Model output discussion - Winter approaches

[Methuselah]

Here it comes, folks... GFS 12Z looks a stonker, at T+003!

    

[swfc]

4 minutes ago, General Cluster said:

Here it comes, folks... GFS 12Z looks a stonker, at T+003!

    

You not getting wood GC with the output. Granted its a bit premeture good to look at tho be it short lived

[SMU]

Afternoon All-

Certainly I am 'more' interested in the developing blocking at 168 onwards than I have been for the current 'weak' block

So many more positives ( if it occurs )

- Vertical WAA over the UK rather than positive tilted jet in the next few days

- Jet Energy surge SE which allows for a cut off low to form over europe > again not present this next few days.

- Deeper cold pooling developing to the East...

Lets see if we get anything like picture 2 into the 144 timeframe > then 120...

Edited November 16, 2020 by Steve Murr

[Griff]

25 minutes ago, General Cluster said:

Here it comes, folks... GFS 12Z looks a stonker, at T+003!

    

Joking aside (well not really) I bet you've cursed it now!!!

Some differences already showing by Saturday into Europe and over Russia...

Edited November 16, 2020 by Griff

[BlueHedgehog074]

Some exquisite solutions on offer earlier today.

In the nearer time frame, it looks like a mixed bag of weather. Using the 06Z GFS as an example during the next few days, the flow is predominately from the South-West to West over the UK from the Atlantic. Mostly mild, particularly towards Southern UK. Little more cooler and blustery towards Western and Northern UK areas at times. 

Today and Tuesday sees some high heights dominate the South and South-East of the UK and Low Pressure dominating to the North-West.  This bringing some rain and drizzle over Northern and Western areas. But generally drier towards Southern and Eastern areas. Rather mild too, especially during brighter breaks over South-Eastern parts. Flow from the West/South-West

 
 

On Wednesday, you can see a disturbance, which is tracking Eastwards through the UK, bringing a spell of heavy rain and strong winds to places. This looks to clear Eastwards later into the afternoon turning the South-Westerly flow towards the North-West with showers following behind over Northern and Western areas. These could become increasingly wintry over high ground to the North through the night. Some clearer spells likely elsewhere.

A chilly start for Thursday as that Low takes a journey further East. Combined with a weak ridge in the Atlantic moving in from the West, a cold flow from the North dominates the UK. Still with a chance of a few wintry showers, mostly for Northern UK and Scotland. 

Ireland may see some less cool temperatures in response to a milder flow spilling in from the Atlantic later in the day with a chance of some rain and showers moving in. You can see a pokey area of Low Pressure (shortwave) advancing Eastwards towards Ireland during the day coming off the main Low in the Western Atlantic. Filling out as it does so:

 

For Friday, there is broad agreement for that Atlantic ridge to get kicked Eastwards over the UK. 

06Z GFS

00Z UKMO

 

00Z ECMWF

Despite using a chart 6 hours later, compared to the ECMWF and UKMO, the GFS seems to be marginally the least progressive with the push Eastwards of the ridge. That Low in the Northern mid Atlantic on the GFS is in a far angrier mood. Feels as though it’s about to lose its temper!  Another thing to note is the upper trough over Scandinavia is much less defined and deep in comparison to the UKMO and ECMWF. 

Some spells of wind and rain moving into North-Western areas during Friday as disturbances from the Atlantic Lows gradually creep further East. 

Essentially though, despite a few odd differences, the models, again using guidance from the 06Z GFS, 00Z ECMWF and 00Z UKMO have the Atlantic and its Lows breaking back through by Saturday (120 hours). And the Westerly to South-Westerly flow returns for all. High heights to the South of the UK and Low heights to the North-West across Iceland. Best of the mildest and brightest conditions towards the East and South of the UK. Cloudier and damp conditions likely towards the North and West. 

06Z GFS

 

00Z ECMWF

00Z UKMO

Both the UKMO and ECMWF seemingly the quickest with bringing the Atlantic Lows Eastwards through Northern UK. But the overall pattern is essentially the same on all 3. 

Towards 144 hours, there’s some shallow ridging of High Pressure shifting downstream from Newfoundland into the mid-Atlantic. Shallow Low Pressure dropping down to the left side of the ridging in the Western Atlantic. 

