Model Output Discussion - Into 2024

[Kasim Awan]

A good example of an easterly which didn't produce much snow accumulation in the South East. Uppers being too high were the culprit, -4/-5 only here vs the -7/-9 forecast on the ECM. That extra 4/5 degrees is enough to drop the snow line by 1,000ft and significantly increase convection. 

[feb1991blizzard]

1 minute ago, Daniel* said:

EPS 168hrs… clearly the op is further north with ridge and less supported.

it’s an improvement on 00z gained more height so we can work on this…

How does the mean compare to 0z mean though?

[Anthony Burden]

Hi just have to comment on the ECM tonight that is some serious cold showing,met office extended stated that a severe cold spell was unlikely,but looking at ECM I’m not so sure.

[Daniel*]

1 minute ago, feb1991blizzard said:

How does the mean compare to 0z mean though?

The means are posted 

[mulzy]

9 minutes ago, LRD said:

MOGREPS 12z ensembles for London

Suggests a pretty cold weekend but maybe with a high starting to sink over us into the middle of next week... hence the rise in 850s. We'd probably see hard frosts and maybe fog though, even with the higher 850s

And it doesn't mean to say there won't be retrogression of that high towards Iceland and Greenland towards the weekend of 13th/14th 

Stamps at day 7.  Wide variety of solutions on offer but I guess it averages out at a UK Hugh.

[Rob 79812010]

18 minutes ago, January Snowstorm said:

I actually can't remember the last cold spell in January!! 2009 was Christmas week and 2010 was late November going by memory.... are we going right back to the 80s for sustained cold in Jan

We had decent one last year from memory??

[Derecho]

23 minutes ago, Kasim Awan said:

 

Not really - the main thing here is the tightness of the easterly flow and relatively warm SSTS. On this night 30cm fell in the South East with largely speaking similar 500mb heights as forecast on ECM.

ECM forecast:

You've shown a chart from the BFTE in 2018 instead, overnight the uppers were much colder (the snowy weather took hold on the 27th Feb)

Completely different scenario, the BFTE had -10 to -15 uppers at the end of that February with the centre of the high well to the north of the UK.

We may get upgrades if an area of low pressure develops but that easterly flow itself would just deliver a few snow showers.

 

Also here are the snow totals for Feb 2021, big totals in Scotland came from days prior to this event and as mentioned the snow in the SE came from an area of low pressure affecting the SE at the time that cleared into the continent.

The below examples are what would cause big snowfalls from an easterly.

Edited January 1 by Derecho

[LRD]

Just now, Mark wheeler said:

Some of them look superb.

It's yesterday's. They won't look like that tonight

[northwestsnow]

Think we'll assume EC det was best case scenario for now...

[Kentspur]

26 minutes ago, Kasim Awan said:

 

Not really - the main thing here is the tightness of the easterly flow and relatively warm SSTS. On this night 30cm fell in the South East with largely speaking similar 500mb heights as forecast on ECM.

ECM forecast:

Mid Kent had a decent fall when we had a bit of a brief Kent Clipper NEly flow (dry here) but then after instead of our holy grail ENEly we ended up Too much East of South flow ESEly and About 2miles north of.me northwards got the goods while we had dregs max we had fall at any time in Gravesend, NW Kent was 4inches the day Maidstone etc had more than double that, the main thing I recall from the Beast week was the depth of cold powdery light snowfall and the howling wind turning my tables and chairs upside down on my balcony by the Thames. Swly/Wly winds our default are barely noticeable where I am as I'm also at the bottom of a North facing road that's hilly and slopes to the Thames. Had slightly more snow fall in last Decembers surprise fall on the 11th than during the beast!

Edited January 1 by Kentspur

[Daniel*]

I’d say now we’re looking at now more a Scotland based high than a UK high of course it is still generally dry but the trend definitely has been to move that further north. Will be interesting if these corrections continue… especially for southeast.

[LRD]

1 minute ago, mulzy said:

Stamps at day 7.  Wide variety of solutions on offer but I guess it averages out at a UK Hugh.

