Model output discussion 24/01/21

[Stu_London]

Encouraging model trends again this morning but still lots of unresolved issues. 

I'm not overly excited about short term prospects for our region (favoured elevated areas to the north of the region might squeeze a covering over the weekend), but it does look like a cold spell of at least 5 days or so is now marginally odds on starting from the end of next week. 

00z evolution shows how that might just be a few days 

06z evolution demonstrates how it could repeatedly reload and give us something more memorable. 

Overall, despite a lot of our region, particularly to the south and east of London drawing a blank so far, there does look to be some less marginal opportunities coming down the line for us. 

Whatever happens, it has been a fantastic season for model watching with some very unusual weather patterns, even if to date, they have promised more that they have delivered.

 

[DJ Fart]

12 minutes ago, Griff said:

Dear Jim, 

Please can you fix it for me so that the block holds... //

 

Sorry to break this to you, mate, but they had to cancel Jim'll Fix It...

[MJB]

 

Control 288h                                            Op 288h 

Nice to see 

[Captain Shortwave]

Several posts have been hidden, can we please refrain from posting about specific members please and stick to model discussion.

Thank you

[Cold Winter Night]

GFS // goes in a different direction than the GFS, but this still is not bad at all.

If this would come to pass, you would have an inversion, with a cold surface under milder T850's. No mild Southerlies.

That high isn't going away, and in the later frames you'll see it getting 'refreshed'. This too is a classic evolution we have seen before. It happens in longer cold spells.

Confidence in a possibly memorable cold spell is growing slowly, but steadily. In this morning's output I have not seen much to add to our worries.

Edited January 29, 2021 by Norrance

[MJB]

Deepest FI and the Control still delivers 

[Griff]

8 minutes ago, Cold Winter Night said:

GFS // goes in a different direction than the GFS, but this still is not bad at all.

If this would come to pass, you would have an inversion, with a cold surface under milder T850's. No mild Southerlies.

That high isn't going away, and in the later frames you'll see it getting 'refreshed'. This too is a classic evolution we have seen before. It happens in longer cold spells.

Confidence in a possibly memorable cold spell is growing slowly, but steadily. In this morning's output I have not seen much to add to our worries.

To be fair the parallel keeps offering up lots of different solutions in FI. I'd settle for everything up to day 10.

[snowblizzard]

2 hours ago, johnholmes said:

Friday 29 January

Looking at the ECMWF outputs first

a)the first from 4-8 inc, shows marked 500 mb trough se from Scandinavia tending to ‘warm’ out/less troughy by the end. It brings the -5 C 850 mb temperature over most of the country by 6 th

b) the 10 day set of charts from today (Fri 29) with the +ve 850 mb values ebbing and flowing for a few days with just the n’ern part of Scotland staying ‘cold’. Then by Thur 4 th Feb the colder 850’s covering all the uk and the -5 and below extending into all but the far south. By next w/e and the -10 is covering much of the country. Brought about by an upper high cell combining with a trough to its east . Of course neither of these charts shows any ppn detail. Various different models can be accessed using this link.

These are ECMWF 500 and surface charts on this link

http://www2.wetter3.de/Fax/00_ECMWF_ENS_p0_500hPa+144_240.gif

and another link into ECMWF charts

http://meteocentre.com/numerical-weather-prediction/

To the anomaly outputs

Ec-gfs and both keep a similar chart to 24 hours ago, some ridging ne of Iceland and a degree of troughing in the uk area and Europe.

Noaa 6-10 and its chart is much as its 24 hour ago showed with a degree of ridging ne of Iceland and troughing into Europe, or at least the far west (Iberia), much as ec-gfs show. Its 8-14 is similar. On both the main upper features are the trough-ridge-trough from Russia into the middle of n America, along with the marked closed upper north of Greenland. The contour lines are higher in value than for a few days, largely due to he marked troughing over n America perhaps?

The upshot is that temperature levels away from the n’ern half of Scotland will vary for several days then pretty much the whole uk looks set to become colder with air sourced from the Scandinavia area holding sway for the latter part of the anomaly time scales. Ppn, ah, the synoptic models will be your guide-perhaps!

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

JH, I really appreciate your unbiased, realistic reviews and outlooks.

They are the only ones that really keep me grounded and prevent my expectations running away with me!

Thank you.

 

 

[tight isobar]

58 minutes ago, Snowjokes92 said:

Wow some places with 18 hours of snow non stop and the front hasnt gone by that last chart! Setting up the snow fields for whats to come!

Indeed I think stalled frontals-with cause massive headaches over coming days..and fax input will be tricky to say the least!!!..output is array with winter goodies....@madness...

