Model output discussion - deep cold inbound?

[ptow]

1 minute ago, Battleground Snow said:

I assume it's because of the short sea track from the near continent helps the 2m temps, where it may mix out more over the longer sea track further north.

Yeh was just looking at that. Its -6/7 just over on the continent and a v short sea track. Thats why we love easterlies in the South

[Methuselah]

According to the GEFS 06z ensembles, even we in Sod's Corner can look forward to a nice wee run of snowy ice-days... So, you guys oop norf will be even more pleased:

    

I can't 100% rule out the projected warm-up, but things don't look good for the 06Z, right now!

[radiohead]

-19 windchill? 

[kold weather]

5 minutes ago, Battleground Snow said:

I assume it's because of the short sea track from the near continent helps the 2m temps, where it may mix out more over the longer sea track further north.

Yeah the low means the air coming into our region is coming off from Belgium and NE France so its only had a very short trek over water which keeps things just about on the right side.

Mind you if the low was to get any closer I think the far SE probably would switch to sleety stuff. Thats about the limit for all of the country to still have snow. There is still a minority of runs (probably 20-25%) that are too warm for parts of the SE, Kent in particular so its something that whilst not as high as a risk as maybe a few days ago, is still a possible spoiler.

Edited February 4, 2021 by kold weather

[IanT]

26 minutes ago, IanT said:

Could you point me to the source of these please? I have been unable to find it through google etc.

Solved. 

Meteociel.fr - Tableaux GEFS v12

WWW.METEOCIEL.FR

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La météo en temps réel et prévisions météo pour la France, Observations météo, modèles numériques et logiciels météo (GFS, ECMWF, UKMO, GEM, AROME...

 

[Captain Shortwave]

10 minutes ago, radiohead said:

-19 windchill? 

The parallel after midweeks develops more of a south easterly flow that brings in clearer conditions as winds fall light on Wednesday and Thursday night, the model expects some extremely cold minima for central and southern England.

 

Thursday night looks pretty close to the temperatures recorded in February 2012. Just interesting and shows what could happen once the easterly dries out and winds fall light.

Edited February 4, 2021 by Captain Shortwave

[Cold Winter Night]

Right now, the thermometer indicates 8c, the cold has not yet arrived. So every time new output comes out, there is still that little bit of fear: It's not going to back down, is it?
We've been there many times in the past decade, much promise, but ending up with a minimum of -0.1c. Woohoo frost

However, this time around, it's different.
This is now looking very solid, no more "It's always day 10".
Confidence based on the output is very high that cold will arrive and that we will have snow.
Now it's about short term details. I think it looks good for snow for all. Dew points are low.
Ice formation on the canals and lakes here in Holland might be an issue with the wind and the snow, but you in Britain don't care about that anyway

The longevity of this cold spell is still in FI.
It is very encouraging that the morning runs show more and more signs of heights rises to our North, like several of us have been saying this would be likely. Northwest or Northeast, both will help to reel in an even longer cold spell (one for the histtory books?).

Personally I think the Atlantic attacks will fail to move or break the block next week, at least for everyone East of the Pennines. Watch for the GEFS and EPS to drop later. Experience tells us that the ensembles are always last to pick up extended Northern blocking.

Background signals are not working against us, so it's not just hopecasting for that to happen.

Enjoy what is coming!

[sheikhy]

Fantastic 06z at 72 hours!!looks similar to gfs maybe even colder!!!!

[Battleground Snow]

10 minutes ago, sheikhy said:

Fantastic 06z at 72 hours!!looks similar to gfs maybe even colder!!!!

Indeed very impressive 850mb temps, especially in the north by sunday morning

GFS attached for same time in this format, can see a difference in the south east

 

Edited February 4, 2021 by Battleground Snow

[kold weather]

7 minutes ago, Captain Shortwave said:

Thursday night looks pretty close to the temperatures recorded in February 2012. Just interesting and shows what could happen once the easterly dries out and winds fall light.

Yeah those are bitterly cold nights. The GFS op obviously doesn't go as cold due to more advancement of cloud ahead of the front, but even then it gets down to -7c half way through the night, and obviously frost hollows would go far lower under snow cover.

Perhaps even more noteable is the cold maxes now being forecasted under snow cover. Both the GFS and ECM have maxes only reachong -1/2c on Tuesday under a consant stream of snow showers.

ECM maxes at 3pm on Tuesday:

Even for areas without snow, the upstream snowfields cool the air down and so makes up the difference.

Edited February 4, 2021 by kold weather

[Ninman]

21 minutes ago, Tim Bland said:

Probably more relevant than T850s at this time of year is the Dew point. As long as uppers are well below zero ;  the If DP is at or below 0c you can usually expect snow. The 06z ensembles mean expect this to be 0c or below up until 14th so that would be 7 days of snow opportunities Ps I expect this could be improved on further in future suites ...

