[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, Harsh Climate said:

I'm not seeing it being dry at all. UKMO would deliver a hell of a lot snow Northern England northwards. I have a feeling we will have a few systems coming in from the NW - SW next week delivering a lot of snow over quite a wide area. This area is looking like being North Midlands/ Central Northern England northwards at the moment but in reality could be hundreds miles either way. 

Again next week looks far from dry!

I mean  it could be dry, and it’s worth mentioning this if the ops show this, but like you said there plenty of evidence that it might not be.

a poster last week said a setup would bring 20cm of snow into the south east via streamers, but when confronted with a chart that showed nothing of the sort the same poster said this is what you would expect from this setup.

 Now the same poster is saying it’s going to be dry based purely on the GFS run contradiction previous stances.

 

[Model Output Discussion - Colder but how cold and for how long?]

3 minutes ago, IDO said:

For London, the ensembles confirm the op was an outlier for 850 temps at D10 (shocker!):

 Manchester: 

The trend was a rise versus the op, a fall at D10.

Also, there is an outlier at 500hPa at D9. 

But overall not a bad mean, even if the OP is maybe a tad colder than likely on this run.

The negative is the synoptic mean at D10:

No mean undercut going on there, and in fact very similar to GEFS:

 

Those charts don’t show outliers with maybe the exception of day 10 .

those ensembles charts aren’t great at showing individual runs, like what met4cast showed yesterday.

[Model Output Discussion - Colder but how cold and for how long?]

8 minutes ago, Kasim Awan said:

Yes but with a slack flow the coverage of these features will be relatively poor, slack flow also means they will struggle to develop into larger features. December 2022 and November 2023 spring to mind. We need the low from Iceland & the one to our South to make better inroads for anything really significant otherwise a slack flow will just generate a lot of very dry cold weather with snow limited to a few coastal areas.

Not sure how many more time you can basically write it’s going to be dry.

i think we get it now.

we've gone from storm of the century to dry as a desert, i now forecast change with new data but maybe just maybe we dial it back a bit.

looking at a few operation 5 days and dismissing unexpected features about 6 times in one morning is a bit much.

[Model Output Discussion - Colder but how cold and for how long?]

12 minutes ago, Kasim Awan said:

For a 25km model to show 30-40cm of snowfall indicates locally 60-70cm of snowfall is likely, say on hills or where streamers within the front align. This is due to the low resolution of the model missing the normal distribution associated with elevation and streamer activity. Combined with 40-50mph winds would likely result in very severe drifts.I can say the GFS18z would produce this with very high confidence. Objective analysis of a model run is not silly, it is factual analysis of data shown to us by the NWP.

You compared it to one of the greatest snow storms in History, it was a little silly when you think about it.

 

[Model Output Discussion - Colder but how cold and for how long?]

5 minutes ago, Cheshire Freeze said:

Yeah no idea where those wedges of heights have disappeared to. Last thing we need is snowmelt and more flooding.

We don’t get to chose the weather we get.

[Model Output Discussion - Colder but how cold and for how long?]

Day 5 low gets moved south. I wouldn’t put to faith on a day 7 low not doing the same.

[Model Output Discussion - Colder but how cold and for how long?]

 

I reckon that mild sector will be squeezed more as we approach.

this is one feature that’s been on the charts since day 10

[Northwest Weather Discussion - Dec 2023 onwards]

looks cold 

[Model Output Discussion - Colder but how cold and for how long?]

19 minutes ago, BLAST FROM THE PAST said:

Oh no!!!! Noooooooo!’   12z flat as pancake

 

BFTP

Did this relate to anything at all? 

[Model Output Discussion - Into 2024]

if next week fails we always have the next chase 

[Model Output Discussion - Into 2024]

GFS is changing in the mid term but it’s sticking to a collapsing GH, it won’t be the first time the GFS has called it correctly but we usually end up in a meeting if the models a half way house.

ECM UKM and GFS to change places in the morning 

[Model Output Discussion - Into 2024]

GFS has lost the deeper low over the Azores 

[Model Output Discussion - Into 2024]

 

changes are minimal Greenland high disintegrating as per the previous run

[Model Output Discussion - Into 2024]

no massive changes by day 5

[Northwest Weather Discussion - Dec 2023 onwards]

43 minutes ago, Joe Bloggs said:

 

This is a classic Manchester snow shadow situation - elsewhere in the NW very good I would imagine, including Liverpool and the Lancs coast. I prefer charts earlier in the run. ECM is epic - not for this chart in particular but for the possibility of cold unstable Arctic air with convection off the Irish Sea. 
 

Hopefully we can tap into both weather types. 

Might be enough of an easterly in the to negate some of the shadow, but yeah south easterly’s suck.

 

[Model Output Discussion - Into 2024]

 

Greenland high holding firm is the key.

looks wintry in the south east

[Model Output Discussion - Into 2024]

1 minute ago, Harsh Climate said:

Has it, it wasn't the ECM 00z 

Probably won't happen anyway 

Yeah it’s been there in one form or another, details change so comes and goes 

[Model Output Discussion - Into 2024]

I predate the 0z run it was more dramatic, but this is a good run

[Model Output Discussion - Into 2024]

Just now, Harsh Climate said:

166h bit strange looking

Must be a feature moving south introducing milder uppers for a short while

Yep it’s been there for ages, this is not a new feature

[Model Output Discussion - Into 2024]

2 minutes ago, bluearmy said:

What route is the shortwave going to take ??

the one that’s slightly more developed than the last run and a bit further south that has been showing on lots of runs since 240?

[Model Output Discussion - Into 2024]

4 minutes ago, northwestsnow said:

UKMO 168 is mainly rain sadly..

Check that against the uppers in places like Europe, not even remotely correct or worth paying attention to.

 

[Model Output Discussion - Into 2024]

21 minutes ago, bluearmy said:

Not sure I’d describe it as ‘nice and safe’ Luke 

It’s bringing back themes we thought we’d dispensed with 

gfs similar with the ridge dropping se

could do with ec not following suit later 

The milder sector and the short wave has been on and off all runs around this time frame for days now, I see the low delveloping and moving south and reintroducing the colder air.

This mild sector will probably be squashed as we approach day dot 

[Northwest Weather Discussion - Dec 2023 onwards]

If you remove the other side of the equation it looks a solid 7 day cold spell, 14 if you add this week in to

 

[Northwest Weather Discussion - Dec 2023 onwards]

8 out of 30 runs are not great for our region as per the image below

if we assume those runs are wrong then the average line plummets by about a 2.4C 

 

obviously if they are right the average increases by 4.4 aka no cold or snow 

[Model Output Discussion - Into 2024]

4 minutes ago, IDO said:

I was talking about the Azores Low that had previously been progged to sit in situ and eventually interact with the Atlantic trough. Models now show it will slide east and interact with the Scandi trough. All three models show this link-up and the variability. There is no Azores High. So it is all about undercutting, which the EC achieves, and GEM and GFS fail to some extent or another!

I meant low as well.

yes the low moves in, in all three models sorry I clearly misread your post