Edited January 29, 2021 by tight isobar

[Man With Beard]

12 minutes ago, snowblizzard said:

JH, I really appreciate your unbiased, realistic reviews and outlooks.

They are the only ones that really keep me grounded and prevent my expectations running away with me!

Thank you.

 

 

I think he's just raised expectations

Looking at the GEFS ensemble diagram for the midlands, a strong cluster is now growing for a sharp drop in upper air temps next weekend. But there's still a few members that won't align in a convenient way for cold.

[lassie23]

The journey to an easterly is a long one, as long as it gets here before the year is out lol

[winterof79]

My Grandma always said "winds from the East a week at least" 

Let's hope we flatten that line later

[ptow]

12 minutes ago, Man Without Beard said:

I think he's just raised expectations

Looking at the GEFS ensemble diagram for the midlands, a strong cluster is now growing for a sharp drop in upper air temps next weekend. But there's still a few members that won't align in a convenient way for cold.

Yes, the op could easily swing back next run. There is some support for this easterly, but similarly support for other outcomes. We have been here many times before

[Purga]

Significant move towards longevity of the cold from 00z to 06z

Both Op & Control going the cold easterly route, always a good sign.

[legritter]

4 minutes ago, lassie23 said:

The journey to an easterly is a long one, as long as it gets here before the year is out lol

Knowing our luck it will arrive in December 2021 ,long fetch easterly with mild muck from Europe. But seriously i think our time this year is looking very promising, we need patience, but im not getting excited just yet , Ecm this morning was good, gfs also getting there, so hopefully come Monday night the fax chart s should look very wintry for the end of the week fri/Saturday. No sausages  for baps ,so cooking up some bacon , brilliant forum , catch you all at 7pm tonight ,. 

[SqueakheartLW]

The GFS trend couldn't be more clear in the last 4 runs in regards to the potential colder spell from midweek onwards

Below are the mean charts as well as the data that shows the average 850hpa temps across all runs

28/01/2021     GFS 12z     -6.6     +216 hours

The 12z showed an average easterly wind at +216 hours which considering we normal see average westerly winds shows just how many colder and blocked options we have on yesterday's 12z. The average 850hpa temperature came out at -6.6 which is -5.1 below the long term mean at this point of the year and this shows up even more on the anomaly chart on the right

28/01/2021     GFS 18z     -6.7     +216 hours

The 18z really continued on from where the 12z left off with another average easterly at +216 hours but the main difference is that pressure is on average slightly higher above Scandi compared with the 12z so probably an increase in the signal for easterly runs in the ensembles. The average 850hpa temperature came out a tiny bit colder than on the 12z at -6.7. just -0.1 lower than the 12z and -5.0 below the long term mean. The anomaly chart looks very similar to the 12z one so no real change in the overall pattern average.

29/01/2021     GFS 00z     -7.8     +222 hours

The 00z continues on the cold theme around +222 hours away with yet again average easterlies showing up. This is 3 runs in a row that have shown this and it is looking more and more likely that it is going to come off. The 850hpa mean on the 00z comes out at -7.8 which is a notable step in the colder direction by -1.1 compared with the 18z yesterday. This is -5.3 below the long term average at 850hpa and keeps the colder theme very much on track. The anomaly chart also shows up this step in the colder direction with slightly deeper blues over the UK compared with both 12z and 18z yesterday.

29/01/2021     GFS 06z     -8.0     +198 hours

Finally we have the latest 06z run and as with all of the previous runs this one also features an average easterly at +198 hours. Starting to look a bit nailed on now isn't it but then things can go massively wrong (Think January 2019). Maybe we need a few more runs showing this average setup and to count down closer to the current time frame to make sure. The average 850hpa temperatures on this latest 06z run are a new low of -8.0 which is -0.2 colder than the 00z was and a good -6.5 colder than the long term mean so very much a cold set of runs. The anomaly chart shows how cold this set of ensembles is with some quite deep blues over the UK.

However for how cold these averages are there are some bad news milder outliers in all of these runs from around the same time period of +190 to +220 hours away and I've posted the worst example of each of these from all 4 recent GFS runs

28/01/2021 12z Member 30     +192 hours

This is the mildest I could find between 190 and 220 hours away in the 12z. The cold on this run is really restricted to Scotland and NI with Wales and England mild and most likely wet too

28/01/2021 18z Member 28     +210 hours

On this example, the mildest between 190 and 220 hours in the 18z we do have the northern blocking and easterlies but generally too far to the north. This leaves England and Wales under low pressure and cold rain whilst Scotland in particular reaps the benefits of the colder continental air and snow.