06Z GFS

 

00Z ECMWF

00Z UKMO

 

00Z GEM

The 06Z GFS, while has a fairly similar sort of pattern, has a more South-West to North-East orientation of that ridge building it over the UK. Also thanks to the orientation of the Low Pressure to the North-West over Iceland and Greenland. Suspect the Jet Stream on that model is somewhat more South-West to North-East through the UK. Which the chart below confirms:

 

Maybe more West-South-West to East-North-East, mind. And quite strong too.  You can see there is some amplification of the Jetstream. Some ebbs and flows. Of which does lead to some interesting outcomes for colder weather later into the run. 

As we get into 192 hours, things start to get a little more tasty for those who love chilly weather. 

Some troughing drops South into the Northern mid-Atlantic. As a result, that mid Atlantic/UK ridging builds over to the East of the UK. The GFS the most eager to have it building over to the North-East towards Scandinavia, as it gets drawn towards the Russian ridge.  

06Z GFS

 

00Z ECMWF 

 

00Z GEM

The GEM is less keen to build it over towards Scandinavia. The ridge gets pushed over towards the East/South-East of the UK over Spain and Germany. What I feel may get the red traffic light alert on Nick Sussex’s cold spell evolution is the fact that Low Pressure appears to get in the way across Western Scandinavia. The Low Pressure in the Atlantic is partly more rounded than on the GFS and ECMWF too. Combined with the Eastern UK ridge struggling to gain much latitude, makes it a challenge for that Atlantic Low to undercut and/or slide underneath the ridge.

The following result at 240 hours on the GEM is this:

 
 

Even though there is a shallow ridge at higher latitudes between Eastern Greenland and Scandinavia, Low Pressure is slow moving out West in the Atlantic. There is a lack of troughing over mainland Europe to drag in any cold from the North or East. You still have some ridging over mainland Europe getting in the way.
 

On the other hand, both the 00Z ECMWF, and more so, the GFS at 240 hours leads to charts that would make a cold weather fan feel as though they’re in snowy heaven! 

06Z GFS 

00Z ECMWF 

Well, perhaps snowy heaven is a bit too strong of a word. The GFS goes for colder weather developing from the East towards the UK as a strong ridge builds over Scandinavia. Atlantic Lows are then forced to drop South-East into Europe as a result. A few showers, possibly wintry in heavy bursts, would be likely towards Eastern UK. 

The ECMWF, while not as remarkable in terms of cold or wintry weather, still shows some great possibilities. Like the GFS, it has ridging developing over mostly North-Western Scandinavia. It is, though, a little bit further North and the ridge sorta gets sucked up towards the ridging across Northern Russia. Upper heights bit less strong than GFS too across the North-East. Still influential enough to disrupt Low Pressure in the Atlantic and send them South-East towards mainland Europe. Quite chilly over the UK perhaps with rain and hill snow across the South.

The orientation and placement of the High on the GFS makes it so that it’s easier for the 850 hPa cold to spill Westwards through the UK from Northern Europe on the High Pressure’s Southern flank. Some warm air advection spilling Northwards through Eastern Greenland via the Western flanks of the Scandinavian ridges on the ECMWF, and especially the GFS, does help to elongate and beat up the Vortex to our North-West over Greenland. Is a tremendous setup to have if you want colder weather developing from the East. However, it’s still crucial to ensure the Scandinavian ridging doesn’t get drawn too far North, otherwise any Easterly could end up setting up too far North to benefit the UK. Also don’t want Atlantic Lows to pile up too much over the Scandinavian ridging as it could collapse the ridge cutting off any cold flow from the East. 

Going deeper into the GFS run, 324 hours, the Easterly gains further power over the UK. Low Pressure continuing to get squashed like mashed potato being diverted to the South of the UK. Signs as well of the Scandinavian High pushing Westwards as the weather patterns amplify upstream and the Polar Vortex over Greenland becomes diluted. 
 

 

Some further wintry showers, perhaps with some sleet and snow mixed in, ganging up over Eastern areas. These probably spilling further West at times. Outcome above sufficient for optimal cold for the UK. 

As ever with these cold weather possibilities, it comes with a warning!

 

It takes a lot to get a proper cold spell of weather for the UK. For everything to fall into the right place! Some of these possibilities I feel may depend on what that possible ridging in the Atlantic and/or UK does later into the weekend. And then just hoping (for those wanting cold), Low Pressure in the Atlantic doesn’t become too powerful and positively tilted and roll over that ridging. 

Unless the support for some High Latitude Blocking, particular via the Scandinavian ridging, grows stronger, a fence feels appealing to sit on right now. 

