Model output discussion - Post SSW - Will it turn cold?

[Deep Snow please]

5 minutes ago, Frosty. said:

Just catching up, the Gfs 6z op turns into an incredible run with all parts of the uk seeing severe wintry weather both from the east and then north..what I'm hoping is we all get to experience the siberian / arctic chill with snow flurries then heavier snow showers and severe frosts, it would be a shame if any coldies miss out!...anyway, an easterly is coming, of that I'm certain!!❄❄❄❄❄❄❄❄❄❄❄❄❄❄❄

*Photos snipped*

 

 

The 06z definitely gives a good spread for all the UK coldies to see something white. I'm happy with any cold, but obviously if the snow can penetrate the entire country that would be great. The Siberian chill lining up is probably going to annoy a few people though, not least the gritters, with that kind of snow intensity we're looking at the road being covered by the time they complete a circuit. 

The key thing to bear in mind here is that this is the furthest into the reliable one of these events has got for a very long time, at this point they usually materialise and with the SSW in the mix there's a good chance of it happening. Which as mentioned above is going to make model watching an arduous task for us coldies in the next week or so. 

[bluearmy]

If it wasn’t felt in London then  it didn’t happen .........

30 mins to the 12z icon .......

looking for the ridge to gain more latitude via some Atlantic WAA and the euro low to deepen  - and that Russian shortwave can ‘do one’ around T180 ! 

[Frosty.]

Some may say the Gfs 6z op is too extreme but actually, confidence is high now that it will become much colder from the east and I'm wishing time away to get there!

[SMU]

knowing our luck the earthquake will disprupt the SSW - lol

So Just looking at the GFS & My fav the IKON again - I have NEVER seen an easterly better than this- Its better than 1987-

Obviouly theres a chance it will happen but equally still more chance that it would be watered down- but for arguments sake *IF* it did land then your talking masses of snowfall for England - If I remember southend had about 60-70 cm of snow - & I think realistically thats the ballpark we would be talking about- But theres so many buts - les just hope we get something close...

1987 V the IKON - we can see the uppers are colder in 1987 but the IKON has lower heights ( the 500 Hpa temp is -42c !!! )

Please let stay like this !!! 7 days !!

 

 

Edited February 17, 2018 by Steve Murr

[MattStoke]

Hmm. A Sudden Shakey World.

Anyway, shouldn't the ICON 12z be out by now?

[The Eagle]

3 minutes ago, MattStoke said:

Hmm. A Sudden Shakey World.

Anyway, shouldn't the ICON 12z be out by now?

It's not fully out until 15:45

 

[Derecho]

11 minutes ago, Steve Murr said:

knowing our luck the earthquake will disprupt the SSW - lol

So Just looking at the GFS & My fav the IKON again - I have NEVER seen an easterly better than this- Its better than 1987-

Obviouly theres a chance it will happen but equally still more chance that it would be watered down- but for arguments sake *IF* it did land then your talking masses of snowfall for England - If I remember southend had about 60-70 cm of snow - & I think realistically thats the ballpark we would be talking about- But theres so many buts - les just hope we get something close...

1987 V the IKON - we can see the uppers are colder in 1987 but the IKON has lower heights ( the 500 Hpa temp is -42c !!! )

Please let stay like this !!! 7 days !!

 

 

It's about as clean as an easterly gets. What intrigues me is that if such a scenario happens, the convection would be epic if the sun manages to break out given the extreme cold uppers above.

If the sun came out maximum temperatures would still be below freezing, if the sun doesn't come out I would expect record low maxima for the time of year.

If it happens....

[carinthian]

21 hours ago, carinthian said:

Just a further thought to the above, forecasts this evening from the computer models now all now showing cold outlook on the agenda. Now SSW has taken place, it sometimes takes up to 10 days for the full cold effect to take place. Our service provider think 70 % certainty now , which is in the high category . Of course timing and depth of cold is still on the cards. Still could switch quickly ( with 96h time ) or more likely Day 6 into the freezer. Fax viewing is now the best option to watch the developing cold and speed of advection. Short wave positioning to the East could also impact greatly as to source of cold ( ie) Arctic C or Continental flow ).

 C

What stunning charts from the models. Seems that the North Russian cold wave is heading west with its deepest cold hitting the British Isles sometime next weekend or soon after. Before then a lot of dry weather for many which will be a welcome change in some localities. Now then , a bit of experience in these matters is now to follow the run of model charts from UKMO for comparison at the 96t and fax chart for the same time. At 96 t the human input is added to the fax charts from the Exeter Guys. Thereafter, you will be able to track trough alignments or developments as the 528 dam or even deepest colder air mass (510dam ) moves closer to the British Isles . Where snow falls can then also be predicted by snow models in the 72 h range  with a higher degree of certainty. There will be adjustments (upgrades and downgrades with all models ) but now getting closer to the reliable time scale for cold invasion my advice is to follow UKMO at 96t, especially fax outputs. We will start with todays run for 96t and see how it progresses tomorrow. Enjoy the rise. By the way we have a severe cold warning here for next Sunday, -20c on the mountain !

