Model output discussion - The run up to Christmas

[Snowmadsam]

Southern areas may wish to keep an eye on the low that's being modelled on the GFS 12z.....may surprise....

 

[Djdazzle]

3 minutes ago, Jason M said:

And that really is the big question isn't it. In a week or so we will know the answer 

The automated forecasts (yes, I know their limitations) are showing daytimes highs no lower than 6C out to Jan 3rd. That’s barely below average!

[snowblind]

12 minutes ago, Neilsouth said:

The media(TV) is making nothing of the upcoming cold, just cooler.. Are the models further ahead than what is currently being forecasted? ( This is a model related question )

I think because at the moment it's still a little bit too far away to be certain of anything and things do have a habit of changing so they won't say anything much until things are a lot clearer. The main risk of anything particularly wintery appears to be towards New Year which is miles away in meterolgical terms. At this stage it doesn't look like being amazingly cold but could be cold enough for snow to cause problems on low ground in some places - which is mentioned in the met office longer range updates. It could well be a forecasting nightmare with snow events cropping up at short notice.

Edited December 21, 2020 by snowblind

[Downburst]

Latest ICON 12z. Still over a week away and this is what it reckons the uppers will be. 

[NewEra21]

Just now, Djdazzle said:

The automated forecasts (yes, I know their limitations) are showing daytimes highs no lower than 6C out to Jan 3rd. That’s barely below average!

They are, but they also were for Xmas Eve and Christmas day. Those two days have now been corrected down to more 3c and 4c. Closer to the time those temps will be adjusted downward, happens all the time.

[Catacol]

4 hours ago, Smartie said:

BANK!! think I'd sacrifice all of next winter for that chart to come off! 

Better hope Catacol  doesn't see that chart seeing as he's recently moved from down this way

Yeah that would just about be the way of things. 27 years in the south of England, 4 snow phases of note in that time. Just as I leave - watch the biggest snowstorm since 1978 hit the SW.......

[Mapantz]

5 minutes ago, Snowmadsam said:

Southern areas may wish to keep an eye on the low that's being modelled on the GFS 12z.....may surprise....

Yep - Extra large rainfall totals for some.

[snowblind]

3 minutes ago, Djdazzle said:

The automated forecasts (yes, I know their limitations) are showing daytimes highs no lower than 6C out to Jan 3rd. That’s barely below average!

I've found that the ones on the met office site have been about 2c above reality for the last few weeks for my location.

[NewEra21]

2 minutes ago, Downburst said:

Latest ICON 12z. Still over a week away and this is what it reckons the uppers will be. 

Really is poor, and that's why we need that trough to get just to the east of us if we're going to see any meaningful cold.

[northwestsnow]

Icon shows our latitude engulfed in warm 850s...

The core cold is noticeable to our NE 

Wouldn't mind a long fetch NEly in January !!

[Snowmadsam]

2 minutes ago, Mapantz said:

Yep - Extra large rainfall totals for some.

yep - really not needed. But good for the ducks right?

elsewhere, still a nice cool/chilly Christmas being forecast on this run 

[Downburst]

2 minutes ago, NewEra21 said:

Really is poor, and that's why we need that trough to get just to the east of us if we're going to see any meaningful cold.

And looking at the ECM 00z, it doesn't suggest any meaningful cold either. This is 10 days away, so we have to see. I have learned like others to not tell folks it's getting cold or going to snow until they already know from watching the TV forecast.  Of course we shall await the this shortwave and that shortwave merchants to educate us why the models are wrong in this instance  

[nsrobins]

44 minutes ago, Jason M said:

Don't over rely on the accuracy of those charts. Back then the best selling home computer was the ZX81 which had a 1K (yes, 1K) memory !!! And yes, I had one   There is more computing power in your TV remote than there was in the mainframes back then and these charts are nothing more than a broad guess. Trust me, 850s were lower than -5c. 

They weren’t that much lower than -5. After the initial Pm/Am incursion, uppers were generally between -4 and -6. The 11th and 12th had slack winds under a col which produced some very cold nights and very low surface temperatures. This contributed to the brief heavy snowfall on the 13th despite the ‘marginal’ uppers.

Reanalysis charts are available here:

Reanalysis archives

WETTERZENTRALE.DE

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Reanalysis archives of the past decades covering Europe.

 

[Howie]

All the cold air is being bottled up over Siberia/east Asia. I wonder what it Will take to move it around 

[That ECM]

T144 Ukmo. Thankfully uppers haven’t updated yet.

[Tim Bland]

12 minutes ago, Snowmadsam said:

Southern areas may wish to keep an eye on the low that's being modelled on the GFS 12z.....may surprise....

 

Hopefully it won’t be too much of a surprise as I’ve been mentioning every day (for the last 3 days) the snow row from the ensembles for the 23-24th. Still just over half the 06z set had it. Probably back edge and won’t settle but will be a nice festive start to the cold spell!

[Matt H]

Just now, That ECM said:

T144 Ukmo. Thankfully uppers haven’t updated yet.

I’m sure @terrier will let us know when the uppers are out!

[NewEra21]

1 minute ago, That ECM said:

T144 Ukmo. Thankfully uppers haven’t updated yet.

Still can't see the uppers being very good, the low is just too ball shaped. We can't really draw the cold from anywhere. That's why we need this trough to be weaker and more stretched out imo.

[seabreeze86]

Christmas Eve now looking really interesting down the east coast.Uppers values plenty low enough for snow. These have constantly upgraded on the GFS as we have gotten near the time as they tend to do if it’s not a north westerly 

Edited December 21, 2020 by seabreeze86

[mountain shadow]

4 minutes ago, That ECM said:

T144 Ukmo. Thankfully uppers haven’t updated yet.

You don't need the 850s to know that isn't great especially the further South and East you go.

The hills and mountains of the North are going to have white out blizzard conditions for sure.

[Man With Beard]

UKMO T144 is good

would be even better if the low could push just a bit further east (likely to happen) and a bit further south (might happen by T168 but corrections often go further north)

Still I think there'll be snow for quite a few on this chart alone, particularly further north and west.

[Allseasons-Si]

9 minutes ago, Frosty Winter said:

I’m sure @terrier will let us know when the uppers are out!

Have i bet him to it

 

 

Edited December 21, 2020 by Allseasons-si

[Weathizard]

That’s the problem with the shape and trajectory of this low at the moment, look at the cold building in Scandinavia at day 5 and in 2 days the south westerly airflow from the Atlantic waters down those 850’s

[terrier]

9 minutes ago, Frosty Winter said:

I’m sure @terrier will let us know when the uppers are out!

No your ok I’ve said my piece now. Some of the members that have been here awhile now can see this set up is nothing but a chilly spell than a big freeze. But some will still keep hyping the charts for something they are not at the moment. Will come back in the new year and see if anything has changed. Anyway merry Christmas and happy new year to everyone. 

Edited December 21, 2020 by terrier

[Skullzrulerz]

1 minute ago, Man With Beard said:

UKMO T144 is good

would be even better if the low could push just a bit further east (likely to happen) and a bit further south (might happen by T168 but corrections often go further north)

Still I think there'll be snow for quite a few on this chart alone, particularly further north and west.

Are we looking at the same charts? The Uppers are shocking poor