The earlier 00Z GFS did try to get something going with High Pressure building over to the East of the UK at times beyond the weekend, nothing really came much of it. Exhibiting a little too much power to those Atlantic Lows as well, although not strong enough to to completely blow away the Eastern UK ridges.

Nevertheless, it is fair to say, when peaking at the 06Z GFS ensembles, the average 2 meter temperature graph for both Aberdeen and London, does show a cool down as we progress into next week:

Little bit more scatter on the London one, but the mean does seem to be heading down somewhat. The Control Run, though, is on the colder side of the ensembles, so I would be careful not to get too sucked in for now.

The 00Z ECMWF ensemble mean at 240 hours not buying into a cold spell. 

 

Mean Low Pressure to the North-West, and higher pressure across the South of the UK. Worth noting that it does have the core of the strongest upper heights to the South-West of the UK and some very shallow upper troughing to the South of the UK over France and Spain, perhaps subtle hints of seeing some Low Pressure trying to dig South-East towards the UK. I think as longs as the Azores High is displaced to the South-West, it can allow Low Pressure to head on more on a South-Easterly track drawing in some chillier Polar Maritime airflows through the UK. Providing, also, the Polar Front Jetstream ain’t tracking too far to the North of the UK. Otherwise it’s an underwhelming mean for cold. However, this can be a typical default scenario an ensemble mean can show if there’s a lot of scatter at these sort of time frames. So something to bare in mind. 

Mushymanrob did cover these charts earlier, but essentially the 8 to 14 day NOAA 500mb anomaly chart has an upper flow (green lines) from the South-West direction through the UK and Atlantic troughing, which digs down quite far South to our West. Considering there is some higher than average heights mostly over the UK and to our East over mainland Europe and Scandinavia, it’s not totally without interest for cold weather possibilities. Though the lack of a proper European trough is discouraging as that could help support any ridging that gets over to Scandinavia. 

http://www.cpc.ncep.noaa.gov//favicon.ico Climate Prediction Center - 8-14 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

Have used these charts a few times before, but probably best to see John’s, Mushy’s, Bluarmy’s etc summary of these charts who tend to have more experience. 

Personally feel it is a bit of a ‘will it’ or ‘won’t it’ situation for a colder spell of weather, especially from some kind of Northern/North-Eastern UK block. Scandinavian blocks are hard to model (I guess you could say that for any type of High Latitude Blocking, but particularly those North-Eastern blocks). The 06Z GFS and 00Z ECMWF does prove you can achieve that positive NAO (North Atlantic Oscillation), but still end up with a chillier spell of weather if the blocking sets up to favourably to our North-East. Clearly the positive NAO pattern on the 06Z GFS does become less positive, probably neutral/negative within time, as heights increase somewhat towards Greenland. I think should the operational models start increasing the Northern/North-Eastern UK blocking possibilities on future runs during the next few days, I believe the railway companies could see a big increase in money as cold weather fans, myself included, purchase tickets to board the Polar Express .

However would feel even more confident from any chances of the NOAA anomaly charts pointing to a stronger Scandinavian and European trough signal. Without that, then as some addressed earlier in the thread, some kind of UK/Eastern UK/Central European High could be more probable. Particularly from an angry Vortex and strong, flat, Atlantic Jetstream that would kill off chances for any UK/European High to get far enough North. A UK/European High could at least bring some surface cold. Despite the flattish 00Z ECMWF mean, to me, it looks like that even if a Scandinavian High struggles to establish, there seems to be a reasonable level of amplification in the flow at times as addressed by various operational model runs and the NOAA 8 to 14 day upper chart. Makes me think that pattern in the next week or two won’t be terribly flat. Favourable for cold, wintry, weather, not certain yet. 

I would be happy, to be honest, for the weather just to dry out a bit, if nothing else really. It looks like ridging will be close by to the South/South-East of the UK at times this week, although those areas not totally avoiding some wetter periods like the North and West. Nothing though desperately unsettled, apart from Wednesday with some ferocious winds. More general ridging later this week could provide a more UK-wide, albeit likely transient, settled period later on Thursday and into Friday. In spite of the focus on what the weather may do in the future, a brief chillier spell later on Wednesday into Thursday with a few odd snow shields over Northern High ground getting trashed. May get some of those in Northern areas excited. 

