model discussion Model output discussion - closing in on Winter

[winterof79]

Forgive my maths and its just one run,but i see two initial shots of cold within 8 days 

 

 

And at day 10 at the turn of the month 

A repeating pattern may well emerge into December so im a tad exited

 

Edited November 19, 2021 by winterof79

[weirpig]

Well the ensembles  are still all over the place at just 144hrs with how the northerly drop occurs   still not totally resolved yet  

[nick sussex]

An improved GFS run from the earlier 00hrs which stuck the low over the UK.

After that it brings down a shallow shortwave from the north which could deliver some interest and hints that there could be a ridge extension ne over the top of those low heights over Central Europe .

Overall not bad at all but the more interesting part is outside of the more reliable timeframe and 850 values at this range are subject to change .

Still after recent downgrades encouraging to see a better GFS run for coldies .

 

 

[Battleground Snow]

17 minutes ago, Griff said:

The GEM has been all over this, @Mike Poole has been hinting! much better

I don't think the gem gets the attention it deserves on here... Verification above GFS, the overnight run has wintry showers even to lower levels at times from Thursday onwards

[carinthian]

1 minute ago, nick sussex said:

An improved GFS run from the earlier 00hrs which stuck the low over the UK.

After that it brings down a shallow shortwave from the north which could deliver some interest and hints that there could be a ridge extension ne over the top of those low heights over Central Europe .

Overall not bad at all but the more interesting part is outside of the more reliable timeframe and 850 values at this range are subject to change .

Still after recent downgrades encouraging to see a better GFS run for coldies .

 

 

Yes, and increase in Arctic heights putting the pressure on the Euro lower heights to hold, which in the longer term may be a good outcome.

C

 

[Griff]

1 minute ago, Battleground Snow said:

I don't think the gem gets the attention it deserves on here... Verification above GFS, the overnight run has wintry showers even to lower levels at times from Thursday onwards

Considering this is the GFS that was the previous 'Para' that everyone (well most) assumed was erroneous! 

[Griff]

What's the wave number? How many? 

Just for...

 

[Methuselah]

43 minutes ago, winterof79 said:

Forgive my maths and its just one run,but i see two initial shots of cold within 8 days 

 

 

And at day 10 at the turn of the month 

A repeating pattern may well emerge into December so im a tad exited

 

Aye. As I was rambling, yesterday, there's something here that reminds me of the late 1960s' winter pattern (as I remember it!) of Atlantic HPs periodically building north, allowing Arctic air to flood southward, bringing two or three ice-days. And, following that, Atlantic LPs came around the top of the (now sinking High) to bring a week or two's relative mildness. Only for the whole thing to repeat itself?

I know I could be fantasising, but I haven't yet seen Mother Theresa on my toast!

Edited November 19, 2021 by Ed Stone

[bluearmy]

24 minutes ago, carinthian said:

Yes, and increase in Arctic heights putting the pressure on the Euro lower heights to hold, which in the longer term may be a good outcome.

C

 

I mused yesterday about one of these dumbelling ridges managing to throw itself ne over scandi at some point if the scandi trough relaxes at some point (that’s going to be down to the Arctic profile ) 

with temps dropping over n scandi I wonder if later week 2 could see this become a trend ? 

[Man With Beard]

ECM cluster D9 - all clusters have lines from the UK back to Greenland - the question is only whether temperatures will be below average or considerably below average.

[bluearmy]

3 minutes ago, Man With Beard said:

ECM cluster D9 - all clusters have lines from the UK back to Greenland - the question is only whether temperatures will be below average or considerably below average.

The control and op in the largest cluster and finally we have all the clusters on the same page which should raise confidence in the 8/10 day current cross model solution. 
There are variances prior to day 9 which dictates how cold the flow will be coming down.

[Bradley in Kent]

So today is HP link up day, the first laying of the blocks. The high we have over southern UK is currently linking with the high further west, but it seems the high behind will lunge itself eastwards pushing the centre over our side. What we'll need now over the weekend is heights to remain stable further west towards North America, and hope that the high hasn't lunged too much our way. Coupled with that, we want the lower heights to keep things propped up to encourage movement north-westwards towards South Greenland. 

Once we get to Sunday, it'll be time to look at what heights are doing over the Labrador Sea, as well as looking to see if Greenland can accept any heights.

Key word here: 'heights'...

[Met4Cast]

Quote

The current flatter pattern appearing on the models is no surprise to anyone who has been looking at the bigger picture & not following every GFS Deterministic run. 

The Det has been consistently in the cold outlier camp and was for several days on the trot, there was never much support from the GEFS or the EPS, it was clear from the start that the GFS Det was on it's own, possibly over-reacting to the emerging MJO phase 4-5-6 signal, although latest MJO forecasts show that signal is pretty much dead now which I suspect is why the GFS Det has also dropped the idea of significant blocking. 