29/01/2021 00z Member 30     +216 hours

The mildest example on the 00z between 190 and 220 hours is Member 30 which clearly shows a warm sector moving in from the SW and this run does get a bit milder for the next few frames at least. There is northern blocking showing up but it is weak and the low in the Atlantic is bossing the pattern here and keeping the UK under Atlantic influences

29/01/2021 06z Member 7     +216 hours

The mildest example on the 06z between 190 and 220 hours is Member 7 which has the Atlantic in full control here with the mildest of all examples across all 4 recent runs. Very little blocking showing up here and the high over Europe is all lined up wrong to deliver any kind of cold weather to the UK. Most of Europe is under mild uppers too, very much like most recent winters really and based on this kind of recent form this situation cannot be ruled out

[Flake news]

1 hour ago, MJB said:

                

Control 240h                                                 Op 240h

They both have identical initial values at corresponding grid points, so they should be similar.  Any differences are artefacts of the calculation method.  

[swebby]

5 hours ago, sebastiaan1973 said:

Lot's of snow moving across the Northsea. Please notice the big area of snow in Central Europe.

They have also had/having some very warm upper air temps across the Pyrenees and Apls - upcoming avalanche issues?

[Frank Trough]

35 minutes ago, Purga said:

Significant move towards longevity of the cold from 00z to 06z

Both Op & Control going the cold easterly route, always a good sign.

I don't think that's really the issue - we know how stubborn properly cold air can be once it gets in. For me the issue remains that a nationwide, proper cold spell is still a week away. We've got to get there first - and regardless of how universally good things look now we ALL know from bitter experience that if there is a way to stop it, we generally find it.  The first warning sign is often a delay of the coldest uppers arriving and it getting progressively put back as the detail gets resolved. 

So i'm just going to watch that cold and hope it makes steady progress towards us in time. Down here we need proper continental cold embedded for snow - nothing else really cuts it. So i'm hoping, but extremely cautious. 

Edited January 29, 2021 by Certain kind of fool

[Chesil View]

2 minutes ago, Certain kind of fool said:

I don't think that's really the issue - we know how stubborn properly cold air can be once it gets in. For me the issue remains that a nationwide, proper cold spell is still a week away. We've got to get there first - and regardless of how universally good things look now we ALL know from bitter experience that if there is a way to stop it, we generally find it.  The first warning sign is often a delay of the coldest uppers arriving and it getting progressively put back as the detail gets resolved. 

So i'm just going to watch that cold and hope it makes steady progress towards us in time. Down here we need proper continental cold embedded for snow - nothing else really cuts it. So i'm hoping, but extremely cautious. 

Best way to be for us south coasters.

[Don]

14 minutes ago, Certain kind of fool said:

I don't think that's really the issue - we know how stubborn properly cold air can be once it gets in. For me the issue remains that a nationwide, proper cold spell is still a week away. We've got to get there first - and regardless of how universally good things look now we ALL know from bitter experience that if there is a way to stop it, we generally find it.  The first warning sign is often a delay of the coldest uppers arriving and it getting progressively put back as the detail gets resolved. 

So i'm just going to watch that cold and hope it makes steady progress towards us in time. Down here we need proper continental cold embedded for snow - nothing else really cuts it. So i'm hoping, but extremely cautious. 

I think that's a very sensible way to view the situation.  Hope yes, but feet must remain firmly on the ground for now, especially for us in the south!

[PiscesStar]

57 minutes ago, legritter said:

Knowing our luck it will arrive in December 2021 ,long fetch easterly with mild muck from Europe. But seriously i think our time this year is looking very promising, we need patience, but im not getting excited just yet , Ecm this morning was good, gfs also getting there, so hopefully come Monday night the fax chart s should look very wintry for the end of the week fri/Saturday. No sausages  for baps ,so cooking up some bacon , brilliant forum , catch you all at 7pm tonight ,. 

I'll have some tomato sauce on mine 

[johnholmes]

38 minutes ago, swebby said:

They have also had/having some very warm upper air temps across the Pyrenees and Apls - upcoming avalanche issues?

The avalanche issues are already there in the Alps with a number of areas with ski transport stopped

[MATTWOLVES 3]

Oh my giddy Aunt,I've only been away for a day and missed about 30 pages.. somethings a foot.. perhaps a foot of snow. Crazy 6z ens,and I've only viewed a quarter of them. Snow risks galore over the coming days also..try naling them lot all down to within a few miles..pin the tail on a donkey springs to mind.

 

 

[turkishfella]

OMG it's just a dream come true hopefully