Model output discussion - here comes the beast!

[Robbie Garrett]

1 minute ago, smhouston said:

For a different thread, but extremely surprised how this has not been publically escalated by the METO. Absolutely dangerous conditions coming up...it's not the snow that kills. Extremely worrying just how cold it'll get and there are a lot of vulnerable people out there.

Quite good points, they've already issued a yellow warning for the SE corner  late Monday afternoon, at a risk of high impact but very unlikely. At this stage the development of these shower bands and the exact locations and timing of these is very uncertain. It's not had a cold spell warning trigger yet.

[interested & confused]

3 hours ago, tight isobar said:

Thats indeed how its looking @frosty..

We could be going WELL INTO MARCH ON THIS ONE NOW!!!!

That would be like Feb/March 1963 IIRC. In March that year I went on a school trip down to Cornwall and the snow was banked up, higher than the train, on either side of the track  

I know many people are going to enjoy the cold, but please keep an eye on older family members, especially those that won't be able to get to the shops themselves.

[North Norfolk coast]

1 minute ago, smhouston said:

I'm not one to usually post on here and I'm definitely one not to ramp. Even the last failed cold spell I warned people not to dismiss the GFS, so I'd like to consider myself pretty grounded when it comes to these situations!

However, wow. I've been a member for a while on here and watch every winter for a special events to be modeled and then disappear eventually, but this one is something else. An absolutely classic winter spell is on the cards as much as I personally don't want it to be atm. How deep the cold gets, and the amount of shower activity to be generated off the North Sea, is something else.

The models will be right this time, except for that low to the south I reckon. All down the east side of the country is 100% going to get an absolute pasting, and no doubt other areas will too. Do not underestimate how heavy and consistent the showers can be generated off the North Sea, and that will not be known until T0.

Literally the best charts I've seen so close to the time from all my years on here, which is quite a long time now (14 years).

For a different thread, but extremely surprised how this has not been publically escalated by the METO. Absolutely dangerous conditions coming up...it's not the snow that kills. Extremely worrying just how cold it'll get and there are a lot of vulnerable people out there.

Can but only agree with what you said,and how the weather models are looking, not seen anything this extreme since 87.A great deal of worry coming up for many both young and old, and those who are carers towards them.

[jmp223]

NAO lower today than it was a few days ago..increased connfidence of the cold pool remaining over the UK well into March

Edited February 23, 2018 by jmp223

[weirpig]

12 minutes ago, Crashlanding said:

looks like the channel low will be too far south for snowmaggedon? 

 

Perhaps   But the control does take it further North    All options on the table.

[pages]

GEFS mean T-168 surperb

would of looked even better but runs 11,12,18, 20 all drop low from the north which interacts with low from south making more messy but even those 4 runs are still cold at t-180 just not as cold.

quite a few get sub -17 in across south at T-144.

 

[bluearmy]

1 hour ago, Interitus said:

This article from the Meteorological Society Weather journal is worth reading at this point - An historical and climatological note on snowfalls associated with cold pools in southern Britain - http://onlinelibrary.wiley.com/doi/10.1002/wea.666/pdf

Jan 1987 rates as the record deep cold pool at around 495/496 dam 1000-500mb thickness.

 

The cold pool crossing central England middle next week currently progged around 504 dam

[beng]

1 minute ago, bluearmy said:

The cold pool crossing central England middle next week currently progged around 504 dam

What stood out for me from those stats is that where the cold pool was over the country for >1 day, snowfall totals were extremely high.

[weirpig]

4 minutes ago, bluearmy said:

The cold pool crossing central England middle next week currently progged around 504 dam

A quick question if i may regrding the Dam  Level   would the unusual low Thickness  cause Showers forming Inland  ?  

[Jason M]

As one of the people on here that usually looks at the charts and find myself wondering what the fuss is about i.e. three days of plus 5c and a bit of wet snow, I have to say that this does look worth ramping. 

I also suspect that the snow risk for South Wales and the SW generally is being underplayed at the moment. 

[winterof79]

There aren't many times you will see sea effect snow.

I can't reiterate  how deeply cold and unstable this air will be.The beeb charts will be struggling even if they went hourly

[karlos1983]

ECM ens still corkers!!!! All the way out!

we’ve hit the jackpot guys n gals! Be sure to enjoy it!!! Especially you lucky bunch down the eastern side of the UK! I don’t envy you, I’m happy for you! Going to be memorable for many!

 

 

Edited February 23, 2018 by karlos1983

[winterof79]

3 minutes ago, weirpig said:

A quick question if i may regrding the Dam  Level   would the unusual low Thickness  cause Showers forming Inland  ?  

They  won't need to

[weirpig]

2 minutes ago, winterof79 said:

They  won't need to

Lol  yes im sure the showers will be rather Beefy  moving well Inland.  I also noticed that Dam figures of 508 are a one in 8 year event  below 500 is nearly once in a generation   just shows how rare this event is 

[Glacier Point]

Away from the impending brutalness, are we about to see another high amplitude MJO wave develop ?

