Model output discussion - mid-winter

[andymusic]

above and below the m4 this time

[Chevron12345]

1 minute ago, andymusic said:

and more snow

Shows a lot of rain too. Especially in wales and south & west.

[shaky]

Midlands gets 2 snowstorms this run?!!been spoilt this winter so far?

[johnholmes]

On to more immediate weather prospects.

Looking at the 500 mb anomaly charts, especially over the 6-10 day period, NOAA as well as ECMWF-GFS both indicate quite low 500 mb contour heights. The flow originating from north of the GT Lakes, so even with its Atlantic traverse the height over parts of the UK is indicated at 522 DM from a closed circulation upper low east of the UK.

I would expect that the flow will be fairly unstable to any sea temperatures so surface wind flow will be important away from any actual surface lows or troughs that are generated in this time scale. Quite a wintry picture seems to be setting up with the possibility also of winds turning more northerly for short spells behind any major surface low.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

They are of course 'mean' charts but have been very consistent for several days. back almost a week in fact, so time wise they are a few days out but the pattern looks highly probable to me. Detail is NOT for these charts but for the 2x or 4x daily synoptic outputs.

 

[Thunderywintrysnow]

North of Ireland buried. And many other locations.

[Lampostwatcher]

5 days of chances of snow on the gfs12z can' grumble ?

[andymusic]

possibly a lot more of England getting in on this - way out now in fI - but it looks very good

[snowice]

3 minutes ago, andymusic said:

above and below the m4 this time

Must be the only motorway in the uk

[Weathizard]

It's difficult to view the models without IMBYness isn't it  Could be a lot of snow for some, personally the UKMO is so much better than the GFS at 144, GFS phases acrosses the Atlantic and complicates matters.

still not bad though

[Methuselah]

Not bad here, either...and not 'quite' even out to the mythical Day 10!

[karyo]

Just now, Weathizard said:

It's difficult to view the models without IMBYness isn't it  Could be a lot of snow for some, personally the UKMO is so much better than the GFS at 144, GFS phases acrosses the Atlantic and complicates matters.

still not bad though

I couldn't agree more! It is a less risky road to take.

 

[ACCOUNT DELETED]

1 minute ago, andymusic said:

possibly a lot more of England getting in on this - way out now in fI - but it looks very good

S&W Wales & SW England and ROI all looking snow free on that chart, looks like we'll see rain or possibly hail & thunder in some heavy showers 

[ITSY]

Not often that even on a WNWly the East of England would receive two snow events, shows the potency of this upcoming spell. Really think that N Ireland, the Republic, W Scotland, and the NW of England could get burried - especially if you're at altitude. Low uppers, constant showers, plenty of potential for more than one low or runner type scenario, with cold applenty in all directions but the south. Even the UKMO, though less potent in terms of its runners/uppers combo for the South of England, shows huge potential.

To those talking about marginality for the south and this being an altitude only or Northern only event, the two southern snow events in December (especially the first one two weeks before Christmas) are proof that uppers only *need* to be -1/-2 even at sea level to deliver serious snowfall. (I grant you that those events weren't on Westerly winds that temper out the cold of the N or NE, but nevertheless, too early to rule anything in or out). 

[mulzy]

AZH could start spoiling the fun after day 10 but that's way out in FI...

[Frosty.]

Well..Big change on the way according to the Gfs 12z and I couldn't be happier, good riddance damp murky static pattern and a big hello to much colder air originating from Greenland  / Northern Canada with snow looking increasingly likely at times next week and frosty / icy conditions, especially further north!

[Blizzardof82]

Warming starting now at 222 Hrs

[Mucka]

I berated this mornings extended MetO forecast, with its talk of milder spells for the South and lack of the "s" word, but it has changed significantly this afternoon.

Now talk of accumulations in the North and no mention of mild. not sure what the the morning forecaster was on.

[Methuselah]

BINGO!

[stewfox]

31 minutes ago, Snowmadsam said:

UKMO sadly, slightly takes away the -4 isotherm at +144

All worth watching! (if any of this is wrong, please tell me!) still very much learning!

• UKMO a crap model always has been

Edited January 12, 2018 by stewfox

[SMU]

pretty Decent 12Z our to about day 10-

If I lived in any of these locations I would be salivating at the models ( +150 M )

-Lake District

-Yorkshire dales

- western Pennines

- peak district

- Shropshire hills

- Exmoor

- Beacons & Snowdonia

- Sperrin in Ireland-

possibly even the Cotswolds - 

we could see DEEP snow accumulating from when the cold spell starts lasting 7-10 days... 

somewhere is going to get North of 30cm of snow from convective showers followed by frontal Atlantic sliders -

The most snowiest spell for the UK since 2010 ... let’s hope it’s backed up by the North Easterly Post 192....

S

Edited January 12, 2018 by Steve Murr

[jgbgt]

4 minutes ago, Ed Stone said:

BINGO!

Is that a 6 hour possible Easterly/North easterly at 13 days away.....all predicated on a second system going SE

[Captain Shortwave]

Longer term the GFS and GEM both less willing to develop that Atlantic ridge at least in the 6-9 day range as heights are now modelled to be lower to our north west. It could be a blip or the models have been too quick to finish off the Canadian lobe of the polar vortex.

   

As we can see instead of the trough moving away east with a slacker northerly developing we see another low approach from the Atlantic, it could however bring snow if the cold air isn't mixed out over the UK.

Before then, we are seeing the models toy with a system moving east Wednesday night into Thursday, this is a risk/reward set up as this would bring an organised band of precipitation, but if the low develops and deepens and hence a more northerly track then that snow becomes a load of wind and rain rather than snow.

The GFS delivers a snow event in a region from the M4 northwards to around the M62. This will change from run to run of course.

[ITSY]

1 minute ago, Steve Murr said:

pretty Decent 12Z our to about day 10-

If I lived in any of these locations I would be salivating at the models ( +150 M )

-Lake District

-Yorkshire dales

- western Pennines

- peak district

- Shropshire hills

- Exmoor

- Beacons & Snowdonia

- Sperrin in Ireland-

possibly even the Cotswolds - 

we could see DEEP snow accumulating from when the cold spell starts lasting 7-10 days... 

somewhere is going to get North of 30cm of snow from convective showers followed by frontal Atlantic spiders -

The most snowiest spell for the UK since 2010 ... let’s hope it’s backed up by the North Easterly Post 192....

S

Absolutely. Massively noteworthy, esp for a NWly. Unlike then though this spell will be fuelled along by Southern envy I suspect....

[stewfox]

7 minutes ago, Ed Stone said:

BINGO!

Yes west next week , east week after ??

[A Frayed Knot]

6 minutes ago, ShortWaveHell said:

not sure what the the morning forecaster was on

Gas and Air ? Maybe