Uncertainty now lies in where exactly high pressure will setup, a wave break NEwards across the UK suggests a period of settled weather for a time, but perhaps turning more unsettled/zonal later on in the forecast period. This puts up a ridge into the Uruals/Russia putting pressure on the vortex, but probably not enough to do much damage to the rapidly strengthening SPV.

My hope is that any zonal/Atlantic progression will be limited, wettest in the N driest in the S type affair, forecasts suggest a continued disconnect between the Strat/Trop for the time being, but if this doesn't last and we see a connection going into December then it might be a pretty big nail into winters coffin.

In short, no notable cold spell in the second half of November, there never was unless you were only looking at the GFS Det.

I posted the above on the 11th November. Since then we've seen a notable cold spell appear within the models, seemingly with ensemble support but that's now been rather significantly watered down. 

For me, this up-coming period of cooler weather wont be particularly notable, below average yes and it'll certainly feel chilly compared to the recent very mild weather, but snow looks rather limited to the hills.

Unfortunately as commented above, the MJO just isn't playing ball. We're seeing a very low amplitude phase 5/6 which does support blocking to the NW, it's just not strong enough to extend that blocking into Greenland to draw the deeper cold southwards, as per the runs a few days ago were suggesting could happen.

So, sustained blocking is unlikely. My hope above re: zonal being limited appears to be coming to fruition, I'm not seeing anything to suggest raging Atlantic zonality and with forecasts continuing to suggest a strat/trop de-coupling into December we're in a relatively good place. 

Without the MJO providing forcing for blocking though, we appear to be entering a bit of a "no mans land" in terms of weather. No forcing in either direction. 

Result? Probably a rather slack/cool pattern into early December with high pressure close to or over the UK. Below average, chilly, frosty by night, snow likely limited to N hills/lower levels by night for a time later next week before the high topples. 

Edited November 19, 2021 by Met4Cast

[northwestsnow]

[Griff]

2 minutes ago, northwestsnow said:

Pleasingly speaks for itself for once

[Eskimo]

7 minutes ago, northwestsnow said:

Significantly below average with majority support. I get people want something special but if we take this as gospel, 850s ~5C below the long-term average screams significant potential to me. 

Edited November 19, 2021 by Eskimo

[mb018538]

4 minutes ago, Griff said:

Pleasingly speaks for itself for once

Can't wait to get myself outside for a nice dose of cold rain! 

[Earthshine]

Forecast looks a bit grim really.  Cold rain is horrible.

[Griff]

4 minutes ago, mb018538 said:

Can't wait to get myself outside for a nice dose of cold rain! 

Good for you, that's the spirit

I'm guessing you understood that I meant with regards to analysis of the data spread, and the agreement. For once it doesn't offer up every possible solution in scatter. 

Fascinating point though, I guess you're right, at some stage this forum relates to actual weather on the ground, but probably very little to do with anything beyond a week away. 

[Methuselah]

I'm not at all sure that the upcoming spell of colder weather has been 'downgraded'. But it's certainly moved forward, in the model runs, so that its end has also now come into view:

    

 

[jules216]

I am spying a good trend for winter overal, early season strát/trop disconnect, we buy some time before -QBO digs in and flushes +QBO from lower levels, to boost Also Nina exhibits east based state although a little bit on the moderate end. Should at least prevent zonal looks on seasonal models for February although these analogs are also watered down with the omnipresent spoiler Euro high which you never know when it wants to spoil potential blocking.

[mb018538]

9 minutes ago, Griff said:

Good for you, that's the spirit

I'm guessing you understood that I meant with regards to analysis of the data spread, and the agreement. For once it doesn't offer up every possible solution in scatter. 

Fascinating point though, I guess you're right, at some stage this forum relates to actual weather on the ground, but probably very little to do with anything beyond a week away. 

Just looks like the usual UK cold setup. Unless you live on a hill or a mountain, which 90% of the country doesn't, then it's just cold rain this time. Perhaps the second helping in around 9/10 days time will bear more fruit!

[Griff]

1 minute ago, mb018538 said:

Just looks like the usual UK cold setup. Unless you live on a hill or a mountain, which 90% of the country doesn't, then it's just cold rain this time. Perhaps the second helping in around 9/10 days time will bear more fruit!

It's a decent leap down for a good start at this time of year

I'm not concerned too much about what happens later, plenty of time for mother nature to do her thing. One way or another. 

Finally looks autumnal for a start. I welcome seasonal weather, feels like it's getting scarce as I get older. 

[throwoff]

24 minutes ago, Earthshine said:

Forecast looks a bit grim really.  Cold rain is horrible.

Get the cold in first. Everything depends on it. 

I will take cold rain as a prelude.

[Scorcher]

I find it amusing that people are desperate to get rid of the current weather and happy to welcome in some cold rain.

It's a beautiful day here today with very little wind, plenty of sun and feeling very pleasant at 14C.

I have no problem with things turning cooler now but please can it be dry with it.