Definitely further south than last night but still plenty of encouragement there if it's cold you're after

But we can certainly see where the ever so slightly disappointing UKMO 12z run has come from

[WYorksWeather]

Looking at the GFS 12z we seem to have increased support for the cold-mild-cold scenario I highlighted as one possibility. Looks like a peak in the initial cold around 7-9th, then something close to average, then very early and tentative signs that it might cool down again around mid-month.

And the GFS has done what I suggested, and taken it's 18z ensembles from overnight and gone away!

[January Snowstorm]

The best prediction of the lot really is that we'll all be awake at 4am  

[bluearmy]

I think the eps clusters will have some stonkers 

Edited January 1 by bluearmy

[Daniel*]

6 minutes ago, WYorksWeather said:

Looking at the GFS 12z we seem to have increased support for the cold-mild-cold scenario I highlighted as one possibility. Looks like a peak in the initial cold around 7-9th, then something close to average, then very early and tentative signs that it might cool down again around mid-month.

And the GFS has done what I suggested, and taken it's 18z ensembles from overnight and gone away!

The uppers don’t tell the whole story if you look at 2m temperatures you will see there is no real recovery still below average. Colder than average dominates but of course increasing scatter as it goes on. No real mild runs really or very slim pickings which is unusual.

Edited January 1 by Daniel*

[Met4Cast]

Models have trended broadly towards the idea of a UK high (6th-12th Jan) however today they have trended towards something a little more amplified.GEFS & the GEM ensembles have shifted the high further NW & around 50-60% of MOGREPS members have the UK under some sort of easterly flow within the above timeframe.

The MJO is now transitioning through phase 2 which for January is usually a signal for unsettled Atlantic weather, but! Westerly momentum has been propagating poleward (2nd image) from the equator into the tropics since early December and this, combined with the recent MJO phase 1 is the background forcing for Atlantic wave breaking & blocking during week 2-3 of January.

Currently, a UK cold high is favoured, lots of dry weather with widespread frosts, it's possible the high will become more amplified and remain further north bringing a heightened risk of snow. What's clear is mild weather is NOT in the forecast for the next 10-15 days.

As forcing from the phase 2 MJO begins to filter through around mid month coupled with falling AAM tendency (-FT and -MT thanks to the MJO returning to the Indian ocean) a stronger Atlantic jet will return, this could undercut any potential blocking & with cold air in place increases the likelihood of high impact snow events along the blocking boundary.

All in all - A cold couple of weeks, exact details re: snow/depth of cold still need to be ironed out but an increasing likelihood of snow later in the period (11th-18th Jan).

[northwestsnow]

There's my sensational developments above ^^

[Derecho]

32 minutes ago, I remember Atlantic 252 said:

something like this? a whiteout here, Kent must have had over a foot

Substantially colder uppers here

EC probably is underdoing the snow amounts a little bit but you'd need the high further north or the flow to be colder to start bringing in the big snow amounts.

[Battleground Snow]

Jma 168,

Decent support for ecm

Edited January 1 by Battleground Snow

[Dennis]

good setup (weekend) on what is to come 

GEM anomaly 

[Kentspur]

14 minutes ago, Kasim Awan said:

A good example of an easterly which didn't produce much snow accumulation in the South East. Uppers being too high were the culprit, -4/-5 only here vs the -7/-9 forecast on the ECM. That extra 4/5 degrees is enough to drop the snow line by 1,000ft and significantly increase convection. 

Isobar not particularly tight either and for here in NW Kent&S Essex/London/Thames etc there's too much N of East in the flow more conducive to a light East Kent clipper

[Mark wheeler]

2 minutes ago, bluearmy said:

I think the eps clusters will have some stockers 

That'll be me watching the 00z runs in the morning.

[Allseasons-Si]

Tha jma is further NW with the high too than this mornings 00z

jma and EC at 168...

 

[WYorksWeather]

2 minutes ago, Daniel* said:

The uppers don’t tell the whole story if you look at 2m temperatures you will see there is no real recovery still below average. Colder than average dominates but of course increasing scatter as it goes on. No real mild runs really or very slim pickings which is unusual.

Yep, less of a recovery there as we're still under high pressure. It's closer to average further north, probably a bit of parochialism from me there, London and the SE will be colder in relative terms, more chance that the north will see milder air return sooner if it sweeps around the top of the high.