El Nino years are typically very Atlantic driven through the second half of November and December, I'll be raising my eyebrow if this kind of blocked pattern is still prevalent in a months time (would rather it be less cyclonic though!).

[Downburst]

A sudden cold outbreak in North America for next week. It's been warmer than average there for some time. 

Now the latest regime chart shows we might see the end to the northern blocking in the next 10 to 15 days, although it is not entirely clear what it will be replaced by, +NAO or Block the most likely at this stage, but no obvious guide other than a very retreated signal for -NAO.

Looking at MJO from todays plots it seems to me we are most likely going into COD territory, so not sure what we can deduce from that in terms of some impetuous indicating a particular regime.

 

Lots of spread here in the forecast, perhaps some sign of the Atlantic block, but very far from certain of course as seen above. If I had to bet I can't see any indication of settled weather until around Nov 20, but so much can change and the 500 anomaly pattern does look like the upper trough is relaxed to normal from around then into first week of December. Expecting an nice sunny start to December

[MattH]

55 minutes ago, Derecho said:

One thing about the model output recently is that it hasn't been a typical Atlantic driven pattern across Europe by any means. Yes it has been very unsettled and wet here but these lows have been tracking further south then usual allowing for some colder then average temperatures across northern Europe recently (especially Scandinavia).

The blocked pattern is emphasised by the temperature anomalies on the chart above for the next week, much warmer then average tropics and Arctic, colder then average temperatures in between over quite a few land areas.

Given El Nino years are typically very Atlantic driven through the second half of November and December, I'll be raising my eyebrow if this kind of blocked pattern is still prevalent in a months time (would rather it be less cyclonic though!).

Here to be proven wrong, but a full-blown 'true' +NAO +AO is unlikely through Nov, IMO. The key ingredient for that will be a rapid sPV and tPV connection and I can't see that anytime soon. The wildcard of a reinforced +IOD may well help, but as we are seeing now, we can still get, what some would call a zonal pattern, but of which, as you've stated isn't true in the sense of a dominant tPV behind it.

It'll be an interesting watch through Nov this year, in particular...

Matt.

[TSNWK]

1 hour ago, MattH said:

Here to be proven wrong, but a full-blown 'true' +NAO +AO is unlikely through Nov, IMO. The key ingredient for that will be a rapid sPV and tPV connection and I can't see that anytime soon. The wildcard of a reinforced +IOD may well help, but as we are seeing now, we can still get, what some would call a zonal pattern, but of which, as you've stated isn't true in the sense of a dominant tPV behind it.

It'll be an interesting watch through Nov this year, in particular...

Matt.

Agree that this pattern is not zonal.. which to my eye is a  succession of low pressure areas spawned in north Western Atlantic picked up by the jet and sent across to NW Europe followed by a day or two quietness as corresponding ridge to the low flows through..

What we have presently might seem the same on the ground but is it fact a static pattern of trough in our sector with low pressures spinning within it  

[Met4Cast]

Worth keeping an eye on the jet stream in the coming couple of weeks as it begins to track further south around the UK & become increasingly amplified to the NW. 

For a while it’ll be in a position to send low pressure systems into the UK in an a-typical SW>NE direction (I.e not full zonal as per above comments). 

Wouldn’t be surprised to see further named storms. A very unsettled period of weather coming up.

Edited October 27, 2023 by Met4Cast

[jules216]

Biggest issue is that Ural or East Európe high pressure all the way from Arabic counties in nov/dec does often more damage then good. Examples only recently 2019/20, another one to note is 1960/61 as both viable options on the table. Particularry that early november pattern looks like a copy of 1960.  I ve never understood the fascination/excitment in UK about the blocking E Európe/Western Russia high that at times reaches Ural.

[Mucka]

It is still away out for any detail but it is starting to look like November could begin with a bang even before Bonfire night.

[Metwatch]

Could get quite wild next Thursday!

[Rain All Night]

14 minutes ago, Mucka said:

It is still away out for any detail but it is starting to look like November could begin with a bang even before Bonfire night.

Got the UKMO now as well

[Met4Cast]

On 15/10/2023 at 22:00, Met4Cast said:

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?

15 days on from this post and things have progressed mostly as expected. Unsettled conditions are likely to prevail as we go into November with the potential for some very unsettled periods of weather with further named storms looking likely. 