Sorry for making you lot fall asleep with this rambly post.   For now am gonna be weary of any blocking outlooks to the North of the UK, unless some of these outcomes creep into a much closer timeframe and support grows. Not to mention the fact ‘we have been here before’.  All though just a bit iffy at the moment. Fair to say that just because a lot of cold weather possibilities in the models fail to materialise, doesn’t mean they will never happen. Plus most Winters will see some chillier periods at times. For all the cold weather fans in particular, will be an interesting ride to come. No doubt some seat hiding 12Z runs coming up

Edited November 16, 2020 by DiagonalRedLine
Removing some extra spaces + removing other recent typos

[sheikhy]

1 minute ago, Griff said:

Joking aside (well not really) I bet you've cursed it now!!!

Some differences already showing by Saturday into Europe and over Russia...

For the better or the worse?

[Griff]

1 minute ago, sheikhy said:

For the better or the worse?

How long does it allow me to edit my posts here? 

[Griff]

6 minutes ago, sheikhy said:

For the better or the worse?

Atlantic makes further inroads than on previous runs, yet to tell if this affects the scandi high which followed....

But the result is it looks more amplified towards Iceland

Edited November 16, 2020 by Griff

[sheikhy]

2 minutes ago, Griff said:

How long does it allow me to edit my posts here? 

To be honest if this forum doesnt get rammed with posts in the next 20 mins then you know things have not gone as planned!!!

[Griff]

This is why the wise probably don't hang on every run...

 

to be fair looks more like UKMO

 

Edited November 16, 2020 by Griff

[swfc]

3 minutes ago, Griff said:

This is why the wise probably don't hang on every run...

 

to be fair looks more like UKMO

 

Yes it looks like it's going down the Gary atm but who knows

[Griff]

who was saying that a potential scandi / greenland link up was better?

Could happen... (Yes bored and avoiding my tax return)

[DavidS]

The NH profile looks different, although the push of heights is further west. There isn’t the open road it had on the 06z

[swfc]

1 minute ago, Griff said:

who was saying that a potential scandi / greenland link up was better?

Could happen... (Yes bored and avoiding my tax return)

Dry tho which is a popular call

[Griff]

STOP THE COUNT!

THE GFS HAS WON, BY A LOT!

(Sorry)

[swfc]

Tbh that's some profile for November to the ene.

[nick sussex]

Hard to have much confidence in the overall evolution given the wild swing between the earlier GFS and this one .

Here it’s more progressive with the low which then takes an age to fill to the east ne .

Having said that we at least still get the ridge pushed north ahead of the upstream troughing .

So not the normal calamity because that ridge is the key early part of our mystery tour!

Over to the ECM now but it could have been worse so I think we’re in a holding position!

[swfc]

850s are looking spot on for southern Europe. Guess it's one run but OK going forward

[Griff]

1 minute ago, nick sussex said:

Hard to have much confidence in the overall evolution given the wild swing between the earlier GFS and this one .

Here it’s more progressive with the low which then takes an age to fill to the east ne .

Having said that we at least still get the ridge pushed north ahead of the upstream troughing .

So not the normal calamity because that ridge is the key early part of our mystery tour!

Over to the ECM now but it could have been worse so I think we’re in a holding position!

 

1 minute ago, swfc said:

850s are looking spot on for southern Europe. Guess it's one run but OK going forward

 

it does look like we can expect some milder settled weather, especially down south

[swfc]

Things could pulled nw to greenland in fi but to much going on before hand. Not bad tho tbhhere we go 

Edited November 16, 2020 by swfc

[Zak M]

GFS quite similar to its previous run.

Except it has much colder uppers coming our way from the continent...

   

[LRD]

Trough disruption-tastic. Heights being dragged to Greenland. 

This could end up being one of my all-time favourite FI runs of all-time great mate

[nick sussex]

1 minute ago, Griff said:

 

 

it does look like we can expect some milder settled weather, especially down south

Settled looks odd on . In terms of temps the 850 values could be misleading , could be an inversion type scenario given the slack flow , much depends on cloud cover .

I think we need more amplification day 6 into 7 . The ridge needs to get as far north as possible.

So when it topples ne wards the cold pool is better placed to feed west sw on its southern flank .

 

 

[swfc]

All academic but it's very rare you see that nhp in November. See you later Atlantic and hello from the nne

[Cheshire Freeze]

Vortex under all kinds of stress in FI of the GFS 12z.

Could be a stonker to finish.