Currently quite a large convective signal across the Indian Ocean (different indices depicting different phase locations due to large aerial extent).

Surface and particularly sub-surface temperatures very conducive in the Western Pacific.

Rapid orbit into the higher aam states entirely feasible during March, with associated blocking signal persisting to the N/NE.

Edited February 23, 2018 by Glacier Point

[Chris.R]

 For my location Thursday morning: 504 DAM thickness and -15 850s. I just have no words! 

[bluearmy]

3 minutes ago, Glacier Point said:

Away from the impending brutalness, are we about to see another high amplitude MJO wave develop ?

Currently quite a large convective signal across the Indian Ocean (different indices depicting different locations due to large aerial extent).

Surface and particularly sub-surface temperatures very conducive in the Western Pacific.

Rapid orbit into the higher aam states entirely feasible during March, with associated blocking signal persisting to the N/NE.

In this instance, we could well see the extended gefs responding to this and the extended eps responding to the next downwelling - both models showing similar solutions for differing reasons !!

[A.J]

the concensus of the model outputs is variations on a theme....It's already chilly, and some bitterly cold air is on its way for all parts of the UK....Widespread snow showers for eastern districts, some penetrating well inland,with the possibilites of frontal snow for the South in a weeks time.....As I mentioned earlier, us southerners could use next friday's frontal attack making more headway into the UK than is currently trended in the GFS output (ECM looks ok still though).....I hope so, as I just recently posted in the SW thread...."I just told the wifey to downgrade her expectations and expect only an inch or two.....Imagine my horror as she replied..."Downgrade?....that's the story of my life!.....but enough of that, what about the snow next week?"......My crushed ego needs a lift....lol

[Man With Beard]

16 minutes ago, karlos1983 said:

ECM ens still corkers!!!! All the way out!

we’ve hit the jackpot guys n gals! Be sure to enjoy it!!! Especially you lucky bunch down the eastern side of the UK! I don’t envy you, I’m happy for you! Going to be memorable for many!

 

 

Three massive ice days possible, Wednesday, Thursday and Friday (I'd expect some ice days in the SE outside of cities on Tuesday too)

But I suspect we might end up talking more about this next week - the snow. For once we can read the precipitation chart as a snow chart! (At least for about 8 days)

Averaging at about 3 inches (about 7.5 cm) for the captial by Sunday - a moderate but not sensational amount.

So the ECM isn't seeing a snowfest yet, while the GFS clearly is. Which will be right??

 

[swebby]

12 hours ago, Purga said:

Any good folks?

Only just glanced at the fax charts, not sure i've ever seen one with a convergence line set up over the channel, pembrokshire dangler yes but over the channel, no.  Would make for some interesting weather in the channel isles....

[Man With Beard]

3 minutes ago, swebby said:

Only just glanced at the fax charts, not sure i've ever seen one with a convergence line set up over the channel, pembrokshire dangler yes but over the channel, no.  Would make for some interesting weather in the channel isles....

One of the peculiarities of the models coming up may be snow where you don't normally expect it. Southern extremities such as IOW, S Devon and the tips of S Cornwall could see major disruptive snowfalls if the winds go direct E or ESE for a prolonged period, as a "channel streamer" may set up as shown in the fax charts. This is a big, big possibility. 

[bluearmy]

Just now, Man With Beard said:

One of the peculiarities of the models coming up may be snow where you don't normally expect it. Southern extremities such as IOW, S Devon and the tips of S Cornwall could see major disruptive snowfalls if the winds go direct E or ESE for a prolonged period, as a "channel streamer" may set up as shown in the fax charts. This is a big, big possibility. 

And it’s been v strong on the ec precip charts for days 

that convergence zone must be pretty much a banker 

[Panayiotis]

6 minutes ago, Man With Beard said:

One of the peculiarities of the models coming up may be snow where you don't normally expect it. Southern extremities such as IOW, S Devon and the tips of S Cornwall could see major disruptive snowfalls if the winds go direct E or ESE for a prolonged period, as a "channel streamer" may set up as shown in the fax charts. This is a big, big possibility. 

I'm hoping a Bristol Channel streamer sets up for Cardiff

[swebby]

8 minutes ago, bluearmy said:

And it’s been v strong on the ec precip charts for days 

that convergence zone must be pretty much a banker 

Quick Q - This is the result of generalised upper wind flows so may have a tendency to move in location? I.e it's not a fixed topographical feature as we see with the Pembrokeshire dangler that results from the Irish and Welsh mountains/hills during a northerly?

MWB - yes i was thinking IOW could well see some significant falls from the current set up but the channel isles is a surprise. Scilly Isles might also find this problematic, especially as they'd be well into the flower producing season which i believe is a large part of the economy.

Edited February 23, 2018 by swebby
correct spelling of Pembrokeshire

[MR EXTREMES]

1 hour ago, Crashlanding said:

looks like the channel low will be too far south for snowmaggedon? 

 

I want it further south to keep cold holding on.

2009/2010 was classic for channel runners but the convection from the northeasterly was amazing.

Just a cm or 2 would make me smile.