Not that I take much notice of the BBC weather page, but for my location it now has snow showers continuing up to 13th Feb, which wasn't the case this morning. They always over do temps and underestimate snow potential, so this caught my eye.

We also know the GEFS ensembles can flip as per the Op. I would expect the 850's mean from 11th to reduce down by a few degrees in the next few days as better handling of the second low comes in to play. GFS likes to resort to bowling over the UK when there is no clear path, so like others, I would expect the second low to firstly be less intense, and then secondly become more shearerd/elongated as it hits the UK Freezer.

Interesting times ahead, and in the mean time, plenty of snowmen (and women, cats/dogs) to be built!

 

 

[SqueakheartLW]

What an update that 06z turned out to be and after both yesterday's 18z and today's 00z both below -10 at 850hpa for upper average at the peak of the cold spell this 06z really had something to live up to. The peak of the cold spell on this one is at 138 hours away so the coldest part of the cold spell in terms of uppers keeps getting pushed further back into the colder spell

That is one set of ensemble average charts at the peak of the cold spell with the beasterly setup showing again. The 850hpa temperatures also look decent too with the 2nd coldest mean so far of -10.6 which is -7.5 below the long term mean and was so close to beating yesterday's 18z which was the coldest at -10.7. The anomaly chart maintains those deep blue colours over the UK like most of the updates have done.

The signal for a milder mid month is also a consistent signal from the GFS too which is something I'd rather not spoil this update by talking about but something we can't ignore as long as it remains there. These are the average charts for the peak of the milder spell showing in today's 06z at 270 hours away

Not the most pleasing set of charts with average SW winds and 850hpa temperatures back above freezing again at 0.7 which is +2.5 above the long term mean. The anomaly chart also shows this with the yellows and oranges over the UK. We have to hope this keeps getting pushed back or watered down until it doesn't happen

GEFS Legacy 00z

I thought as a bonus extra here I would feature the GEFS Legacy and see what it is showing for today and if it is also on board with the colder spell like the main models. This is the ensemble mean chart for the GEFS Legacy 00z

It too appears to be showing this cold spell too and looks to be very much on a par with the main GFS with the ensemble mean around -10 for several days. Using the table of the ensemble members I have had to use a spreadsheet to calculate where the peak of the cold spell is and this is at 150 hours away with a decent 850hpa temperature average of -10.3.

 

[sheikhy]

Ecm 06z actually has that low ever so slightly further north than the gfs 06z!!more snow further north and west?!

[Nick F]

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

[Battleground Snow]

1 minute ago, Nick F said:

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

Wow I had to double check that's INCHES and not cms

[Radiating Dendrite]

Just now, Battleground Snow said:

Wow I had to double check that's INCHES and not cms

So did I! Wow  

[Griff]

3 minutes ago, Nick F said:

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

 

1 minute ago, Battleground Snow said:

Wow I had to double check that's INCHES and not cms

Wow, that can't be right? 

[Snowman.]

4 minutes ago, Nick F said:

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

Calamity in EA and SE if that comes off.

 

 

[Speedbird]

2 minutes ago, Griff said:

 

Wow, that can't be right? 

I agree.  It's likely to be more

[Ben Sainsbury]

6 minutes ago, Nick F said:

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

I see that the EC uses the Kuchera ratio? Is this ratio constant throughout or does it vary depending on the atmospheric conditions?

If it is constant, say rain 1:10 snow, then chances are accumulations could be even higher?

Edited February 4, 2021 by Ben Sainsbury

[Yarmy]

7 minutes ago, Nick F said:

06z EC showing a lot of snow for E Anglia and into the northern Home Counties as well as the NE by the end of the run / Monday morning

That's Ryan Maue's weather business, isn't it?  I'm not sure whether he's applying the Kuchera method to the raw ECM output, or that's what the model itself is predicting? 14.4 inches seems like...a lot.

[Battleground Snow]

MJO update,

It's slightly gaining amplitude on both the ECM and GEFS, this could be important in helping maintain pressure to our North and deflecting the Atlantic away.

I really wish we could see the Ukmo plots for this

[sheikhy]

Wow thats 6 inches for me

[Mark wheeler]

13 minutes ago, Battleground Snow said:

Wow I had to double check that's INCHES and not cms

Wow so that’s 14cm showing for London for example too .

[Youcan'tbecirrus]

10 minutes ago, Snowman. said:

Calamity in EA and SE if that comes off.

 

 

Can you imagine what it was like with 21 inches in '87.