Model output discussion 24/01/21

[Purga]

Just a snippet of the latest METO update

"Mild at first in the south; though high pressure building up over the north of the UK during this period is likely to bring easterly winds, cold temperatures, and coastal snow showers. A pattern of wintry showers persisting across the far north, elsewhere seeing mostly fine weather, widespread frosts, fog, and icy patches".

A big step forward !

Sorry it's in the wrong thread - but these are exciting times

[tight isobar]

For once in a long time...words fail me...doesn't get any better for the UK folks!!...@eps @gefs. @2m temp plots..the BEAST AWAITS!!!!...images to follow.  #500 geopotentials.

Edited January 29, 2021 by tight isobar

[turkishfella]

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

[ALL ABOARD]

9 minutes ago, turkishfella said:

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

Yes. 

With such an unstable flow though I'd expect troughs rather than showers... 

 

[danm]

13 minutes ago, turkishfella said:

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

Yes, definitely possible with cold enough 850 temps moving across a relatively warm North Sea. This creates instability and convection which could reach the south coast. 

[Sawel]

On 28/01/2021 at 13:35, NeilN said:

When was the last time a -16 / -20 upper hit the UK? 1986? 1979? 

Meant to reply to this yesterday but didn't have time! With everyone getting in an 'easterly mood' then here we go...

I've spent a lot of time (too much, but thanks lockdown) looking through archived charts of historic UK cold spells. Archived charts on Wetterzentrale are better for a few reasons but mainly because you can view archived charts in 6 hour increments. On Meteociel, they're done in 12 hour increments so you can miss extreme charts. Plus the resolution is quite poor.

According to these charts -20c uppers have hit the extreme SE of England during the 1987 easterly. The 12th of January being that special day. The 1987 easterly is unrivalled for two reasons - Firstly, the sheer depth of the cold across the entire UK with the -20c line apparently making it to our shores. But what is also staggering is that -18c is covering much of England and Scotland and even reaches the middle of Ireland! -16c has even managed to go beyond the west coast of Ireland and well beyond into the Atlantic ocean. For such brutally cold uppers to move that far west really highlights the severity of the 1987 easterly cold spell.  Staggering!

12th January 1987 - 0z, 12z and 18z below. These are the coldest charts that exist for our shores.

 

 

[tight isobar]

19 minutes ago, turkishfella said:

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

Also with the convective scope the coast CAN become a snow hugger..via convetion=overheads... Everything in the bucket for most..if not ALL...keep watching !!!!!

[Man With Beard]

27 minutes ago, turkishfella said:

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

Got to get the flow off the sea, so ESE for Brighton. Need a really strong Scandi High for this. The longer the sea track the better.

As Danm says above, though, the south coast can definitely get caught by North Sea convection - anywhere east of high ground, really.

Edited January 29, 2021 by Man Without Beard

[feb1991blizzard]

Just now, Man Without Beard said:

Got to get the flow off the sea, so ESE for Brighton. Need a really strong Scandi High for this. The longer the sea track the better.

North Easterly would do though if it was really potent, there isn't a huge mountain range to the East so some heavy showers could make their way through London and the SE but yes the heaviest would occur with what you said.

[BLIZZARDMAN]

Long way off but this is simply stunning

[Paul]

42 minutes ago, turkishfella said:

Guys, can someone with more knowledge help me please. Can we expect sea-effect-snow from this system for the south coast? I am in Brighton.

Handy article about Sea Effect snow here:

Sea Effect Snow - the UK version of Lake Effect snow. Very cold air across the North Sea

WWW.NETWEATHER.TV

---

Very cold easterly flow, found when a high pressure sits over Scandinavia and brings air to the UK from Siberia. If conditions are right, significant snow can result.

 

[Snipper]

3 minutes ago, BLIZZARDMAN said:

Long way off but this is simply stunning

Looks a bit rude to me. 

[Battleground Snow]

Arpege showing some quite significant snow for midweek.

 

[Battleground Snow]

All good on icon so far!

 

[Radiating Dendrite]

1 minute ago, Battleground Snow said:

Arpege showing some quite significant snow for midweek.

 

Need that another 75 miles south!

[Johnp]

3 minutes ago, Radiating Dendrite said:

Need that another 75 miles south!

I fear we'll be hearing a lot about the M4 next week

[sheikhy]

Look for an upgrade between 96 and 144 hours on the gfs 12z!!especially in regards to that snow band for tuesday and wednesday!!knowing our luck it will carry on pushing everything north and east!

[MattStoke]

8 minutes ago, Battleground Snow said:

Arpege showing some quite significant snow for midweek.

 

By early Wednesday:

It has snow falling for over 24 hours for large parts of England and Wales.

Edited January 29, 2021 by MattStoke

[sheikhy]

1 minute ago, MattStoke said:

By early Wednesday:

 

It has snow falling for over 24 hours for large parts of England and Wales.

Exactly in line with the meto warnings!!

[MattStoke]

1 minute ago, sheikhy said:

Exactly in line with the meto warnings!!

Only difference is that it never turns to rain/freezing rain. Just snow throughout.

[Johnp]

12z Icon not quite as good as the 6z, with it having the high a bit far south east for my liking. 

[tight isobar]

Once again regs snow=precip charts theyare futile in any circumstances @nowcast apply...and with the transitionary phasing they will need more scrutiny than ever...at corrections \alignments...anyway we are out of the stalls on the 12 suites...and it's all gravy!!!..as we gain.

Edited January 29, 2021 by tight isobar

[Chesil View]

45 minutes ago, Sawel said:

Meant to reply to this yesterday but didn't have time! With everyone getting in an 'easterly mood' then here we go...

I've spent a lot of time (too much, but thanks lockdown) looking through archived charts of historic UK cold spells. Archived charts on Wetterzentrale are better for a few reasons but mainly because you can view archived charts in 6 hour increments. On Meteociel, they're done in 12 hour increments so you can miss extreme charts. Plus the resolution is quite poor.

According to these charts -20c uppers have hit the extreme SE of England during the 1987 easterly. The 12th of January being that special day. The 1987 easterly is unrivalled for two reasons - Firstly, the sheer depth of the cold across the entire UK with the -20c line apparently making it to our shores. But what is also staggering is that -18c is covering much of England and Scotland and even reaches the middle of Ireland! -16c has even managed to go beyond the west coast of Ireland and well beyond into the Atlantic ocean. For such brutally cold uppers to move that far west really highlights the severity of the 1987 easterly cold spell.  Staggering!

12th January 1987 - 0z, 12z and 18z below. These are the coldest charts that exist for our shores.

 

 

Indeed Sawel That is your textbook long fetch easterly and worthy of the Frost fair winters 1740 or 1684. 

According to the late great Philip Eden. The January 87 spell was the coldest across southern England since 1740 and to think I worked outside thatching roofs right through it.

[ICE COLD]

The -15 line got in on the 6z on closer inspection . Can we go lower on the 12z ?? 

[SLEETY]

yES minus 18c will be in the next runs from gfs or ECm GET THE SLEDGES ordered