Meanwhile, the MJO continues its slow but likely progression into phase 8, I'm not seeing any abrupt pattern changes for the next couple of weeks however we may begin to see high pressure strengthening to the north/NE towards the middle/latter part of November. WWB in the Pacific have somewhat faded although importantly no long term return to easterlies around the dateline so I don't personally anticipate the AAM falling too considerably. We have, as expected seen a gradual rise.

So.. unsettled for the near and medium term with the broadscale tropospheric pattern likely developing into something capable of producing wave 1 activity into the stratosphere through November. I mentioned a potential battle between lows over the UK and high pressure to the NE and that still seems to be the broad direction of travel. 

As air cools to the NE and with seasonal wavelength changes, late November could be *potentially* interesting..

[Downburst]

42 minutes ago, RainAllNight said:

Got the UKMO now as well

951 mb smack over Ireland 06:00 Thursday morning on ECM. Storm force 10 on the south coast. Fills then and might go north, but lots to work out with further runs to come. 

[Cambrian]

Yes, much to be resolved on this one, no doubt all the way up to the event itself.

For now, 12z GEM op has outputted a particularly extreme outcome for next Thursday at day 6, on a track that takes in a large area for some very strong winds. 

< 950 mb depression running through Ireland, out into the Irish Sea, the centre clipping northwest Wales, northwest England and into Scotland. Heavy rain for many areas throughout the day, strongest winds south of the centre, mean wind speeds 120 km /  hr (75 mph) through and around the Bristol Channel, gusts around 160 km / hr (100 mph)

   

Over-land gusts through a swathe of southern Ireland, Wales and England, 90 - 120 km / hr (60 - 75 mph). Many broadleaf trees still in good leaf - not good. 

GEM is often very useful for good ball park predictions of lows at 3-6 days out. Let’s hope it’s overdoing it on this occasion. 

[WYorksWeather]

18 minutes ago, Cambrian said:

Yes, much to be resolved on this one, no doubt all the way up to the event itself.

For now, 12z GEM op has outputted a particularly extreme outcome for next Thursday at day 6, on a track that takes in a large area for some very strong winds. 

< 950 mb depression running through Ireland, out into the Irish Sea, the centre clipping northwest Wales, northwest England and into Scotland. Heavy rain for many areas throughout the day, strongest winds south of the centre, mean wind speeds 120 km /  hr (75 mph) through and around the Bristol Channel, gusts around 160 km / hr (100 mph)

   

Over-land gusts through a swathe of southern Ireland, Wales and England, 90 - 120 km / hr (60 - 75 mph). Many broadleaf trees still in good leaf - not good. 

GEM is often very useful for good ball park predictions of lows at 3-6 days out. Let’s hope it’s overdoing it on this occasion. 

SST anomalies are generally still positive across any generally westerly direction (NW, W, SW). Of course in absolute terms they're not that high, but it does aid in the development of these lows as has been seen more dramatically over in North America recently.

[Man With Beard]

Understandably some concerns already for next week, but some models are showing a heck of a lot of rain in the next 48 hours for many areas, not just NE Scotland:

[Bricriu]

6 hours ago, jules216 said:

Biggest issue is that Ural or East Európe high pressure all the way from Arabic counties in nov/dec does often more damage then good. Examples only recently 2019/20, another one to note is 1960/61 as both viable options on the table. Particularry that early november pattern looks like a copy of 1960.  I ve never understood the fascination/excitment in UK about the blocking E Európe/Western Russia high that at times reaches Ural.

Was it not Ural Blocking that led to the cold spell back in the Winter of 2009 and 2010?

[Cheshire Freeze]

2 minutes ago, Bricriu said:

Was it not Ural Blocking that led to the cold spell back in the Winter of 2009 and 2010?

2009 featured it.

Personally it’s something I like to see in November as it often precedes a cold December.

[WYorksWeather]

Usual 12z GFS vs 12z ECM comparison.

On the 850hPa ensembles, we have a broadly average GFS mean with the operational generally below average, ECM just generally close to average.

 

As yesterday, having a look at the MSLP charts, there is increasing support for a rise in pressure on the GFS 12z, but there is still a lot of scatter, and the rise in pressure doesn't take place at least until day 10, so we still need to be patient on this.