C

Edited February 17, 2018 by carinthian

[Singularity]

 

Going to be picky here but it's edged a bit toward the consensus a bit here with the Atlantic trough extension suppressing the initial ridge a little more. 

 

Makes quite a difference to the uppers for eastern parts. Not a lot of change in surface conditions though, maybe a 1*C increase in max temp. Still more of an E flow than GFS has so not as 'mild' as that model's been putting out for Tue.

As you may have guessed, I'm killing time here while the run evolves toward where any changes will be much more important.

[Weathizard]

ICON looks bit worse at day 4, angle of WAA and heights not as prominent as it's morning run.

 

Pressure much higher to our south, i do not like that trend at all!

Edited February 17, 2018 by Weathizard

[The Eagle]

Not quite as favorable short term on ICON. Initial westery push of cold air further south.

[winterof79]

36 minutes ago, Southender said:

Correct Steve. About 65cm here in Jan ‘87. As a 7 year old it was up to my chest and above my head in drifts. As you say unlikely to happen probably ever again, but we can dream. 

Try being stationed in Germany -16 during the day.

Hopefully the Easterly will be ushered in quicker than expected after this weekends outputs.

If my memory serves me correctly some of the best falls of snow from the East started with snow grains blowing in the wind for a couple of days freezing the ground and then 

 

EDIT let the knee jerking begin 

Edited February 17, 2018 by winterof79

[Met4Cast]

Not the best start to the 12z, ICON has everything further South

Lets hope that's not a trend that continues on the other models.. 

[Weathizard]

Shows you how that minor angle tweak has a knock on effect to the angle of the easterly along with the pressure rise to our south... the icon is still decent but not in the same league as this morning.

[Ali1977]

1 minute ago, Daniel Smith said:

Not the best start to the 12z, ICON has everything further South

Lets hope that's not a trend that continues on the other models.. 

I might be wrong but GFS looks better at 54 for the Easterly setting up quicker

[karlos1983]

It can’t be a trend if it’s only happened once 

[Singularity]

At this stage I'm reading this not as a harbinger of a trend that other models will follow, but an adjustment toward the GFS 06z, which is hardly surprising given that the previous few ICON runs have been pretty much optimal for getting the cold west as soon as possible.

I think it will be very telling whether the model can still move the deep cold across the UK by Sunday morning. Part of what allowed such a quick move of the deep cold on the 00z run was the Atlantic running over the block a bit and 'ironing it out' so a more NE rather than NNE angle to the eastern side of the trough is not necessarily a problem going forward provided that is only for Wed-Thu with the trough then disrupting against the block. 

That crucial caveat is about to play out on this run and the break away of a trough some way SW of the UK is looking rather messy. Tense isn't it?

 

[That ECM]

5 minutes ago, Ali1977 said:

I might be wrong but GFS looks better at 54 for the Easterly setting up quicker

I would say it's a bit like my front room, not a lot in it Ali

[reef]

Now the 12z runs are coming out this thread will no doubt get very busy, so if you could be so kind as to consider which thread your post should be in then it will make things more enjoyable for all and save the team work removing posts.

For discussion on today's Earthquake:

https://www.netweather.tv/forum/topic/47470-earthquake-activity-thread/

SSW related cold spell discussion:

https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

Model moans and ramps thread:

https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

Many thanks.

 

[Singularity]

6 minutes ago, Ali1977 said:

I might be wrong but GFS looks better at 54 for the Easterly setting up quicker

 

Good spot, some improvement now more evident as of +69.

ICON and GFS meeting in the middle perhaps?

[winterof79]

The ICON is like a pace maker, you have done your job now step off the track son.

[Ali1977]

1 minute ago, Singularity said:

 

Good spot, some improvement now more evident as of +69.

ICON and GFS meeting in the middle perhaps?

Yep looks much better at 84

[AWD]

Worth noting that the latest from the Met Office is for a dry E/SE airmass later this week and into next weekend so charts like this;

Might not be a million miles away from the general expected theme here.  I expect, initially at least, a lot of the 12z output to have the high closer to the UK than most would like, hence the dry, SE theme setting in.

The "snowy easterly" for this week (if ever there was one) has sailed and IMO, we are looking at cycle 2 to get a colder, more unstable continental airmass to the UK in the following week.

I'm confident a colder period of weather will hit our shores, it's just going to be a longer, drawn out process than most would like.  Better late than never as the saying goes.

[Met4Cast]

ICON gets there in the end, perhaps delayed by a few hours but nothing shockingly bad. GFS whilst a poorer start is ironically better by 90hrs with more of an Easterly flow than the previous run.

[Singularity]

 

Even though the ICON 12z now has a bit of that upper air warming related to a flow off the Alps for Saturday, the profile either side remains a lot better than the 00z ECM.