Looking at the OP runs, at T+72, we have low pressure very much in control, and more low pressure waiting in the wings to our west. Similar to yesterday, GFS is much more bullish on the Greenland high compared to ECM.

 

At T+120, both GFS and ECM develop a very complex low pressure setup with three separate deep lows as part of a broader area of low pressure in the Atlantic. GFS gives an early hit to the north with one of the lows at this stage, whereas ECM generally has the system centred further west. GFS and ECM are both continuing to build a Greenland high, GFS much more so than ECM.

 

Stepping through more slowly given the storm risk - at T+144, GFS has the low sitting to our south-west on the previous frame deepening and giving a direct hit to southern England. ECM instead merges all the lows into one and gives a hit more towards NI, NW England, and Scotland. Hence, too early to be sure about impacts in particular areas at this stage. Regardless of location, any landfall over the UK would almost certainly mean a Met Office named storm.

 

At T+168, GFS has the main low clearing away towards NE Scotland, while ECM keeps it mostly anchored over the UK. Naturally, in both cases it is weakening through landfall.

 

At T+192, GFS sends another low through the Channel, possibly enough for a second named storm, though of course a small change of track could see it miss the UK. ECM follows a similar pattern, but is more of a direct hit.

 

Skipping ahead to T+240, GFS fills the low, but of course a rise in pressure comes from such a low base that it is still very unsettled. ECM is slower to clear the second named storm candidate. Possibly the only bright spot is that there does seem to be some sort of attempt to get the Azores high going, but it's still a long way from the UK and not in a position to change the pattern at this point.

 

The GFS extended finally starts to show something of a pattern change. The Azores high begins to build in, but then a deep low smashes into Greenland and completely destroys the Greenland high, and we end up with a Scandinavian high, and an end to the relentless series of lows. What we end up with is a complex battleground. The wind direction charts show wild swings, with milder south-westerlies interspersed with colder northerlies and north-easterlies. The position at T+384 is shown below.

I'll simply allow the rainfall accumulation charts to T+240 to speak for themselves. The forecasts for E Scotland remain quite concerning.

 

 

[Man With Beard]

ECM continues to be wild for next Thursday morning - 947mb MSLP as the storm enters Ireland

Last night's ECM ensembles were mostly similar, ranging between 941mb and 960mb

Many other models almost as severe this morning: UKMO 954mb, ICON 955mb, GEM 958mb

[January Snowstorm]

18 minutes ago, Man With Beard said:

ECM continues to be wild for next Thursday morning - 947mb MSLP as the storm enters Ireland

Last night's ECM ensembles were mostly similar, ranging between 941mb and 960mb

Many other models almost as severe this morning: UKMO 954mb, ICON 955mb, GEM 958mb

Major doubts over where the low develops though from Southwest Ireland to Northern England. Impossible to know who will get stormy weather. The only certainty is plenty rain

[Paul_1978]

40 minutes ago, January Snowstorm said:

Major doubts over where the low develops though from Southwest Ireland to Northern England. Impossible to know who will get stormy weather. The only certainty is plenty rain

It looks like most of the UK will be affected, and for at least 48 hours. GFS has a further deep low into the following weekend. Looks like a nasty low (or two!), and some rough weather ahead. 

[ANYWEATHER]

1 hour ago, January Snowstorm said:

Major doubts over where the low develops though from Southwest Ireland to Northern England. Impossible to know who will get stormy weather. The only certainty is plenty rain

Plenty of rain yes ,but will be scooting through pretty quickly with those high winds ......!

[matty40s]

The worldwide weather watchers are on to this as well..

 

[alexisj9]

38 minutes ago, ANYWEATHER said:

Plenty of rain yes ,but will be scooting through pretty quickly with those high winds ......!

Unless there a long line hogging the south coast or east Scotland again.

[johnholmes]

28 minutes ago, matty40s said:

The worldwide weather watchers are on to this as well..

 

The ECMWF output suggests around 965 MB centred over the Scottish border area, I'll show this when I get time to put together NOAA and ECMWF latest outputs.

[northwestsnow]

Low after low after low looking at the 00z data.

Is it asking too much from the weather God's for some dry seasonal weather ?

Desperately hoping for a change from this rubbish.